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Android ImageView.setMatrix() and .invalidate() - repainting takes too much time

Task: I want to resize and move an image across the screen. I want to do this smoothly no matter how big the image is. The code should be supported by the API level 8.
Problem: I tried to use ImageView with scaleType="matrix". Calling ImageView.setMatrix() and then ImageView.invalidate() works great with small images but horrible with big ones. No matter how big the ImageView is.
Can I somehow speed up repainting of the ImageView so it will not recalculate whole image? Maybe there is a way to accomplish the task using different component?
EDIT: More information on what I am trying to achieve.
pw, ph - width and height of the picture (in pixels)
dw, dh - width and height of the device's display (in pixels)
fw, fh - width and height of the visible frame (in pixels)
x, y - position of top left corner of the frame (in pixels)
I want to display a part of the image on the screen. Properties x, y, fw and fh are changing constantly.
I am looking for a part of code (idea), or components which for these 8 specified variables will quickly generate and display the part of the image.
EDIT 2: Info on pw and ph
I assume pw and ph can hold values from 1 to infinity. If this approach causes a lot of trouble we can assume the picture is not bigger than the picture taken with the device's camera.

With your help (community) I figured out the solution.
I am sure that there are other better ways to do it but my solution is not very complicated and should work with any image, any Android since API level 8.
The solution is to use two ImageView objects instead of one.
The first ImageView will be working like before but loaded image will be scaled down so that it's width will be smaller than the width of the ImageView and it's height will be smaller than the height of the ImageView.
The second ImageView will be blank at the start. Everytime the x, y, fw and fh properties are changing the AsyncTask will be executed to load only visible part of the image. When properties are changing fast the AsyncTask will not be able to finish in time. It will have to be canceled and new one will be started. When it finishes the result Bitmap will be loaded onto the second ImageView so it will be visible to user. When the properties changes again loaded Bitmap will be deleted, so it will not cover moving Bitmap loaded to the first ImageView. Note: BitmapRegionDecoder which I will use to load sub-image is available since Android API level 10, so API 8 and API 9 users will only see scaled down image. I decided it is OK.
Code needed:
Setting the first (bottom) ImageView scaleType="matrix" (best in XML)
Setting the second (top) ImageView scaleType="fitXY" (best in XML)
Functions from Android Documentation (here) - thanks to user Vishavjeet Singh.
NOTE: Notice the || operator instead of && while calculating inSampleSize. We want the image loaded to be smaller than ImageView so that we are sure we have enough RAM to load it. (I presume ImageView size is not bigger than the size of the device display. I also presume that the device has enough memory to load at least 2 Bitmaps of the size of the device display. Please tell me if I am making a mistake here.)
NOTE 2: I am loading images using InputStream. To load a file different way you will have to change code in try{...} catch(...){...} blocks.
public static int calculateInSampleSize(
BitmapFactory.Options options, int reqWidth, int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
final int halfHeight = height / 2;
final int halfWidth = width / 2;
// Calculate the largest inSampleSize value that is a power of 2 and keeps both
// height and width larger than the requested height and width.
while ((halfHeight / inSampleSize) > reqHeight
|| (halfWidth / inSampleSize) > reqWidth) {
inSampleSize *= 2;
}
}
return inSampleSize;
}
public Bitmap decodeSampledBitmapFromResource(Uri fileUri,
int reqWidth, int reqHeight) {
// First decode with inJustDecodeBounds=true to check dimensions
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
try {
InputStream is = this.getContentResolver().openInputStream(fileUri);
BitmapFactory.decodeStream(is, null, options);
} catch (Exception e) {
e.printStackTrace();
return null;
}
// Calculate inSampleSize
options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
try {
InputStream is = this.getContentResolver().openInputStream(fileUri);
return BitmapFactory.decodeStream(is, null, options);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
Function returning a sub-image of an image.
NOTE: Size of Rectangle that will be cut out of source image is relative to the image. Values that specify it are from 0 to 1 because the size of the ImageView and loaded Bitmaps differs from the size of the original image.
public Bitmap getCroppedBitmap (Uri fileUri, int outWidth, int outHeight,
double rl, double rt, double rr, double rb) {
// rl, rt, rr, rb are relative (values from 0 to 1) to the size of the image.
// That is because image moving will be smaller than the original.
if (Build.VERSION.SDK_INT >= 10) {
// Ensure that device supports at least API level 10
// so we can use BitmapRegionDecoder
BitmapRegionDecoder brd;
try {
// Again loading from URI. Change the code so it suits yours.
InputStream is = this.getContentResolver().openInputStream(fileUri);
brd = BitmapRegionDecoder.newInstance(is, true);
BitmapFactory.Options options = new BitmapFactory.Options();
options.outWidth = (int)((rr - rl) * brd.getWidth());
options.outHeight = (int)((rb - rt) * brd.getHeight());
options.inSampleSize = calculateInSampleSize(options,
outWidth, outHeight);
return brd.decodeRegion(new Rect(
(int) (rl * brd.getWidth()),
(int) (rt * brd.getHeight()),
(int) (rr * brd.getWidth()),
(int) (rb * brd.getHeight())
), options);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
else
return null;
}
AsyncTask loading the sub-image Bitmap.
NOTE: notice declaring a variable of the type of this class. It will be used later.
private LoadHiResImageTask loadHiResImageTask = new LoadHiResImageTask();
private class LoadHiResImageTask extends AsyncTask<Double, Void, Bitmap> {
/** The system calls this to perform work in a worker thread and
* delivers it the parameters given to AsyncTask.execute() */
protected Bitmap doInBackground(Double... numbers) {
return getCroppedBitmap(
// You will have to change first parameter here!
Uri.parse(imagesToCrop[0]),
numbers[0].intValue(), numbers[1].intValue(),
numbers[2], numbers[3], numbers[4], numbers[5]);
}
/** The system calls this to perform work in the UI thread and delivers
* the result from doInBackground() */
protected void onPostExecute(Bitmap result) {
ImageView hiresImage = (ImageView) findViewById(R.id.hiresImage);
hiresImage.setImageBitmap(result);
hiresImage.postInvalidate();
}
}
Function that will make it all work together.
This function will be called every time the x, y, fw or fh property changes.
NOTE: hiresImage in my code is the id of the second (top) ImageView
private void updateImageView () {
// ... your code to update ImageView matrix ...
//
// imageToCrop.setImageMatrix(m);
// imageToCrop.postInvalidateDelayed(10);
if (Build.VERSION.SDK_INT >= 10) {
ImageView hiresImage = (ImageView) findViewById(R.id.hiresImage);
hiresImage.setImageDrawable(null);
hiresImage.invalidate();
if (loadHiResImageTask.getStatus() != AsyncTask.Status.FINISHED) {
loadHiResImageTask.cancel(true);
}
loadHiResImageTask = null;
loadHiResImageTask = new LoadHiResImageTask();
loadHiResImageTask.execute(
(double) hiresImage.getWidth(),
(double) hiresImage.getHeight(),
// x, y, fw, fh are properties from the question
(double) x / d.getIntrinsicWidth(),
(double) y / d.getIntrinsicHeight(),
(double) x / d.getIntrinsicWidth()
+ fw / d.getIntrinsicWidth(),
(double) y / d.getIntrinsicHeight()
+ fh / d.getIntrinsicHeight());
}
}

Try loading source bitmap by BitmapFactory Options in just decode bounds
public static int calculateInSampleSize(
BitmapFactory.Options options, int reqWidth, int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
final int halfHeight = height / 2;
final int halfWidth = width / 2;
// Calculate the largest inSampleSize value that is a power of 2 and keeps both
// height and width larger than the requested height and width.
while ((halfHeight / inSampleSize) > reqHeight
&& (halfWidth / inSampleSize) > reqWidth) {
inSampleSize *= 2;
}
}
return inSampleSize;
}
public static Bitmap decodeSampledBitmapFromResource(Resources res, int resId,
int reqWidth, int reqHeight) {
// First decode with inJustDecodeBounds=true to check dimensions
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(res, resId, options);
// Calculate inSampleSize
options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
return BitmapFactory.decodeResource(res, resId, options);
}
After writing these 2 methods
mImageView.setImageBitmap(
decodeSampledBitmapFromResource(getResources(), R.id.myimage, 100, 100));
set bitmap on imageview like this
then try scaling the image it will do for a large bitmap efficiently
You can read here further
http://developer.android.com/training/displaying-bitmaps/load-bitmap.html

As you already said you could crop your big image and place it one by one to the new imageView.
But from the other side I could suggest you to cut your big image into several small ones and in this case you probably save memory and speed because you won't load the whole image into your memory.
You will gain similar that for example google maps have - they have many small tiles that are loaded by demand. They don't load the whole world map but the small parts of it.
In this case you will build something like ListView when each new item will be an imageview and contains some small image that is part of a big image. By the way with such approach you could get even repeated tiled background and change them on runtime.

