Develop Reference

Call setVisibility while the view is animated

When i call setVisibility on view's child while the (parent) view is animated with ViewCompat.postOnAnimation things get broken. (setVisibility doesn't work + some other things get broken).
Question - is there any method of animation or workaround which allows to call setVisibility on child while the parent is animated?
This is very important request and i think not so unusual, because for example http request is returned in random time, and the view can be animated anytime during that.
Code request edit:
Regarding code, it is bit complicated. I will first explain. It is animation in the custom CoordinatorLayout Behavior, clone of the standard BottomSheetBehavior (sliding of sheet from bottom to up).
Animation is launched by calling this:
ViewCompat.postOnAnimation(child, new SettleRunnable(child, targetState));
SettleRunnable is this:
private class SettleRunnable implements Runnable {
private final View mView;
#State
private final int mTargetState;
SettleRunnable(View view, #State int targetState) {
mView = view;
mTargetState = targetState;
}
#Override
public void run() {
if (mViewDragHelper != null && mViewDragHelper.continueSettling(true)) {
ViewCompat.postOnAnimation(mView, this);
} else {
setStateInternal(mTargetState);
}
}
}
So as you can see, all the animation movement is done by mViewDragHelper.continueSettling. Drag helper is standard class ViewDragHelper.
ViewDragHelper.continueSettling looks like this
public boolean continueSettling(boolean deferCallbacks) {
if (mDragState == STATE_SETTLING) {
boolean keepGoing = mScroller.computeScrollOffset();
final int x = mScroller.getCurrX();
final int y = mScroller.getCurrY();
final int dx = x - mCapturedView.getLeft();
final int dy = y - mCapturedView.getTop();
if (dx != 0) {
ViewCompat.offsetLeftAndRight(mCapturedView, dx);
}
if (dy != 0) {
ViewCompat.offsetTopAndBottom(mCapturedView, dy);
}
if (dx != 0 || dy != 0) {
mCallback.onViewPositionChanged(mCapturedView, x, y, dx, dy);
}
if (keepGoing && x == mScroller.getFinalX() && y == mScroller.getFinalY()) {
// Close enough. The interpolator/scroller might think we're still moving
// but the user sure doesn't.
mScroller.abortAnimation();
keepGoing = false;
}
if (!keepGoing) {
if (deferCallbacks) {
mParentView.post(mSetIdleRunnable);
} else {
setDragState(STATE_IDLE);
}
}
}
return mDragState == STATE_SETTLING;
}
It simply animates the sheet up or down to desired position according the chosen target state.
Pseudo code of problem is:
launchAnimation(); // it takes eg 300 ms
changeVisibilityOfAnimatedViewChildren(); // this is problem
I can wait until the animation finishes, but as i said, in case of http request it is bit problem, i would like to ideally refresh the data right away without waiting.
Animated element is CoordinatorLayout. Affected child by setVisibility is one or more its children.
Judging by this link, android seems to have generally problem with animations and setVisibility.
Possible solutions i am thinking of now:
Maybe if i would change the visibility with another parallel postOnAnimation() task (?)
Or because it are basically just step by step subsequent calls of moving function mViewDragHelper.continueSettling() why don't do it without postOnAnimation()? I could run the task also without it. But i guess that postOnAnimation chooses some correct delay of animation step for concrete device + probably some other things.

You can add AnimatorListenerAdapter to your parent animation, and override onAnimationEnd() method. In this method you can call the child animation. However, I would rather change alpha of view than visibility. You can achieve more smoothly effect in this case.
For example, consider this code:
parentAnimationInstance.addListener(new AnimatorListenerAdapter() {
#Override
public void onAnimationEnd(Animator animation) {
super.onAnimationEnd(animation);
childView.animate()
.alpha(1.f)
.setDuration(200)
.start();
}
});

