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I know this is quite the same question as partial-invalidation-in-custom-android-view-with-hardware-acceleration but I thought I will explain my problem more detailled and hope someone will have an answer on how to solve the problem.

I wrote a simple TicTacToe app which was working fine on the emulator. But wasn't working on the device since I found out it was working as expected on the device when I disabled hardware acceleration.

All the fields are drawn with Canvas.drawBitmap(), also the "empty" fields with an empty white image. The lines are drawn with Canvas.drawLine() I'm using partial invalidation with invalidate(Rect) because I want to redraw only the area which was choosen to set a cross/circle with the according image using again Canvas.drawBitmap(). But then the whole area is invalidated, means I see the whole area/screen is gray (the white images and lines disappeared) and only the image for the cross/circle is set in the choosen area.

When I print out the invalidated field rect with Canvas.getClipBounds() in the method onDraw(), with hardware acceleration it is the whole area (example "0,0,320,407") and without hardware acceleration the same rect which I invalidated with invalidate(Rect) (e.g. "106,135,106,135").

At the moment as workaround I redraw all the fields whith the according image and lines. How can I prevent to have the whole area invalidated with hardware acceleration?

If this matters: I'm using Android version 4.1.2 on Samsung Galaxy Young Duos S6312.

Regards Sandro

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sandro piras
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I have post my answer in your given link. To understand the problem , you should know the difference between software rendering and hardware rendering. That's really a big topic which I won't cover here. I think the best approach is to read the source code(I did the same thing a few days ago). The key question is "what is DisplayList and when it is used" . Repeat my answer here, the Canvas in onDraw is simply used to rebuild the DisplayList. That doesn't mean everything in your View will be redrawn.

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suitianshi
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  • This has not been my experience. The performance is such that the entire view is redrawn. I've verified this by splitting my custom bitmap into a 4x4 grid of child views and only invalidating the child views that have changed, and performance is much much better. – jjxtra Oct 02 '15 at 16:22
  • @PsychoDad， how do you know "the entire view is redrawn" ? – suitianshi Oct 08 '15 at 13:13
  • @suitianshi because the performance is so much worse compared to making a grid of views and only invalidating the views that change. – jjxtra Oct 08 '15 at 14:21
  • The `onDraw` method of your custom view will be called to redraw the entire DisplayList before rendering it to the screen .So are you sure the performance cost is not caused by your drawing code ? If so, can you provide an result of your profiling ? – suitianshi Oct 08 '15 at 14:53