Loading Bitmaps and Storing them Statically Alternatives?

I have created a small applicaiton (a game), that reuses the same set of images several times. SO i thought i should create a class that is responsible for loading all of the different images once, from which i can then access them statically from other classes. However, i believe this may have caused an issue with the Garbage Collector, which causes my App to lag whenever the GC is run. Here is What the ImgLoader class looks like:
public class ImgLoader extends View {
public static Bitmap tree1;
public ImgLoader(Context context) {
super(context);
loadImgs();
}
public void loadImgs() {
System.gc(); // Manually Call GC
// TREES
tree1 = BitmapFactory.decodeResource(getResources(), R.drawable.tree);
tree1 = getResizedBitmap(tree1, MainActivity.height / 2,
MainActivity.width / 10);
}
public Bitmap getResizedBitmap(Bitmap bm, int newHeight, int newWidth) {
int width = bm.getWidth();
int height = bm.getHeight();
float scaleWidth = ((float) newWidth) / width;
float scaleHeight = ((float) newHeight) / height;
// CREATE A MATRIX FOR THE MANIPULATION
Matrix matrix = new Matrix();
// RESIZE THE BIT MAP
matrix.postScale(scaleWidth, scaleHeight);
// "RECREATE" THE NEW BITMAP
Bitmap resizedBitmap = Bitmap.createBitmap(bm, 0, 0, width, height,
matrix, false);
return resizedBitmap;
}
public static Bitmap RotateBitmap(Bitmap source, float angle) {
Matrix matrix = new Matrix();
matrix.postRotate(angle);
return Bitmap.createBitmap(source, 0, 0, source.getWidth(),
source.getHeight(), matrix, true);
}
}
Note, i only use one Bitmap for the question. Essentially, when i want to use an image in my application, i say:
object.image = ImgLoader.tree1;
What is an alternative to doing this, that is not so memory intensive?
Thank you!

This seems like very bad practice to me, especially because you are loading multiple Bitmaps and keep static references of them.
Since even small Bitmaps consume considerably large amounts of memory, you will run into OutOfMemoryErrors very soon.
A Bitmap 512x512 already consumes 1 Megabyte of RAM (in 32 Bit) color. You can load your Bitmaps in RGB_565 (16 Bit) to reduce memory consuption.
Why not just load the Bitmap from the Resources when you need it?

try getting them in InputStream format ... they will be in byte .. but personnaly,( and its really personnally ) i prefer to load every image when i need it instead of leaving them in a memory .. for future use , the number of images can increase , plus , as u mentionned and i noticed in your code , the images are store locally ( not doenloaded ) so it shldnt b a big problem to reload them .. but again its my own opinion

Don't think it has anything to do with the gc; you are loading images when you manually call the gc.
I believe it's the loading of images that is causing your app to lag. You could load the bitmap asynchronously.

InputStream - At what point is data downloaded

I have 4 lines of code to download an Bitmap,
URL u = new URL(webaddress);
InputStream in = null;
in = u.openStream();
icon = BitmapFactory.decodeStream(in);
I'm planning on changing the last line to do something similar to this tutorial where I only load into memory an image of set size to reduce memory usage. However i don't want this to involve another server call/download so I'm curious which of the four lines above actually downloads the data from the source?
Im going to be changing the last line of code to the last two functions in the tutorial mentioned above so could do with knowing if its going to mean downloading more or less data, (I'm trying to only download a small image from one that could be for example 5 megapixels)
Apologies if this is simple / the wrong way to think about it im not very experienced with data streams.
EDIT
im using these two functions to replace the last line of code above:
calling:
image = decodeSampledBitmapFromStram(in, 300,300);
Image quality is not a priority, will this mean more data downloaded?
private static int calculateInSampleSize(BitmapFactory.Options options,
int reqWidth, int reqHeight) {
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
// Calculate ratios of height and width to requested height and
// width
final int heightRatio = Math.round((float) height
/ (float) reqHeight);
final int widthRatio = Math.round((float) width / (float) reqWidth);
// Choose the smallest ratio as inSampleSize value, this will
// guarantee
// a final image with both dimensions larger than or equal to the
// requested height and width.
inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
}
return inSampleSize;
}
private Bitmap decodeSampledBitmapFromStream(InputStream in, int reqWidth, int reqHeight) {
// First decode with inJustDecodeBounds=true to check dimensions
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
Rect padding = new Rect();
BitmapFactory.decodeStream(in, padding, options);
// Calculate inSampleSize
options.inSampleSize = calculateInSampleSize(options, reqWidth,
reqHeight);
// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
return BitmapFactory.decodeStream(in, padding, options);
}

The last of your four lines is responsible for the entire download. BitmapFactory.decodeStream(in); is going to continue pulling data from that stream until either the entire image has been downloaded or an error occurs midway through.
As for the bandwidth issue, I'd be very careful to understand exactly how the decoder downsamples large images before trying things out. In reducing a large image to a smaller size, the only way to do this in a high-quality manner is to downsample by averaging pixels in the original image. If the decoder does downsample in this manner, then you won't save any bandwidth, because the decoder will still need to read every pixel of the original image, even if not every pixel gets stored in RAM. You can downsample more quickly by not reading every pixel in the original image, at the cost of final image quality. Along those lines, I did notice an option for preferring "Quality over Speed":
http://developer.android.com/reference/android/graphics/BitmapFactory.Options.html#inPreferQualityOverSpeed
I have a feeling that, for this particular option, you gain more speed by reading less data, but the API states this only works for JPEGs. Not sure if that helps your particular use case, but it might be worth looking into.

The following document would help you better understand about streaming http://docs.oracle.com/javase/tutorial/essential/io/streams.html. In short, once a connection to the resource location is established, a definite sized buffer (portion of data) is retrieved/read. Typically, this process is continued until all of the portions are read.
The main advantage of streaming is to operate in a piece meal fashion. For example, say if you want to download an image that is 500 MB in size. Rather than transferring this in one shot, streaming allows to download in chunks. This is better in error handling, retries, peak network utilization etc.

outOfMemoryException profile picture [duplicate]

I have a ListView with a couple of image buttons on each row. When the user clicks the list row, it launches a new activity. I have had to build my own tabs because of an issue with the camera layout. The activity that gets launched for the result is a map. If I click on my button to launch the image preview (load an image off the SD card) the application returns from the activity back to the ListView activity to the result handler to relaunch my new activity which is nothing more than an image widget.
The image preview on the ListView is being done with the cursor and ListAdapter. This makes it pretty simple, but I am not sure how I can put a resized image (I.e. Smaller bit size not pixel as the src for the image button on the fly. So I just resized the image that came off the phone camera.
The issue is that I get an OutOfMemoryError when it tries to go back and re-launch the 2nd activity.
Is there a way I can build the list adapter easily row by row, where I can resize on the fly (bitwise)?
This would be preferable as I also need to make some changes to the properties of the widgets/elements in each row as I am unable to select a row with the touch screen because of the focus issue. (I can use rollerball.)
I know I can do an out of band resize and save my image, but that is not really what I want to do, but some sample code for that would be nice.
As soon as I disabled the image on the ListView it worked fine again.
FYI: This is how I was doing it:
String[] from = new String[] { DBHelper.KEY_BUSINESSNAME, DBHelper.KEY_ADDRESS,
DBHelper.KEY_CITY, DBHelper.KEY_GPSLONG, DBHelper.KEY_GPSLAT,
DBHelper.KEY_IMAGEFILENAME + ""};
int[] to = new int[] { R.id.businessname, R.id.address, R.id.city, R.id.gpslong,
R.id.gpslat, R.id.imagefilename };
notes = new SimpleCursorAdapter(this, R.layout.notes_row, c, from, to);
setListAdapter(notes);
Where R.id.imagefilename is a ButtonImage.
Here is my LogCat:
01-25 05:05:49.877: ERROR/dalvikvm-heap(3896): 6291456-byte external allocation too large for this process.
01-25 05:05:49.877: ERROR/(3896): VM wont let us allocate 6291456 bytes
01-25 05:05:49.877: ERROR/AndroidRuntime(3896): Uncaught handler: thread main exiting due to uncaught exception
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): java.lang.OutOfMemoryError: bitmap size exceeds VM budget
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.graphics.BitmapFactory.nativeDecodeStream(Native Method)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:304)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.graphics.BitmapFactory.decodeFile(BitmapFactory.java:149)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.graphics.BitmapFactory.decodeFile(BitmapFactory.java:174)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.graphics.drawable.Drawable.createFromPath(Drawable.java:729)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.ImageView.resolveUri(ImageView.java:484)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.ImageView.setImageURI(ImageView.java:281)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.SimpleCursorAdapter.setViewImage(SimpleCursorAdapter.java:183)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.SimpleCursorAdapter.bindView(SimpleCursorAdapter.java:129)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.CursorAdapter.getView(CursorAdapter.java:150)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.AbsListView.obtainView(AbsListView.java:1057)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.ListView.makeAndAddView(ListView.java:1616)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.ListView.fillSpecific(ListView.java:1177)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.ListView.layoutChildren(ListView.java:1454)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.AbsListView.onLayout(AbsListView.java:937)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.view.View.layout(View.java:5611)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.LinearLayout.layoutHorizontal(LinearLayout.java:1108)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.LinearLayout.onLayout(LinearLayout.java:922)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.view.View.layout(View.java:5611)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.FrameLayout.onLayout(FrameLayout.java:294)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.view.View.layout(View.java:5611)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:999)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.LinearLayout.onLayout(LinearLayout.java:920)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.view.View.layout(View.java:5611)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.FrameLayout.onLayout(FrameLayout.java:294)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.view.View.layout(View.java:5611)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.view.ViewRoot.performTraversals(ViewRoot.java:771)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.view.ViewRoot.handleMessage(ViewRoot.java:1103)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.os.Handler.dispatchMessage(Handler.java:88)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.os.Looper.loop(Looper.java:123)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.app.ActivityThread.main(ActivityThread.java:3742)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at java.lang.reflect.Method.invokeNative(Native Method)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at java.lang.reflect.Method.invoke(Method.java:515)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:739)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:497)
01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at dalvik.system.NativeStart.main(Native Method)
01-25 05:10:01.127: ERROR/AndroidRuntime(3943): ERROR: thread attach failed
I also have a new error when displaying an image:
22:13:18.594: DEBUG/skia(4204): xxxxxxxxxxx jpeg error 20 Improper call to JPEG library in state %d
22:13:18.604: INFO/System.out(4204): resolveUri failed on bad bitmap uri:
22:13:18.694: ERROR/dalvikvm-heap(4204): 6291456-byte external allocation too large for this process.
22:13:18.694: ERROR/(4204): VM won't let us allocate 6291456 bytes
22:13:18.694: DEBUG/skia(4204): xxxxxxxxxxxxxxxxxxxx allocPixelRef failed