removeView doesn't remove View immediately and destroys Layout

I'm trying to dynamically remove some components in a LinearLayout in Android. The logic I have implemented is: If someone clicks a Button in my (Sidebar)Fragment I start an Animation that moves the clicked Button up and the Other Buttons out of the left side of the Display. The Animation triggers an AnimationListener that, after the Animation is complete, iterates over all Buttons in the Layout and removes all non clicked Buttons.
The Problem is: if I disable the Fade Out Animation and step in with the debugger i can see, that after removeView() the Views are still there.
The even bigger Problem is that my Button that should still be Visible (the clicked one) disappears and only shows up again, if I set X and Y Position manually at a later Time.
Is there any way i can "fix" the Button while removal and when does removeView() actually remove the View/update the Layout?
I already tried to remove all Views and then add the Button again with the same result.
Some snippets to clear things up a Bit:
//Start Animation over all Components
//Commented out the move outside animation to ensure the Layout doesn't get streched in this process
for (mComponentIterator = mLayout.getChildCount() - 1; mComponentIterator >= 0; mComponentIterator--) {
final ImageTextButton currentButton = (ImageTextButton) mLayout
.getChildAt(mComponentIterator);
ObjectAnimator buttonAnimation;
if (!currentButton.equals(pClickedButton)) {
// buttonAnimation = ObjectAnimator.ofFloat(currentButton, View.X, POSITION_OUTSIDE);
} else {
// buttonAnimation = ObjectAnimator.ofFloat(currentButton, View.Y, POSITION_UPPER);
animations.add( ObjectAnimator.ofFloat(currentButton, View.Y, POSITION_UPPER));
currentButton.setFocused(true);
mSelectedButton = currentButton;
}
// animations.add(buttonAnimation);
}
buttonAnimations.playTogether(animations);
buttonAnimations.setDuration(mShortAnimationDuration);
buttonAnimations.setInterpolator(new DecelerateInterpolator());
buttonAnimations.addListener(new AnimatorListenerAdapter() {
#Override
public void onAnimationEnd(Animator arg0) {
for (mComponentIterator = mLayout.getChildCount() - 1; mComponentIterator >= 0; mComponentIterator--) {
final ImageTextButton currentButton = (ImageTextButton) mLayout
.getChildAt(mComponentIterator);
if (currentButton.equals(mSelectedButton)) {
if (mCurrentFragment != null) {
//This changes the Layout in another
mListener.onChangeLayoutRequest(R.id.maincontent, mCurrentFragment);
}
} else {
mLayout.removeView(currentButton);
}
}
}
});
buttonAnimations.start();
//Callback when Activity is ready
mCurrentFragment.SetOnActivityCreatedListener(new OnActivityCreatedListener() {
#Override
public void onActivityCreated(Activity activity) {
Drawable grayMenuBackground = getActivity().getResources().getDrawable(
R.drawable.bg_menuitem);
Drawable coloredMenuBackground = grayMenuBackground.getConstantState()
.newDrawable();
coloredMenuBackground.setColorFilter(mSelectedMenuColor,
PorterDuff.Mode.SRC_ATOP);
LinearLayout.LayoutParams rightGravityParams = new LinearLayout.LayoutParams(
LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
rightGravityParams.gravity = Gravity.TOP;
rightGravityParams.weight = 0;
Drawable seperator = getResources().getDrawable(R.drawable.seperator_menu);
seperator.setBounds(new Rect(0, 0, mSelectedButton.getWidth(), 1));
int insertIndex = 1;
for (Button menuButton : mCurrentFragment.getMenuItems()) {
//Some Button setupcode
mLayout.addView(menuButton, insertIndex++);
}
//Here the Button gets visible again
mSelectedButton.setLayoutParams(rightGravityParams);
mSelectedButton.setX(POSITION_LEFT);
mSelectedButton.setY(POSITION_UPPER);
}
});
Im stuck at this problem for two days now. Currently the Buttons Animate in the right manner, then, right after the animation has finished, all Buttons dissapear(also the Clicked Button). Then, after 1/2sec. the other fragment needs to load, the clicked button appears again
PS: I already scheduled the removal with ''mLayout.post()'' with the same result

