CODEWITHSUNDEEP
androidanimationpivot
TalMihr
TalMihr

Reputation: 1548

Android setting pivot point for scale animation

I am trying to scale views to a certain size but can't quite understand how pivoting works.

Say I want to scale the view upwards only. What value should the "pivotY" hold? In XML, it is a percentage. How is it when applying pivot point programmatically?

Example:

ObjectAnimator scaleY = ObjectAnimator.ofFloat(view, "scaleY", scaleSize);
ObjectAnimator pivotY = ObjectAnimator.ofFloat(view, "pivotY", pivotPoint);

AnimatorSet set = new AnimatorSet();
set.PlayTogether(scaleY, pivotY);

Upvotes: 26

Views: 40274

Answers (3)

Juan M. Rivero
Juan M. Rivero

Reputation: 807

Your pivot point takes your view as reference. So a pivot point set at 0,0 means it matches the top left side of your view.

So this animation:

ObjectAnimator.ofFloat(view, "scaleY", 1f, 0f)

Will be affected by pivotY

view.pivotY = 0 // will shrink the view towards the view top
view.pivotY = view.measuredHeight.toFloat() // will shrink the view towards the view bottom
view.resetPivot() // will shrink the view towards the center

In the same way, this animation:

ObjectAnimator.ofFloat(view, "scaleX", 1f, 0f)

Will be affected by pivotX

view.pivotX = 0 // will shrink the view towards the view left
view.pivotX = view.measuredHeight.toFloat() // will shrink the view towards the view right
view.resetPivot() // will shrink the view towards the center

Upvotes: 1

DoruChidean
DoruChidean

Reputation: 8138

Use: 

view.setPivotY(view.getMeasuredHeight());

If you need to animate your object from the bottom.

Upvotes: 12

TalMihr
TalMihr

Reputation: 1548

Quite simple actually.

If you want to scale upwards one clear option is:

 view.setPivotY(100);

and downwards:

 view.setPivotY(0);

then animate.

Upvotes: 61

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