The Tor Browser: layout/base/MaskLayerImageCache.h@6474c204b198 (annotated)

layout/base/MaskLayerImageCache.h@6474c204b198 (annotated)

layout/base/MaskLayerImageCache.h

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #ifndef MASKLAYERIMAGECACHE_H_
 #define MASKLAYERIMAGECACHE_H_
 #include "DisplayItemClip.h"
 #include "nsPresContext.h"
 #include "mozilla/gfx/Matrix.h"
 namespace mozilla {
 namespace layers {
 class ImageContainer;
 }
 /**
  * Keeps a record of image containers for mask layers, containers are mapped
  * from the rounded rects used to create them.
  * The cache stores MaskLayerImageEntries indexed by MaskLayerImageKeys.
  * Each MaskLayerImageEntry owns a heap-allocated MaskLayerImageKey
  * (heap-allocated so that a mask layer's userdata can keep a pointer to the
  * key for its image, in spite of the hashtable moving its entries around).
  * The key consists of the rounded rects used to create the mask,
  * an nsRefPtr to the ImageContainer containing the image, and a count
  * of the number of layers currently using this ImageContainer.
  * When the key's layer count is zero, the cache
  * may remove the entry, which deletes the key object.
  */
 class MaskLayerImageCache
 {
   typedef mozilla::layers::ImageContainer ImageContainer;
 public:
   MaskLayerImageCache();
   ~MaskLayerImageCache();
   /**
    * Representation of a rounded rectangle in device pixel coordinates, in
    * contrast to DisplayItemClip::RoundedRect, which uses app units.
    * In particular, our internal representation uses a gfxRect, rather than
    * an nsRect, so this class is easier to use with transforms.
    */
   struct PixelRoundedRect
   {
     PixelRoundedRect(const DisplayItemClip::RoundedRect& aRRect,
                      nsPresContext* aPresContext)
       : mRect(aPresContext->AppUnitsToGfxUnits(aRRect.mRect.x),
               aPresContext->AppUnitsToGfxUnits(aRRect.mRect.y),
               aPresContext->AppUnitsToGfxUnits(aRRect.mRect.width),
               aPresContext->AppUnitsToGfxUnits(aRRect.mRect.height))
     {
       MOZ_COUNT_CTOR(PixelRoundedRect);
       NS_FOR_CSS_HALF_CORNERS(corner) {
         mRadii[corner] = aPresContext->AppUnitsToGfxUnits(aRRect.mRadii[corner]);
       }
     }
     PixelRoundedRect(const PixelRoundedRect& aPRR)
       : mRect(aPRR.mRect)
     {
       MOZ_COUNT_CTOR(PixelRoundedRect);
       NS_FOR_CSS_HALF_CORNERS(corner) {
         mRadii[corner] = aPRR.mRadii[corner];
       }
     }
     ~PixelRoundedRect()
     {
       MOZ_COUNT_DTOR(PixelRoundedRect);
     }
     // Applies the scale and translate components of aTransform.
     // It is an error to pass a matrix which does more than just scale
     // and translate.
     void ScaleAndTranslate(const gfx::Matrix& aTransform)
     {
       NS_ASSERTION(aTransform._12 == 0 && aTransform._21 == 0,
                    "Transform has a component other than scale and translate");
       mRect = aTransform.TransformBounds(mRect);
       for (size_t i = 0; i < ArrayLength(mRadii); i += 2) {
         mRadii[i] *= aTransform._11;
         mRadii[i + 1] *= aTransform._22;
       }
     }
     bool operator==(const PixelRoundedRect& aOther) const {
       if (!mRect.IsEqualInterior(aOther.mRect)) {
         return false;
       }
       NS_FOR_CSS_HALF_CORNERS(corner) {
         if (mRadii[corner] != aOther.mRadii[corner]) {
           return false;
         }
       }
       return true;
     }
     bool operator!=(const PixelRoundedRect& aOther) const {
       return !(*this == aOther);
     }
     // Create a hash for this object.
     PLDHashNumber Hash() const
     {
       PLDHashNumber hash = HashBytes(&mRect.x, 4*sizeof(gfxFloat));
       hash = AddToHash(hash, HashBytes(mRadii, 8*sizeof(gfxFloat)));
       return hash;
     }
     gfx::Rect mRect;
     // Indices into mRadii are the NS_CORNER_* constants in nsStyleConsts.h
     gfxFloat mRadii[8];
   private:
     PixelRoundedRect() MOZ_DELETE;
