Why does partial invalidate span the entire View?

Question

I am trying to partially invalidate an android View. I use View.invalidate( l, t, b, r ) and it appears to invalidate vertically (top and bottom) values correctly, however, no matter which left and right values I use, it invalidates entire across the View.

For example, my view is gray. I wish to invalidate the green area, however, it invalidates the green and red area. It always spans the entire horizontal direction entirely across the View. I have attempted to put small values such as View.invalidate( 0, 0, 50, 50 ) and it still causes this behavior.

Image Link (not enough rep to post images)

Why is this happening?

does it work the same regardless of layer type you use (View#setLayerType)? — pskink, Jul 18 '15 at 20:26
Setting it to hardware appears to work but "software" and "none" do not. — Anthony Massie, Jul 18 '15 at 20:40

score 1 · Accepted Answer · edited May 23 '17 at 12:23

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The behavior changed with hardware accelaration, the default after Honeycomb. Now when you invalidate() a view providing a dirty region, the clip bound is not set (canvas.getClipBounds()). However, only objects intersecting the dirty region will be redrawn.

See for reference this answer by Romain Guy, the author of the rendering pipeline.

edited May 23 '17 at 12:23

Community

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answered Jul 18 '15 at 21:30

Gil Vegliach

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Thank you for the explanation :) I was pulling my hair out trying to research exactly what is going on – Anthony Massie Jul 20 '15 at 00:50

Why does partial invalidate span the entire View?

1 Answers1