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      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 #ifndef CompositingReasons_h
      6 #define CompositingReasons_h
      7 
      8 #include "platform/PlatformExport.h"
      9 #include "wtf/MathExtras.h"
     10 #include <stdint.h>
     11 
     12 namespace blink {
     13 
     14 const uint64_t CompositingReasonNone                                     = 0;
     15 const uint64_t CompositingReasonAll                                      = ~static_cast<uint64_t>(0);
     16 
     17 // Intrinsic reasons that can be known right away by the layer
     18 const uint64_t CompositingReason3DTransform                              = UINT64_C(1) << 0;
     19 const uint64_t CompositingReasonVideo                                    = UINT64_C(1) << 1;
     20 const uint64_t CompositingReasonCanvas                                   = UINT64_C(1) << 2;
     21 const uint64_t CompositingReasonPlugin                                   = UINT64_C(1) << 3;
     22 const uint64_t CompositingReasonIFrame                                   = UINT64_C(1) << 4;
     23 const uint64_t CompositingReasonBackfaceVisibilityHidden                 = UINT64_C(1) << 5;
     24 const uint64_t CompositingReasonActiveAnimation                          = UINT64_C(1) << 6;
     25 const uint64_t CompositingReasonTransitionProperty                       = UINT64_C(1) << 7;
     26 const uint64_t CompositingReasonPositionFixed                            = UINT64_C(1) << 8;
     27 const uint64_t CompositingReasonOverflowScrollingTouch                   = UINT64_C(1) << 9;
     28 const uint64_t CompositingReasonOverflowScrollingParent                  = UINT64_C(1) << 10;
     29 const uint64_t CompositingReasonOutOfFlowClipping                        = UINT64_C(1) << 11;
     30 const uint64_t CompositingReasonVideoOverlay                             = UINT64_C(1) << 12;
     31 const uint64_t CompositingReasonWillChangeCompositingHint                = UINT64_C(1) << 13;
     32 
     33 // Overlap reasons that require knowing what's behind you in paint-order before knowing the answer
     34 const uint64_t CompositingReasonAssumedOverlap                           = UINT64_C(1) << 14;
     35 const uint64_t CompositingReasonOverlap                                  = UINT64_C(1) << 15;
     36 const uint64_t CompositingReasonNegativeZIndexChildren                   = UINT64_C(1) << 16;
     37 const uint64_t CompositingReasonScrollsWithRespectToSquashingLayer       = UINT64_C(1) << 17;
     38 const uint64_t CompositingReasonSquashingSparsityExceeded                = UINT64_C(1) << 18;
     39 const uint64_t CompositingReasonSquashingClippingContainerMismatch       = UINT64_C(1) << 19;
     40 const uint64_t CompositingReasonSquashingOpacityAncestorMismatch         = UINT64_C(1) << 20;
     41 const uint64_t CompositingReasonSquashingTransformAncestorMismatch       = UINT64_C(1) << 21;
     42 const uint64_t CompositingReasonSquashingFilterMismatch                  = UINT64_C(1) << 22;
     43 const uint64_t CompositingReasonSquashingWouldBreakPaintOrder            = UINT64_C(1) << 23;
     44 const uint64_t CompositingReasonSquashingVideoIsDisallowed               = UINT64_C(1) << 24;
     45 const uint64_t CompositingReasonSquashedLayerClipsCompositingDescendants = UINT64_C(1) << 25;
     46 const uint64_t CompositingReasonSquashingRenderPartIsDisallowed          = UINT64_C(1) << 26;
     47 const uint64_t CompositingReasonSquashingReflectionIsDisallowed          = UINT64_C(1) << 27;
     48 const uint64_t CompositingReasonSquashingBlendingIsDisallowed            = UINT64_C(1) << 28;
     49 
     50 // Subtree reasons that require knowing what the status of your subtree is before knowing the answer
     51 const uint64_t CompositingReasonTransformWithCompositedDescendants       = UINT64_C(1) << 29;
     52 const uint64_t CompositingReasonOpacityWithCompositedDescendants         = UINT64_C(1) << 30;
     53 const uint64_t CompositingReasonMaskWithCompositedDescendants            = UINT64_C(1) << 31;
     54 const uint64_t CompositingReasonReflectionWithCompositedDescendants      = UINT64_C(1) << 32;
     55 const uint64_t CompositingReasonFilterWithCompositedDescendants          = UINT64_C(1) << 33;
     56 const uint64_t CompositingReasonBlendingWithCompositedDescendants        = UINT64_C(1) << 34;
     57 const uint64_t CompositingReasonClipsCompositingDescendants              = UINT64_C(1) << 35;
     58 const uint64_t CompositingReasonPerspectiveWith3DDescendants             = UINT64_C(1) << 36;
     59 const uint64_t CompositingReasonPreserve3DWith3DDescendants              = UINT64_C(1) << 37;
     60 const uint64_t CompositingReasonReflectionOfCompositedParent             = UINT64_C(1) << 38;
     61 const uint64_t CompositingReasonIsolateCompositedDescendants             = UINT64_C(1) << 39;
     62 
     63 // The root layer is a special case that may be forced to be a layer, but also it needs to be
     64 // a layer if anything else in the subtree is composited.