To fix the OutOfMemory error, you should do something like this:
BitmapFactory.Options options = new BitmapFactory.Options();
options.inSampleSize = 8;
Bitmap preview_bitmap = BitmapFactory.decodeStream(is, null, options);
This inSampleSize option reduces memory consumption.
Here's a complete method. First it reads image size without decoding the content itself. Then it finds the best inSampleSize value, it should be a power of 2, and finally the image is decoded.
// Decodes image and scales it to reduce memory consumption
private Bitmap decodeFile(File f) {
try {
// Decode image size
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
BitmapFactory.decodeStream(new FileInputStream(f), null, o);
// The new size we want to scale to
final int REQUIRED_SIZE=70;
// Find the correct scale value. It should be the power of 2.
int scale = 1;
while(o.outWidth / scale / 2 >= REQUIRED_SIZE &&
o.outHeight / scale / 2 >= REQUIRED_SIZE) {
scale *= 2;
}
// Decode with inSampleSize
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize = scale;
return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
} catch (FileNotFoundException e) {}
return null;
}

The Android Training class, "Displaying Bitmaps Efficiently", offers some great information for understanding and dealing with the exception `java.lang.OutOfMemoryError: bitmap size exceeds VM budget when loading Bitmaps.
Read Bitmap Dimensions and Type
The BitmapFactory class provides several decoding methods (decodeByteArray(), decodeFile(), decodeResource(), etc.) for creating a Bitmap from various sources. Choose the most appropriate decode method based on your image data source. These methods attempt to allocate memory for the constructed bitmap and therefore can easily result in an OutOfMemory exception. Each type of decode method has additional signatures that let you specify decoding options via the BitmapFactory.Options class. Setting the inJustDecodeBounds property to true while decoding avoids memory allocation, returning null for the bitmap object but setting outWidth, outHeight and outMimeType. This technique allows you to read the dimensions and type of the image data prior to the construction (and memory allocation) of the bitmap.
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(getResources(), R.id.myimage, options);
int imageHeight = options.outHeight;
int imageWidth = options.outWidth;
String imageType = options.outMimeType;
To avoid java.lang.OutOfMemory exceptions, check the dimensions of a bitmap before decoding it unless you absolutely trust the source to provide you with predictably sized image data that comfortably fits within the available memory.
Load a scaled-down version into Memory
Now that the image dimensions are known, they can be used to decide if the full image should be loaded into memory or if a subsampled version should be loaded instead. Here are some factors to consider:
Estimated memory usage of loading the full image in memory.
The amount of memory you are willing to commit to loading this image given any other memory requirements of your application.
Dimensions of the target ImageView or UI component that the image is to be loaded into.
Screen size and density of the current device.
For example, it’s not worth loading a 1024x768 pixel image into memory if it will eventually be displayed in a 128x96 pixel thumbnail in an ImageView.
To tell the decoder to subsample the image, loading a smaller version into memory, set inSampleSize to true in your BitmapFactory.Options object. For example, an image with resolution 2048x1536 that is decoded with an inSampleSize of 4 produces a bitmap of approximately 512x384. Loading this into memory uses 0.75MB rather than 12MB for the full image (assuming a bitmap configuration of ARGB_8888). Here’s a method to calculate a sample size value that is a power of two based on a target width and height:
public static int calculateInSampleSize(
BitmapFactory.Options options, int reqWidth, int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
final int halfHeight = height / 2;
final int halfWidth = width / 2;
// Calculate the largest inSampleSize value that is a power of 2 and keeps both
// height and width larger than the requested height and width.
while ((halfHeight / inSampleSize) > reqHeight
&& (halfWidth / inSampleSize) > reqWidth) {
inSampleSize *= 2;
}
}
return inSampleSize;
}
Note: A power of two value is calculated because the decoder uses a
final value by rounding down to the nearest power of two, as per the
inSampleSize documentation.
To use this method, first decode with inJustDecodeBounds set to true, pass the options through and then decode again using the new inSampleSizevalue andinJustDecodeBoundsset tofalse`:
public static Bitmap decodeSampledBitmapFromResource(Resources res, int resId,
int reqWidth, int reqHeight) {
// First decode with inJustDecodeBounds=true to check dimensions
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(res, resId, options);
// Calculate inSampleSize
options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
return BitmapFactory.decodeResource(res, resId, options);
}
This method makes it easy to load a bitmap of arbitrarily large size into an ImageView that displays a 100x100 pixel thumbnail, as shown in the following example code:
mImageView.setImageBitmap(
decodeSampledBitmapFromResource(getResources(), R.id.myimage, 100, 100));
You can follow a similar process to decode bitmaps from other sources, by substituting the appropriate BitmapFactory.decode* method as needed.

I've made a small improvement to Fedor's code. It basically does the same, but without the (in my opinion) ugly while loop and it always results in a power of two. Kudos to Fedor for making the original solution, I was stuck until I found his, and then I was able to make this one :)
private Bitmap decodeFile(File f){
Bitmap b = null;
//Decode image size
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
FileInputStream fis = new FileInputStream(f);
BitmapFactory.decodeStream(fis, null, o);
fis.close();
int scale = 1;
if (o.outHeight > IMAGE_MAX_SIZE || o.outWidth > IMAGE_MAX_SIZE) {
scale = (int)Math.pow(2, (int) Math.ceil(Math.log(IMAGE_MAX_SIZE /
(double) Math.max(o.outHeight, o.outWidth)) / Math.log(0.5)));
}
//Decode with inSampleSize
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize = scale;
fis = new FileInputStream(f);
b = BitmapFactory.decodeStream(fis, null, o2);
fis.close();
return b;
}

I come from iOS experience and I was frustrated to discover an issue with something so basic as loading and showing an image. After all, everyone that is having this issue is trying to display reasonably sized images. Anyway, here are the two changes that fixed my problem (and made my app very responsive).
1) Every time you do BitmapFactory.decodeXYZ(), make sure to pass in a BitmapFactory.Options with inPurgeable set to true (and preferably with inInputShareable also set to true).
2) NEVER use Bitmap.createBitmap(width, height, Config.ARGB_8888). I mean NEVER! I've never had that thing not raise memory error after few passes. No amount of recycle(), System.gc(), whatever helped. It always raised exception. The one other way that actually works is to have a dummy image in your drawables (or another Bitmap that you decoded using step 1 above), rescale that to whatever you want, then manipulate the resulting Bitmap (such as passing it on to a Canvas for more fun). So, what you should use instead is: Bitmap.createScaledBitmap(srcBitmap, width, height, false). If for whatever reason you MUST use the brute force create method, then at least pass Config.ARGB_4444.
This is almost guaranteed to save you hours if not days. All that talk about scaling the image, etc. does not really work (unless you consider getting wrong size or degraded image a solution).

