I use this code to make 100 screen captures:
Rectangle screenRect = new Rectangle(Toolkit.getDefaultToolkit().getScreenSize());
for(int i = 0; i < 100; i++){
BufferedImage capture = new Robot().createScreenCapture(screenRect);
ImageIO.write(capture, "jpg", new File("D:/pictures/pic" + i + ".jpg"));
}
Why is the cursor blinking when are taking the captures? Is something wrong in my code?
No, there is nothing wrong with your code. From the Javadocs:
This image does not include the mouse cursor.
So Java hides the cursor momentarily in order to take the screenshot, then it makes it visible again.
Related
I'm using a piece of code to grab a screenshot of my application screen for a group project. On my Macbook Pro the code freezes the screen whereas on my teammates's PC's (all Windows) it runs just fine and exports a .png file in their root dir.
The code
public void screenShot(){
//Creating an rbg array of total pixels
int[] pixels = new int[WIDTH * HEIGHT];
int bindex;
// allocate space for RBG pixels
ByteBuffer fb = ByteBuffer.allocateDirect(WIDTH * HEIGHT * 3);
// grab a copy of the current frame contents as RGB
glReadPixels(0, 0, WIDTH, HEIGHT, GL_RGB, GL_UNSIGNED_BYTE, fb);
// convert RGB data in ByteBuffer to integer array
for (int i=0; i < pixels.length; i++) {
bindex = i * 3;
pixels[i] =
((fb.get(bindex) << 16)) +
((fb.get(bindex+1) << 8)) +
((fb.get(bindex+2) << 0));
}
//Allocate colored pixel to buffered Image
BufferedImage imageIn = null;
try{
//THIS LINE
imageIn = new BufferedImage(WIDTH, HEIGHT,BufferedImage.TYPE_INT_RGB);
//THIS LINE ^^^^^
imageIn.setRGB(0, 0, WIDTH, HEIGHT, pixels, 0 , WIDTH);
} catch (Exception e) {
e.printStackTrace();
}
The problem
When debugging I can see that when stepping in at this line
imageIn = new BufferedImage(WIDTH, HEIGHT,BufferedImage.TYPE_INT_RGB);
the debugger doesn't go to the BufferedImage constructor but to GLFWKeyCallbackI.callback() and after that to GLFWCursorEnterCallbackI.callback(). After this it stops altogether.
What I tried
In my main class above all the rest of the code making a buffered Image as such:
BufferedImage imageIn = new BufferedImage(100,100,BufferedImage.TYPE_INT_RGB);
It also freezes the simulation but it does seems to actually execute the line.
I'm not sure what else I could try, I saw a few other posts ranging between 2005 and today asking similar Mac questions without an answer.
I delved a bit deeper and discovered the issue. As mentioned in a comment here if I provide this VM option "-Djava.awt.headless=true" it seems to fix the issue.
The below data matrix is being read well using Barcode Scanner, zxing mobile app. However, the same is not being read by zxing java library.
I have some image transformation code commented. Even transforming the image, rotation or scaling doesn't help.
Ideally, I would like to perform all possible image pre-processing programatically until decoded.
What is the logic the mobile app using, since am scanning the same image from the computer screen and it is working.
Please find below, the code am using for decoding.
public class BarcodeReader {
private static Map<DecodeHintType,Object> hintsMap;
public static void main(String...args){
BufferedImage before = null;
hintsMap = new EnumMap<DecodeHintType, Object>(DecodeHintType.class);
hintsMap.put(DecodeHintType.TRY_HARDER, Boolean.TRUE);
hintsMap.put(DecodeHintType.POSSIBLE_FORMATS, EnumSet.allOf(BarcodeFormat.class));
//hintsMap.put(DecodeHintType.PURE_BARCODE, Boolean.FALSE);
try
{
before = ImageIO.read(new File("C:/ocr.jpg"));
decode(before);
/* for(int i=1; i < 1000;i++){
AffineTransform transform = new AffineTransform();
double rad = (double)i/100;
double scale = (double)i/100;
System.out.println("rad "+scale);
//transform.rotate(rad, before.getWidth()/2, before.getHeight()/2);
transform.scale(scale, scale);
BufferedImage after = new BufferedImage(before.getWidth(), before.getHeight(), BufferedImage.TYPE_INT_ARGB);
AffineTransformOp op = new AffineTransformOp(transform, AffineTransformOp.TYPE_BILINEAR);
after = op.filter(before, after);
decode(after);
}*/
//tmpBfrImage = tmpBfrImage.getSubimage(200, 100, 800, 800);
}
catch (IOException tmpIoe)
{
tmpIoe.printStackTrace();
}
}
public static void decode(BufferedImage tmpBfrImage){
if (tmpBfrImage == null)
throw new IllegalArgumentException("Could not decode image.");
LuminanceSource tmpSource = new BufferedImageLuminanceSource(tmpBfrImage);
BinaryBitmap tmpBitmap = new BinaryBitmap(new HybridBinarizer(tmpSource));
MultiFormatReader tmpBarcodeReader = new MultiFormatReader();
Result tmpResult;
String tmpFinalResult;
try
{
if (hintsMap != null && ! hintsMap.isEmpty())
tmpResult = tmpBarcodeReader.decode(tmpBitmap, hintsMap);
else
tmpResult = tmpBarcodeReader.decode(tmpBitmap);
// setting results.
tmpFinalResult = String.valueOf(tmpResult.getText());
System.out.println(tmpFinalResult);
System.exit(0);;
}
catch (Exception tmpExcpt)
{
tmpExcpt.printStackTrace();
}
}
}
I had problems at multiple levels. I downloaded zxing source from github and debugged it.
