Changeset 108181 in webkit


Ignore:
Timestamp:
Feb 18, 2012, 7:53:29 PM (13 years ago)
Author:
mitz@apple.com
Message:

<rdar://problem/10891801> BackingStore::scroll() unnecessarily copies pixels around
​https://bugs.webkit.org/show_bug.cgi?id=78976

Reviewed by Anders Carlsson.

Rather than move pixels in the backing store in response to scrolling, we can maintain a
mapping, for the most recently scrolled rect, from backing store coordinates to view
client coordinates.

  • UIProcess/BackingStore.h:
  • UIProcess/mac/BackingStoreMac.mm:

(WebKit::BackingStore::performWithScrolledRectTransform): Added. Given a block to be
performed on a rect, divides the rect into parts such that for each part the mapping from
backing store coordinates to client coordinates is a (uniform) translation, and performs
the block on that part, passing it the translation that applies to the part.
(WebKit::BackingStore::resetScrolledRect): Added. Copies everything in the scrolled rect
back to where it should be under the identity map, and resets the scrolled rect and offset.
(WebKit::BackingStore::paint): Changed to call through performWithScrolledRectTransform().
(WebKit::BackingStore::incorporateUpdate): Ditto.
(WebKit::BackingStore::scroll): Now instead of copying pixels, just updates the scrolled
rect and offset.

Location:
trunk/Source/WebKit2
Files:
3 edited

Legend:

Unmodified
Added
Removed

  • trunk/Source/WebKit2/ChangeLog

    r108135 r108181  
     12012-02-18  Dan Bernstein  <mitz@apple.com>
     2
     3        <rdar://problem/10891801> BackingStore::scroll() unnecessarily copies pixels around
     4        https://bugs.webkit.org/show_bug.cgi?id=78976
     5
     6        Reviewed by Anders Carlsson.
     7
     8        Rather than move pixels in the backing store in response to scrolling, we can maintain a
     9        mapping, for the most recently scrolled rect, from backing store coordinates to view
     10        client coordinates.
     11
     12        * UIProcess/BackingStore.h:
     13        * UIProcess/mac/BackingStoreMac.mm:
     14        (WebKit::BackingStore::performWithScrolledRectTransform): Added. Given a block to be
     15        performed on a rect, divides the rect into parts such that for each part the mapping from
     16        backing store coordinates to client coordinates is a (uniform) translation, and performs
     17        the block on that part, passing it the translation that applies to the part.
     18        (WebKit::BackingStore::resetScrolledRect): Added. Copies everything in the scrolled rect
     19        back to where it should be under the identity map, and resets the scrolled rect and offset.
     20        (WebKit::BackingStore::paint): Changed to call through performWithScrolledRectTransform().
     21        (WebKit::BackingStore::incorporateUpdate): Ditto.
     22        (WebKit::BackingStore::scroll): Now instead of copying pixels, just updates the scrolled
     23        rect and offset.
     24
    1252012-02-17  No'am Rosenthal  <noam.rosenthal@nokia.com>
    226

  • trunk/Source/WebKit2/UIProcess/BackingStore.h

    r101293 r108181  
    2727#define BackingStore_h
    2828
    29 #include <WebCore/IntSize.h>
     29#include <WebCore/IntRect.h>
    3030#include <wtf/Noncopyable.h>
    3131#include <wtf/PassOwnPtr.h>
    … …  
    4646#include <WebCore/WidgetBackingStore.h>
    4747#endif
    48 
    49 namespace WebCore {
    50     class IntRect;
    51 }
    5248
    5349namespace WebKit {
    … …  
    9389    CGContextRef backingStoreContext();
    9490
     91    void performWithScrolledRectTransform(const WebCore::IntRect&, void (^)(const WebCore::IntRect&, const WebCore::IntSize&));
     92    void resetScrolledRect();
     93
    9594    RetainPtr<CGLayerRef> m_cgLayer;
    9695    RetainPtr<CGContextRef> m_bitmapContext;
     96
     97    // The rectange that was scrolled most recently.
     98    WebCore::IntRect m_scrolledRect;
     99
     100    // Contents of m_scrolledRect are offset by this amount (and wrapped around) with respect to
     101    // their original location.
     102    WebCore::IntSize m_scrolledRectOffset;
    97103#elif PLATFORM(WIN) || PLATFORM(WIN_CAIRO)
    98104    OwnPtr<HBITMAP> m_bitmap;