It's a known bug, it's not because of large files. Since Android Caches the Drawables, it's going out of memory after using few images. But I've found an alternate way for it, by skipping the android default cache system.
Solution:
Move the images to "assets" folder and use the following function to get BitmapDrawable:
public static Drawable getAssetImage(Context context, String filename) throws IOException {
AssetManager assets = context.getResources().getAssets();
InputStream buffer = new BufferedInputStream((assets.open("drawable/" + filename + ".png")));
Bitmap bitmap = BitmapFactory.decodeStream(buffer);
return new BitmapDrawable(context.getResources(), bitmap);
}

I had this same issue and solved it by avoiding the BitmapFactory.decodeStream or decodeFile functions and instead used BitmapFactory.decodeFileDescriptor
decodeFileDescriptor looks like it calls different native methods than the decodeStream/decodeFile.
Anyways, what worked was this (note that I added some options as some had above, but that's not what made the difference. What is critical is the call to BitmapFactory.decodeFileDescriptor instead of decodeStream or decodeFile):
private void showImage(String path) {
Log.i("showImage","loading:"+path);
BitmapFactory.Options bfOptions=new BitmapFactory.Options();
bfOptions.inDither=false; //Disable Dithering mode
bfOptions.inPurgeable=true; //Tell to gc that whether it needs free memory, the Bitmap can be cleared
bfOptions.inInputShareable=true; //Which kind of reference will be used to recover the Bitmap data after being clear, when it will be used in the future
bfOptions.inTempStorage=new byte[32 * 1024];
File file=new File(path);
FileInputStream fs=null;
try {
fs = new FileInputStream(file);
} catch (FileNotFoundException e) {
//TODO do something intelligent
e.printStackTrace();
}
try {
if(fs!=null) bm=BitmapFactory.decodeFileDescriptor(fs.getFD(), null, bfOptions);
} catch (IOException e) {
//TODO do something intelligent
e.printStackTrace();
} finally{
if(fs!=null) {
try {
fs.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
//bm=BitmapFactory.decodeFile(path, bfOptions); This one causes error: java.lang.OutOfMemoryError: bitmap size exceeds VM budget
im.setImageBitmap(bm);
//bm.recycle();
bm=null;
}
I think there is a problem with the native function used in decodeStream/decodeFile. I have confirmed that a different native method is called when using decodeFileDescriptor. Also what I've read is "that Images (Bitmaps) are not allocated in a standard Java way but via native calls; the allocations are done outside of the virtual heap, but are
counted against it!"

I think best way to avoid the OutOfMemoryError is to face it and understand it.
I made an app to intentionally cause OutOfMemoryError, and monitor memory usage.
After I've done a lot of experiments with this App, I've got the following conclusions:
I'm gonna talk about SDK versions before Honey Comb first.
Bitmap is stored in native heap, but it will get garbage collected automatically, calling recycle() is needless.
If {VM heap size} + {allocated native heap memory} >= {VM heap size limit for the device}, and you are trying to create bitmap, OOM will be thrown.
NOTICE: VM HEAP SIZE is counted rather than VM ALLOCATED MEMORY.
VM Heap size will never shrink after grown, even if the allocated VM memory is shrinked.
So you have to keep the peak VM memory as low as possible to keep VM Heap Size from growing too big to save available memory for Bitmaps.
Manually call System.gc() is meaningless, the system will call it first before trying to grow the heap size.
Native Heap Size will never shrink too, but it's not counted for OOM, so no need to worry about it.
Then, let's talk about SDK Starts from Honey Comb.
Bitmap is stored in VM heap, Native memory is not counted for OOM.
The condition for OOM is much simpler: {VM heap size} >= {VM heap size limit for the device}.
So you have more available memory to create bitmap with the same heap size limit, OOM is less likely to be thrown.
Here is some of my observations about Garbage Collection and Memory Leak.
You can see it yourself in the App. If an Activity executed an AsyncTask that was still running after the Activity was destroyed, the Activity will not get garbage collected until the AsyncTask finish.
This is because AsyncTask is an instance of an anonymous inner class, it holds a reference of the Activity.
Calling AsyncTask.cancel(true) will not stop the execution if the task is blocked in an IO operation in background thread.
Callbacks are anonymous inner classes too, so if a static instance in your project holds them and do not release them, memory would be leaked.
If you scheduled a repeating or delayed task, for example a Timer, and you do not call cancel() and purge() in onPause(), memory would be leaked.

I have seen a lot of questions about OOM exceptions and caching lately. The developer guide has a really good article on this, but some tends to fail on implementing it in a suitable way.
Because of this I wrote an example application that demonstrates caching in an Android environment. This implementation has not yet gotten an OOM.
Look at the end of this answer for a link to the source code.
Requirements:
Android API 2.1 or higher (I simply could not manage to get the available memory for an application in API 1.6 - that is the only piece of code that doesn't work in API 1.6)
Android support package
Features:
Retains the cache if there is an orientation change, using a singleton
Use one eighth of the assigned application memory to the cache (modify if you want)
Large bitmaps gets scaled (you can define the maximum pixels that you want to allow)
Controls that there is an internet connection available before downloading the bitmaps
Makes sure that you are only instantiating one task per row
If you are flinging the ListView away, it simply won't download the bitmaps between
This does not include:
Disk caching. This should be easy to implement anyway - just point to a different task that grabs the bitmaps from the disk
Sample code:
The images that are being downloaded are images (75x75) from Flickr. However, put whatever image urls you want to be processed, and the application will scale it down if it exceeds the maximum. In this application the urls are simply in a String array.
The LruCache has a good way to deal with bitmaps. However, in this application I put an instance of an LruCache inside another cache class that I created in order to get the application more feasible.
Cache.java's critical stuff (the loadBitmap() method is the most important):
public Cache(int size, int maxWidth, int maxHeight) {
// Into the constructor you add the maximum pixels
// that you want to allow in order to not scale images.
mMaxWidth = maxWidth;
mMaxHeight = maxHeight;
mBitmapCache = new LruCache<String, Bitmap>(size) {
protected int sizeOf(String key, Bitmap b) {
// Assuming that one pixel contains four bytes.
return b.getHeight() * b.getWidth() * 4;
}
};
mCurrentTasks = new ArrayList<String>();
}
/**
* Gets a bitmap from cache.
* If it is not in cache, this method will:
*
* 1: check if the bitmap url is currently being processed in the
* BitmapLoaderTask and cancel if it is already in a task (a control to see
* if it's inside the currentTasks list).
*
* 2: check if an internet connection is available and continue if so.
*
* 3: download the bitmap, scale the bitmap if necessary and put it into
* the memory cache.
*
* 4: Remove the bitmap url from the currentTasks list.
*
* 5: Notify the ListAdapter.
*
* #param mainActivity - Reference to activity object, in order to
* call notifyDataSetChanged() on the ListAdapter.
* #param imageKey - The bitmap url (will be the key).
* #param imageView - The ImageView that should get an
* available bitmap or a placeholder image.
* #param isScrolling - If set to true, we skip executing more tasks since
* the user probably has flinged away the view.
*/
public void loadBitmap(MainActivity mainActivity,
String imageKey, ImageView imageView,
boolean isScrolling) {
final Bitmap bitmap = getBitmapFromCache(imageKey);
if (bitmap != null) {
imageView.setImageBitmap(bitmap);
} else {
imageView.setImageResource(R.drawable.ic_launcher);
if (!isScrolling && !mCurrentTasks.contains(imageKey) &&
mainActivity.internetIsAvailable()) {
BitmapLoaderTask task = new BitmapLoaderTask(imageKey,
mainActivity.getAdapter());
task.execute();
}
}
}
You shouldn't need to edit anything in the Cache.java file unless you want to implement disk caching.
MainActivity.java's critical stuff:
public void onScrollStateChanged(AbsListView view, int scrollState) {
if (view.getId() == android.R.id.list) {
// Set scrolling to true only if the user has flinged the
// ListView away, hence we skip downloading a series
// of unnecessary bitmaps that the user probably
// just want to skip anyways. If we scroll slowly it
// will still download bitmaps - that means
// that the application won't wait for the user
// to lift its finger off the screen in order to
// download.
if (scrollState == SCROLL_STATE_FLING) {
mIsScrolling = true;
} else {
mIsScrolling = false;
mListAdapter.notifyDataSetChanged();
}
}
}
// Inside ListAdapter...
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
View row = convertView;
final ViewHolder holder;
if (row == null) {
LayoutInflater inflater = getLayoutInflater();
row = inflater.inflate(R.layout.main_listview_row, parent, false);
holder = new ViewHolder(row);
row.setTag(holder);
} else {
holder = (ViewHolder) row.getTag();
}
final Row rowObject = getItem(position);
// Look at the loadBitmap() method description...
holder.mTextView.setText(rowObject.mText);
mCache.loadBitmap(MainActivity.this,
rowObject.mBitmapUrl, holder.mImageView,
mIsScrolling);
return row;
}
getView() gets called very often. It's normally not a good idea to download images there if we haven't implemented a check that ensure us that we won't start an infinite amount of threads per row. Cache.java checks whether the rowObject.mBitmapUrl already is in a task and if it is, it won't start another. Therefore, we are most likely not exceeding the work queue restriction from the AsyncTask pool.
Download:
You can download the source code from https://www.dropbox.com/s/pvr9zyl811tfeem/ListViewImageCache.zip.
Last words:
I have tested this for a few weeks now, I haven't gotten a single OOM exception yet. I have tested this on the emulator, on my Nexus One and on my Nexus S. I have tested image urls that contain images that were in HD quality. The only bottleneck is that it takes more time to download.
There is only one possible scenario where I can imagine that the OOM will appear, and that is if we download many, really big images, and before they get scaled and put into cache, will simultaneously take up more memory and cause an OOM. But that isn't even an ideal situation anyway and it most likely won't be possible to solve in a more feasible way.
Report errors in the comments! :-)