     65 const uint64_t CompositingReasonRoot                                     = UINT64_C(1) << 40;
     66 
     67 // CompositedLayerMapping internal hierarchy reasons
     68 const uint64_t CompositingReasonLayerForAncestorClip                     = UINT64_C(1) << 41;
     69 const uint64_t CompositingReasonLayerForDescendantClip                   = UINT64_C(1) << 42;
     70 const uint64_t CompositingReasonLayerForPerspective                      = UINT64_C(1) << 43;
     71 const uint64_t CompositingReasonLayerForHorizontalScrollbar              = UINT64_C(1) << 44;
     72 const uint64_t CompositingReasonLayerForVerticalScrollbar                = UINT64_C(1) << 45;
     73 const uint64_t CompositingReasonLayerForOverflowControlsHost             = UINT64_C(1) << 46;
     74 const uint64_t CompositingReasonLayerForScrollCorner                     = UINT64_C(1) << 47;
     75 const uint64_t CompositingReasonLayerForScrollingContents                = UINT64_C(1) << 48;
     76 const uint64_t CompositingReasonLayerForScrollingContainer               = UINT64_C(1) << 49;
     77 const uint64_t CompositingReasonLayerForSquashingContents                = UINT64_C(1) << 50;
     78 const uint64_t CompositingReasonLayerForSquashingContainer               = UINT64_C(1) << 51;
     79 const uint64_t CompositingReasonLayerForForeground                       = UINT64_C(1) << 52;
     80 const uint64_t CompositingReasonLayerForBackground                       = UINT64_C(1) << 53;
     81 const uint64_t CompositingReasonLayerForMask                             = UINT64_C(1) << 54;
     82 const uint64_t CompositingReasonLayerForClippingMask                     = UINT64_C(1) << 55;
     83 const uint64_t CompositingReasonLayerForScrollingBlockSelection          = UINT64_C(1) << 56;
     84 
     85 // Composited elements with inline transforms trigger assumed overlap so that
     86 // we can update their transforms quickly.
     87 const uint64_t CompositingReasonInlineTransform                          = UINT64_C(1) << 57;
     88 
     89 // Various combinations of compositing reasons are defined here also, for more intutive and faster bitwise logic.