  • trunk/Source/WebKit2/UIProcess/mac/BackingStoreMac.mm

    r95901 r108181  
    3232#import "WebPageProxy.h"
    3333#import <WebCore/GraphicsContext.h>
     34#import <WebCore/Region.h>
    3435
    3536using namespace WebCore;
    … …  
    3738namespace WebKit {
    3839
     40void BackingStore::performWithScrolledRectTransform(const IntRect& rect, void (^block)(const IntRect&, const IntSize&))
     41{
     42    if (m_scrolledRect.isEmpty() || m_scrolledRectOffset.isZero() || !m_scrolledRect.intersects(rect)) {
     43        block(rect, IntSize());
     44        return;
     45    }
     46
     47    // The part of rect that's outside the scrolled rect is not translated.
     48    Region untranslatedRegion = rect;
     49    untranslatedRegion.subtract(m_scrolledRect);
     50    Vector<IntRect> untranslatedRects = untranslatedRegion.rects();
     51    for (size_t i = 0; i < untranslatedRects.size(); ++i)
     52        block(untranslatedRects[i], IntSize());
     53
     54    // The part of rect that intersects the scrolled rect comprises up to four parts, each subject
     55    // to a different translation (all translations are equivalent modulo the dimensions of the
     56    // scrolled rect to the scroll offset).
     57    IntRect intersection = rect;
     58    intersection.intersect(m_scrolledRect);
     59
     60    IntRect scrolledRect = m_scrolledRect;
     61    IntSize offset = m_scrolledRectOffset;
     62    scrolledRect.move(-offset);
     63
     64    IntRect part = intersection;
     65    part.intersect(scrolledRect);
     66    if (!part.isEmpty())
     67        block(part, offset);
     68
     69    part = intersection;
     70    offset += IntSize(0, -m_scrolledRect.height());
     71    scrolledRect.move(IntSize(0, m_scrolledRect.height()));
     72    part.intersect(scrolledRect);
     73    if (!part.isEmpty())
     74        block(part, offset);
     75
     76    part = intersection;
     77    offset += IntSize(-m_scrolledRect.width(), 0);
     78    scrolledRect.move(IntSize(m_scrolledRect.width(), 0));
     79    part.intersect(scrolledRect);
     80    if (!part.isEmpty())
     81        block(part, offset);
     82
     83    part = intersection;
     84    offset += IntSize(0, m_scrolledRect.height());
     85    scrolledRect.move(IntSize(0, -m_scrolledRect.height()));
     86    part.intersect(scrolledRect);
     87    if (!part.isEmpty())
     88        block(part, offset);
     89}
     90
     91void BackingStore::resetScrolledRect()
     92{
     93    ASSERT(!m_scrolledRect.isEmpty());
     94
     95    if (m_scrolledRectOffset.isZero()) {
     96        m_scrolledRect = IntRect();
     97        return;
     98    }
     99
     100    RetainPtr<CGColorSpaceRef> colorSpace(AdoptCF, CGColorSpaceCreateDeviceRGB());
     101    RetainPtr<CGContextRef> context(AdoptCF, CGBitmapContextCreate(0, m_scrolledRect.size().width(), m_scrolledRect.size().height(), 8, m_scrolledRect.size().width() * 4, colorSpace.get(), kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Host));
     102
     103    CGContextTranslateCTM(context.get(), -m_scrolledRect.location().x(), -m_scrolledRect.location().y());
     104    CGContextTranslateCTM(context.get(), 0, m_scrolledRect.size().height());
     105    CGContextScaleCTM(context.get(), 1, -1);
     106    paint(context.get(), m_scrolledRect);
     107
     108    IntRect sourceRect(IntPoint(), m_scrolledRect.size());
     109    paintBitmapContext(backingStoreContext(), context.get(), m_scrolledRect.location(), sourceRect);
     110
     111    m_scrolledRect = IntRect();
     112    m_scrolledRectOffset = IntSize();
     113}
     114
    39115void BackingStore::paint(PlatformGraphicsContext context, const IntRect& rect)
    40116{
    41     if (m_cgLayer) {
    42         CGContextSaveGState(context);
    43         CGContextClipToRect(context, rect);
    44 
    45         CGContextScaleCTM(context, 1, -1);
    46         CGContextDrawLayerAtPoint(context, CGPointMake(0, -m_size.height()), m_cgLayer.get());
    47 
    48         CGContextRestoreGState(context);
    49         return;