I did the following to take the image and resize it on the fly. Hope this helps
Bitmap bm;
bm = Bitmap.createScaledBitmap(BitmapFactory.decodeFile(filepath), 100, 100, true);
mPicture = new ImageView(context);
mPicture.setImageBitmap(bm);

unfortunately if None of the Above works, then Add this to your Manifest file. Inside application tag
<application
android:largeHeap="true"

It seems that this is a very long running problem, with a lot of differing explanations. I took the advice of the two most common presented answers here, but neither one of these solved my problems of the VM claiming it couldn't afford the bytes to perform the decoding part of the process. After some digging I learned that the real problem here is the decoding process taking away from the NATIVE heap.
See here: BitmapFactory OOM driving me nuts
That lead me to another discussion thread where I found a couple more solutions to this problem. One is to callSystem.gc(); manually after your image is displayed. But that actually makes your app use MORE memory, in an effort to reduce the native heap. The better solution as of the release of 2.0 (Donut) is to use the BitmapFactory option "inPurgeable". So I simply added o2.inPurgeable=true; just after o2.inSampleSize=scale;.
More on that topic here: Is the limit of memory heap only 6M?
Now, having said all of this, I am a complete dunce with Java and Android too. So if you think this is a terrible way to solve this problem, you are probably right. ;-) But this has worked wonders for me, and I have found it impossible to run the VM out of heap cache now. The only drawback I can find is that you are trashing your cached drawn image. Which means if you go RIGHT back to that image, you are redrawing it each and every time. In the case of how my application works, that is not really a problem. Your mileage may vary.

Use this bitmap.recycle(); This helps without any image quality issue.

I have resolved the same issue in the following manner.
Bitmap b = null;
Drawable d;
ImageView i = new ImageView(mContext);
try {
b = Bitmap.createBitmap(320,424,Bitmap.Config.RGB_565);
b.eraseColor(0xFFFFFFFF);
Rect r = new Rect(0, 0,320 , 424);
Canvas c = new Canvas(b);
Paint p = new Paint();
p.setColor(0xFFC0C0C0);
c.drawRect(r, p);
d = mContext.getResources().getDrawable(mImageIds[position]);
d.setBounds(r);
d.draw(c);
/*
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inTempStorage = new byte[128*1024];
b = BitmapFactory.decodeStream(mContext.getResources().openRawResource(mImageIds[position]), null, o2);
o2.inSampleSize=16;
o2.inPurgeable = true;
*/
} catch (Exception e) {
}
i.setImageBitmap(b);

I have a much more effective solution which does not need scaling of any sort. Simply decode your bitmap only once and then cache it in a map against its name. Then simply retrieve the bitmap against the name and set it in the ImageView. There is nothing more that needs to be done.
This will work because the actual binary data of the decoded bitmap is not stored within the dalvik VM heap. It is stored externally. So every time you decode a bitmap, it allocates memory outside of VM heap which is never reclaimed by GC
To help you better appreciate this, imagine you have kept ur image in the drawable folder. You just get the image by doing a getResources().getDrwable(R.drawable.). This will NOT decode your image everytime but re-use an already decoded instance everytime you call it. So in essence it is cached.
Now since your image is in a file somewhere (or may even be coming from an external server), it is YOUR responsibility to cache the decoded bitmap instance to be reused any where it is needed.
Hope this helps.

There are two issues here....
Bitmap memory isn't in the VM heap but rather in the native heap - see BitmapFactory OOM driving me nuts
Garbage collection for the native heap is lazier than the VM heap - so you need to be quite aggressive about doing bitmap.recycle and bitmap =null every time you go through an Activity's onPause or onDestroy

This worked for me!
public Bitmap readAssetsBitmap(String filename) throws IOException {
try {
BitmapFactory.Options options = new BitmapFactory.Options();
options.inPurgeable = true;
Bitmap bitmap = BitmapFactory.decodeStream(assets.open(filename), null, options);
if(bitmap == null) {
throw new IOException("File cannot be opened: It's value is null");
} else {
return bitmap;
}
} catch (IOException e) {
throw new IOException("File cannot be opened: " + e.getMessage());
}
}

Great answers here, but I wanted a fully usable class to address this problem.. so I did one.
Here is my BitmapHelper class that is OutOfMemoryError proof :-)
import java.io.File;
import java.io.FileInputStream;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
public class BitmapHelper
{
//decodes image and scales it to reduce memory consumption
public static Bitmap decodeFile(File bitmapFile, int requiredWidth, int requiredHeight, boolean quickAndDirty)
{
try
{
//Decode image size
BitmapFactory.Options bitmapSizeOptions = new BitmapFactory.Options();
bitmapSizeOptions.inJustDecodeBounds = true;
BitmapFactory.decodeStream(new FileInputStream(bitmapFile), null, bitmapSizeOptions);
// load image using inSampleSize adapted to required image size
BitmapFactory.Options bitmapDecodeOptions = new BitmapFactory.Options();
bitmapDecodeOptions.inTempStorage = new byte[16 * 1024];
bitmapDecodeOptions.inSampleSize = computeInSampleSize(bitmapSizeOptions, requiredWidth, requiredHeight, false);
bitmapDecodeOptions.inPurgeable = true;
bitmapDecodeOptions.inDither = !quickAndDirty;
bitmapDecodeOptions.inPreferredConfig = quickAndDirty ? Bitmap.Config.RGB_565 : Bitmap.Config.ARGB_8888;
Bitmap decodedBitmap = BitmapFactory.decodeStream(new FileInputStream(bitmapFile), null, bitmapDecodeOptions);
// scale bitmap to mathc required size (and keep aspect ratio)
float srcWidth = (float) bitmapDecodeOptions.outWidth;
float srcHeight = (float) bitmapDecodeOptions.outHeight;
float dstWidth = (float) requiredWidth;
float dstHeight = (float) requiredHeight;
float srcAspectRatio = srcWidth / srcHeight;
float dstAspectRatio = dstWidth / dstHeight;
// recycleDecodedBitmap is used to know if we must recycle intermediary 'decodedBitmap'
// (DO NOT recycle it right away: wait for end of bitmap manipulation process to avoid
// java.lang.RuntimeException: Canvas: trying to use a recycled bitmap android.graphics.Bitmap#416ee7d8
// I do not excatly understand why, but this way it's OK
boolean recycleDecodedBitmap = false;
Bitmap scaledBitmap = decodedBitmap;
if (srcAspectRatio < dstAspectRatio)
{
scaledBitmap = getScaledBitmap(decodedBitmap, (int) dstWidth, (int) (srcHeight * (dstWidth / srcWidth)));
// will recycle recycleDecodedBitmap
recycleDecodedBitmap = true;
}
else if (srcAspectRatio > dstAspectRatio)
{
scaledBitmap = getScaledBitmap(decodedBitmap, (int) (srcWidth * (dstHeight / srcHeight)), (int) dstHeight);
recycleDecodedBitmap = true;
}
// crop image to match required image size
int scaledBitmapWidth = scaledBitmap.getWidth();
int scaledBitmapHeight = scaledBitmap.getHeight();
Bitmap croppedBitmap = scaledBitmap;
if (scaledBitmapWidth > requiredWidth)
{
int xOffset = (scaledBitmapWidth - requiredWidth) / 2;
croppedBitmap = Bitmap.createBitmap(scaledBitmap, xOffset, 0, requiredWidth, requiredHeight);
scaledBitmap.recycle();
}
else if (scaledBitmapHeight > requiredHeight)
{
int yOffset = (scaledBitmapHeight - requiredHeight) / 2;
croppedBitmap = Bitmap.createBitmap(scaledBitmap, 0, yOffset, requiredWidth, requiredHeight);
scaledBitmap.recycle();
}
if (recycleDecodedBitmap)
{
decodedBitmap.recycle();
}
decodedBitmap = null;
scaledBitmap = null;
return croppedBitmap;
}
catch (Exception ex)
{
ex.printStackTrace();
}
return null;
}
/**
* compute powerOf2 or exact scale to be used as {#link BitmapFactory.Options#inSampleSize} value (for subSampling)
*
* #param requiredWidth
* #param requiredHeight
* #param powerOf2
* weither we want a power of 2 sclae or not
* #return
*/
public static int computeInSampleSize(BitmapFactory.Options options, int dstWidth, int dstHeight, boolean powerOf2)
{
int inSampleSize = 1;
// Raw height and width of image
final int srcHeight = options.outHeight;
final int srcWidth = options.outWidth;
if (powerOf2)
{
//Find the correct scale value. It should be the power of 2.
int tmpWidth = srcWidth, tmpHeight = srcHeight;
while (true)
{
if (tmpWidth / 2 < dstWidth || tmpHeight / 2 < dstHeight)
break;
tmpWidth /= 2;
tmpHeight /= 2;
inSampleSize *= 2;
}
}
else
{
// Calculate ratios of height and width to requested height and width
final int heightRatio = Math.round((float) srcHeight / (float) dstHeight);
final int widthRatio = Math.round((float) srcWidth / (float) dstWidth);
// Choose the smallest ratio as inSampleSize value, this will guarantee
// a final image with both dimensions larger than or equal to the
// requested height and width.
inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
}
return inSampleSize;
}
public static Bitmap drawableToBitmap(Drawable drawable)
{
if (drawable instanceof BitmapDrawable)
{
return ((BitmapDrawable) drawable).getBitmap();
}
Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
drawable.draw(canvas);
return bitmap;
}
public static Bitmap getScaledBitmap(Bitmap bitmap, int newWidth, int newHeight)
{
int width = bitmap.getWidth();
int height = bitmap.getHeight();
float scaleWidth = ((float) newWidth) / width;
float scaleHeight = ((float) newHeight) / height;
// CREATE A MATRIX FOR THE MANIPULATION
Matrix matrix = new Matrix();
// RESIZE THE BIT MAP
matrix.postScale(scaleWidth, scaleHeight);
// RECREATE THE NEW BITMAP
Bitmap resizedBitmap = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix, false);
return resizedBitmap;
}
}