What happens if you simply do:
button.setVisibility(View.GONE) ;
Added some comments along your code.
//Start Animation over all Components
//Commented out the move outside animation to ensure the Layout doesn't get streched in this process
for (mComponentIterator = mLayout.getChildCount() - 1; mComponentIterator >= 0; mComponentIterator--) {
final ImageTextButton currentButton = (ImageTextButton) mLayout
.getChildAt(mComponentIterator);
ObjectAnimator buttonAnimation;
if (!currentButton.equals(pClickedButton)) {
// buttonAnimation = ObjectAnimator.ofFloat(currentButton, View.X, POSITION_OUTSIDE);
} else {
// buttonAnimation = ObjectAnimator.ofFloat(currentButton, View.Y, POSITION_UPPER);
/*
* You say that you want to keep the clicked button, yet you
* add it to the animations?
*/
animations.add( ObjectAnimator.ofFloat(currentButton, View.Y, POSITION_UPPER));
currentButton.setFocused(true);
mSelectedButton = currentButton;
}
// animations.add(buttonAnimation);
}
buttonAnimations.playTogether(animations);
buttonAnimations.setDuration(mShortAnimationDuration);
buttonAnimations.setInterpolator(new DecelerateInterpolator());
buttonAnimations.addListener(new AnimatorListenerAdapter() {
#Override
public void onAnimationEnd(Animator arg0) {
for (mComponentIterator = mLayout.getChildCount() - 1; mComponentIterator >= 0; mComponentIterator--) {
final ImageTextButton currentButton = (ImageTextButton) mLayout
.getChildAt(mComponentIterator);
if (currentButton.equals(mSelectedButton)) {
if (mCurrentFragment != null) {
//This changes the Layout in another
/*
* What exactly does this do and why does it have to
* be done (numberOfButtons - 1) times?
*/
mListener.onChangeLayoutRequest(R.id.maincontent, mCurrentFragment);
}
} else {
/*
* This does indeed only remove the non selected buttons
* I think, but the animation is still applied to
* the selcted button.
* So it makes sense that you have to reset X and Y
* to see it again.
*/
mLayout.removeView(currentButton);
}
}
}
});
buttonAnimations.start();
//Callback when Activity is ready
mCurrentFragment.SetOnActivityCreatedListener(new OnActivityCreatedListener() {
#Override
public void onActivityCreated(Activity activity) {
Drawable grayMenuBackground = getActivity().getResources().getDrawable(
R.drawable.bg_menuitem);
Drawable coloredMenuBackground = grayMenuBackground.getConstantState()
.newDrawable();
coloredMenuBackground.setColorFilter(mSelectedMenuColor,
PorterDuff.Mode.SRC_ATOP);
LinearLayout.LayoutParams rightGravityParams = new LinearLayout.LayoutParams(
LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
rightGravityParams.gravity = Gravity.TOP;
rightGravityParams.weight = 0;
Drawable seperator = getResources().getDrawable(R.drawable.seperator_menu);
seperator.setBounds(new Rect(0, 0, mSelectedButton.getWidth(), 1));
int insertIndex = 1;
for (Button menuButton : mCurrentFragment.getMenuItems()) {
//Some Button setupcode
mLayout.addView(menuButton, insertIndex++);
}
//Here the Button gets visible again
mSelectedButton.setLayoutParams(rightGravityParams);
mSelectedButton.setX(POSITION_LEFT);
mSelectedButton.setY(POSITION_UPPER);
}
});

