So, I'm experimenting trying to create a circular reveal on API level 21 on a TextView but I keep getting this error. At first I thought it had something to do with the lifecycle of the fragment I was attempting it but then I just tried the same thing in an activity and it still wouldn't work.
Here's the code:
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Window w = getWindow();
w.setFlags(
WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS,
WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
w.setStatusBarColor(Color.parseColor("#0277bd"));
setContentView(R.layout.activity_main);
TextView tv = (TextView) findViewById(R.id.text);
int a = (tv.getLeft() + tv.getRight()) / 2;
int b = (tv.getTop() + tv.getBottom()) / 2;
int radius = tv.getWidth();
Animator anim = ViewAnimationUtils.createCircularReveal(tv, a, b, 0, radius);
anim.start();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
return super.onCreateOptionsMenu(menu);
}
}
It's still early days so I can't really find any answers about this. Any ideas?
You're getting the error because the view you passed in hasn't been measured and laid out on the screen yet. ViewAnimationUtils.createCircularReveal
needs the target view to be measured to calculate the animation. You'll also find that your variables a
and b
are always 0.
If you want to experiment, create the animation and start it within a button click listener. Here's an example using your code:
Button button = (Button) findViewById(R.id.your_button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
TextView tv = (TextView) findViewById(R.id.text);
int a = (tv.getLeft() + tv.getRight()) / 2;
int b = (tv.getTop() + tv.getBottom()) / 2;
int radius = tv.getWidth();
Animator anim = ViewAnimationUtils.createCircularReveal(tv, a, b, 0, radius);
anim.start();
}
});
You can use Runnable
to do the animation. The Runnable
will run after the view's creation. No need to post delay.
view.post(new Runnable()
{
@Override
public void run(){
//create your anim here
}
});
Or you can do this.
tv.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
if (android.os.Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
tv.getViewTreeObserver().removeGlobalOnLayoutListener(this);
} else {
tv.getViewTreeObserver().removeOnGlobalLayoutListener(this);
}
Animator anim = ViewAnimationUtils.createCircularReveal(tv, a, b, 0, radius);
anim.start();
}
});
Adding GlobalLayoutListener to wait for the view to be inflated worked for me.
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