Francisco Durdin Garcia Francisco Durdin Garcia - 2 years ago 302
Android Question

Pulsating button animation android

Right now im working with a Voice recognition application and I want to make my play/stop button "pulse" when it's recording. Something like this:
enter image description here

I have tried to make a ScaleAnimation, doing the button grow, but of course, it makes grow all the button.

public static ObjectAnimator pulseAnimation(ImageView target){

ObjectAnimator scaleDown = ObjectAnimator.ofPropertyValuesHolder(target,
PropertyValuesHolder.ofFloat("scaleX", 1.1f),
PropertyValuesHolder.ofFloat("scaleY", 1.1f));

return scaleDown;

So the idea is achieve something like that but just with a alpha behind the actual button. I want to know if it's possible to do this with an alpha animation or something before add a second "Alpha Button" behind my button to make it grow and achieve this effect.

Thank you so much in advance!

Answer Source

Finally I found the solution! I overrided the onDraw method and draw a first circle for my button and, when my boolean is true. I draw a second circle with an alpha as a background. Making a pulsating effect:

protected void onDraw(Canvas canvas) {

    int w = getMeasuredWidth();
    int h = getMeasuredHeight();
    mCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    mBackgroundPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    mBackgroundPaint.setColor(Util.adjustAlpha(mColor, 0.4f));
    //Draw circle
    canvas.drawCircle(w/2, h/2, MIN_RADIUS_VALUE , mCirclePaint);        
    if (mAnimationOn) {
        if (mRadius >= MAX_RADIUS_VALUE)
            mPaintGoBack = true;
        else if(mRadius <= MIN_RADIUS_VALUE)
            mPaintGoBack = false;
        //Draw pulsating shadow
        canvas.drawCircle(w / 2, h / 2, mRadius, mBackgroundPaint);
        mRadius = mPaintGoBack ? (mRadius - 0.5f) : (mRadius + 0.5f);

 public void animateButton(boolean animate){
    if (!animate)
        mRadius = MIN_RADIUS_VALUE;
    mAnimationOn = animate;
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