View Drag Helper helper - java

I am trying to get the ViewDragHelper to work with a vertical LinearLayout, - Container - which has
A ---- List View
B ---- horizontal linear layout
C ---- Support Map Fragment
as children views.
A has layout_height="0dp". Pulling down on B, should proportionally increase the height of A, there by revealing the contents on the ListView, thereby automatically re positioning B and resizing C in the process.
The following is the code for the Container LinearLayout.
public class MyLinearLayout extends LinearLayout {
private LinearLayout headerLayout;
private ListView filtersListView;
private ViewDragHelper viewDragHelper;
private int MARGIN;
public MyLinearLayout (Context context) {
super(context);
init();
}
public MyLinearLayout (Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public MyLinearLayout (Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
private void init() {
viewDragHelper = ViewDragHelper.create(this, 1, new DragHelperCallback());
float GESTURE_THRESHOLD_DP = 10.0f;
float scale = getResources().getDisplayMetrics().density;
MARGIN = (int) (GESTURE_THRESHOLD_DP * scale + 0.5f);
}
#Override
protected void onFinishInflate() {
Log.i("Places", "onFinishInflate");
super.onFinishInflate();
headerLayout = (LinearLayout) findViewById(R.id.header);
filtersListView = (ListView) findViewById(R.id.filters_list);
}
#Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
Log.i("Places", "onInterceptTouchEvent");
return viewDragHelper.shouldInterceptTouchEvent(ev);
}
#Override
public boolean onTouchEvent(MotionEvent event) {
Log.i("Places", "onTouchEvent");
viewDragHelper.processTouchEvent(event);
LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, (int) event.getRawY());
layoutParams.setMargins(MARGIN, MARGIN, MARGIN, MARGIN);
filtersListView.setLayoutParams(layoutParams);
return true;
}
private class DragHelperCallback extends ViewDragHelper.Callback {
#Override
public boolean tryCaptureView(View child, int pointerId) {
Log.i("Places", "tryCaptureView " + (child == headerLayout));
return child == headerLayout;
}
#Override
public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) {
Log.i("Places", "onViewPositionChanged " + changedView.getClass().getName());
super.onViewPositionChanged(changedView, left, top, dx, dy);
}
#Override
public void onViewReleased(View releasedChild, float xvel, float yvel) {
Log.i("Places", "onViewReleased " + releasedChild.getClass().getName());
super.onViewReleased(releasedChild, xvel, yvel);
}
}
}
I have looked at the the following.
ViewDragHelper: how to use it?


Your ViewDragHelper is a bit off. Specifically you're missing the clampViewPositionVertical() override, which is required to enable dragging of the view at all. Right now, your ViewDragHelper is actually doing no work. You are probably getting some motion because you are manipulating the LayoutParams directly for every onTouchEvent(), which will also cause some problems.
You likely want your callback code to look more like this:
#Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
return viewDragHelper.shouldInterceptTouchEvent(ev);
}
#Override
public boolean onTouchEvent(MotionEvent event) {
viewDragHelper.processTouchEvent(event);
return true;
}
private class DragHelperCallback extends ViewDragHelper.Callback {
#Override
public int clampViewPositionVertical(View child, int top, int dy) {
//Never go below fully visible
final int bottomBound = getHeight() - child.getHeight();
//Never go above the top
final int topBound = 0;
return Math.max(Math.min(top, bottomBound), topBound);
}
#Override
public boolean tryCaptureView(View child, int pointerId) {
//Capture touches to the header view
return child == headerLayout;
}
#Override
public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) {
if (dy == 0) return;
//React to the position change of the header by modifying layout
LinearLayout.LayoutParams layoutParams = (LayoutParams) filtersListView.getLayoutParams();
layoutParams.height += dy;
filtersListView.setLayoutParams(layoutParams);
}
}
This sets the drag bounds of your "header view" to move freely between the top of the container view and the bottom (clamping it so it doesn't go off-screen). By itself, this will only move the header view. Moving your LayoutParams code into onViewPositionChanged() lets your top/bottom views react to the exact drag distance.
Two Warnings:
Don't add margins to your LayoutParams. The way you are using them to constantly modify proportions will cause the dragging to jump. If you need to inset the ListView content, use padding or another nested container.
Changing the layout of an entire view continuously like this can be very expensive (layout passes are not cheap, and you trigger one every time you modify LayoutParams). This may work for a very simple layout, but if your view gets more complex you will likely see performance suffer on older hardware.

