import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

gfx/layers/RotatedBuffer.h

@@ -0,0 +1,430 @@
+/* -*- 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 ROTATEDBUFFER_H_
+#define ROTATEDBUFFER_H_
+
+#include "gfxTypes.h"
+#include <stdint.h>                     // for uint32_t
+#include "mozilla/Assertions.h"         // for MOZ_ASSERT, etc
+#include "mozilla/RefPtr.h"             // for RefPtr, already_AddRefed
+#include "mozilla/gfx/2D.h"             // for DrawTarget, etc
+#include "mozilla/mozalloc.h"           // for operator delete
+#include "nsCOMPtr.h"                   // for already_AddRefed
+#include "nsDebug.h"                    // for NS_RUNTIMEABORT
+#include "nsISupportsImpl.h"            // for MOZ_COUNT_CTOR, etc
+#include "nsRegion.h"                   // for nsIntRegion
+#include "LayersTypes.h"
+
+namespace mozilla {
+namespace gfx {
+class Matrix;
+} // namespace gfx
+
+namespace layers {
+
+class TextureClient;
+class PaintedLayer;
+
+/**
+ * This is a cairo/Thebes surface, but with a literal twist. Scrolling
+ * causes the layer's visible region to move. We want to keep
+ * reusing the same surface if the region size hasn't changed, but we don't
+ * want to keep moving the contents of the surface around in memory. So
+ * we use a trick.
+ * Consider just the vertical case, and suppose the buffer is H pixels
+ * high and we're scrolling down by N pixels. Instead of copying the
+ * buffer contents up by N pixels, we leave the buffer contents in place,
+ * and paint content rows H to H+N-1 into rows 0 to N-1 of the buffer.
+ * Then we can refresh the screen by painting rows N to H-1 of the buffer
+ * at row 0 on the screen, and then painting rows 0 to N-1 of the buffer
+ * at row H-N on the screen.
+ * mBufferRotation.y would be N in this example.
+ */
+class RotatedBuffer {
+public:
+  typedef gfxContentType ContentType;
+
+  RotatedBuffer(const gfx::IntRect& aBufferRect,
+                const gfx::IntPoint& aBufferRotation)
+    : mBufferRect(aBufferRect)
+    , mBufferRotation(aBufferRotation)
+    , mDidSelfCopy(false)
+  { }
+  RotatedBuffer()
+    : mDidSelfCopy(false)
+  { }
+
+  /*
+   * Which buffer should be drawn to/read from.
+   */
+  enum ContextSource {
+    BUFFER_BLACK, // The normal buffer, or buffer with black background when using component alpha.
+    BUFFER_WHITE, // The buffer with white background, only valid with component alpha.
+    BUFFER_BOTH // The combined black/white buffers, only valid for writing operations, not reading.
+  };
+  // It is the callers repsonsibility to ensure aTarget is flushed after calling
+  // this method.
+  void DrawBufferWithRotation(gfx::DrawTarget* aTarget, ContextSource aSource,
+                              float aOpacity = 1.0,
+                              gfx::CompositionOp aOperator = gfx::CompositionOp::OP_OVER,
+                              gfx::SourceSurface* aMask = nullptr,
+                              const gfx::Matrix* aMaskTransform = nullptr) const;
+
+  /**
+   * |BufferRect()| is the rect of device pixels that this
+   * RotatedBuffer covers.  That is what DrawBufferWithRotation()
+   * will paint when it's called.
+   */
+  const gfx::IntRect& BufferRect() const { return mBufferRect; }
+  const gfx::IntPoint& BufferRotation() const { return mBufferRotation; }
+
+  virtual bool HaveBuffer() const = 0;
+  virtual bool HaveBufferOnWhite() const = 0;
+
+  virtual already_AddRefed<gfx::SourceSurface> GetSourceSurface(ContextSource aSource) const = 0;
+
+protected:
+
+  enum XSide {
+    LEFT, RIGHT
+  };
+  enum YSide {
+    TOP, BOTTOM
+  };
+  gfx::IntRect GetQuadrantRectangle(XSide aXSide, YSide aYSide) const;
+
+  gfx::Rect GetSourceRectangle(XSide aXSide, YSide aYSide) const;
+
+  /*
+   * If aMask is non-null, then it is used as an alpha mask for rendering this
+   * buffer. aMaskTransform must be non-null if aMask is non-null, and is used
+   * to adjust the coordinate space of the mask.
