image/ISurfaceProvider.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 /**
   7  * An interface for objects which can either store a surface or dynamically
   8  * generate one, and various implementations.
   9  */
  10
  11 #ifndef mozilla_image_ISurfaceProvider_h
  12 #define mozilla_image_ISurfaceProvider_h
  13
  14 #include "mozilla/Attributes.h"
  15 #include "mozilla/Maybe.h"
  16 #include "mozilla/MemoryReporting.h"
  17 #include "mozilla/NotNull.h"
  18 #include "mozilla/TimeStamp.h"
  19 #include "mozilla/gfx/2D.h"
  20 #include "mozilla/image/WebRenderImageProvider.h"
  21
  22 #include "imgFrame.h"
  23 #include "SurfaceCache.h"
  24
  25 namespace mozilla {
  26 namespace image {
  27
  28 class CachedSurface;
  29 class DrawableSurface;
  30
  31 /**
  32  * An interface for objects which can either store a surface or dynamically
  33  * generate one.
  34  */
  35 class ISurfaceProvider : public WebRenderImageProvider {
  36  public:
  37   // Subclasses may or may not be XPCOM classes, so we just require that they
  38   // implement AddRef and Release.
  39   NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING
  40
  41   /// @return key data used for identifying which image this ISurfaceProvider is
  42   /// associated with in the surface cache.
  43   ImageKey GetImageKey() const { return mImageKey; }
  44
  45   /// @return key data used to uniquely identify this ISurfaceProvider's cache
  46   /// entry in the surface cache.
  47   const SurfaceKey& GetSurfaceKey() const { return mSurfaceKey; }
  48
  49   /// @return a drawable reference to a surface.
  50   DrawableSurface Surface();
  51
  52   /// @return true if DrawableRef() will return a completely decoded surface.
  53   virtual bool IsFinished() const = 0;
  54
  55   /// @return true if the underlying decoder is currently fully decoded. For
  56   /// animated images, this means that at least every frame has been decoded
  57   /// at least once. It does not guarantee that all of the frames are present,
  58   /// as the surface provider has the option to discard as it deems necessary.
  59   virtual bool IsFullyDecoded() const { return IsFinished(); }
  60
  61   /// @return the number of bytes of memory this ISurfaceProvider is expected to
  62   /// require. Optimizations may result in lower real memory usage. Trivial
  63   /// overhead is ignored. Because this value is used in bookkeeping, it's
  64   /// important that it be constant over the lifetime of this object.
  65   virtual size_t LogicalSizeInBytes() const = 0;
  66
  67   typedef imgFrame::AddSizeOfCbData AddSizeOfCbData;
  68   typedef imgFrame::AddSizeOfCb AddSizeOfCb;
  69
  70   /// @return the actual number of bytes of memory this ISurfaceProvider is
  71   /// using. May vary over the lifetime of the ISurfaceProvider. The default
  72   /// implementation is appropriate for static ISurfaceProviders.
  73   virtual void AddSizeOfExcludingThis(MallocSizeOf aMallocSizeOf,
  74                                       const AddSizeOfCb& aCallback) {
  75     DrawableFrameRef ref = DrawableRef(/* aFrame = */ 0);
  76     if (!ref) {
  77       return;
  78     }
  79
  80     ref->AddSizeOfExcludingThis(aMallocSizeOf, aCallback);
  81   }
  82
  83   virtual void Reset() {}
  84   virtual void Advance(size_t aFrame) {}
  85   virtual bool MayAdvance() const { return false; }
  86   virtual void MarkMayAdvance() {}
  87
  88   /// @return the availability state of this ISurfaceProvider, which indicates
  89   /// whether DrawableRef() could successfully return a surface. Should only be
  90   /// called from SurfaceCache code as it relies on SurfaceCache for
  91   /// synchronization.
  92   AvailabilityState& Availability() { return mAvailability; }
  93   const AvailabilityState& Availability() const { return mAvailability; }
  94
  95  protected:
  96   ISurfaceProvider(const ImageKey aImageKey, const SurfaceKey& aSurfaceKey,
  97                    AvailabilityState aAvailability)
  98       : WebRenderImageProvider(aImageKey),
  99         mImageKey(aImageKey),
 100         mSurfaceKey(aSurfaceKey),
 101         mAvailability(aAvailability) {
 102     MOZ_ASSERT(aImageKey, "Must have a valid image key");
 103   }
 104
 105   virtual ~ISurfaceProvider() {}
 106
 107   /// @return an eagerly computed drawable reference to a surface. For
 108   /// dynamically generated animation surfaces, @aFrame specifies the 0-based
 109   /// index of the desired frame.
 110   virtual DrawableFrameRef DrawableRef(size_t aFrame) = 0;
 111
 112   /// @return an imgFrame at the 0-based index of the desired frame, as
 113   /// specified by @aFrame. Only applies for animated images.
