src/third_party/WebKit/Source/core/rendering/compositing/CompositingReasonFinder.cpp

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "config.h"
   6 #include "core/rendering/compositing/CompositingReasonFinder.h"
   7
   8 #include "core/CSSPropertyNames.h"
   9 #include "core/dom/Document.h"
  10 #include "core/frame/FrameView.h"
  11 #include "core/frame/Settings.h"
  12 #include "core/page/Page.h"
  13 #include "core/rendering/RenderView.h"
  14 #include "core/rendering/compositing/RenderLayerCompositor.h"
  15
  16 namespace blink {
  17
  18 CompositingReasonFinder::CompositingReasonFinder(RenderView& renderView)
  19     : m_renderView(renderView)
  20     , m_compositingTriggers(static_cast<CompositingTriggerFlags>(AllCompositingTriggers))
  21 {
  22     updateTriggers();
  23 }
  24
  25 void CompositingReasonFinder::updateTriggers()
  26 {
  27     m_compositingTriggers = 0;
  28
  29     Settings& settings = m_renderView.document().page()->settings();
  30     if (settings.preferCompositingToLCDTextEnabled()) {
  31         m_compositingTriggers |= ScrollableInnerFrameTrigger;
  32         m_compositingTriggers |= OverflowScrollTrigger;
  33         m_compositingTriggers |= ViewportConstrainedPositionedTrigger;
  34     }
  35 }
  36
  37 bool CompositingReasonFinder::hasOverflowScrollTrigger() const
  38 {
  39     return m_compositingTriggers & OverflowScrollTrigger;
  40 }
  41
  42 bool CompositingReasonFinder::isMainFrame() const
  43 {
  44     // FIXME: LocalFrame::isMainFrame() is probably better.
  45     return !m_renderView.document().ownerElement();
  46 }
  47
  48 CompositingReasons CompositingReasonFinder::directReasons(const RenderLayer* layer) const
  49 {
  50     ASSERT(potentialCompositingReasonsFromStyle(layer->renderer()) == layer->potentialCompositingReasonsFromStyle());
  51     CompositingReasons styleDeterminedDirectCompositingReasons = layer->potentialCompositingReasonsFromStyle() & CompositingReasonComboAllDirectStyleDeterminedReasons;
  52     return styleDeterminedDirectCompositingReasons | nonStyleDeterminedDirectReasons(layer);
  53 }
  54
  55 // This information doesn't appear to be incorporated into CompositingReasons.
  56 bool CompositingReasonFinder::requiresCompositingForScrollableFrame() const
  57 {
  58     // Need this done first to determine overflow.
  59     ASSERT(!m_renderView.needsLayout());
  60     if (isMainFrame())
  61         return false;
  62
  63     if (!(m_compositingTriggers & ScrollableInnerFrameTrigger))
  64         return false;
  65
  66     return m_renderView.frameView()->isScrollable();
  67 }
  68
  69 CompositingReasons CompositingReasonFinder::potentialCompositingReasonsFromStyle(RenderObject* renderer) const
  70 {
  71     CompositingReasons reasons = CompositingReasonNone;
  72
  73     RenderStyle* style = renderer->style();
  74
  75     if (requiresCompositingForTransform(renderer))
  76         reasons |= CompositingReason3DTransform;
  77
  78     if (style->backfaceVisibility() == BackfaceVisibilityHidden)
  79         reasons |= CompositingReasonBackfaceVisibilityHidden;
  80
  81     if (requiresCompositingForAnimation(style))
  82         reasons |= CompositingReasonActiveAnimation;
  83
  84     if (style->hasWillChangeCompositingHint() && !style->subtreeWillChangeContents())
  85         reasons |= CompositingReasonWillChangeCompositingHint;
  86
  87     if (style->hasInlineTransform())
  88         reasons |= CompositingReasonInlineTransform;
  89
  90     if (style->transformStyle3D() == TransformStyle3DPreserve3D)
  91         reasons |= CompositingReasonPreserve3DWith3DDescendants;
  92
  93     if (style->hasPerspective())
  94         reasons |= CompositingReasonPerspectiveWith3DDescendants;
  95
  96     // If the implementation of createsGroup changes, we need to be aware of that in this part of code.