Android invalidate(Rect) invalidates entire region

I don't understand why invalidate(Rect) is invalidating the entire region.
The region is divided up into 5 sections and a line graph is being drawn in each one. Each section contains 100 points. As the data arrives for times tn to tn+100 I call invalidate(new Rect(left, top, right bottom)) where top is the top of the screen in height (but a lower numerical value than bottom). This invokes a call to the onDraw() method. The region from tn to tn+100 is drawn, but the previously drawn segment in region tn-100 to tn is erased. It continues that way forever. Each invalidate draws in only that region (since that is the only data I have) which IS correct, but all the previously drawn data is erased. So I get a marching segment!
In other words, I get identical behavior if I call invalidate() or invalidate(Rect).
I am assuming that the parameters of the Rect() are pixels and are getting the values based upon the height and width of the AlertDialog window in which this is being drawn.
The hope is eventually to reduce the region of 'Rect()' so I can simulate real time drawing and only invalidate time step t to t+1 instead of a region.
I must be doing something stupid.
I hope that the fact it is being done in an AlertDialog is not the issue.
This part is for trying to help 'android developer' help a noob like me get this right.
First the sequence of events:
1. Data is received via Bluetooth in a callback
2. If it is the right type of data, a BroadcastReceiver in the main activity (UI thread) is signaled and from there a routine is called that sets the parameters of a WaveFormView extends View class and then ShowDialog(id) is called which calls the onCreateDialog(id) callback in the main activity.
3. Then I call invalidate().
4. The dialog pops up and then the graph is drawn.
5. All subsequent calls to ShowDialog(id) bypass the onCreateDialog(id)
That works but the entire region is always invalidated regardless of the parameters. There are also no user events here. From your example the best I could come up with is the following where I place invalidate in the onShow() instead of calling myself after the showDialog(id)
#Override
protected Dialog onCreateDialog(int id)
{
Log.d(TAG, "Alert Dialog 'onCreateDialog' method has been called with id " + id);
Builder bldr = new AlertDialog.Builder(this);
AlertDialog alert = bldr.setView(waveForm).setNegativeButton("Dismiss " + id,
new DialogInterface.OnClickListener()
{
public void onClick(DialogInterface dialog, int id)
{
dialog.cancel();
}
}).create();
// I tried adding this and invalidating here worked only first pass
alert.setOnShowListener(
new DialogInterface.OnShowListener()
{
#Override
public void onShow(DialogInterface dialog)
{
// call to invalidate
waveForm.drawArea();
}
});
//alert.getWindow().setLayout(alert.getWindow().getAttributes().width, alert.getWindow().getAttributes().height / 2);
alert.getWindow().setLayout(waveForm.getCurrentWidth(), waveForm.getCurrentHeight());
return alert;
}
However the onShow() does not get called.
The method in the main activity that calls the showDialog is
private void displayRtsa(int[] rtsaReceived)
{
// rtsaReceived[0] has the agentsink hash code
int agent = rtsaReceived[0];
// rtsaReceived[1] has the index of the RtsaData object updated
int index = rtsaReceived[1];
TreeMap<Integer, RtsaData[]> agentRtsa = BluetoothPanService.getAgentRtsaMap();
RtsaData[] rtsaDataValues = agentRtsa.get(agent);
int dialogId = 0;
synchronized(dialogIds)
{
int i = 0;
if(dialogIds.containsKey(agent + index) == false)
{
for(i = 0; i < dialogIds.size(); i++)
{
if(dialogIds.containsValue(i) == false)
{
break;
}
}
dialogIds.put(agent + index, i);
}
dialogId = dialogIds.get(agent + index);
}
final int id = dialogId;
Log.d(TAG, "Dialog id being shown = " + dialogId);
waveForm.setPeriod(rtsaDataValues[index].getPeriod());
waveForm.setMaxMin(rtsaDataValues[index].getMinValue(), rtsaDataValues[index].getMaxValue());
waveForm.setColor(Color.argb(255, 255, 200, 0));
waveForm.setData(rtsaDataValues[index].getData());
waveForm.setTitle(rtsaDataValues[index].getType());
showDialog(id);
// invalidate
// waveForm.drawArea(); (try to do in onCreateDialog callback)
}
This is probably a completely wrong approach. Probably openGl is the only way.
By the way, thanks for putting up with me!