Related

notifyItemRemoved() scrolls the recycler view but does not call onScrolled()

I have a recyclerView set up to work as a carousel view. As the items move they expand as they get close to the centre of the screen. The method to scale the views is called by overriding onScrolled(). My problem is when deleting an item the view is scrolled but onScrolled() is not called and the views do not scale. Is there a way to know when a view is removed and the animation is finished?
I can not override onItemRangeRemoved() because that is only called at the start of the delete.
#Override
public void onChanged() {
super.onChanged();
initEmptyView();
addOnScrollListener(new OnScrollListener() {
#Override
public void onScrolled(#NonNull RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
onScrollChanged();
}
});
}
public void onScrollChanged(){
for (int i = 0; i < getChildCount(); i++){
View child = getChildAt(i);
int childCenterX = (child.getLeft() + child.getRight()) / 2;
double spreadFactor = 150;
float scaleValue = getGaussianScale(childCenterX, 1f, 0.1f, spreadFactor);
child.setScaleX(scaleValue);
child.setScaleY(scaleValue);
}
int currentPosition = myLayoutManager.findFirstCompletelyVisibleItemPosition();
((TopUp) context).setCurrentPosition(currentPosition);
}

Found it.
recyclerView.setItemAnimator(new DefaultItemAnimator(){
#Override
public void onRemoveFinished(RecyclerView.ViewHolder item) {
super.onRemoveFinished(item);
}
});

What is the best way to automatically scroll to the top of a recycler view after hitting the bottom?

I'm creating an android app that displays a recyclerview of cards. I have implemented an auto-scroll feature as part of my linear layout manager that will smoothscroll to the last element in the recyclerview.
I would like the list to snap back to the top of the recyclerview once it has detected that the last element is visible.
Here is the code for my custom layout manager.
public class ScrollLayoutManager extends LinearLayoutManager {
private static final float MILLISECONDS_PER_INCH = 10000f; //default is 25f (bigger = slower)
public ScrollLayoutManager(Context context) {
super(context);
}
public ScrollLayoutManager(Context context, int orientation, boolean reverseLayout) {
super(context, orientation, reverseLayout);
}
public ScrollLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
#Override
public void smoothScrollToPosition(RecyclerView recyclerView, RecyclerView.State state, int position) {
final LinearSmoothScroller linearSmoothScroller = new LinearSmoothScroller(recyclerView.getContext()) {
#Override
public PointF computeScrollVectorForPosition(int targetPosition) {
return super.computeScrollVectorForPosition(targetPosition);
}
#Override
protected float calculateSpeedPerPixel(DisplayMetrics displayMetrics) {
return MILLISECONDS_PER_INCH / displayMetrics.densityDpi;
}
};
linearSmoothScroller.setTargetPosition(position);
startSmoothScroll(linearSmoothScroller);
}
}

You might want attach a RecyclerView.OnScrollListener (docs) to your RecyclerView and override onScrolled() and use either findLastCompletelyVisibleItemPosition() (docs) or findLastVisibleItemPosition() (docs), depending on your needs, in combination with getItemCount() (docs) to check if you hit the last item and then scroll back to the top.

