According to 'sources/android-18/android/widget/ProgressBar.java' in Android SDK the call of setProgress() will result in the call of invalidate().
private synchronized void doRefreshProgress(int id, int progress, boolean fromUser,
boolean callBackToApp) {
float scale = mMax > 0 ? (float) progress / (float) mMax : 0;
final Drawable d = mCurrentDrawable;
if (d != null) {
Drawable progressDrawable = null;
if (d instanceof LayerDrawable) {
progressDrawable = ((LayerDrawable) d).findDrawableByLayerId(id);
if (progressDrawable != null && canResolveLayoutDirection()) {
progressDrawable.setLayoutDirection(getLayoutDirection());
}
}
final int level = (int) (scale * MAX_LEVEL);
(progressDrawable != null ? progressDrawable : d).setLevel(level);
} else {
>>> invalidate();
}
if (callBackToApp && id == R.id.progress) {
onProgressRefresh(scale, fromUser);
}
}
Try to use setProgressDrawable(). It seems that invalidate() is not called in that case.