821453 - Lightweight theme buttons don't have a gradient on 4.2.1

Status: RESOLVED FIXED

(Firefox for Android Graveyard :: Theme and Visual Design, defect)

Description

[Sriram Ramasubramanian [:sriram]]

With changes to mutate() in the Android drawables, the BitmapDrawable inside a LayerDrawable, which inturn is inside a ShapeDrawable (and oh! that's inside a LevelDrawable) cannot show transparency, starting 4.2.1.

Also, it's better to combine the layers in a LayerDrawable into a single Drawable using shaders. This reduces the number of times a paint is drawn. This is also better over the PorterDuffXfermode approach.

Comment 1

[Sriram Ramasubramanian [:sriram]]

Attachment: Patch

This patch solves the problem on 4.2.1 and lower.

From view's perspective:
1. A view either gets a Color based or Texture based LightweightThemeDrawable. TabsPanel is special which gets both.
2. The view sets an alpha value --> this is used for the LinearGradient used with the bitmap shader.

On LightweightThemeDrawable:
1. A texture-paint is created based on the given texture -- this uses a bitmap-shader.
2. A color-paint is created based on the given color.
3. A bitmap-paint is created based on the given bitmap and the linear-gradient to apply. It's based to combine these shaders into one ComposeShader, that will make the paint draw in one go. (Ofcourse, porter-duff is needed, as always).

Suggestions:
It might be better to combine the texture-paint's shader and the color-paint's shader with the bitmap-paint. That will ensure paint the canvas only once -- which is a performance win. However, I didn't want to overload this patch and would like to do as a followup.

Comment 2

[Mark Finkle (:mfinkle) (use needinfo?)]

Comment on attachment 691982 [details] [diff] [review]
Patch

Thanks for adding the comments too

Comment 3

[Sriram Ramasubramanian [:sriram]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/bc1e8c9266ea

Comment 4

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/bc1e8c9266ea

Comment 5

[Sriram Ramasubramanian [:sriram]]

Comment on attachment 691982 [details] [diff] [review]
Patch

[Approval Request Comment]
Bug caused by (feature/regressing bug #): Android's bug on mutating drawable. (Someone watched X-men there!)
User impact if declined: JB phones will not show personas properly.
Testing completed (on m-c, etc.): Landed on m-c on 12/15
Risk to taking this patch (and alternatives if risky): Very low. This optimizes the drawable for performance. This is needed for bug 822421 to land.
String or UUID changes made by this patch: None.

Comment 6

[Sriram Ramasubramanian [:sriram]]

https://hg.mozilla.org/releases/mozilla-aurora/rev/9883439ebee8