Refactor canvas drawing to be more data driven

• Component: WebCore Misc.
• Status: RESOLVED FIXED

[Tim Dresser]

From bug 73059:

CCLayerImpl-derived classes all currently handle drawing themselves internally, making direct GL calls.  This is problematic for several reasons.  Testing these layers is tricky because testing must be done at a mock GL interface level rather than at a higher abstract level.  It makes culling closely dependent on how each layer draws.  It also makes some optimizations like layer squashing impossible.

To fix this, CCLayerImpl-derived classes should produce a set of quads to render with some basic information in them about how they are to be drawn.  This list can then be processed and drawn in a more data-driven and abstract manner.


CCCanvasLayerImpl still handles drawing internally, and should be transitioned to the data-driven approach.
This builds on the initial refactor from bug 76274.

[Tim Dresser]

Created attachment 123126 [details]
Patch

[Adrienne Walker]

Comment on attachment 123126 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=123126&action=review

> Source/WebCore/platform/graphics/chromium/LayerRendererChromium.cpp:687
> +    if (!quad->hasAlpha()) {
> +        // Even though the WebGL layer's texture was likely allocated
> +        // as GL_RGB, disable blending anyway for better robustness.
> +        context()->disable(GraphicsContext3D::BLEND);
> +    } else {
> +        GC3Denum sfactor = quad->premultipliedAlpha() ? GraphicsContext3D::ONE : GraphicsContext3D::SRC_ALPHA;
> +        GLC(context(), context()->blendFunc(sfactor, GraphicsContext3D::ONE_MINUS_SRC_ALPHA));
> +    }

Enabling/disabling alpha is already done by the drawQuad routine above because all quads need that commonly, so no need to do that here.  Can you also make sure blendFunc gets reset properly, since it only is currently set at the beginning of the frame?

> Source/WebCore/platform/graphics/chromium/LayerRendererChromium.cpp:695
> +    if (!quad->hasAlpha())
> +        context()->enable(GraphicsContext3D::BLEND);

Not needed either for the above reason.

> Source/WebCore/platform/graphics/chromium/cc/CCDrawQuad.h:53
> +    const IntSize& bounds() const { return m_sharedQuadState->bounds(); }

I don't think this function needs to be added to either CCDrawQuad or the shared quad state.  Isn't bounds() just quad->quadRect().size()?

[Tim Dresser]

Created attachment 123191 [details]
Patch

[Adrienne Walker]

Comment on attachment 123191 [details]
Patch

Thanks! This looks good to me.  jamesr?

[James Robinson]

Comment on attachment 123191 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=123191&action=review

R=me, one nit

> Source/WebCore/platform/graphics/chromium/LayerRendererChromium.cpp:685
> +    drawTexturedQuad(quad->layerTransform(), quad->quadRect().size().width(), quad->quadRect().size().height(), quad->opacity(), sharedGeometryQuad(),

can I get a temporary const reference to size in this piece? this line's pretty long, even by webkit standards

[Tim Dresser]

Created attachment 123316 [details]
Patch for landing

[WebKit Review Bot]

Comment on attachment 123316 [details]
Patch for landing

Rejecting attachment 123316 [details] from commit-queue.

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[W. James MacLean]

Comment on attachment 123316 [details]
Patch for landing

Submitting to commit queue on behalf of Tim Dresser.

[WebKit Review Bot]

Comment on attachment 123316 [details]
Patch for landing

Clearing flags on attachment: 123316

Committed r105529: <http://trac.webkit.org/changeset/105529>

[WebKit Review Bot]

All reviewed patches have been landed.  Closing bug.