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 nsDisplayListBuilder; 16 class nsDOMCSSDeclaration; 17 18 namespace mozilla { 19 20 /** 21 * This class receives various notifications about style changes and content 22 * changes that affect layerization decisions, and implements the heuristics 23 * that drive those decisions. It manages per-frame state to support those 24 * heuristics. 25 */ 26 class ActiveLayerTracker { 27 public: 28 static void Shutdown(); 29 30 /* 31 * We track style changes to selected styles: 32 * eCSSProperty_transform, eCSSProperty_translate, 33 * eCSSProperty_rotate, eCSSProperty_scale 34 * eCSSProperty_offset_path, eCSSProperty_offset_distance, 35 * eCSSProperty_offset_rotate, eCSSProperty_offset_anchor, 36 * eCSSProperty_opacity 37 * eCSSProperty_left, eCSSProperty_top, 38 * eCSSProperty_right, eCSSProperty_bottom 39 * and use that information to guess whether style changes are animated. 40 */ 41 42 /** 43 * Notify aFrame's style property as having changed due to a restyle, 44 * and therefore possibly wanting an active layer to render that style. 45 * Any such marking will time out after a short period. 46 * @param aProperty the property that has changed 47 */ 48 static void NotifyRestyle(nsIFrame* aFrame, nsCSSPropertyID aProperty); 49 /** 50 * Notify aFrame's left/top/right/bottom properties as having (maybe) 51 * changed due to a restyle, and therefore possibly wanting an active layer 52 * to render that style. Any such marking will time out after a short period. 53 */ 54 static void NotifyOffsetRestyle(nsIFrame* aFrame); 55 /** 56 * Mark aFrame as being known to have an animation of aProperty. 57 * Any such marking will time out after a short period. 58 * aNewValue and aDOMCSSDecl are used to determine whether the property's 59 * value has changed. 60 */ 61 static void NotifyAnimated(nsIFrame* aFrame, nsCSSPropertyID aProperty, 62 const nsACString& aNewValue, 63 nsDOMCSSDeclaration* aDOMCSSDecl); 64 /** 65 * Notify aFrame as being known to have an animation of aProperty through an 66 * inline style modification during aScrollFrame's scroll event handler. 67 */ 68 static void NotifyAnimatedFromScrollHandler(nsIFrame* aFrame, 69 nsCSSPropertyID aProperty, 70 nsIFrame* aScrollFrame); 71 /** 72 * Notify that a property in the inline style rule of aFrame's element 73 * has been modified. 74 * This notification is incomplete --- not all modifications to inline 75 * style will trigger this. 76 * aNewValue and aDOMCSSDecl are used to determine whether the property's 77 * value has changed. 78 */ 79 static void NotifyInlineStyleRuleModified(nsIFrame* aFrame, 80 nsCSSPropertyID aProperty, 81 const nsACString& aNewValue, 82 nsDOMCSSDeclaration* aDOMCSSDecl); 83 /** 84 * Notify that a frame needs to be repainted. This is important for layering 85 * decisions where, say, aFrame's transform is updated from JS, but we need 86 * to repaint aFrame anyway, so we get no benefit from giving it its own 87 * layer. 88 */ 89 static void NotifyNeedsRepaint(nsIFrame* aFrame); 90 /** 91 * Return true if aFrame's property style in |aPropertySet| should be 92 * considered as being animated for constructing active layers. 93 */ 94 static bool IsStyleAnimated(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame, 95 const nsCSSPropertyIDSet& aPropertySet); 96 /** 97 * Return true if any of aFrame's offset property styles should be considered 98 * as being animated for constructing active layers. 99 */ 100 static bool IsOffsetStyleAnimated(nsIFrame* aFrame); 101 /** 102 * Return true if aFrame's background-position-x or background-position-y 103 * property is animated. 104 */ 105 static bool IsBackgroundPositionAnimated(nsDisplayListBuilder* aBuilder, 106 nsIFrame* aFrame); 107 /** 108 * Return true if aFrame's transform-like property, 109 * i.e. transform/translate/rotate/scale, is animated. 110 */ 111 static bool IsTransformAnimated(nsDisplayListBuilder* aBuilder, 112 nsIFrame* aFrame); 113 /** 114 * Return true if aFrame's transform style should be considered as being 115 * animated for pre-rendering. 116 */ 117 static bool IsTransformMaybeAnimated(nsIFrame* aFrame); 118 /** 119 * Return true if aFrame either has an animated scale now, or is likely to 120 * have one in the future because it has a CSS animation or transition 121 * (which may not be playing right now) that affects its scale. 122 */ 123 static bool IsScaleSubjectToAnimation(nsIFrame* aFrame); 124 125 /** 126 * Transfer the LayerActivity property to the frame's content node when the 127 * frame is about to be destroyed so that layer activity can be tracked 128 * throughout reframes of an element. Only call this when aFrame is the 129 * primary frame of aContent. 130 */ 131 static void TransferActivityToContent(nsIFrame* aFrame, nsIContent* aContent); 132 /** 133 * Transfer the LayerActivity property back to the content node's primary 134 * frame after the frame has been created. 135 */ 136 static void TransferActivityToFrame(nsIContent* aContent, nsIFrame* aFrame); 137 138 /* 139 * We track modifications to the content of certain frames (i.e. canvas 140 * frames) and use that to make layering decisions. 141 */ 142 143 /** 144 * Mark aFrame's content as being active. This marking will time out after 145 * a short period. 146 */ 147 static void NotifyContentChange(nsIFrame* aFrame); 148 /** 149 * Return true if this frame's content is still marked as active. 150 */ 151 static bool IsContentActive(nsIFrame* aFrame); 152 153 /** 154 * Called before and after a scroll event handler is executed, with the 155 * scrollframe or nullptr, respectively. This acts as a hint to treat 156 * inline style changes during the handler differently. 157 */ 158 static void SetCurrentScrollHandlerFrame(nsIFrame* aFrame); 159 }; 160 161 } // namespace mozilla 162 163 #endif /* ACTIVELAYERTRACKER_H_ */ 164