My AsyncTask does not update UI smoothly (animation) - android-asynctask

Question

I want to make a TextView appear little by little, like animation. The problem is, the animation is not smooth. It gets stuck for a little while sometimes and then resumes. Sometimes even worse, it goes back... I mean, the TextView gets bigger and bigger but suddenly gets smaller then bigger again. Could anyone help me?
private class UnfoldTask extends AsyncTask<Integer, Integer, Integer> {
View view;
public UnfoldTask(View v) {
this.view = v;
ViewGroup.LayoutParams pa = view.getLayoutParams();
pa.height = 0;
view.setLayoutParams(pa);
}
#Override
protected Integer doInBackground(Integer... maxHeight) {
ViewGroup.LayoutParams pa = view.getLayoutParams();
while (pa.height < maxHeight[0]) {
pa.height += (int) (24 * getResources().getDisplayMetrics().density + 0.5f);
sleep(100);
publishProgress(pa.height);
}
return maxHeight[0];
}
private void sleep(int i) {
try {
Thread.sleep(i);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
#Override
protected void onProgressUpdate(Integer... values) {
ViewGroup.LayoutParams pa = view.getLayoutParams();
pa.height = values[0];
view.setLayoutParams(pa);
}
#Override
protected void onPostExecute(Integer result) {
ViewGroup.LayoutParams pa = view.getLayoutParams();
pa.height = result;
view.setLayoutParams(pa);
}
}

Answer 1

You should be using a scale animation for this. Here's an example:
ScaleAnimation animation = new ScaleAnimation(1, 2, 1, 2, centerX, centerY); // Scales from normal size (1) to double size (2). centerX/Y is the center of your text view. Change this to set the pivot point of your animation.
animation.setDuration(1000);
myTextView.startAnimation(animation);

Answer 2

You can use droidQuery to simplify this:
//this will set the height of myView to 0px.
$.with(myView).height(0);
//when you are ready to animate to height (in pixels):
$.with(myView).animate("{height:" + height + "}", new AnimationOptions());
Check the documentation if you want to get fancy - such as adding duration, and event callbacks. If you are still noticing non-smooth animation, consider adding the application attribute to your AndroidManifest:
android:hardwareAccelerated="true"