implement eraser using PorterDuff Xfer mode

[bizzguy]

This requires a bump for minimum SDK from 9 to 11 because of the View setLayer method. This commit also has a bunch of changes to the layouts that occurred just because of reformatting.

Erases get added to undo/redo stack properly.

Also tested with screen rotation.

[RiccardoMoro]

Thanks (again) for the pull request! I'm reviewing this in a few days, this weekend max

[RiccardoMoro]

I'm having a problem on KitKat and below, the eraser seems to be painting black instead of actually canceling the previous paint

[RiccardoMoro]

But when I take the "screenshot" of the draw, the erased content is rendered correctly even on KitKat-

[RiccardoMoro]

Also, if you add just a dot, it's rendered with the paint, instead of erasing

[bizzguy]

I was having a similar problem (painting in black) until I added the "setLayer" command which solved it for API 21 and above.

I'll try to do some more testing on KitKat and see what I can find.

This is turning out to be harder than I thought.

There is another approach - specify a background color and then paint in the background color for erase.

This might be more robust than the Xfer mode approach.

I'll try again.

Thanks

Jim

On Tue, Apr 18, 2017 at 4:54 AM, Riccardo Moro [email protected] wrote:

Also, if you add just a dot, it's rendered with the paint, instead of erasing

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[rajajawahar]

If we add a background for the image, the above trick won't work..

[RiccardoMoro]

@rajajawahar correct..

[rajajawahar]

Is there a way we can remove the HistoryPath when user in EraserMode.. Something like that.. I was trying to acheive it.. But it din't worked at all.. Can you help me out for eraser.. If I add Image to the view from Gallery or Camera..