     90 const uint64_t CompositingReasonComboAllDirectReasons =
     91     CompositingReason3DTransform
     92     | CompositingReasonVideo
     93     | CompositingReasonCanvas
     94     | CompositingReasonPlugin
     95     | CompositingReasonIFrame
     96     | CompositingReasonBackfaceVisibilityHidden
     97     | CompositingReasonActiveAnimation
     98     | CompositingReasonTransitionProperty
     99     | CompositingReasonPositionFixed
    100     | CompositingReasonOverflowScrollingTouch
    101     | CompositingReasonOverflowScrollingParent
    102     | CompositingReasonOutOfFlowClipping
    103     | CompositingReasonVideoOverlay
    104     | CompositingReasonWillChangeCompositingHint;
    105 
    106 const uint64_t CompositingReasonComboAllDirectStyleDeterminedReasons =
    107     CompositingReason3DTransform
    108     | CompositingReasonBackfaceVisibilityHidden
    109     | CompositingReasonActiveAnimation
    110     | CompositingReasonTransitionProperty
    111     | CompositingReasonWillChangeCompositingHint;
    112 
    113 const uint64_t CompositingReasonComboCompositedDescendants =
    114     CompositingReasonTransformWithCompositedDescendants
    115     | CompositingReasonIsolateCompositedDescendants
    116     | CompositingReasonOpacityWithCompositedDescendants
    117     | CompositingReasonMaskWithCompositedDescendants
    118     | CompositingReasonFilterWithCompositedDescendants
    119     | CompositingReasonBlendingWithCompositedDescendants
    120     | CompositingReasonReflectionWithCompositedDescendants
    121     | CompositingReasonClipsCompositingDescendants;
    122 
    123 const uint64_t CompositingReasonCombo3DDescendants =
    124     CompositingReasonPreserve3DWith3DDescendants
    125     | CompositingReasonPerspectiveWith3DDescendants;
    126 
    127 const uint64_t CompositingReasonComboAllStyleDeterminedReasons =
    128     CompositingReasonComboAllDirectStyleDeterminedReasons
    129     | CompositingReasonComboCompositedDescendants
    130     | CompositingReasonCombo3DDescendants
    131     | CompositingReasonInlineTransform;
    132 
    133 const uint64_t CompositingReasonComboReasonsThatRequireOwnBacking =
    134     CompositingReasonComboAllDirectReasons
    135     | CompositingReasonOverlap
    136     | CompositingReasonAssumedOverlap
    137     | CompositingReasonNegativeZIndexChildren
    138     | CompositingReasonScrollsWithRespectToSquashingLayer
    139     | CompositingReasonSquashingSparsityExceeded
    140     | CompositingReasonSquashingClippingContainerMismatch
    141     | CompositingReasonSquashingOpacityAncestorMismatch
    142     | CompositingReasonSquashingTransformAncestorMismatch
    143     | CompositingReasonSquashingFilterMismatch
    144     | CompositingReasonSquashingWouldBreakPaintOrder
    145     | CompositingReasonSquashingVideoIsDisallowed
    146     | CompositingReasonSquashedLayerClipsCompositingDescendants
    147     | CompositingReasonSquashingRenderPartIsDisallowed
    148     | CompositingReasonSquashingReflectionIsDisallowed
    149     | CompositingReasonSquashingBlendingIsDisallowed
    150     | CompositingReasonTransformWithCompositedDescendants
    151     | CompositingReasonOpacityWithCompositedDescendants
    152     | CompositingReasonMaskWithCompositedDescendants
    153     | CompositingReasonFilterWithCompositedDescendants
    154     | CompositingReasonBlendingWithCompositedDescendants
    155     | CompositingReasonIsolateCompositedDescendants
    156     | CompositingReasonPreserve3DWith3DDescendants; // preserve-3d has to create backing store to ensure that 3d-transformed elements intersect.
    157 
    158 const uint64_t CompositingReasonComboSquashableReasons =
    159     CompositingReasonOverlap
    160     | CompositingReasonAssumedOverlap
    161     | CompositingReasonOverflowScrollingParent;
    162 
    163 typedef uint64_t CompositingReasons;
    164 
    165 // Any reasons other than overlap or assumed overlap will require the layer to be separately compositing.
    166 inline bool requiresCompositing(CompositingReasons reasons)
    167 {
    168     return reasons & ~CompositingReasonComboSquashableReasons;
    169 }
    170 
    171 // If the layer has overlap or assumed overlap, but no other reasons, then it should be squashed.
    172 inline bool requiresSquashing(CompositingReasons reasons)
    173 {
    174     return !requiresCompositing(reasons) && (reasons & CompositingReasonComboSquashableReasons);
    175 }
    176 
    177 struct CompositingReasonStringMap {
    178     CompositingReasons reason;
    179     const char* shortName;
    180     const char* description;
    181 };
    182 
    183 PLATFORM_EXPORT extern const CompositingReasonStringMap kCompositingReasonStringMap[];
    184 PLATFORM_EXPORT extern size_t kNumberOfCompositingReasons;
    185 
    186 } // namespace blink
    187 
    188 #endif // CompositingReasons_h
    189