None of the answers above worked for me, but I did come up with a horribly ugly workaround that solved the problem. I added a very small, 1x1 pixel image to my project as a resource, and loaded it into my ImageView before calling into garbage collection. I think it might be that the ImageView was not releasing the Bitmap, so GC never picked it up. It's ugly, but it seems to be working for now.
if (bitmap != null)
{
bitmap.recycle();
bitmap = null;
}
if (imageView != null)
{
imageView.setImageResource(R.drawable.tiny); // This is my 1x1 png.
}
System.gc();
imageView.setImageBitmap(...); // Do whatever you need to do to load the image you want.

This works for me.
Bitmap myBitmap;
BitmapFactory.Options options = new BitmapFactory.Options();
options.InPurgeable = true;
options.OutHeight = 50;
options.OutWidth = 50;
options.InSampleSize = 4;
File imgFile = new File(filepath);
myBitmap = BitmapFactory.DecodeFile(imgFile.AbsolutePath, options);
and this is on C# monodroid.
you can easily change the path of the image. what important here is the options to be set.

This seems like the appropriate place to share my utility class for loading and processing images with the community, you are welcome to use it and modify it freely.
package com.emil;
import java.io.IOException;
import java.io.InputStream;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
/**
* A class to load and process images of various sizes from input streams and file paths.
*
* #author Emil http://stackoverflow.com/users/220710/emil
*
*/
public class ImageProcessing {
public static Bitmap getBitmap(InputStream stream, int sampleSize, Bitmap.Config bitmapConfig) throws IOException{
BitmapFactory.Options options=ImageProcessing.getOptionsForSampling(sampleSize, bitmapConfig);
Bitmap bm = BitmapFactory.decodeStream(stream,null,options);
if(ImageProcessing.checkDecode(options)){
return bm;
}else{
throw new IOException("Image decoding failed, using stream.");
}
}
public static Bitmap getBitmap(String imgPath, int sampleSize, Bitmap.Config bitmapConfig) throws IOException{
BitmapFactory.Options options=ImageProcessing.getOptionsForSampling(sampleSize, bitmapConfig);
Bitmap bm = BitmapFactory.decodeFile(imgPath,options);
if(ImageProcessing.checkDecode(options)){
return bm;
}else{
throw new IOException("Image decoding failed, using file path.");
}
}
public static Dimensions getDimensions(InputStream stream) throws IOException{
BitmapFactory.Options options=ImageProcessing.getOptionsForDimensions();
BitmapFactory.decodeStream(stream,null,options);
if(ImageProcessing.checkDecode(options)){
return new ImageProcessing.Dimensions(options.outWidth,options.outHeight);
}else{
throw new IOException("Image decoding failed, using stream.");
}
}
public static Dimensions getDimensions(String imgPath) throws IOException{
BitmapFactory.Options options=ImageProcessing.getOptionsForDimensions();
BitmapFactory.decodeFile(imgPath,options);
if(ImageProcessing.checkDecode(options)){
return new ImageProcessing.Dimensions(options.outWidth,options.outHeight);
}else{
throw new IOException("Image decoding failed, using file path.");
}
}
private static boolean checkDecode(BitmapFactory.Options options){
// Did decode work?
if( options.outWidth<0 || options.outHeight<0 ){
return false;
}else{
return true;
}
}
/**
* Creates a Bitmap that is of the minimum dimensions necessary
* #param bm
* #param min
* #return
*/
public static Bitmap createMinimalBitmap(Bitmap bm, ImageProcessing.Minimize min){
int newWidth, newHeight;
switch(min.type){
case WIDTH:
if(bm.getWidth()>min.minWidth){
newWidth=min.minWidth;
newHeight=ImageProcessing.getScaledHeight(newWidth, bm);
}else{
// No resize
newWidth=bm.getWidth();
newHeight=bm.getHeight();
}
break;
case HEIGHT:
if(bm.getHeight()>min.minHeight){
newHeight=min.minHeight;
newWidth=ImageProcessing.getScaledWidth(newHeight, bm);
}else{
// No resize
newWidth=bm.getWidth();
newHeight=bm.getHeight();
}
break;
case BOTH: // minimize to the maximum dimension
case MAX:
if(bm.getHeight()>bm.getWidth()){
// Height needs to minimized
min.minDim=min.minDim!=null ? min.minDim : min.minHeight;
if(bm.getHeight()>min.minDim){
newHeight=min.minDim;
newWidth=ImageProcessing.getScaledWidth(newHeight, bm);
}else{
// No resize
newWidth=bm.getWidth();
newHeight=bm.getHeight();
}
}else{
// Width needs to be minimized
min.minDim=min.minDim!=null ? min.minDim : min.minWidth;
if(bm.getWidth()>min.minDim){
newWidth=min.minDim;
newHeight=ImageProcessing.getScaledHeight(newWidth, bm);
}else{
// No resize
newWidth=bm.getWidth();
newHeight=bm.getHeight();
}
}
break;
default:
// No resize
newWidth=bm.getWidth();
newHeight=bm.getHeight();
}
return Bitmap.createScaledBitmap(bm, newWidth, newHeight, true);
}
public static int getScaledWidth(int height, Bitmap bm){
return (int)(((double)bm.getWidth()/bm.getHeight())*height);
}
public static int getScaledHeight(int width, Bitmap bm){
return (int)(((double)bm.getHeight()/bm.getWidth())*width);
}
/**
* Get the proper sample size to meet minimization restraints
* #param dim
* #param min
* #param multipleOf2 for fastest processing it is recommended that the sample size be a multiple of 2
* #return
*/
public static int getSampleSize(ImageProcessing.Dimensions dim, ImageProcessing.Minimize min, boolean multipleOf2){
switch(min.type){
case WIDTH:
return ImageProcessing.getMaxSampleSize(dim.width, min.minWidth, multipleOf2);
case HEIGHT:
return ImageProcessing.getMaxSampleSize(dim.height, min.minHeight, multipleOf2);
case BOTH:
int widthMaxSampleSize=ImageProcessing.getMaxSampleSize(dim.width, min.minWidth, multipleOf2);
int heightMaxSampleSize=ImageProcessing.getMaxSampleSize(dim.height, min.minHeight, multipleOf2);
// Return the smaller of the two
if(widthMaxSampleSize<heightMaxSampleSize){
return widthMaxSampleSize;
}else{
return heightMaxSampleSize;
}
case MAX:
// Find the larger dimension and go bases on that
if(dim.width>dim.height){
return ImageProcessing.getMaxSampleSize(dim.width, min.minDim, multipleOf2);
}else{
return ImageProcessing.getMaxSampleSize(dim.height, min.minDim, multipleOf2);
}
}
return 1;
}
public static int getMaxSampleSize(int dim, int min, boolean multipleOf2){
int add=multipleOf2 ? 2 : 1;
int size=0;
while(min<(dim/(size+add))){
size+=add;
}
size = size==0 ? 1 : size;
return size;
}
public static class Dimensions {
int width;
int height;
public Dimensions(int width, int height) {
super();
this.width = width;
this.height = height;
}
#Override
public String toString() {
return width+" x "+height;
}
}
public static class Minimize {
public enum Type {
WIDTH,HEIGHT,BOTH,MAX
}
Integer minWidth;
Integer minHeight;
Integer minDim;
Type type;
public Minimize(int min, Type type) {
super();
this.type = type;
switch(type){
case WIDTH:
this.minWidth=min;
break;
case HEIGHT:
this.minHeight=min;
break;
case BOTH:
this.minWidth=min;
this.minHeight=min;
break;
case MAX:
this.minDim=min;
break;
}
}
public Minimize(int minWidth, int minHeight) {
super();
this.type=Type.BOTH;
this.minWidth = minWidth;
this.minHeight = minHeight;
}
}
/**
* Estimates size of Bitmap in bytes depending on dimensions and Bitmap.Config
* #param width
* #param height
* #param config
* #return
*/
public static long estimateBitmapBytes(int width, int height, Bitmap.Config config){
long pixels=width*height;
switch(config){
case ALPHA_8: // 1 byte per pixel
return pixels;
case ARGB_4444: // 2 bytes per pixel, but depreciated
return pixels*2;
case ARGB_8888: // 4 bytes per pixel
return pixels*4;
case RGB_565: // 2 bytes per pixel
return pixels*2;
default:
return pixels;
}
}
private static BitmapFactory.Options getOptionsForDimensions(){
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds=true;
return options;
}
private static BitmapFactory.Options getOptionsForSampling(int sampleSize, Bitmap.Config bitmapConfig){
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = false;
options.inDither = false;
options.inSampleSize = sampleSize;
options.inScaled = false;
options.inPreferredConfig = bitmapConfig;
return options;
}
}