i think it depends on what exactly you do the invalidation on . if the view you are calling the invalidation on didn't handle a rectangular invalidation , the default invalidation takes place.
in any case , if you wish to change the behavior , you can change it yourself. for the "onDraw" method , use the next code in order to fetch the invalidated rectangle :
public class InvalidateTestActivity extends Activity
{
static class CustomView extends ImageView
{
public CustomView(Context context)
{
super(context);
}
#Override
protected void onDraw(Canvas canvas)
{
final Rect r = canvas.getClipBounds();
Log.d("DEBUG", "rectangle of invalidation:" + r);
super.onDraw(canvas);
}
}
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
CustomView customView = new CustomView(this);
customView.setLayoutParams(new FrameLayout.LayoutParams(200, 200));
customView.setBackgroundColor(0xffff0000);
customView.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v)
{
v.invalidate(new Rect(0, 0, 49, 49));
}
});
setContentView(customView);
}
}

If you have hardware acceleration enabled it looks like it just invalidates the whole view...
ViewGroup:
public final void invalidateChild(View child, final Rect dirty) {
final AttachInfo attachInfo = mAttachInfo;
if (attachInfo != null && attachInfo.mHardwareAccelerated) {
// HW accelerated fast path
onDescendantInvalidated(child, child);
return;
}

What's the best way to check if the view is visible on the window?

What's the best way to check if the view is visible on the window?
I have a CustomView which is part of my SDK and anybody can add CustomView to their layouts. My CustomView is taking some actions when it is visible to the user periodically. So if view becomes invisible to the user then it needs to stop the timer and when it becomes visible again it should restart its course.
But unfortunately there is no certain way of checking if my CustomView becomes visible or invisible to the user. There are few things that I can check and listen to: onVisibilityChange //it is for view's visibility change, and is introduced in new API 8 version so has backward compatibility issue
onWindowVisibilityChange //but my CustomView can be part of a ViewFlipper's Views so it can pose issues
onDetachedFromWindows //this not as useful
onWindowFocusChanged //Again my CustomView can be part of ViewFlipper's views. So if anybody has faced this kind of issues please throw some light.

In my case the following code works the best to listen if the View is visible or not:
#Override
protected void onWindowVisibilityChanged(int visibility) {
super.onWindowVisibilityChanged(visibility);
Log.e(TAG, "is view visible?: " + (visibility == View.VISIBLE));
}

onDraw() is called each time the view needs to be drawn. When the view is off screen then onDraw() is never called. When a tiny bit of the view is becomes visible to the user then onDraw() is called. This is not ideal but I cannot see another call to use as I want to do the same thing. Remember to call the super.onDraw or the view won't get drawn. Be careful of changing anything in onDraw that causes the view to be invalidate as that will cause another call to onDraw.
If you are using a listview then getView can be used whenever your listview becomes shown to the user.
obviously the activity onPause() is called all your views are all covered up and are not visible to the user. perhaps calling invalidate() on the parent and if ondraw() is not called then it is not visible.

This is a method that I have used quite a bit in my apps and have had work out quite well for me:
static private int screenW = 0, screenH = 0;
#SuppressWarnings("deprecation") static public boolean onScreen(View view) {
int coordinates[] = { -1, -1 };
view.getLocationOnScreen(coordinates);
// Check if view is outside left or top
if (coordinates[0] + view.getWidth() < 0) return false;
if (coordinates[1] + view.getHeight() < 0) return false;
// Lazy get screen size. Only the first time.
if (screenW == 0 || screenH == 0) {
if (MyApplication.getSharedContext() == null) return false;
Display display = ((WindowManager)MyApplication.getSharedContext().getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
try {
Point screenSize = new Point();
display.getSize(screenSize); // Only available on API 13+
screenW = screenSize.x;
screenH = screenSize.y;
} catch (NoSuchMethodError e) { // The backup methods will only be used if the device is running pre-13, so it's fine that they were deprecated in API 13, thus the suppress warnings annotation at the start of the method.
screenW = display.getWidth();
screenH = display.getHeight();
}
}
// Check if view is outside right and bottom
if (coordinates[0] > screenW) return false;
if (coordinates[1] > screenH) return false;
// Else, view is (at least partially) in the screen bounds
return true;
}
To use it, just pass in any view or subclass of view (IE, just about anything that draws on screen in Android.) It'll return true if it's on screen or false if it's not... pretty intuitive, I think.
If you're not using the above method as a static, then you can probably get a context some other way, but in order to get the Application context from a static method, you need to do these two things:
1 - Add the following attribute to your application tag in your manifest:
android:name="com.package.MyApplication"
2 - Add in a class that extends Application, like so:
public class MyApplication extends Application {
// MyApplication exists solely to provide a context accessible from static methods.
private static Context context;
#Override public void onCreate() {
super.onCreate();
MyApplication.context = getApplicationContext();
}
public static Context getSharedContext() {
return MyApplication.context;
}
}

