android - ObjectAnimator animate LinearLayout width

Question

Ok, so i checked out http://android-developers.blogspot.com/2011/02/animation-in-honeycomb.html

He says you can animate the property of an object in a given time. And i tried moving around objects and it looks fine. I encountered a problem when i went changing the width of a LinearLayout. I got this:

10-26 14:51:27.190: E/PropertyValuesHolder(12681): Couldn't find setter/getter for       property width with value type float

Then i tried extending LinearLayout, with "myWidth"

public void setMyWidth(int myWidth) {
    LinearLayout.LayoutParams params = (LayoutParams) getLayoutParams();
    params.weight = myWidth;
    setLayoutParams(params);
    requestLayout();
    this.myWidth = myWidth;
}

No luck. Then i tried changing LayoutParams.width, turns out width and height are the only public properties in java history, and ObjectAnimator needs getter and setter. No luck. I'm embarassed to say i tried extending LayoutParams too... with no luck ofc.

Anybody succeded doing such a thing? I used old android.view.animation and i got what i wanted, but i'm curious for the future.

Answer 1

In situations where there isn't a simple property getter/setter you should use ValueAnimator and perform the animation manually.

Assuming:

• v is the view you're animating
• END_WIDTH is the target width of the view in pixels.
• DURATION is the desired length of the animation in milliseconds.

Your code should look something like this:

    ValueAnimator anim = ValueAnimator.ofInt(v.getMeasuredWidth(), END_WIDTH);
    anim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator valueAnimator) {
            int val = (Integer) valueAnimator.getAnimatedValue();
            ViewGroup.LayoutParams layoutParams = v.getLayoutParams();
            layoutParams.width = val;
            v.setLayoutParams(layoutParams);
        }
    });
    anim.setDuration(DURATION);
    anim.start();