In one of my application i need to take picture either from Camera/Gallery. If user click image from Camera(may be 2MP, 5MP or 8MP), image size varies from kBs to MBs. If image size is less(or up to 1-2MB) above code working fine but if i have image of size above 4MB or 5MB then OOM comes in frame :(
then i have worked to solve this issue & finally i've made the below improvement to Fedor's(All Credit to Fedor for making such a nice solution) code :)
private Bitmap decodeFile(String fPath) {
// Decode image size
BitmapFactory.Options opts = new BitmapFactory.Options();
/*
* If set to true, the decoder will return null (no bitmap), but the
* out... fields will still be set, allowing the caller to query the
* bitmap without having to allocate the memory for its pixels.
*/
opts.inJustDecodeBounds = true;
opts.inDither = false; // Disable Dithering mode
opts.inPurgeable = true; // Tell to gc that whether it needs free
// memory, the Bitmap can be cleared
opts.inInputShareable = true; // Which kind of reference will be used to
// recover the Bitmap data after being
// clear, when it will be used in the
// future
BitmapFactory.decodeFile(fPath, opts);
// The new size we want to scale to
final int REQUIRED_SIZE = 70;
// Find the correct scale value.
int scale = 1;
if (opts.outHeight > REQUIRED_SIZE || opts.outWidth > REQUIRED_SIZE) {
// Calculate ratios of height and width to requested height and width
final int heightRatio = Math.round((float) opts.outHeight
/ (float) REQUIRED_SIZE);
final int widthRatio = Math.round((float) opts.outWidth
/ (float) REQUIRED_SIZE);
// Choose the smallest ratio as inSampleSize value, this will guarantee
// a final image with both dimensions larger than or equal to the
// requested height and width.
scale = heightRatio < widthRatio ? heightRatio : widthRatio;//
}
// Decode bitmap with inSampleSize set
opts.inJustDecodeBounds = false;
opts.inSampleSize = scale;
Bitmap bm = BitmapFactory.decodeFile(fPath, opts).copy(
Bitmap.Config.RGB_565, false);
return bm;
}
I hope this will help the buddies facing the same problem!
for more please refer this

I just ran into this issue a couple minutes ago. I solved it by doing a better job at managing my listview adapter. I thought it was an issue with the hundreds of 50x50px images I was using, turns out I was trying to inflate my custom view each time the row was being shown. Simply by testing to see if the row had been inflated I eliminated this error, and I am using hundreds of bitmaps. This is actually for a Spinner, but the base adapter works all the same for a ListView. This simple fix also greatly improved the performance of the adapter.
#Override
public View getView(final int position, View convertView, final ViewGroup parent) {
if(convertView == null){
LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate(R.layout.spinner_row, null);
}
...

This issue only happens in Android emulators. I also faced this issue in an emulator but when I checked in a device then it worked fine.
So please check in a device. It may be run in device.

I've spent the entire day testing these solutions and the only thing that worked for me is the above approaches for getting the image and manually calling the GC, which I know is not supposed to be necessary, but it is the only thing that worked when I put my app under heavy load testing switching between activities. My app has a list of thumbnail images in a listview in (lets say activity A) and when you click on one of those images it takes you to another activity (lets say activity B) that shows a main image for that item. When I would switch back and forth between the two activities, I would eventually get the OOM error and the app would force close.
When I would get half way down the listview it would crash.
Now when I implement the following in activity B, I can go through the entire listview with no issue and keep going and going and going...and its plenty fast.
#Override
public void onDestroy()
{
Cleanup();
super.onDestroy();
}
private void Cleanup()
{
bitmap.recycle();
System.gc();
Runtime.getRuntime().gc();
}

All the solutions here require setting a IMAGE_MAX_SIZE. This limits devices with more powerful hardware and if the image size is too low it looks ugly on the HD screen.
I came out with a solution that works with my Samsung Galaxy S3 and several other devices including less powerful ones, with better image quality when a more powerful device is used.
The gist of it is to calculate the maximum memory allocated for the app on a particular device, then set the scale to be lowest possible without exceeding this memory. Here's the code:
public static Bitmap decodeFile(File f)
{
Bitmap b = null;
try
{
// Decode image size
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
FileInputStream fis = new FileInputStream(f);
try
{
BitmapFactory.decodeStream(fis, null, o);
}
finally
{
fis.close();
}
// In Samsung Galaxy S3, typically max memory is 64mb
// Camera max resolution is 3264 x 2448, times 4 to get Bitmap memory of 30.5mb for one bitmap
// If we use scale of 2, resolution will be halved, 1632 x 1224 and x 4 to get Bitmap memory of 7.62mb
// We try use 25% memory which equals to 16mb maximum for one bitmap
long maxMemory = Runtime.getRuntime().maxMemory();
int maxMemoryForImage = (int) (maxMemory / 100 * 25);
// Refer to
// http://developer.android.com/training/displaying-bitmaps/cache-bitmap.html
// A full screen GridView filled with images on a device with
// 800x480 resolution would use around 1.5MB (800*480*4 bytes)
// When bitmap option's inSampleSize doubled, pixel height and
// weight both reduce in half
int scale = 1;
while ((o.outWidth / scale) * (o.outHeight / scale) * 4 > maxMemoryForImage)
scale *= 2;
// Decode with inSampleSize
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize = scale;
fis = new FileInputStream(f);
try
{
b = BitmapFactory.decodeStream(fis, null, o2);
}
finally
{
fis.close();
}
}
catch (IOException e)
{
}
return b;
}
I set the maximum memory used by this bitmap to be 25% of maximum allocated memory, you may need to adjust this to your needs and make sure this bitmap is cleaned up and don't stay in memory when you've finished using it. Typically I use this code to perform image rotation (source and destination bitmap) so my app needs to load 2 bitmaps in memory at the same time, and 25% gives me a good buffer without running out of memory when performing image rotation.
Hope this helps someone out there..

use these code for every image in select from SdCard or drewable to convert bitmap object.
Resources res = getResources();
WindowManager window = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
Display display = window.getDefaultDisplay();
#SuppressWarnings("deprecation")
int width = display.getWidth();
#SuppressWarnings("deprecation")
int height = display.getHeight();
try {
if (bitmap != null) {
bitmap.recycle();
bitmap = null;
System.gc();
}
bitmap = Bitmap.createScaledBitmap(BitmapFactory
.decodeFile(ImageData_Path.get(img_pos).getPath()),
width, height, true);
} catch (OutOfMemoryError e) {
if (bitmap != null) {
bitmap.recycle();
bitmap = null;
System.gc();
}
BitmapFactory.Options options = new BitmapFactory.Options();
options.inPreferredConfig = Config.RGB_565;
options.inSampleSize = 1;
options.inPurgeable = true;
bitmapBitmap.createScaledBitmap(BitmapFactory.decodeFile(ImageData_Path.get(img_pos)
.getPath().toString(), options), width, height,true);
}
return bitmap;
use your image path instend of ImageData_Path.get(img_pos).getPath() .

Generally android device heap size is only 16MB (varies from device/OS see post Heap Sizes), if you are loading the images and it crosses the size of 16MB , it will throw out of memory exception, instead of using the Bitmap for , loading images from SD card or from resources or even from network try to using getImageUri , loading bitmap require more memory , or you can set bitmap to null if your work done with that bitmap.