In addition to the view.getVisibility() there is view.isShown().
isShown checks the view tree to determine if all ancestors are also visible.
Although, this doesn't handle obstructed views, only views that are hidden or gone in either themselves or one of its parents.

In dealing with a similar issue, where I needed to know if the view has some other window on top of it, I used this in my custom View:
#Override
public void onWindowFocusChanged(boolean hasWindowFocus) {
super.onWindowFocusChanged(hasWindowFocus);
if (!hasWindowFocus) {
} else {
}
}

This can be checked using getGlobalVisibleRect method. If rectangle returned by this method has exactly the same size as View has, then current View is completely visible on the Screen.
/**
* Returns whether this View is completely visible on the screen
*
* #param view view to check
* #return True if this view is completely visible on the screen, or false otherwise.
*/
public static boolean onScreen(#NonNull View view) {
Rect visibleRect = new Rect();
view.getGlobalVisibleRect(visibleRect);
return visibleRect.height() == view.getHeight() && visibleRect.width() == view.getWidth();
}
If you need to calculate visibility percentage you can do it using square calculation:
float visiblePercentage = (visibleRect.height() * visibleRect.width()) / (float)(view.getHeight() * view.getWidth())

This solution takes into account view obstructed by statusbar and toolbar, also as view outside the window (e.g. scrolled out of screen)
/**
* Test, if given {#code view} is FULLY visible in window. Takes into accout window decorations
* (statusbar and toolbar)
*
* #param view
* #return true, only if the WHOLE view is visible in window
*/
public static boolean isViewFullyVisible(View view) {
if (view == null || !view.isShown())
return false;
//windowRect - will hold available area where content remain visible to users
//Takes into account screen decorations (e.g. statusbar)
Rect windowRect = new Rect();
view.getWindowVisibleDisplayFrame(windowRect);
//if there is toolBar, get his height
int actionBarHeight = 0;
Context context = view.getContext();
if (context instanceof AppCompatActivity && ((AppCompatActivity) context).getSupportActionBar() != null)
actionBarHeight = ((AppCompatActivity) context).getSupportActionBar().getHeight();
else if (context instanceof Activity && ((Activity) context).getActionBar() != null)
actionBarHeight = ((Activity) context).getActionBar().getHeight();
//windowAvailableRect - takes into account toolbar height and statusbar height
Rect windowAvailableRect = new Rect(windowRect.left, windowRect.top + actionBarHeight, windowRect.right, windowRect.bottom);
//viewRect - holds position of the view in window
//(methods as getGlobalVisibleRect, getHitRect, getDrawingRect can return different result,
// when partialy visible)
Rect viewRect;
final int[] viewsLocationInWindow = new int[2];
view.getLocationInWindow(viewsLocationInWindow);
int viewLeft = viewsLocationInWindow[0];
int viewTop = viewsLocationInWindow[1];
int viewRight = viewLeft + view.getWidth();
int viewBottom = viewTop + view.getHeight();
viewRect = new Rect(viewLeft, viewTop, viewRight, viewBottom);
//return true, only if the WHOLE view is visible in window
return windowAvailableRect.contains(viewRect);
}

you can add to your CustomView's constractor a an onScrollChangedListener from ViewTreeObserver
so if your View is scrolled of screen you can call view.getLocalVisibleRect() and determine if your view is partly offscreen ...
you can take a look to the code of my library : PercentVisibleLayout
Hope it helps!