    50     }
    51 
    52     ASSERT(m_bitmapContext);
    53     paintBitmapContext(context, m_bitmapContext.get(), rect.location(), rect);
     117    // FIXME: This is defined outside the block to work around bugs in llvm-gcc 4.2.
     118    __block CGRect source;
     119    performWithScrolledRectTransform(rect, ^(const IntRect& part, const IntSize& offset) {
     120        if (m_cgLayer) {
     121            CGContextSaveGState(context);
     122            CGContextClipToRect(context, part);
     123
     124            CGContextScaleCTM(context, 1, -1);
     125            CGContextDrawLayerAtPoint(context, CGPointMake(-offset.width(), offset.height() - m_size.height()), m_cgLayer.get());
     126
     127            CGContextRestoreGState(context);
     128            return;
     129        }
     130
     131        ASSERT(m_bitmapContext);
     132        source = part;
     133        source.origin.x += offset.width();
     134        source.origin.y += offset.height();
     135        paintBitmapContext(context, m_bitmapContext.get(), part.location(), source);
     136    });
    54137}
    55138
    … …  
    102185    IntPoint updateRectLocation = updateInfo.updateRectBounds.location();
    103186
    104     GraphicsContext graphicsContext(context);
     187    GraphicsContext ctx(context);
     188    __block GraphicsContext* graphicsContext = &ctx;
    105189
    106190    // Paint all update rects.
    … …  
    108192        IntRect updateRect = updateInfo.updateRects[i];
    109193        IntRect srcRect = updateRect;
    110         srcRect.move(-updateRectLocation.x(), -updateRectLocation.y());
    111 
    112         bitmap->paint(graphicsContext, updateInfo.deviceScaleFactor, updateRect.location(), srcRect);
     194        // FIXME: This is defined outside the block to work around bugs in llvm-gcc 4.2.
     195        __block IntRect srcPart;
     196        performWithScrolledRectTransform(srcRect, ^(const IntRect& part, const IntSize& offset) {
     197            srcPart = part;
     198            srcPart.move(-updateRectLocation.x(), -updateRectLocation.y());
     199            bitmap->paint(*graphicsContext, updateInfo.deviceScaleFactor, part.location() + offset, srcPart);
     200        });
    113201    }
    114202}
    … …  
    119207        return;
    120208
    121     if (m_cgLayer) {
    122         CGContextRef layerContext = CGLayerGetContext(m_cgLayer.get());
    123 
    124         // Scroll the layer by painting it into itself with the given offset.
    125         CGContextSaveGState(layerContext);
    126         CGContextClipToRect(layerContext, scrollRect);
    127         CGContextScaleCTM(layerContext, 1, -1);
    128         CGContextDrawLayerAtPoint(layerContext, CGPointMake(scrollOffset.width(), -m_size.height() - scrollOffset.height()), m_cgLayer.get());
    129         CGContextRestoreGState(layerContext);
    130 
    131         return;
    132     }
    133 
    134     ASSERT(m_bitmapContext);
    135 
    136     CGContextSaveGState(m_bitmapContext.get());
    137     CGContextClipToRect(m_bitmapContext.get(), scrollRect);
    138     CGPoint destination = CGPointMake(scrollRect.x() + scrollOffset.width(), scrollRect.y() + scrollOffset.height());
    139     paintBitmapContext(m_bitmapContext.get(), m_bitmapContext.get(), destination, scrollRect);
    140     CGContextRestoreGState(m_bitmapContext.get());
     209    if (!m_scrolledRect.isEmpty() && m_scrolledRect != scrollRect)
     210        resetScrolledRect();
     211
     212    m_scrolledRect = scrollRect;
     213
     214    int width = (m_scrolledRectOffset.width() - scrollOffset.width()) % m_scrolledRect.width();
     215    if (width < 0)
     216        width += m_scrolledRect.width();
     217    m_scrolledRectOffset.setWidth(width);
     218
     219    int height = (m_scrolledRectOffset.height() - scrollOffset.height()) % m_scrolledRect.height();
     220    if (height < 0)
     221        height += m_scrolledRect.height();
     222    m_scrolledRectOffset.setHeight(height);
    141223}
    142224
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