Vertical ViewPager. Stop scrolling past certain point

I've created a vertical ViewPager, using ViewPage.PageTransformer and swapping X and Y coordinates. (I use this approach)
Now, what I want it to do is to stop scrolling at a certain point (I want the last view to take only 65% of the screen's height, but the full width).
Usually, I would override getPageWidth() in this case, but since my width and height are kind of mixed up right now, when I do that, my view takes 65% of both the height and width of the screen.
So how should I fix this?
Thank you!
MyViewPager.java
public class MyViewPager extends ViewPager {
public MyViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
private void init() {
setPageTransformer(true, new VerticalPageTransformer());
setOverScrollMode(OVER_SCROLL_NEVER);
}
private class VerticalPageTransformer implements ViewPager.PageTransformer {
#Override
public void transformPage(View view, float position) {
if (position < -1) {
view.setAlpha(0);
} else if (position <= 1) {
view.setAlpha(1);
view.setTranslationX(view.getWidth() * -position);
float yPosition = position * view.getHeight();
view.setTranslationY(yPosition);
} else {
view.setAlpha(0);
}
}
}
private MotionEvent swapXY(MotionEvent ev) {
float width = getWidth();
float height = getHeight();
float newX = (ev.getY() / height) * width;
float newY = (ev.getX() / width) * height;
ev.setLocation(newX, newY);
return ev;
}
#Override
public boolean onTouchEvent(MotionEvent ev) {
return super.onTouchEvent(swapXY(ev));
}
#Override
public boolean onInterceptTouchEvent(MotionEvent ev){
boolean intercepted = super.onInterceptTouchEvent(swapXY(ev));
swapXY(ev);
return intercepted;
}
}
MyPagerAdapter.java
public class MyPagerAdapter extends PagerAdapter {
private Context context;
private LayoutInflater layoutInflater;
public MyPagerAdapter(Context context) {
this.context = context;
layoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
#Override
public int getCount() {
return 2;
}
#Override
public boolean isViewFromObject(View view, Object object) {
return view == object;
}
#Override
public Object instantiateItem(ViewGroup container, final int position) {
if (position == 0) {
View view = layoutInflater.inflate(R.layout.item_profile_picture, container, false);
container.addView(view);
return view;
}
else {
View view = layoutInflater.inflate(R.layout.item_profile_info, container, false);
container.addView(view);
return view;
}
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((FrameLayout) object);
}
#Override
public float getPageWidth(int position) {
if (position == 1) return (0.65f);
return super.getPageWidth(position);
}
}

Hi as far as I understand you are trying to stop at certain point without having the overscroll. Add overscroll(never) method to the viewpager that you want. And manage your margins on the objects. Wrap content as much as possible.

Solved this problem by using this library.

NestedScrollView not fling with Recyclerview inside

I have a layout like that:
<NestedScrollView>
<RecyclerView> // vertical recycler view
<RecyclerView/> // horizontal recycler view
<RecyclerView/>
<RecyclerView/>
...
<RecyclerView>
</NestedScrollView>
The result looks like Google play store:
And I disabled NestedScrolling in horizontal Recycler view:
horizontalRecyclerView.setHasFixedSize(true);
horizontalRecyclerView.setNestedScrollingEnabled(false);
My problem:
The vertical recyclerview does not scroll fling, whenever ACTION_UP happen, the vertical recyclerview also stop scrolling.
How can I nest vertical recyclerview inside nestedscrollview, and horizontal recyclerview inside vertical recyclerview like Playstore and keep the scroll smooth.
Solved:
Using custom nested scroll view of #vrund purohit (code below), and disabled nestedscroll both vertical and horizontal recyclerview:
verticalRecyclerView.setNestedScrollingEnabled(false);
... add each horizontal recyclerviews:
horizontalRecyclerView.setNestedScrollingEnabled(false);

Use below code for smooth scroll:
ViewCompat.setNestedScrollingEnabled(recyclerView, false);

Add this in your RecyclerView xml:
android:nestedScrollingEnabled="false"

