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  • akling@apple.com's avatar
    Caching of generated images in CSS should be smarter. · f7adfcf4
    akling@apple.com authored 
    <http://webkit.org/b/115902>
<rdar://problem/13542727>

Reviewed by Antti Koivisto.

Add an IntSize => GeneratorGeneratedImage cache at the CSSImageGeneratorValue level.

CSSGradientValue is currently the only CSSImageGeneratorValue subclass that makes use of the cache.
Generated images are kept for 3 seconds after last use.

The main problem with the previous approach was that background renderers (e.g <body>, <tr>, etc)
would be passed to multiple CSSImageGeneratorValue::getImage() calls with different sizes requested
for each of the descendent renderers that inherit their background from the same parent.
The cache wasn't smart enough for this, it just thought the background renderer was changing size
a lot, and would regenerate the image over and over.

We already had caching of intermediate image buffers for GeneratorGeneratedImage::drawPattern().
This removes the eviction timer from that cache so that the intermediate images can live a bit longer.

(WebCore::CSSImageGeneratorValue::cachedImageForSize):
(WebCore::CSSImageGeneratorValue::saveCachedImageForSize):

    Renamed from getImage() and putImage().

(WebCore::CSSImageGeneratorValue::evictCachedGeneratedImage):
(WebCore::CSSImageGeneratorValue::CachedGeneratedImage::CachedGeneratedImage):
(WebCore::CSSImageGeneratorValue::CachedGeneratedImage::evictionTimerFired):

    Let the CachedGeneratedImage throw itself out from cache when the timer fires.

* css/CSSImageGeneratorValue.h:
(CachedGeneratedImage):

    Exactly what it sounds like. These go into CSSImageGeneratorValue::m_images with the size
    as the hash key.

* platform/graphics/GeneratorGeneratedImage.cpp:
(WebCore::GeneratorGeneratedImage::drawPattern):
* platform/graphics/GeneratorGeneratedImage.h:
(WebCore::GeneratorGeneratedImage::~GeneratorGeneratedImage):
(WebCore::GeneratorGeneratedImage::GeneratorGeneratedImage):

    Keep the intermediate image for drawPattern() until destruction instead of dropping it on
    a timer. These objects are now evicted by the CSSImageGeneratorValue's image cache
    after 3 seconds of disuse rather than kept for the lifetime of the renderer.

* css/CSSCanvasValue.cpp:
(WebCore::CSSCanvasValue::canvasChanged):
(WebCore::CSSCanvasValue::canvasResized):
* css/CSSCrossfadeValue.cpp:
(WebCore::CSSCrossfadeValue::crossfadeChanged):
* rendering/style/StyleGeneratedImage.cpp:
(WebCore::StyleGeneratedImage::addClient):
* css/CSSImageGeneratorValue.cpp:
(WebCore::CSSImageGeneratorValue::addClient):
(WebCore::CSSImageGeneratorValue::removeClient):

    CSSImageGeneratorValue::m_clients is now a HashCountedSet<RenderObject*>, tweak accordingly.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@149886 268f45cc-cd09-0410-ab3c-d52691b4dbfc
    f7adfcf4