  97     ASSERT((renderer->isTransparent() || renderer->hasMask() || renderer->hasFilter() || renderer->hasBlendMode()) == renderer->createsGroup());
  98
  99     if (style->hasMask())
 100         reasons |= CompositingReasonMaskWithCompositedDescendants;
 101
 102     if (style->hasFilter())
 103         reasons |= CompositingReasonFilterWithCompositedDescendants;
 104
 105     // See RenderLayer::updateTransform for an explanation of why we check both.
 106     if (renderer->hasTransformRelatedProperty() && style->hasTransform())
 107         reasons |= CompositingReasonTransformWithCompositedDescendants;
 108
 109     if (renderer->isTransparent())
 110         reasons |= CompositingReasonOpacityWithCompositedDescendants;
 111
 112     if (renderer->hasBlendMode())
 113         reasons |= CompositingReasonBlendingWithCompositedDescendants;
 114
 115     if (renderer->hasReflection())
 116         reasons |= CompositingReasonReflectionWithCompositedDescendants;
 117
 118     ASSERT(!(reasons & ~CompositingReasonComboAllStyleDeterminedReasons));
 119     return reasons;
 120 }
 121
 122 bool CompositingReasonFinder::requiresCompositingForTransform(RenderObject* renderer) const
 123 {
 124     // Note that we ask the renderer if it has a transform, because the style may have transforms,
 125     // but the renderer may be an inline that doesn't suppport them.
 126     return renderer->hasTransformRelatedProperty() && renderer->style()->transform().has3DOperation();
 127 }
 128
 129 CompositingReasons CompositingReasonFinder::nonStyleDeterminedDirectReasons(const RenderLayer* layer) const
 130 {
 131     CompositingReasons directReasons = CompositingReasonNone;
 132     RenderObject* renderer = layer->renderer();
 133
 134     if (hasOverflowScrollTrigger()) {
 135         if (layer->clipParent())
 136             directReasons |= CompositingReasonOutOfFlowClipping;
 137
 138         if (const RenderLayer* scrollingAncestor = layer->ancestorScrollingLayer()) {
 139             if (scrollingAncestor->needsCompositedScrolling() && layer->scrollParent())
 140                 directReasons |= CompositingReasonOverflowScrollingParent;
 141         }
 142
 143         if (layer->needsCompositedScrolling())
 144             directReasons |= CompositingReasonOverflowScrollingTouch;
 145     }
 146
 147     if (requiresCompositingForPositionFixed(layer))
 148         directReasons |= CompositingReasonPositionFixed;
 149
 150     directReasons |= renderer->additionalCompositingReasons();
 151
 152     ASSERT(!(directReasons & CompositingReasonComboAllStyleDeterminedReasons));
 153     return directReasons;
 154 }
 155
 156 bool CompositingReasonFinder::requiresCompositingForAnimation(RenderStyle* style) const
 157 {
 158     if (style->subtreeWillChangeContents())
 159         return style->isRunningAnimationOnCompositor();
 160
 161     return style->shouldCompositeForCurrentAnimations();
 162 }
 163
 164 bool CompositingReasonFinder::requiresCompositingForPositionFixed(const RenderLayer* layer) const
 165 {
 166     if (!(m_compositingTriggers & ViewportConstrainedPositionedTrigger))
 167         return false;
 168     // Don't promote fixed position elements that are descendants of a non-view container, e.g. transformed elements.
 169     // They will stay fixed wrt the container rather than the enclosing frame.
 170     return layer->scrollsWithViewport() && m_renderView.frameView()->isScrollable();
 171 }
 172
 173 }