+   */
+  void DrawBufferQuadrant(gfx::DrawTarget* aTarget, XSide aXSide, YSide aYSide,
+                          ContextSource aSource,
+                          float aOpacity,
+                          gfx::CompositionOp aOperator,
+                          gfx::SourceSurface* aMask,
+                          const gfx::Matrix* aMaskTransform) const;
+
+  /** The area of the PaintedLayer that is covered by the buffer as a whole */
+  gfx::IntRect             mBufferRect;
+  /**
+   * The x and y rotation of the buffer. Conceptually the buffer
+   * has its origin translated to mBufferRect.TopLeft() - mBufferRotation,
+   * is tiled to fill the plane, and the result is clipped to mBufferRect.
+   * So the pixel at mBufferRotation within the buffer is what gets painted at
+   * mBufferRect.TopLeft().
+   * This is "rotation" in the sense of rotating items in a linear buffer,
+   * where items falling off the end of the buffer are returned to the
+   * buffer at the other end, not 2D rotation!
+   */
+  gfx::IntPoint            mBufferRotation;
+  // When this is true it means that all pixels have moved inside the buffer.
+  // It's not possible to sync with another buffer without a full copy.
+  bool                  mDidSelfCopy;
+};
+
+class SourceRotatedBuffer : public RotatedBuffer
+{
+public:
+  SourceRotatedBuffer(gfx::SourceSurface* aSource, gfx::SourceSurface* aSourceOnWhite,
+                      const gfx::IntRect& aBufferRect,
+                      const gfx::IntPoint& aBufferRotation)
+    : RotatedBuffer(aBufferRect, aBufferRotation)
+    , mSource(aSource)
+    , mSourceOnWhite(aSourceOnWhite)
+  { }
+
+  virtual already_AddRefed<gfx::SourceSurface> GetSourceSurface(ContextSource aSource) const;
+
+  virtual bool HaveBuffer() const { return !!mSource; }
+  virtual bool HaveBufferOnWhite() const { return !!mSourceOnWhite; }
+
+private:
+  RefPtr<gfx::SourceSurface> mSource;
+  RefPtr<gfx::SourceSurface> mSourceOnWhite;
+};
+
+// Mixin class for classes which need logic for loaning out a draw target.
+// See comments on BorrowDrawTargetForQuadrantUpdate.
+class BorrowDrawTarget
+{
+protected:
+  void ReturnDrawTarget(gfx::DrawTarget*& aReturned);
+
+  // The draw target loaned by BorrowDrawTargetForQuadrantUpdate. It should not
+  // be used, we just keep a reference to ensure it is kept alive and so we can
+  // correctly restore state when it is returned.
+  RefPtr<gfx::DrawTarget> mLoanedDrawTarget;
+  gfx::Matrix mLoanedTransform;
+};
+
+/**
+ * This class encapsulates the buffer used to retain PaintedLayer contents,
+ * i.e., the contents of the layer's GetVisibleRegion().
+ */
+class RotatedContentBuffer : public RotatedBuffer
+                           , public BorrowDrawTarget
+{
+public:
+  typedef gfxContentType ContentType;
+
+  /**
+   * Controls the size of the backing buffer of this.
+   * - SizedToVisibleBounds: the backing buffer is exactly the same
+   *   size as the bounds of PaintedLayer's visible region
+   * - ContainsVisibleBounds: the backing buffer is large enough to
+   *   fit visible bounds.  May be larger.
+   */
+  enum BufferSizePolicy {
+    SizedToVisibleBounds,
+    ContainsVisibleBounds
+  };
+
+  explicit RotatedContentBuffer(BufferSizePolicy aBufferSizePolicy)
+    : mBufferProvider(nullptr)
+    , mBufferProviderOnWhite(nullptr)
+    , mBufferSizePolicy(aBufferSizePolicy)
+  {
+    MOZ_COUNT_CTOR(RotatedContentBuffer);
+  }
+  virtual ~RotatedContentBuffer()
+  {
+    MOZ_COUNT_DTOR(RotatedContentBuffer);
+  }
+
+  /**
+   * Wipe out all retained contents. Call this when the entire
+   * buffer becomes invalid.
+   */
+  void Clear()
+  {
+    mDTBuffer = nullptr;
+    mDTBufferOnWhite = nullptr;
+    mBufferProvider = nullptr;
+    mBufferProviderOnWhite = nullptr;
+    mBufferRect.SetEmpty();
+  }
+
+  /**
+   * This is returned by BeginPaint. The caller should draw into mTarget.