I had this same problem and I solved this issue by customizing NeatedScrollView.
Here is the class for that.
MyNestedScrollView
public class MyNestedScrollView extends NestedScrollView {
#SuppressWarnings("unused")
private int slop;
#SuppressWarnings("unused")
private float mInitialMotionX;
#SuppressWarnings("unused")
private float mInitialMotionY;
public MyNestedScrollView(Context context) {
super(context);
init(context);
}
private void init(Context context) {
ViewConfiguration config = ViewConfiguration.get(context);
slop = config.getScaledEdgeSlop();
}
public MyNestedScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public MyNestedScrollView(Context context, AttributeSet attrs,
int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context);
}
private float xDistance, yDistance, lastX, lastY;
#SuppressWarnings("unused")
#Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
final float x = ev.getX();
final float y = ev.getY();
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
xDistance = yDistance = 0f;
lastX = ev.getX();
lastY = ev.getY();
// This is very important line that fixes
computeScroll();
break;
case MotionEvent.ACTION_MOVE:
final float curX = ev.getX();
final float curY = ev.getY();
xDistance += Math.abs(curX - lastX);
yDistance += Math.abs(curY - lastY);
lastX = curX;
lastY = curY;
if (xDistance > yDistance) {
return false;
}
}
return super.onInterceptTouchEvent(ev);
}
public interface OnScrollChangedListener {
void onScrollChanged(NestedScrollView who, int l, int t, int oldl,
int oldt);
}
private OnScrollChangedListener mOnScrollChangedListener;
public void setOnScrollChangedListener(OnScrollChangedListener listener) {
mOnScrollChangedListener = listener;
}
#Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
if (mOnScrollChangedListener != null) {
mOnScrollChangedListener.onScrollChanged(this, l, t, oldl, oldt);
}
}
}
Happy coding.

[RESOLVED] I have same issue with Horizontal recycleview. Change Gradle repo for recycleview
compile 'com.android.support:recyclerview-v7:23.2.1'
Write this: linearLayoutManager.setAutoMeasureEnabled(true);
Fixed bugs related to various measure-spec methods in update
Check http://developer.android.com/intl/es/tools/support-library/features.html#v7-recyclerview
I have found issue with 23.2.1 library: When item is match_parent recycle view fill full item to view, please always go with min height or "wrap_content".
Thanks

I've solved the issue by using below code:
myRecyclerView.setLayoutManager(new LinearLayoutManager(getContext(), LinearLayoutManager.VERTICAL, false){
#Override
public boolean canScrollHorizontally() {
return true;
}
#Override
public boolean canScrollVertically() {
return true;
}
});

Popup gridview cell onTOuch

I have a grid View In which I am adding Button dynamically.
I am setting OnTouch listener to grid view.
I want when my finger move on the particular cell then that cell element should get popup
similar way our android keyboard do.
public class MainActivity extends Activity {
private ArrayList<Integer> data;
private GridView gv;
private TextView biggerView = null;
#SuppressLint("NewApi")
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
createData();
gv = (GridView) findViewById(R.id.grid);
gv.setNumColumns(10);
gv.setAdapter(new FilterButtonAdapter(data, this));
gv.setOnTouchListener(new OnTouchListener() {
#Override
public boolean onTouch(View arg0, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_MOVE) {
try {
int position = gv.pointToPosition((int) event.getX(),
(int) event.getY());
View v = (View) gv.getChildAt(position);
if (v != null) {
gv.requestFocus();
gv.setSelection(gv.pointToPosition( (int)
event.getX(), (int) event.getY()));
}
return true;
} catch (Exception e) {
return true;
}
}
if (event.getAction() == MotionEvent.ACTION_UP) {
int position = gv.pointToPosition((int) event.getX(),
(int) event.getY());
View v = (View) gv.getChildAt(position);
if (v != null) {
gv.clearFocus();
TextView tv = (TextView) v.findViewById(R.id.texttoadd);
Toast.makeText(MainActivity.this, tv.getText(),
Toast.LENGTH_SHORT).show();
}
return true;
}
return false;
}
});
}
private void createData() {
data = new ArrayList<Integer>();
for (int i = 0; i < 200; i++) {
data.add(i);
}
}
enter code here
i have write this code which is giving me the selected item but when item are more then grid is scrolled and after that the am not getting the item which i am selecting
i have figured out that the x and y position is getting change when grid is scrolled
i may be wrong
please help

