layout/painting/DisplayListClipState.cpp

   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 #include "DisplayListClipState.h"
   8
   9 #include "nsDisplayList.h"
  10
  11 namespace mozilla {
  12
  13 const DisplayItemClipChain* DisplayListClipState::GetCurrentCombinedClipChain(
  14     nsDisplayListBuilder* aBuilder) {
  15   if (mCurrentCombinedClipChainIsValid) {
  16     return mCurrentCombinedClipChain;
  17   }
  18   if (!mClipChainContentDescendants && !mClipChainContainingBlockDescendants) {
  19     mCurrentCombinedClipChain = nullptr;
  20     mCurrentCombinedClipChainIsValid = true;
  21     return nullptr;
  22   }
  23
  24   mCurrentCombinedClipChain = aBuilder->CreateClipChainIntersection(
  25       mCurrentCombinedClipChain, mClipChainContentDescendants,
  26       mClipChainContainingBlockDescendants);
  27   mCurrentCombinedClipChainIsValid = true;
  28   return mCurrentCombinedClipChain;
  29 }
  30
  31 static void ApplyClip(nsDisplayListBuilder* aBuilder,
  32                       const DisplayItemClipChain*& aClipToModify,
  33                       const ActiveScrolledRoot* aASR,
  34                       DisplayItemClipChain& aClipChainOnStack) {
  35   aClipChainOnStack.mASR = aASR;
  36   if (aClipToModify && aClipToModify->mASR == aASR) {
  37     // Intersect with aClipToModify and replace the clip chain item.
  38     aClipChainOnStack.mClip.IntersectWith(aClipToModify->mClip);
  39     aClipChainOnStack.mParent = aClipToModify->mParent;
  40     aClipToModify = &aClipChainOnStack;
  41   } else if (!aClipToModify ||
  42              ActiveScrolledRoot::IsAncestor(aClipToModify->mASR, aASR)) {
  43     // Add a new clip chain item at the bottom.
  44     aClipChainOnStack.mParent = aClipToModify;
  45     aClipToModify = &aClipChainOnStack;
  46   } else {
  47     // We need to insert / intersect a DisplayItemClipChain in the middle of the
  48     // aClipToModify chain. This is a very rare case.
  49     // Find the common ancestor and have the builder create the
  50     // DisplayItemClipChain intersection. This will create new
  51     // DisplayItemClipChain objects for all descendants of ancestorSC and we
  52     // will not hold on to a pointer to aClipChainOnStack.
  53     const DisplayItemClipChain* ancestorSC = aClipToModify;
  54     while (ancestorSC &&
  55            ActiveScrolledRoot::IsAncestor(aASR, ancestorSC->mASR)) {
  56       ancestorSC = ancestorSC->mParent;
  57     }
  58     ancestorSC = aBuilder->CopyWholeChain(ancestorSC);
  59     aClipChainOnStack.mParent = nullptr;
  60     aClipToModify = aBuilder->CreateClipChainIntersection(
  61         ancestorSC, aClipToModify, &aClipChainOnStack);
  62   }
  63 }
  64
  65 void DisplayListClipState::ClipContainingBlockDescendants(
  66     nsDisplayListBuilder* aBuilder, const nsRect& aRect, const nscoord* aRadii,
  67     DisplayItemClipChain& aClipChainOnStack) {
  68   if (aRadii) {
  69     aClipChainOnStack.mClip.SetTo(aRect, aRadii);
  70   } else {
  71     aClipChainOnStack.mClip.SetTo(aRect);
  72   }
  73   const ActiveScrolledRoot* asr = aBuilder->CurrentActiveScrolledRoot();
  74   ApplyClip(aBuilder, mClipChainContainingBlockDescendants, asr,
  75             aClipChainOnStack);
  76   InvalidateCurrentCombinedClipChain(asr);
  77 }
  78
  79 void DisplayListClipState::ClipContentDescendants(
  80     nsDisplayListBuilder* aBuilder, const nsRect& aRect, const nscoord* aRadii,
  81     DisplayItemClipChain& aClipChainOnStack) {
  82   if (aRadii) {
  83     aClipChainOnStack.mClip.SetTo(aRect, aRadii);
  84   } else {
  85     aClipChainOnStack.mClip.SetTo(aRect);
  86   }
  87   const ActiveScrolledRoot* asr = aBuilder->CurrentActiveScrolledRoot();
  88   ApplyClip(aBuilder, mClipChainContentDescendants, asr, aClipChainOnStack);
  89   InvalidateCurrentCombinedClipChain(asr);
  90 }
  91
  92 void DisplayListClipState::ClipContentDescendants(
  93     nsDisplayListBuilder* aBuilder, const nsRect& aRect,
  94     const nsRect& aRoundedRect, const nscoord* aRadii,
  95     DisplayItemClipChain& aClipChainOnStack) {
  96   if (aRadii) {
  97     aClipChainOnStack.mClip.SetTo(aRect, aRoundedRect, aRadii);
  98   } else {
  99     nsRect intersect = aRect.Intersect(aRoundedRect);
 100     aClipChainOnStack.mClip.SetTo(intersect);
 101   }
 102   const ActiveScrolledRoot* asr = aBuilder->CurrentActiveScrolledRoot();
 103   ApplyClip(aBuilder, mClipChainContentDescendants, asr, aClipChainOnStack);
 104   InvalidateCurrentCombinedClipChain(asr);
 105 }
 106
 107 void DisplayListClipState::InvalidateCurrentCombinedClipChain(
 108     const ActiveScrolledRoot* aInvalidateUpTo) {
 109   mClippedToDisplayPort = false;
 110   mCurrentCombinedClipChainIsValid = false;
 111   while (mCurrentCombinedClipChain &&
 112          ActiveScrolledRoot::IsAncestor(aInvalidateUpTo,
 113                                         mCurrentCombinedClipChain->mASR)) {
 114     mCurrentCombinedClipChain = mCurrentCombinedClipChain->mParent;
 115   }
 116 }
 117
 118 void DisplayListClipState::ClipContainingBlockDescendantsToContentBox(
 119     nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,
 120     DisplayItemClipChain& aClipChainOnStack, uint32_t aFlags) {
 121   nscoord radii[8];
 122   bool hasBorderRadius = aFrame->GetContentBoxBorderRadii(radii);
 123   if (!hasBorderRadius &&
 124       (aFlags & ASSUME_DRAWING_RESTRICTED_TO_CONTENT_RECT)) {
 125     return;
 126   }
 127
 128   nsRect clipRect = aFrame->GetContentRectRelativeToSelf() +
 129                     aBuilder->ToReferenceFrame(aFrame);
 130   // If we have a border-radius, we have to clip our content to that
 131   // radius.
 132   ClipContainingBlockDescendants(
 133       aBuilder, clipRect, hasBorderRadius ? radii : nullptr, aClipChainOnStack);
 134 }
 135
 136 DisplayListClipState::AutoSaveRestore::AutoSaveRestore(
 137     nsDisplayListBuilder* aBuilder)
 138     : mBuilder(aBuilder),
 139       mState(aBuilder->ClipState()),
 140       mSavedState(aBuilder->ClipState())
 141 #ifdef DEBUG
 142       ,
 143       mClipUsed(false),
 144       mRestored(false)
 145 #endif
 146 {
 147 }
 148
 149 }  // namespace mozilla