The first problem was adding the below line as hints screws up the recognition hintsMap.put(DecodeHintType.PURE_BARCODE, Boolean.FALSE);
Looking at their source code for DataMatrixReader, there was a line doing this
if (hints != null && hints.containsKey(DecodeHintType.PURE_BARCODE))
So, irrespective of setting PURE_BARCODE true or false, it considers it as true. Ideally hints should not contain the key.
The second problem was with the way the detector for DataMatrix works.
The detector was identifying the 'L' by looking at the number of black and white transitions from each vertices. Ideally, the transitions from Top-Left to Bottom-Left and Bottom-Left to Bottom-Right should have 0 transitions.
However, since the line was drawn closer towards the outer edge of the box, the transitions were not becoming 0. I made changes to move it closer to the center of the Left and Bottom Black Lines. This means moving the vertical red line to the right and the bottom red line a bit upwards. I added a new method Correct Points, that makes the necessary correction. This correction works for me, ideally one should be making the correction a bit more smarter.
ResultPoint pointA = correctPoints(cornerPoints[0], Vertices.TOPLEFT);
ResultPoint pointB = correctPoints(cornerPoints[1], Vertices.BOTTOMLEFT);
ResultPoint pointC = correctPoints(cornerPoints[2], Vertices.TOPRIGHT);
ResultPoint pointD = correctPoints(cornerPoints[3], Vertices.BOTTOMRIGHT);
---
---
private ResultPoint correctPoints(ResultPoint point, Vertices vertice){
if(vertice.equals(Vertices.TOPLEFT))
return new ResultPoint(point.getX()+10, point.getY()+5);
else if(vertice.equals(Vertices.BOTTOMLEFT)){
return new ResultPoint(point.getX()+10, point.getY()-5);
}else if(vertice.equals(Vertices.TOPRIGHT)){
return new ResultPoint(point.getX(), point.getY()+10);
}else{
return new ResultPoint(point.getX()-10, point.getY()-5);
}
}
After making these changes, data matrix detection was working for images that were as bad as or even poorer than these.
I was having similar problems using ZXing to decode DataMatrix barcodes. From what I can see, ZXing doesn't traverse the entire image you send it, but rather starts from the middle and expands out until it has found a barcode. So, if the DataMatrix barcode isn't centered in the image, ZXing will not be able to reliably find it. I implemented (a rather slow) workaround that fixes this problem, by creating different cropped versions of the image:
My core decode method is similar to that of the original post. My image traversal logic is as follows:
// Read the original image
final BufferedImage image = ImageIO.read(...);
final int width = image.getWidth();
final int height = image.getHeight();
// Try detect codes using different sections of the image.
//
// +------+------+
// | ##|## |
// | ##|## |
// | ##|## |
// +------+------+
// | | |
// | | |
// | | |
// +------+------+
//
// We create 9 cropped versions of the image, with each cropped
// version being 1/4 of the original image. We traverse the
// original image from left-to-right, top-to-bottom, and create
// 9 sub-images that we try to decode in turn.
for (int i=0; i<3; i++) {
for (int j=0; j<3; j++) {
final int x = i * width / 4;
final int y = j * height / 4;
final BufferedImage crop = image.getSubimage(x, y, width / 2, height / 2);
decoded(crop);
}
}
I am trying to extract all the frames of an animated gif to an array of bufferedimages. I have been reading Convert each animated GIF frame to a separate BufferedImage and it was fairly easy to write each frame to a seperate file. But my problem comes up when I try to fill an ArrayList with the frames instead of writing them. Every image in the ArrayList is just the last frame of the gif.
To make it more clear, this code will write each frame to seperate files perfectly:
ArrayList<BufferedImage> frames = new ArrayList<BufferedImage>();
BufferedImage master = new BufferedImage(128, 128, BufferedImage.TYPE_INT_ARGB);
ImageReader ir = new GIFImageReader(new GIFImageReaderSpi());
ir.setInput(ImageIO.createImageInputStream(gif));
for (int i = 0; i < ir.getNumImages(true); i++)
{
master.getGraphics().drawImage(ir.read(i), 0, 0, null);
ImageIO.write(master, "gif", new File(dirGifs + "/frames" + i + ".gif"));
}
However, this code will only gives me an ArrayList full of the same frame (being the last frame of the gif)
ArrayList<BufferedImage> frames = new ArrayList<BufferedImage>();
BufferedImage master = new BufferedImage(128, 128, BufferedImage.TYPE_INT_ARGB);
ImageReader ir = new GIFImageReader(new GIFImageReaderSpi());
ir.setInput(ImageIO.createImageInputStream(gif));
for (int i = 0; i < ir.getNumImages(true); i++)
{
master.getGraphics().drawImage(ir.read(i), 0, 0, null);
frames.add(master);
}
I thought that it was because I wasnt disposing of the graphics afterwards, but I tried creating a graphics object and disposing it and nothing changed. Need help!