   };
   /**
    * A key to identify cached image containers.
    * The const-ness of this class is with respect to its use as a key into a
    * hashtable, so anything not used to create the hash is mutable.
    * mLayerCount counts the number of mask layers which have a reference to
    * MaskLayerImageEntry::mContainer; it is maintained by MaskLayerUserData,
    * which keeps a reference to the key. There will usually be mLayerCount + 1
    * pointers to a key object (the +1 being from the hashtable entry), but this
    * invariant may be temporarily broken.
    */
   struct MaskLayerImageKey
   {
     MaskLayerImageKey()
       : mLayerCount(0)
       , mRoundedClipRects()
     {
       MOZ_COUNT_CTOR(MaskLayerImageKey);
     }
     MaskLayerImageKey(const MaskLayerImageKey& aKey)
       : mLayerCount(aKey.mLayerCount)
       , mRoundedClipRects(aKey.mRoundedClipRects)
     {
       MOZ_COUNT_CTOR(MaskLayerImageKey);
     }
     ~MaskLayerImageKey()
     {
       MOZ_COUNT_DTOR(MaskLayerImageKey);
     }
     void AddRef() const { ++mLayerCount; }
     void Release() const
     {
       NS_ASSERTION(mLayerCount > 0, "Inconsistent layer count");
       --mLayerCount;
     }
     PLDHashNumber Hash() const
     {
       PLDHashNumber hash = 0;
       for (uint32_t i = 0; i < mRoundedClipRects.Length(); ++i) {
         hash = AddToHash(hash, mRoundedClipRects[i].Hash());
       }
       return hash;
     }
     bool operator==(const MaskLayerImageKey& aOther) const
     {
       return mRoundedClipRects == aOther.mRoundedClipRects;
     }
     mutable uint32_t mLayerCount;
     nsTArray<PixelRoundedRect> mRoundedClipRects;
   };
   // Find an image container for aKey, returns nullptr if there is no suitable
   // cached image. If there is an image, then aKey is set to point at the stored
   // key for the image.
   ImageContainer* FindImageFor(const MaskLayerImageKey** aKey);
   // Add an image container with a key to the cache
   // The image container used will be set as the container in aKey and aKey
   // itself will be linked from this cache
   void PutImage(const MaskLayerImageKey* aKey,
                 ImageContainer* aContainer);
   // Sweep the cache for old image containers that can be deleted
   void Sweep();
 protected:
   class MaskLayerImageEntry : public PLDHashEntryHdr
   {
   public:
     typedef const MaskLayerImageKey& KeyType;
     typedef const MaskLayerImageKey* KeyTypePointer;
     MaskLayerImageEntry(KeyTypePointer aKey) : mKey(aKey)
     {
       MOZ_COUNT_CTOR(MaskLayerImageEntry);
     }
     MaskLayerImageEntry(const MaskLayerImageEntry& aOther)
       : mKey(aOther.mKey.get())
     {
       NS_ERROR("ALLOW_MEMMOVE == true, should never be called");
     }
     ~MaskLayerImageEntry()
     {
       MOZ_COUNT_DTOR(MaskLayerImageEntry);
     }
     // KeyEquals(): does this entry match this key?
     bool KeyEquals(KeyTypePointer aKey) const
     {
       return *mKey == *aKey;
     }
     // KeyToPointer(): Convert KeyType to KeyTypePointer
     static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
     // HashKey(): calculate the hash number
     static PLDHashNumber HashKey(KeyTypePointer aKey)
     {
       return aKey->Hash();
     }
     // ALLOW_MEMMOVE can we move this class with memmove(), or do we have
     // to use the copy constructor?
     enum { ALLOW_MEMMOVE = true };
     bool operator==(const MaskLayerImageEntry& aOther) const
     {
       return KeyEquals(aOther.mKey);
     }
     nsAutoPtr<const MaskLayerImageKey> mKey;
     nsRefPtr<ImageContainer> mContainer;
   };
   nsTHashtable<MaskLayerImageEntry> mMaskImageContainers;
   // helper funtion for Sweep(), called for each entry in the hashtable
   static PLDHashOperator SweepFunc(MaskLayerImageEntry* aEntry, void* aUserArg);
 };
 }
 #endif

The Tor Browser / annotate

layout/base/MaskLayerImageCache.h@6474c204b198 (annotated)

layout/base/MaskLayerImageCache.h