850227 - Progressively redraw area outside of visible area of screen

Status: RESOLVED INVALID

(Firefox for Android Graveyard :: Toolbar, defect)

Description

[Scott Johnson (:jwir3)]

Attachment: progressive-zoom-update

From bug 836565:

> An issue here is that when the zoom level changes, we redraw the entire display-port
> in a single, un-cancellable transaction - this may cause a bigger delay than is
> necessary.
>
> Instead, we could redraw the visible area and progressively update the area outside 
> of that afterwards, which ought to provide a faster initial update (assuming that 
> update time is almost entirely drawing and the page is reasonably uniform, you're 
> looking at a time reduction of ~75%). Note the comment 'Only draw progressively when 
> the resolution is unchanged.' in BasicTiledThebesLayer.

This is being split out into a separate bug, since it's probably something that we want to to anyway, unrelated to reflow-on-zoom. I'm attaching the patch that was originally attached to bug 836565 and re-requesting review.

Comment 1

[Benoit Girard (:BenWa)]

Comment on attachment 723958 [details] [diff] [review]
progressive-zoom-update

Review of attachment 723958 [details] [diff] [review]:
-----------------------------------------------------------------

::: gfx/layers/basic/BasicTiledThebesLayer.cpp
@@ +633,5 @@
>        // Store the old valid region, then clear it before painting.
>        // We clip the old valid region to the visible region, as it only gets
>        // used to decide stale content (currently valid and previously visible)
> +      nsIntRegion oldValidRegion;
> +      // If the resolution has changed, don't retain any old content.

// Only retain content if the resolution has not changed.

@@ +635,5 @@
>        // used to decide stale content (currently valid and previously visible)
> +      nsIntRegion oldValidRegion;
> +      // If the resolution has changed, don't retain any old content.
> +      if (mTiledBuffer.GetFrameResolution() == mPaintData.mResolution) {
> +        nsIntRegion oldValidRegion = mTiledBuffer.GetValidRegion();

This oldValidRegion is shadowing oldValidRegion on line 636.

Comment 2

[Chris Lord [:cwiiis]]

This isn't really valid anymore.