Develop Reference

RotateAnimation behaves weird after changing the position of a View

I am using RotateAnimation to rotate the imageView to -30 degrees. And it works good. Now I change the position of the view by setting different values for X and Y. All good until now.
Now when I perform the same RotateAnimation again to this view after the position changed, it works weird (see the video link below) and I cannot find the reason. I have tried a lot but without success. It seems like related to the pivotX and pivotY after changing the position but I cannot find the actual cause.
Code for RotateAnimation
final RotateAnimation rotateAnim = new RotateAnimation(0f, -30f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 1f);
rotateAnim.setDuration(2000);
rotateAnim.setFillAfter(false);
ivFace.startAnimation(rotateAnim);
Code of changing the position of an imageview
ivFace.setX(300);
ivFace.setY(200);
Here I am posting the video also for better understanding
https://www.youtube.com/watch?v=uVWlrTNDKCM

Looks like the RotationAnimation is still rotating around the 'old' view position, probably because it is 'final' and thats why it is tied to the Views 'old' position the moment it is created. You could create a new RotationAnimation for every position change, which might solve the issue, although I would suggest using ViewPropertyAnimator and/or ObjectAnimator for both, translating your View to another position and rotating it.

Rotate android drawable from xml without cutting

I have to do this in xml of an item of a recycler view (I'm using databinding and the viewholder pattern). Based on the value of the variable that is bound to the view, I need to rotate a drawable and set it as the src of an ImageView.
I've checked many options online but haven't found any, rotating the original xml drawable 45 degrees cuts of some parts of the shape which is a curved rectangle. This results in a shape that does not match the requirements.
I need suggestions on how to get this done from inside the xml or adapter without rewriting it to use getView.

Hello #staa99 try following code may it will help you.
ImageView imageView = findViewById(R.id.imageView);
RotateAnimation anim = new RotateAnimation(0, 45,
Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF,0.5f);
anim.setInterpolator(new LinearInterpolator());
anim.setDuration(1000);
anim.setFillEnabled(true);
anim.setFillAfter(true);
imageView.startAnimation(anim);

The solution I eventually used was to create four different vector variables based of the original with rotation info included. I then used a variable bound to the view to store the data that determines the vector drawable to display.
This solution is not good when you need a large or unknown number of possible rotations, or if the angles are calculated at runtime. However, I've not seen a way to do that from xml so you still need to do it from java/kotlin code

How to explain the Coordinate system on Android animation?

As we know , the android coordinate system is start from the top left corner of the android screen. The x-axis is down growth and the y-axis is right growth.But I found it's not right for the animation.
For example, I initialized the TranslateAnimation using the constructed function:
TranslateAnimation ta = new TranslateAnimation(0.0f, 200, 0.0f, 200);
Does the coordinate system have changed ? I found it didn't start from the top left corner.
Then I initialized the other translateAnimation for moving up and right direction :
TranslateAnimation ta = new TranslateAnimation(0.0f, 200, 0.0f, -200);
ta.setReaptMode(Animation.REVERSE);
The same behavior would be found.
I am confused about it.

I believe that constructor for TranslateAnimation uses deltas. See this. Or look at the constructor sig. : (float fromXDelta, float toXDelta, float fromYDelta, float toYDelta). So if you want your anim. to jump up first, you could use a negative third ctor param.
More precisely:
An animation can never start until after the layout has been measured. One usually shouldn't have to worry about how this works beyond that the algorithm is mostly very good and you can take control of its strategies by setting layout parameters. In short, by the time an animation might be started, we know where you want the view to be on the screen, because you set layout parameters.
Translate animation then takes deltas from that position. So your current animation shouldn't start from the top left, but rather wherever those layout params were evaluated by onMeasure.
Some would say- how annoying. It's gonna get complicated even if you just want to do some simple up-down type animations... Well, here's an advisable development strategy; it snould make android animation development a breeeze. Set an animationListener on every animation. In onAnimationEnd, in possibly a parametized way, reset the layout parameters on the view your animating to where you expect it to be. That way, you'll get no surprising "jumps" when you re-apply an animation again. You may need to invalidate in some circumstances, or clearAnimation. The reason that this works is that the measure pass will be caused to come round again and you'll have a new offset for your TranslateAnimation. Finally, you may want to do all this resetting posted to the message queue of a view using post(Runnable runnable) in the listener, so you're off the last pass of the animation draw.
I too found android Animations can occasionally surprise you and cause jumpy behaviour. But if you do it like this, constructors taking delta params shouldn't be confusing again.

Android Animate view from off screen not working

I have a view that is positioned totally off screen and I am trying to animate it onto the screen.
When I call:
view.startAnimation(tA);
nothing happens, tA.initialize and tA.applyTransformation never get called.
If I move the view so that any part of it is visible before I start the animation, then the animation works correctly.
What is preventing a view from being animated when it is positioned off the parent View?

It's my understanding from researching the same problem that Android Animations do not do well when provided with offscreen coordinates for their start or finish.
There is some dialog on the Android forums about this bug having been addressed but I'm still experiencing problems on 4.2.
Edit:
On second thought, I just ran across this answer and it provides a working alternative if you can use the newer APIs (ObjectAnimator).
View view = this;
ObjectAnimator anim = ObjectAnimator.ofFloat(view, "y", 0, 100);
anim.setDuration(super.animationDuration());
anim.start();
Where the properties of ObjectAnimator.ofFloat(view, "y", 0, 100); are
ObjectAnimator.ofFloat(Object objBeingAnimated, String propertyBeingAnimated, float startValue, float endValue)

I found this answer using ValueAnimator to modify the MarginLayoutParams.topMargin (in my case) in onAnimationUpdate(), which fixed the issue. My View starts out with its margin set so that the View is off screen.
The ObjectAnimator approach was promising but did not work for me, it had the same cutoff issue for off-screen views that I got with TranslateAnimation.

Android Progressbar: Indeterminate animation without images

I'd like to create an indeterminate animation that simply fades from one color to another (a pulse, if you will). I don't think this should require the use of images but despite my best efforts, I'm not sure I understand how to use something like AlphaAnimation with a Shape to accomplish this.
Could someone please provide some insight as to how to accomplish this? I have a feeling I'm missing something pretty straightforward here. (Examples are always appreciated!)
Thanks!

This is a trivial task in 3.0 - you can set up an ObjectAnimator to change the "color" or "backgroundColor" of an object (View, ColorDrawable, whatever has the property) between two values. See the ApiDemo animations/BouncingBalls for an example of this.
But assuming you're using pre-3.0 APIs, there are a couple of approaches. First, you could set up your own handler to give you the timing events you need, then calculate the new color at each point.
It's probably slightly easier (if not entirely intuitive) to use an AlphaAnimation. All you really want from the animation is percentage values, not to fade anything. So you don't set the animation on a view, but just set it up to run internally from a value of 0 to 1, then get the current animated value in your onDraw() method and set the current color appropriately.
For example, this will set up and start the alpha animation to run for one second:
Transformation transform = new Transformation();
AlphaAnimation anim = new AlphaAnimation(0f, 1f);
anim.setDuration(1000);
anim.start();
Then in your drawing loop, you grab the current animated value:
long time = getDrawingTime();
anim.getTransformation(time, transform);
float elapsedFraction = transform.getAlpha();
Once you have the elapsedFraction (a value between 0 and 1), you can calculate the appropriate in-between color value.
The code above may not match your situation exactly, but you should be able to do something similar to get what you want.