1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/image/src/SurfaceCache.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,180 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +/**
1.10 + * SurfaceCache is a service for caching temporary surfaces in imagelib.
1.11 + */
1.12 +
1.13 +#ifndef MOZILLA_IMAGELIB_SURFACECACHE_H_
1.14 +#define MOZILLA_IMAGELIB_SURFACECACHE_H_
1.15 +
1.16 +#include "mozilla/HashFunctions.h" // for HashGeneric and AddToHash
1.17 +#include "gfxPoint.h" // for gfxSize
1.18 +#include "nsCOMPtr.h" // for already_AddRefed
1.19 +#include "mozilla/gfx/Point.h" // for mozilla::gfx::IntSize
1.20 +#include "SVGImageContext.h" // for SVGImageContext
1.21 +
1.22 +class gfxDrawable;
1.23 +
1.24 +namespace mozilla {
1.25 +
1.26 +namespace gfx {
1.27 +class DrawTarget;
1.28 +} // namespace gfx
1.29 +
1.30 +namespace image {
1.31 +
1.32 +class Image;
1.33 +
1.34 +/*
1.35 + * ImageKey contains the information we need to look up all cached surfaces for
1.36 + * a particular image.
1.37 + */
1.38 +typedef Image* ImageKey;
1.39 +
1.40 +/*
1.41 + * SurfaceKey contains the information we need to look up a specific cached
1.42 + * surface. Together with an ImageKey, this uniquely identifies the surface.
1.43 + *
1.44 + * XXX(seth): Right now this is specialized to the needs of VectorImage. We'll
1.45 + * generalize it in bug 919071.
1.46 + */
1.47 +class SurfaceKey
1.48 +{
1.49 + typedef gfx::IntSize IntSize;
1.50 +public:
1.51 + SurfaceKey(const IntSize& aSize,
1.52 + const gfxSize aScale,
1.53 + const SVGImageContext* aSVGContext,
1.54 + const float aAnimationTime,
1.55 + const uint32_t aFlags)
1.56 + : mSize(aSize)
1.57 + , mScale(aScale)
1.58 + , mSVGContextIsValid(aSVGContext != nullptr)
1.59 + , mAnimationTime(aAnimationTime)
1.60 + , mFlags(aFlags)
1.61 + {
1.62 + // XXX(seth): Would love to use Maybe<T> here, but see bug 913586.
1.63 + if (mSVGContextIsValid)
1.64 + mSVGContext = *aSVGContext;
1.65 + }
1.66 +
1.67 + bool operator==(const SurfaceKey& aOther) const
1.68 + {
1.69 + bool matchesSVGContext = aOther.mSVGContextIsValid == mSVGContextIsValid &&
1.70 + (!mSVGContextIsValid || aOther.mSVGContext == mSVGContext);
1.71 + return aOther.mSize == mSize &&
1.72 + aOther.mScale == mScale &&
1.73 + matchesSVGContext &&
1.74 + aOther.mAnimationTime == mAnimationTime &&
1.75 + aOther.mFlags == mFlags;
1.76 + }
1.77 +
1.78 + uint32_t Hash() const
1.79 + {
1.80 + uint32_t hash = HashGeneric(mSize.width, mSize.height);
1.81 + hash = AddToHash(hash, mScale.width, mScale.height);
1.82 + hash = AddToHash(hash, mSVGContextIsValid, mSVGContext.Hash());
1.83 + hash = AddToHash(hash, mAnimationTime, mFlags);
1.84 + return hash;
1.85 + }
1.86 +
1.87 + IntSize Size() const { return mSize; }
1.88 +
1.89 +private:
1.90 + IntSize mSize;
1.91 + gfxSize mScale;
1.92 + SVGImageContext mSVGContext;
1.93 + bool mSVGContextIsValid;
1.94 + float mAnimationTime;
1.95 + uint32_t mFlags;
1.96 +};
1.97 +
1.98 +/**
1.99 + * SurfaceCache is an imagelib-global service that allows caching of temporary
1.100 + * surfaces. Surfaces expire from the cache automatically if they go too long
1.101 + * without being accessed.
1.102 + *
1.103 + * SurfaceCache is not thread-safe; it should only be accessed from the main
1.104 + * thread.
1.105 + */
1.106 +struct SurfaceCache
1.107 +{
1.108 + typedef gfx::IntSize IntSize;
1.109 +
1.110 + /*
1.111 + * Initialize static data. Called during imagelib module initialization.
1.112 + */
1.113 + static void Initialize();
1.114 +
1.115 + /*
1.116 + * Release static data. Called during imagelib module shutdown.
1.117 + */
1.118 + static void Shutdown();
1.119 +
1.120 + /*
1.121 + * Look up a surface in the cache.
1.122 + *
1.123 + * @param aImageKey Key data identifying which image the surface belongs to.
1.124 + * @param aSurfaceKey Key data which uniquely identifies the requested surface.
1.125 + *
1.126 + * @return the requested surface, or nullptr if not found.
1.127 + */
1.128 + static already_AddRefed<gfxDrawable> Lookup(const ImageKey aImageKey,
1.129 + const SurfaceKey& aSurfaceKey);
1.130 +
1.131 + /*
1.132 + * Insert a surface into the cache. It is an error to call this function
1.133 + * without first calling Lookup to verify that the surface is not already in
1.134 + * the cache.
1.135 + *
1.136 + * @param aTarget The new surface (in the form of a DrawTarget) to insert
1.137 + * into the cache.
1.138 + * @param aImageKey Key data identifying which image the surface belongs to.
1.139 + * @param aSurfaceKey Key data which uniquely identifies the requested surface.
1.140 + */
1.141 + static void Insert(mozilla::gfx::DrawTarget* aTarget,
1.142 + const ImageKey aImageKey,
1.143 + const SurfaceKey& aSurfaceKey);
1.144 +
1.145 + /*
1.146 + * Checks if a surface of a given size could possibly be stored in the cache.
1.147 + * If CanHold() returns false, Insert() will always fail to insert the
1.148 + * surface, but the inverse is not true: Insert() may take more information
1.149 + * into account than just image size when deciding whether to cache the
1.150 + * surface, so Insert() may still fail even if CanHold() returns true.
1.151 + *
1.152 + * Use CanHold() to avoid the need to create a temporary surface when we know
1.153 + * for sure the cache can't hold it.
1.154 + *
1.155 + * @param aSize The dimensions of a surface in pixels.
1.156 + *
1.157 + * @return false if the surface cache can't hold a surface of that size.
1.158 + */
1.159 + static bool CanHold(const IntSize& aSize);
1.160 +
1.161 + /*
1.162 + * Evicts any cached surfaces associated with the given image from the cache.
1.163 + * This MUST be called, at a minimum, when the image is destroyed. If
1.164 + * another image were allocated at the same address it could result in
1.165 + * subtle, difficult-to-reproduce bugs.
1.166 + *
1.167 + * @param aImageKey The image which should be removed from the cache.
1.168 + */
1.169 + static void Discard(const ImageKey aImageKey);
1.170 +
1.171 + /*
1.172 + * Evicts all caches surfaces from ths cache.
1.173 + */
1.174 + static void DiscardAll();
1.175 +
1.176 +private:
1.177 + virtual ~SurfaceCache() = 0; // Forbid instantiation.
1.178 +};
1.179 +
1.180 +} // namespace image
1.181 +} // namespace mozilla
1.182 +
1.183 +#endif // MOZILLA_IMAGELIB_SURFACECACHE_H_