 114   virtual already_AddRefed<imgFrame> GetFrame(size_t aFrame) {
 115     MOZ_ASSERT_UNREACHABLE("Surface provider does not support direct access!");
 116     return nullptr;
 117   }
 118
 119   /// @return true if this ISurfaceProvider is locked. (@see SetLocked())
 120   /// Should only be called from SurfaceCache code as it relies on SurfaceCache
 121   /// for synchronization.
 122   virtual bool IsLocked() const = 0;
 123
 124   /// If @aLocked is true, hint that this ISurfaceProvider is in use and it
 125   /// should avoid releasing its resources. Should only be called from
 126   /// SurfaceCache code as it relies on SurfaceCache for synchronization.
 127   virtual void SetLocked(bool aLocked) = 0;
 128
 129  private:
 130   friend class CachedSurface;
 131   friend class DrawableSurface;
 132
 133   const ImageKey mImageKey;
 134   const SurfaceKey mSurfaceKey;
 135   AvailabilityState mAvailability;
 136 };
 137
 138 /**
 139  * A reference to a surface (stored in an imgFrame) that holds the surface in
 140  * memory, guaranteeing that it can be drawn. If you have a DrawableSurface
 141  * |surf| and |if (surf)| returns true, then calls to |surf->Draw()| and
 142  * |surf->GetSourceSurface()| are guaranteed to succeed.
 143  *
 144  * Note that the surface may be computed lazily, so a DrawableSurface should not
 145  * be dereferenced (i.e., operator->() should not be called) until you're
 146  * sure that you want to draw it.
 147  */
 148 class MOZ_STACK_CLASS DrawableSurface final {
 149  public:
 150   DrawableSurface() : mHaveSurface(false) {}
 151
 152   explicit DrawableSurface(NotNull<ISurfaceProvider*> aProvider)
 153       : mProvider(aProvider), mHaveSurface(true) {}
 154
 155   DrawableSurface(DrawableSurface&& aOther)
 156       : mDrawableRef(std::move(aOther.mDrawableRef)),
 157         mProvider(std::move(aOther.mProvider)),
 158         mHaveSurface(aOther.mHaveSurface) {
 159     aOther.mHaveSurface = false;
 160   }
 161
 162   DrawableSurface& operator=(DrawableSurface&& aOther) {
 163     MOZ_ASSERT(this != &aOther, "Self-moves are prohibited");
 164     mDrawableRef = std::move(aOther.mDrawableRef);
 165     mProvider = std::move(aOther.mProvider);
 166     mHaveSurface = aOther.mHaveSurface;
 167     aOther.mHaveSurface = false;
 168     return *this;
 169   }
 170
 171   /**
 172    * If this DrawableSurface is dynamically generated from an animation, attempt
 173    * to seek to frame @aFrame, where @aFrame is a 0-based index into the frames
 174    * of the animation. Otherwise, nothing will blow up at runtime, but we assert
 175    * in debug builds, since calling this in an unexpected situation probably
 176    * indicates a bug.
 177    *
 178    * @return a successful result if we could obtain frame @aFrame. Note that
 179    * |mHaveSurface| being true means that we're guaranteed to have *some* frame,
 180    * so the caller can dereference this DrawableSurface even if Seek() fails,
 181    * but while nothing will blow up, the frame won't be the one they expect.
 182    */
 183   nsresult Seek(size_t aFrame) {
 184     MOZ_ASSERT(mHaveSurface, "Trying to seek an empty DrawableSurface?");
 185
 186     if (!mProvider) {
 187       MOZ_ASSERT_UNREACHABLE("Trying to seek a static DrawableSurface?");
 188       return NS_ERROR_FAILURE;
 189     }
 190
 191     mDrawableRef = mProvider->DrawableRef(aFrame);
 192
 193     return mDrawableRef ? NS_OK : NS_ERROR_FAILURE;
 194   }
 195
 196   already_AddRefed<imgFrame> GetFrame(size_t aFrame) {
 197     MOZ_ASSERT(mHaveSurface, "Trying to get on an empty DrawableSurface?");
 198
 199     if (!mProvider) {
 200       MOZ_ASSERT_UNREACHABLE("Trying to get on a static DrawableSurface?");
 201       return nullptr;
 202     }
 203
 204     return mProvider->GetFrame(aFrame);
 205   }
 206
 207   void Reset() {
 208     if (!mProvider) {
 209       MOZ_ASSERT_UNREACHABLE("Trying to reset a static DrawableSurface?");
 210       return;
 211     }
 212
 213     mProvider->Reset();
 214   }
 215
 216   void Advance(size_t aFrame) {
 217     if (!mProvider) {
 218       MOZ_ASSERT_UNREACHABLE("Trying to advance a static DrawableSurface?");
 219       return;