It's because the BufferedImage master is being stored in the ArrayList as a reference and not as a copy. So each element of the ArrayList points to the same BufferedImage. I think the easiest way to solve this is just to put the line BufferedImage master = new BufferedImage(128, 128, BufferedImage.TYPE_INT_ARGB); inside the for loop, so a new instance of BufferedImage is created on each iteration.
Colouredmirrorball pointed out that I could solve this problem by creating a new instance of the bufferedimage. So I created a new instance for each array element first and then set the element's data to the same as the master image. The following piece of code gives me an array of frames extracted from an animated gif file.
public ArrayList<BufferedImage> getFrames(File gif) throws IOException {
ArrayList<BufferedImage> frames = new ArrayList<BufferedImage>();
BufferedImage master = new BufferedImage(128, 128, BufferedImage.TYPE_INT_ARGB);
ImageReader ir = new GIFImageReader(new GIFImageReaderSpi());
ir.setInput(ImageIO.createImageInputStream(gif));
for (int i = 0; i < ir.getNumImages(true); i++) {
frames.add(new BufferedImage(128, 128, BufferedImage.TYPE_INT_ARGB));
master.getGraphics().drawImage(ir.read(i), 0, 0, null);
frames.get(i).setData(master.getData());
}
return frames;
}
I want to read the image selected by user using JFileChooser and then be able to get the color Channels(R,G,B) and the width and height of the image.
Is this the right approach to read the selected image file.
File im1 = new File(chooser.getSelectedFile(), null);
BufferedImage buff =ImageIO.read(im1);
Or is there a better way to read the image file in order to get the values of its separate color channels and get its separate values.
Your code looks okay. Just keep going with width, height and RGB.
File im1 = chooser.getSelectedFile();
BufferedImage buff = ImageIO.read(im1);
if (buff != null) {
System.out.println(buff.getWidth() + " " + buff.getHeight());
System.out.println(buff.getRGB(0, 0));
}
I haven't found any 'better' way to load the image so I believe you're doing it right.
To answer your whole question, here's an example how to get specific color channels out of the image.
Color c = new Color(image.getRGB());
int red = c.getRed();
int green = c.getGreen();
int blue = c.getBlue();
I am making a icon for my app.. The app is basically a friend finder. I am creating a overlay that looks much like the icons from Google Latitude. I have an image that changes due to the user and I have the boarder. I've been able to do the layered drawable and overlay fine, but the problem is, the image stretches to the size of the border. This is a problem because, if you've never seen the Google Lat icons, it has a point on the bottom with open space between it.
What I need to do is, somehow restrict the size of the changing image to the bounds of the square portion of the border. Any Help would be much appreciated. Here is my snippet:
BitmapFactory.Options options = new BitmapFactory.Options();
options.inSampleSize = 25;
Bitmap bit = BitmapFactory.decodeFile(photo, options);
draw = new BitmapDrawable(bit);
Resources r = getResources();
Drawable[] layers = new Drawable[2];
layers[0] = draw;
layers[1] = r.getDrawable(R.drawable.border);
LayerDrawable layerDrawable = new LayerDrawable(layers);
draw = layerDrawable;
}else{
draw = this.getResources().getDrawable(R.drawable.androidmarker);
}
HelloItemizedOverlay itemizedoverlay = new HelloItemizedOverlay(draw, this);
GeoPoint point = new GeoPoint(lat,lon);
OverlayItem overlayitem = new OverlayItem(point, username, avail + " : " + status + " : Position updated at : " + update_at);
items.add(overlayitem);
itemizedoverlay.addOverlay(overlayitem);
mapOverlays.add(itemizedoverlay);
Funny that shorty after I posted this, I found the answer. I was looking in all of the wrong places to resize the image. I tried the bitmap, the drawable, the layers inside of the layerdrawable. But, what I never tried was the layerdrawable itself. The solution is below:
Resources r = getResources();
Drawable[] layers = new Drawable[2];
layers[0] = draw;
layers[1] = r.getDrawable(R.drawable.border);
LayerDrawable layerDrawable = new LayerDrawable(layers);
layerDrawable.setLayerInset(0, 0, 0, 0, 12);
draw = layerDrawable;
The layerDrawable inset method is as follows:
layerDrawable.setLayerInset(*index of layer*, *left inset*, *top*, *right*, *bottom*);
Thanks guys!