I think that suggested in the question way of touch position detection might be not effective, because there's more high-level way to obtain scrolling position.
The main ideas of the implementation are the following:
Use onScrollChanged() to track scroll position at every moment;
Display selection as separate view above GridView;
Track if selected item is visible (using this question);
So, to obtain proper scroll callback, slightly customized GridView is needed:
public class ScrollAwareGridView extends GridView {
/** Callback interface to report immediate scroll changes */
public interface ImmediateScrollListener {
void onImmediateScrollChanged();
}
/** External listener for */
private ImmediateScrollListener mScrollListener = null;
public ScrollAwareGridView(final Context context) {
super(context);
}
public ScrollAwareGridView(final Context context, final AttributeSet attrs) {
super(context, attrs);
}
public ScrollAwareGridView(final Context context, final AttributeSet attrs, final int defStyle) {
super(context, attrs, defStyle);
}
#Override
protected void onScrollChanged(final int l, final int t, final int oldl, final int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
if (null != mScrollListener) {
mScrollListener.onImmediateScrollChanged();
}
}
/**
* #param listener {#link ImmediateScrollListener}
*/
public void setImmediateScrollListener(final ImmediateScrollListener listener) {
mScrollListener = listener;
}
}
It will be placed in the xml the following way (main.xml):
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.example.TestApp.ScrollAwareGridView
android:id="#+id/grid"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:numColumns="3" />
<!-- Selection view -->
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/selectedImage"
android:visibility="gone" />
</RelativeLayout>
In above xml there's also selection view presented.
Activity will handle selection of items (however, it might be better to keep selection and scroll tracking logic in separate object (grid adapter or specific grid fragment) in order not to keep grid-specific logic in Activity code):
public class MyActivity extends Activity implements ScrollAwareGridView.ImmediateScrollListener, AdapterView.OnItemClickListener {
private static final String TAG = "MyActivity";
/** To start / pause music */
private ImageView mSelectedImage = null;
/** position of selected item in the adapter */
private int mSelectedPosition;
/** Main grid view */
private ScrollAwareGridView mGrid;
/** Adapter for grid view */
private ImageAdapter mAdapter;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Show the layout with the test view
setContentView(R.layout.main);
mSelectedImage = (ImageView) findViewById(R.id.selectedImage);
mGrid = (ScrollAwareGridView) findViewById(R.id.grid);
if (null != mGrid) {
mAdapter = new ImageAdapter(this);
mGrid.setAdapter(mAdapter);
mGrid.setImmediateScrollListener(this);
mGrid.setOnItemClickListener(this);
}
}
#Override
protected void onPause() {
super.onPause();
}
#Override
protected void onResume() {
super.onResume();
mSelectedImage.setImageBitmap(null);
mSelectedImage.setVisibility(View.GONE);
mSelectedPosition = -1;
}
#Override
public void onImmediateScrollChanged() {
if (mSelectedPosition >= 0) {
int firstPosition = mGrid.getFirstVisiblePosition(); // This is the same as child #0
int wantedChild = mSelectedPosition - firstPosition;
// Say, first visible position is 8, you want position 10, wantedChild will now be 2
// So that means your view is child #2 in the ViewGroup:
if (wantedChild < 0 || wantedChild >= mGrid.getChildCount()) {
Log.w(TAG, "Unable to get view for desired position, because it's not being displayed on screen.");