 220     }
 221
 222     mProvider->Advance(aFrame);
 223   }
 224
 225   bool MayAdvance() const {
 226     if (!mProvider) {
 227       MOZ_ASSERT_UNREACHABLE("Trying to advance a static DrawableSurface?");
 228       return false;
 229     }
 230
 231     return mProvider->MayAdvance();
 232   }
 233
 234   void MarkMayAdvance() {
 235     if (!mProvider) {
 236       MOZ_ASSERT_UNREACHABLE("Trying to advance a static DrawableSurface?");
 237       return;
 238     }
 239
 240     mProvider->MarkMayAdvance();
 241   }
 242
 243   bool IsFullyDecoded() const {
 244     if (!mProvider) {
 245       MOZ_ASSERT_UNREACHABLE(
 246           "Trying to check decoding state of a static DrawableSurface?");
 247       return false;
 248     }
 249
 250     return mProvider->IsFullyDecoded();
 251   }
 252
 253   void TakeProvider(WebRenderImageProvider** aOutProvider) {
 254     mProvider.forget(aOutProvider);
 255   }
 256
 257   explicit operator bool() const { return mHaveSurface; }
 258   imgFrame* operator->() { return DrawableRef().get(); }
 259
 260  private:
 261   DrawableSurface(const DrawableSurface& aOther) = delete;
 262   DrawableSurface& operator=(const DrawableSurface& aOther) = delete;
 263
 264   DrawableFrameRef& DrawableRef() {
 265     MOZ_ASSERT(mHaveSurface);
 266
 267     // If we weren't created with a DrawableFrameRef directly, we should've been
 268     // created with an ISurfaceProvider which can give us one. Note that if
 269     // Seek() has been called, we'll already have a DrawableFrameRef, so we
 270     // won't need to get one here.
 271     if (!mDrawableRef) {
 272       MOZ_ASSERT(mProvider);
 273       mDrawableRef = mProvider->DrawableRef(/* aFrame = */ 0);
 274     }
 275
 276     MOZ_ASSERT(mDrawableRef);
 277     return mDrawableRef;
 278   }
 279
 280   DrawableFrameRef mDrawableRef;
 281   RefPtr<ISurfaceProvider> mProvider;
 282   bool mHaveSurface;
 283 };
 284
 285 // Surface() is implemented here so that DrawableSurface's definition is
 286 // visible.
 287 inline DrawableSurface ISurfaceProvider::Surface() {
 288   return DrawableSurface(WrapNotNull(this));
 289 }
 290
 291 /**
 292  * An ISurfaceProvider that stores a single surface.
 293  */
 294 class SimpleSurfaceProvider final : public ISurfaceProvider {
 295  public:
 296   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(SimpleSurfaceProvider, override)
 297
 298   SimpleSurfaceProvider(const ImageKey aImageKey, const SurfaceKey& aSurfaceKey,
 299                         NotNull<imgFrame*> aSurface)
 300       : ISurfaceProvider(aImageKey, aSurfaceKey,
 301                          AvailabilityState::StartAvailable()),
 302         mSurface(aSurface) {
 303     MOZ_ASSERT(aSurfaceKey.Size() == mSurface->GetSize());
 304   }
 305
 306   bool IsFinished() const override { return mSurface->IsFinished(); }
 307
 308   size_t LogicalSizeInBytes() const override {
 309     gfx::IntSize size = mSurface->GetSize();
 310     return size.width * size.height * mSurface->GetBytesPerPixel();
 311   }
 312
 313   nsresult UpdateKey(layers::RenderRootStateManager* aManager,
 314                      wr::IpcResourceUpdateQueue& aResources,
 315                      wr::ImageKey& aKey) override;
 316
 317  protected:
 318   DrawableFrameRef DrawableRef(size_t aFrame) override {
 319     MOZ_ASSERT(aFrame == 0,
 320                "Requesting an animation frame from a SimpleSurfaceProvider?");
 321     return mSurface->DrawableRef();
 322   }
 323
 324   bool IsLocked() const override { return bool(mLockRef); }
 325
 326   void SetLocked(bool aLocked) override {
 327     if (aLocked == IsLocked()) {
 328       return;  // Nothing changed.
 329     }
 330
 331     // If we're locked, hold a DrawableFrameRef to |mSurface|, which will keep
 332     // any volatile buffer it owns in memory.
 333     mLockRef = aLocked ? mSurface->DrawableRef() : DrawableFrameRef();
 334   }
 335
 336  private:
 337   virtual ~SimpleSurfaceProvider() {}
 338
 339   NotNull<RefPtr<imgFrame>> mSurface;
 340   DrawableFrameRef mLockRef;
 341 };
 342
 343 }  // namespace image
 344 }  // namespace mozilla
 345
 346 #endif  // mozilla_image_ISurfaceProvider_h