layout/painting/ActiveLayerTracker.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef ACTIVELAYERTRACKER_H_
   8 #define ACTIVELAYERTRACKER_H_
   9
  10 #include "nsCSSPropertyID.h"
  11
  12 class nsIFrame;
  13 class nsIContent;
  14 class nsCSSPropertyIDSet;
  15 class nsDOMCSSDeclaration;
  16
  17 namespace mozilla {
  18
  19 class nsDisplayListBuilder;
  20
  21 /**
  22  * This class receives various notifications about style changes and content
  23  * changes that affect layerization decisions, and implements the heuristics
  24  * that drive those decisions. It manages per-frame state to support those
  25  * heuristics.
  26  */
  27 class ActiveLayerTracker {
  28  public:
  29   static void Shutdown();
  30
  31   /*
  32    * We track style changes to selected styles:
  33    *   eCSSProperty_transform, eCSSProperty_translate,
  34    *   eCSSProperty_rotate, eCSSProperty_scale
  35    *   eCSSProperty_offset_path, eCSSProperty_offset_distance,
  36    *   eCSSProperty_offset_rotate, eCSSProperty_offset_anchor,
  37    *   eCSSProperty_offset_position, eCSSProperty_opacity
  38    * and use that information to guess whether style changes are animated.
  39    */
  40
  41   /**
  42    * Notify aFrame's style property as having changed due to a restyle,
  43    * and therefore possibly wanting an active layer to render that style.
  44    * Any such marking will time out after a short period.
  45    * @param aProperty the property that has changed
  46    */
  47   static void NotifyRestyle(nsIFrame* aFrame, nsCSSPropertyID aProperty);
  48
  49   /**
  50    * Notify that a property in the inline style rule of aFrame's element
  51    * has been modified.
  52    */
  53   static void NotifyInlineStyleRuleModified(nsIFrame* aFrame,
  54                                             nsCSSPropertyID aProperty);
  55   /**
  56    * Notify that a frame needs to be repainted. This is important for layering
  57    * decisions where, say, aFrame's transform is updated from JS, but we need
  58    * to repaint aFrame anyway, so we get no benefit from giving it its own
  59    * layer.
  60    */
  61   static void NotifyNeedsRepaint(nsIFrame* aFrame);
  62   /**
  63    * Return true if aFrame's property style in |aPropertySet| should be
  64    * considered as being animated for constructing active layers.
  65    */
  66   static bool IsStyleAnimated(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,
  67                               const nsCSSPropertyIDSet& aPropertySet);
  68   /**
  69    * Return true if aFrame's transform-like property,
  70    * i.e. transform/translate/rotate/scale, is animated.
  71    */
  72   static bool IsTransformAnimated(nsDisplayListBuilder* aBuilder,
  73                                   nsIFrame* aFrame);
  74   /**
  75    * Return true if aFrame's transform style should be considered as being
  76    * animated for pre-rendering.
  77    */
  78   static bool IsTransformMaybeAnimated(nsIFrame* aFrame);
  79   /**
  80    * Return true if aFrame either has an animated scale now, or is likely to
  81    * have one in the future because it has a CSS animation or transition
  82    * (which may not be playing right now) that affects its scale.
  83    */
  84   static bool IsScaleSubjectToAnimation(nsIFrame* aFrame);
  85
  86   /**
  87    * Transfer the LayerActivity property to the frame's content node when the
  88    * frame is about to be destroyed so that layer activity can be tracked
  89    * throughout reframes of an element. Only call this when aFrame is the
  90    * primary frame of aContent.
  91    */
  92   static void TransferActivityToContent(nsIFrame* aFrame, nsIContent* aContent);
  93   /**
  94    * Transfer the LayerActivity property back to the content node's primary
  95    * frame after the frame has been created.
  96    */
  97   static void TransferActivityToFrame(nsIContent* aContent, nsIFrame* aFrame);
  98 };
  99
 100 }  // namespace mozilla
 101
 102 #endif /* ACTIVELAYERTRACKER_H_ */