My 2 cents: i solved my OOM errors with bitmaps by:
a) scaling my images by a factor of 2
b) using Picasso library in my custom Adapter for a ListView, with a one-call in getView like this: Picasso.with(context).load(R.id.myImage).into(R.id.myImageView);

Such OutofMemoryException cannot be totally resolved by calling the System.gc() and so on .
By referring to the Activity Life Cycle
The Activity States are determined by the OS itself subject to the memory usage for each process and the priority of each process.
You may consider the size and the resolution for each of the bitmap pictures used. I recommend to reduce the size ,resample to lower resolution , refer to the design of galleries (one small picture PNG , and one original picture.)

This code will help to load large bitmap from drawable
public class BitmapUtilsTask extends AsyncTask<Object, Void, Bitmap> {
Context context;
public BitmapUtilsTask(Context context) {
this.context = context;
}
/**
* Loads a bitmap from the specified url.
*
* #param url The location of the bitmap asset
* #return The bitmap, or null if it could not be loaded
* #throws IOException
* #throws MalformedURLException
*/
public Bitmap getBitmap() throws MalformedURLException, IOException {
// Get the source image's dimensions
int desiredWidth = 1000;
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(context.getResources(), R.drawable.green_background , options);
int srcWidth = options.outWidth;
int srcHeight = options.outHeight;
// Only scale if the source is big enough. This code is just trying
// to fit a image into a certain width.
if (desiredWidth > srcWidth)
desiredWidth = srcWidth;
// Calculate the correct inSampleSize/scale value. This helps reduce
// memory use. It should be a power of 2
int inSampleSize = 1;
while (srcWidth / 2 > desiredWidth) {
srcWidth /= 2;
srcHeight /= 2;
inSampleSize *= 2;
}
// Decode with inSampleSize
options.inJustDecodeBounds = false;
options.inDither = false;
options.inSampleSize = inSampleSize;
options.inScaled = false;
options.inPreferredConfig = Bitmap.Config.ARGB_8888;
options.inPurgeable = true;
Bitmap sampledSrcBitmap;
sampledSrcBitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.green_background , options);
return sampledSrcBitmap;
}
/**
* The system calls this to perform work in a worker thread and delivers
* it the parameters given to AsyncTask.execute()
*/
#Override
protected Bitmap doInBackground(Object... item) {
try {
return getBitmap();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
}

Java: Getting a font with a specific height in pixels

It’s easy to determine the rendered height of a font using FontMetrics, but what about the other way around? How can I obtain a font that will fit into a specific height in pixels?
"Give me Verdana in a size that is 30 pixels high from ascender to descender."
How do I ask Java for this?

I know this is a very old question, but someone might still find it:
The font height in Java (and many other places) is given in "typographic points", which are defined as roughly 1/72nd of an inch.
To calculate the points needed for a certain pixel height, you should be able to use the following:
double fontSize= 72.0 * pixelSize / Toolkit.getDefaultToolkit().getScreenResolution();
I haven't tested this extensively yet, but it seems to work for the monitors that I've used. I'll report back if I ever find a case where it doesn't work.
For the standard system fonts I've used this with, this sets the height of a capital letter (i.e. the ascent) to the provided pixel size. If you need to set the ascent+descent to the pixel size, you can correct the value using the FontMetrics:
FontMetrics m= g.getFontMetrics(font); // g is your current Graphics object
double totalSize= fontSize * (m.getAscent() + m.getDescent()) / m.getAscent();
Of course, the actual pixel-height of some specific letters will depend on the letter and the font used, so if you want to make sure that your "H" is some exact number of pixels tall, you might still want to use the trial-and-error methods mentioned in the other answers. Just keep in mind that if you use these methods to get the size for each specific text you want to display (as #Bob suggested), you might end up with a random font-size-mess on your screen where a text like "ace" will have much bigger letters than "Tag". To avoid this, I would pick one specific letter or letter sequence ("T" or "Tg" or something) and fix that one to your pixel height once and then use the font size you get from that everywhere.

I don't think there's a "direct" way to find a font by height; only an indirect way... by looping through the sizes, and testing the height of each is <= required height.
If you're doing this once, just loop through them... if you've doing it "on the fly" then do a binary search, it'll be quicker.

I'm not aware of a way to get a font by its actual height in pixels. It depends on the context it's used in so there's probably no shorter way than to sample for the best match. It should be pretty quick to look for sizes up or down from the designed height. Here's an example method that does that:
public Font getFont(String name, int style, int height) {
int size = height;
Boolean up = null;
while (true) {
Font font = new Font(name, style, size);
int testHeight = getFontMetrics(font).getHeight();
if (testHeight < height && up != Boolean.FALSE) {
size++;
up = Boolean.TRUE;
} else if (testHeight > height && up != Boolean.TRUE) {
size--;
up = Boolean.FALSE;
} else {
return font;
}
}
}

WhiteFang34's code is useful in combination with the following method that returns the actual height of a specific string. It might be a bit slow for real-time rendering, especially for large fonts/strings and I'm sure it can be further optimised, but for now it meets my own needs and is fast enough to run in a back-end process.
/*
* getFontRenderedHeight
* *************************************************************************
* Summary: Font metrics do not give an accurate measurement of the rendered
* font height for certain strings because the space between the ascender
* limit and baseline is not always fully used and descenders may not be
* present. for example the strings '0' 'a' 'f' and 'j' are all different
* heights from top to bottom but the metrics returned are always the same.
* If you want to place text that exactly fills a specific height, you need
* to work out what the exact height is for the specific string. This method
* achieves that by rendering the text and then scanning the top and bottom
* rows until the real height of the string is found.
*/
/**
* Calculate the actual height of rendered text for a specific string more
* accurately than metrics when ascenders and descenders may not be present
* <p>
* Note: this method is probably not very efficient for repeated measurement
* of large strings and large font sizes but it works quite effectively for
* short strings. Consider measuring a subset of your string value. Also
* beware of measuring symbols such as '-' and '.' the results may be
* unexpected!
*
* #param string
* The text to measure. You might be able to speed this process
* up by only measuring a single character or subset of your
* string i.e if you know your string ONLY contains numbers and
* all the numbers in the font are the same height, just pass in
* a single digit rather than the whole numeric string.
* #param font
* The font being used. Obviously the size of the font affects
* the result
* #param targetGraphicsContext
* The graphics context the text will actually be rendered in.
* This is passed in so the rendering options for anti-aliasing
* can be matched.
* #return Integer - the exact actual height of the text.
* #author Robert Heritage [mrheritage#gmail.com]
*/
public Integer getFontRenderedHeight(String string, Font font, Graphics2D targetGraphicsContext) {
BufferedImage image;
Graphics2D g;
Color textColour = Color.white;
// In the first instance; use a temporary BufferedImage object to render
// the text and get the font metrics.
image = new BufferedImage(1, 1, BufferedImage.TYPE_INT_RGB);
g = image.createGraphics();
FontMetrics metrics = g.getFontMetrics(font);
Rectangle2D rect = metrics.getStringBounds(string, g);
// now set up the buffered Image with a canvas size slightly larger than
// the font metrics - this guarantees that there is at least one row of
// black pixels at the top and the bottom
image = new BufferedImage((int) rect.getWidth() + 1, (int) metrics.getHeight() + 2, BufferedImage.TYPE_INT_RGB);
g = image.createGraphics();
// take the rendering hints from the target graphics context to ensure
// the results are accurate.
g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, targetGraphicsContext.getRenderingHint(RenderingHints.KEY_ANTIALIASING));
g.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, targetGraphicsContext.getRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING));
g.setColor(textColour);
g.setFont(font);
g.drawString(string, 0, image.getHeight());
// scan the bottom row - descenders will be cropped initially, so the
// text will need to be moved up (down in the co-ordinates system) to
// fit it in the canvas if it contains any. This may need to be done a
// few times until there is a row of black pixels at the bottom.
boolean foundBottom, foundTop = false;
int offset = 0;
do {
g.setColor(Color.BLACK);
g.fillRect(0, 0, image.getWidth(), image.getHeight());
g.setColor(textColour);
g.drawString(string, 0, image.getHeight() - offset);
foundBottom = true;
for (int x = 0; x < image.getWidth(); x++) {
if (image.getRGB(x, image.getHeight() - 1) != Color.BLACK.getRGB()) {
foundBottom = false;
}
}
offset++;
} while (!foundBottom);
System.out.println(image.getHeight());
// Scan the top of the image downwards one line at a time until it
// contains a non-black pixel. This loop uses the break statement to
// stop the while loop as soon as a non-black pixel is found, this
// avoids the need to scan the rest of the line
int y = 0;
do {
for (int x = 0; x < image.getWidth(); x++) {
if (image.getRGB(x, y) != Color.BLACK.getRGB()) {
foundTop = true;
break;
}
}
y++;
} while (!foundTop);
return image.getHeight() - y;
}