in your custom view, set the listeners:
getViewTreeObserver().addOnScrollChangedListener(this);
getViewTreeObserver().addOnGlobalLayoutListener(this);
I am using this code to animate a view once when it is visible to user.
2 cases should be considered.
Your view is not in the screen. But it will be visible if user scrolled it
public void onScrollChanged() {
final int i[] = new int[2];
this.getLocationOnScreen(i);
if (i[1] <= mScreenHeight - 50) {
this.post(new Runnable() {
#Override
public void run() {
Log.d("ITEM", "animate");
//animate once
showValues();
}
});
getViewTreeObserver().removeOnScrollChangedListener(this);
getViewTreeObserver().removeOnGlobalLayoutListener(this);
}
}
Your view is initially in screen.(Not in somewhere else invisible to user in scrollview, it is in initially on screen and visible to user)
public void onGlobalLayout() {
final int i[] = new int[2];
this.getLocationOnScreen(i);
if (i[1] <= mScreenHeight) {
this.post(new Runnable() {
#Override
public void run() {
Log.d("ITEM", "animate");
//animate once
showValues();
}
});
getViewTreeObserver().removeOnGlobalLayoutListener(this);
getViewTreeObserver().removeOnScrollChangedListener(this);
}
}

Applying successive animations to ImageView in Android

I would like to apply successive animations (say ScaleAnimation) to an ImageView showing a resource image. The animation is triggered by a button. For example, I would like to incrementally enlarge an image upon each button click.
I've set fillAfter="true" on the animation. However, all the animations start from the original state of the ImageView. It seems as if the ImageView resets its state and the animation is always the same, instead of starting from the final state of the previous animation.
What am I doing wrong?
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button button = (Button)findViewById(R.id.Button01);
button.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
animate();
}});
}
private void animate() {
ImageView imageView = (ImageView) findViewById(R.id.ImageView01);
ScaleAnimation scale = new ScaleAnimation((float)1.0, (float)1.5, (float)1.0, (float)1.5);
scale.setFillAfter(true);
scale.setDuration(500);
imageView.startAnimation(scale);
}

It seems as if the ImageView resets
its state and the animation is always
the same, instead of starting from the
final state of the previous animation.
Precisely! I'm sure there's a use for fillAfter="true", but I haven't figured out the point for it yet.
What you need to do is set up an AnimationListener on each Animation of relevance, and do something in the listener's onAnimationEnd() to actually persist the end state of your animation. I haven't played with ScaleAnimation so I'm not quite sure what the way to "persist the end state" would be. If this were an AlphaAnimation, going from 1.0 to 0.0, you would make the widget INVISIBLE or GONE in onAnimationEnd(), for example.

I've had the same problem and created the following code to easily use different animations. It only supports translation and alpha levels for now as I haven't used scaling, but could easily be extended to support more features.
I reset the scroll and the visibility before starting the animation, but that's just because I needed on/off animations.
And the "doEnd" boolean is there to avoid a stack overflow on the recursion (scrollTo calls onAnimationEnd for some obscure reason...)
private void setViewPos(View view, Animation anim, long time){
// Get the transformation
Transformation trans = new Transformation();
anim.getTransformation(time, trans);
// Get the matrix values
float[] values = new float[9];
Matrix m = trans.getMatrix();
m.getValues(values);
// Get the position and apply the scroll
final float x = values[Matrix.MTRANS_X];
final float y = values[Matrix.MTRANS_Y];
view.scrollTo(-(int)x, -(int)y);
// Show/hide depending on final alpha level
if (trans.getAlpha() > 0.5){
view.setVisibility(VISIBLE);
} else {
view.setVisibility(INVISIBLE);
}
}
private void applyAnimation(final View view, final Animation anim){
view.scrollTo(0, 0);
view.setVisibility(VISIBLE);
anim.setAnimationListener(new AnimationListener(){
private boolean doEnd = true;
#Override
public void onAnimationEnd(Animation animation) {
if (doEnd){
doEnd = false;
setViewPos(view, animation, anim.getStartTime() + anim.getDuration());
}
}
#Override
public void onAnimationRepeat(Animation animation) {
}
#Override
public void onAnimationStart(Animation animation) {
}
});
view.startAnimation(anim);
}