mSelectedImage.setVisibility(View.INVISIBLE);
return;
} else {
mSelectedImage.setVisibility(View.VISIBLE);
}
// Could also check if wantedPosition is between listView.getFirstVisiblePosition() and listView.getLastVisiblePosition() instead.
final View selectedView = mGrid.getChildAt(wantedChild);
if (null != selectedView && mSelectedImage.getVisibility() == View.VISIBLE) {
// Put selected view on new position
final ViewGroup.MarginLayoutParams zoomedImageLayoutParams = (ViewGroup.MarginLayoutParams) mSelectedImage.getLayoutParams();
// 200 is difference between zoomed and not zoomed images dimensions
// TODO: Avoid hardcoded values and use resources
final Integer thumbnailX = mGrid.getLeft() + selectedView.getLeft() - (ImageAdapter.HIGHLIGHTED_GRID_ITEM_DIMENSION - ImageAdapter.GRID_ITEM_DIMENSION) / 2;
final Integer thumbnailY = mGrid.getTop() + selectedView.getTop() - (ImageAdapter.HIGHLIGHTED_GRID_ITEM_DIMENSION - ImageAdapter.GRID_ITEM_DIMENSION) / 2;
zoomedImageLayoutParams.setMargins(thumbnailX,
thumbnailY,
0,
0);
mSelectedImage.setLayoutParams(zoomedImageLayoutParams);
}
}
}
#Override
public void onItemClick(final AdapterView<?> parent, final View view, final int position, final long id) {
mSelectedPosition = position;
final Bitmap bm = mAdapter.getImage(position);
// Obtain image from adapter, with check if image presented
if (bm != null) {
final ViewGroup.MarginLayoutParams zoomedImageLayoutParams = (ViewGroup.MarginLayoutParams) mSelectedImage.getLayoutParams();
// 200 is difference between zoomed and not zoomed images dimensions
// TODO: Avoid hardcoded values and use resources
final Integer thumbnailX = mGrid.getLeft() + view.getLeft() - (ImageAdapter.HIGHLIGHTED_GRID_ITEM_DIMENSION - ImageAdapter.GRID_ITEM_DIMENSION) / 2;
final Integer thumbnailY = mGrid.getTop() + view.getTop() - (ImageAdapter.HIGHLIGHTED_GRID_ITEM_DIMENSION - ImageAdapter.GRID_ITEM_DIMENSION) / 2;
zoomedImageLayoutParams.setMargins(thumbnailX,
thumbnailY,
0,
0);
zoomedImageLayoutParams.height = ImageAdapter.HIGHLIGHTED_GRID_ITEM_DIMENSION;
zoomedImageLayoutParams.width = ImageAdapter.HIGHLIGHTED_GRID_ITEM_DIMENSION;
mSelectedImage.setImageBitmap(bm);
mSelectedImage.setScaleType(ImageView.ScaleType.CENTER);
mSelectedImage.setLayoutParams(zoomedImageLayoutParams);
mSelectedImage.setVisibility(View.VISIBLE);
}
}
}
Below is GridViews adapter. However there's nothing specific in it which related to scrolling tracking (most of code I've reused from this answer):
public class ImageAdapter extends BaseAdapter {
private static final String TAG = "ImageAdapter";
/** For creation of child ImageViews */
private Context mContext;
public static final Integer[] IMAGES_RESOURCES = {
R.drawable.image001, R.drawable.image002, R.drawable.image003, R.drawable.image004,
R.drawable.image005, R.drawable.image006, R.drawable.image007, R.drawable.image008,
R.drawable.image009, R.drawable.image010, R.drawable.image011, R.drawable.image012,
R.drawable.image013, R.drawable.image014, R.drawable.image015, R.drawable.image016,
R.drawable.image017, R.drawable.image018, R.drawable.image019, R.drawable.image020,
R.drawable.image021, R.drawable.image022, R.drawable.image023, R.drawable.image024,
R.drawable.image025, R.drawable.image026, R.drawable.image027, R.drawable.image028,
R.drawable.image029, R.drawable.image030, R.drawable.image031, R.drawable.image032,
R.drawable.image033, R.drawable.image034, R.drawable.image035, R.drawable.image036,
R.drawable.image037, R.drawable.image038, R.drawable.image039, R.drawable.image040,
R.drawable.image041, R.drawable.image042, R.drawable.image043, R.drawable.image044,
R.drawable.image045, R.drawable.image046, R.drawable.image047, R.drawable.image048,
R.drawable.image049, R.drawable.image050
};
// TODO: use resources for that sizes, otherwise You'll GET PROBLEMS on other displays!
public final static int GRID_ITEM_DIMENSION = 300;
public final static int HIGHLIGHTED_GRID_ITEM_DIMENSION = 500;
private Bitmap mHolder = null;
private static final int CACHE_SIZE = 50 * 1024 * 1024; // 8 MiB cache
/** Cache to store all decoded images */
private LruCache<Integer, Bitmap> mBitmapsCache = new LruCache<Integer, Bitmap>(CACHE_SIZE) {
#Override
protected int sizeOf(final Integer key, final Bitmap value) {
return value.getByteCount();
}
#Override
protected void entryRemoved(final boolean evicted, final Integer key, final Bitmap oldValue, final Bitmap newValue) {
if (!oldValue.equals(mHolder)) {
oldValue.recycle();
}
}
};
// Constructor
public ImageAdapter(Context c){
mContext = c;
mHolder = BitmapFactory.decodeResource(c.getResources(), R.drawable.ic_launcher, null);
}
#Override
public int getCount() {
return IMAGES_RESOURCES.length;
}
#Override
public Object getItem(int position) {
return IMAGES_RESOURCES[position];
}
#Override
public long getItemId(int position) {
return position;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
if (convertView == null) {
imageView = new ImageView(mContext);
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setLayoutParams(new GridView.LayoutParams(GRID_ITEM_DIMENSION, GRID_ITEM_DIMENSION));
} else {
imageView = (ImageView) convertView;
}
final Bitmap itemBitmap = mBitmapsCache.get(IMAGES_RESOURCES[position]);
if (itemBitmap == null || itemBitmap.isRecycled()) {
Log.e(TAG, position + " is missed, launch decode for " + IMAGES_RESOURCES[position]);
imageView.setImageBitmap(mHolder);
mBitmapsCache.put(IMAGES_RESOURCES[position], mHolder);
new BitmapWorkerTask(mBitmapsCache, mContext.getResources(), this).execute(IMAGES_RESOURCES[position]);
} else {
Log.e(TAG, position + " is here for " + IMAGES_RESOURCES[position]);
imageView.setImageBitmap(itemBitmap);
}
return imageView;
}
/**
* Obtains image at position (if there's only holder, then null to be returned)
*
* #param position int position in the adapter
*
* #return {#link Bitmap} image at position or null if image is not loaded yet
*/
public Bitmap getImage(final int position) {
final Bitmap bm = mBitmapsCache.get(IMAGES_RESOURCES[position]);
return ((mHolder.equals(bm) || bm == null) ? null : bm.copy(Bitmap.Config.ARGB_8888, false));
}
/** AsyncTask for decoding images from resources */
static class BitmapWorkerTask extends AsyncTask<Integer, Void, Bitmap> {
private int data = 0;
private final LruCache<Integer, Bitmap> mCache;
private final Resources mRes;
private final BaseAdapter mAdapter;
public BitmapWorkerTask(LruCache<Integer, Bitmap> cache, Resources res, BaseAdapter adapter) {
// nothing to do here
mCache = cache;
mRes = res;
mAdapter = adapter;
}
// Decode image in background.
#Override
protected Bitmap doInBackground(Integer... params) {
data = params[0];
// Use sizes for selected bitmaps for good up-scaling
return decodeSampledBitmapFromResource(mRes, data, GRID_ITEM_DIMENSION, GRID_ITEM_DIMENSION);
}
// Once complete, see if ImageView is still around and set bitmap.
#Override
protected void onPostExecute(Bitmap bitmap) {
mCache.put(data, bitmap);
mAdapter.notifyDataSetChanged();
}
}
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;
options.outHeight = GRID_ITEM_DIMENSION;
options.outWidth = GRID_ITEM_DIMENSION;
return BitmapFactory.decodeResource(res, resId, options);
}
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) {
// 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;
}
}

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