+   * mRegionToDraw must be drawn. mRegionToInvalidate has been invalidated
+   * by RotatedContentBuffer and must be redrawn on the screen.
+   * mRegionToInvalidate is set when the buffer has changed from
+   * opaque to transparent or vice versa, since the details of rendering can
+   * depend on the buffer type.  mDidSelfCopy is true if we kept our buffer
+   * but used MovePixels() to shift its content.
+   */
+  struct PaintState {
+    PaintState()
+      : mRegionToDraw()
+      , mRegionToInvalidate()
+      , mMode(SurfaceMode::SURFACE_NONE)
+      , mClip(DrawRegionClip::NONE)
+      , mContentType(gfxContentType::SENTINEL)
+      , mDidSelfCopy(false)
+    {}
+
+    nsIntRegion mRegionToDraw;
+    nsIntRegion mRegionToInvalidate;
+    SurfaceMode mMode;
+    DrawRegionClip mClip;
+    ContentType mContentType;
+    bool mDidSelfCopy;
+  };
+
+  enum {
+    PAINT_WILL_RESAMPLE = 0x01,
+    PAINT_NO_ROTATION = 0x02,
+    PAINT_CAN_DRAW_ROTATED = 0x04
+  };
+  /**
+   * Start a drawing operation. This returns a PaintState describing what
+   * needs to be drawn to bring the buffer up to date in the visible region.
+   * This queries aLayer to get the currently valid and visible regions.
+   * The returned mTarget may be null if mRegionToDraw is empty.
+   * Otherwise it must not be null.
+   * mRegionToInvalidate will contain mRegionToDraw.
+   * @param aFlags when PAINT_WILL_RESAMPLE is passed, this indicates that
+   * buffer will be resampled when rendering (i.e the effective transform
+   * combined with the scale for the resolution is not just an integer
+   * translation). This will disable buffer rotation (since we don't want
+   * to resample across the rotation boundary) and will ensure that we
+   * make the entire buffer contents valid (since we don't want to sample
+   * invalid pixels outside the visible region, if the visible region doesn't
+   * fill the buffer bounds).
+   * PAINT_CAN_DRAW_ROTATED can be passed if the caller supports drawing
+   * rotated content that crosses the physical buffer boundary. The caller
+   * will need to call BorrowDrawTargetForPainting multiple times to achieve
+   * this.
+   */
+  PaintState BeginPaint(PaintedLayer* aLayer,
+                        uint32_t aFlags);
+
+  struct DrawIterator {
+    friend class RotatedContentBuffer;
+    DrawIterator()
+      : mCount(0)
+    {}
+
+    nsIntRegion mDrawRegion;
+
+  private:
+    uint32_t mCount;
+  };
+
+  /**
+   * Fetch a DrawTarget for rendering. The DrawTarget remains owned by
+   * this. See notes on BorrowDrawTargetForQuadrantUpdate.
+   * May return null. If the return value is non-null, it must be
+   * 'un-borrowed' using ReturnDrawTarget.
+   *
+   * If PAINT_CAN_DRAW_ROTATED was specified for BeginPaint, then the caller
+   * must call this function repeatedly (with an iterator) until it returns
+   * nullptr. The caller should draw the mDrawRegion of the iterator instead
+   * of mRegionToDraw in the PaintState.
+   *
+   * @param aPaintState Paint state data returned by a call to BeginPaint
+   * @param aIter Paint state iterator. Only required if PAINT_CAN_DRAW_ROTATED
+   * was specified to BeginPaint.
+   */
+  gfx::DrawTarget* BorrowDrawTargetForPainting(PaintState& aPaintState,
+                                               DrawIterator* aIter = nullptr);
+
+  enum {
+    BUFFER_COMPONENT_ALPHA = 0x02 // Dual buffers should be created for drawing with
+                                  // component alpha.
+  };
+  /**
+   * Return a new surface of |aSize| and |aType|.
+   *
+   * If the created buffer supports azure content, then the result(s) will
+   * be returned in aBlackDT/aWhiteDT, otherwise aBlackSurface/aWhiteSurface
+   * will be used.
+   */
+  virtual void
+  CreateBuffer(ContentType aType, const gfx::IntRect& aRect, uint32_t aFlags,
+               RefPtr<gfx::DrawTarget>* aBlackDT, RefPtr<gfx::DrawTarget>* aWhiteDT) = 0;
+
+  /**
+   * Get the underlying buffer, if any. This is useful because we can pass
+   * in the buffer as the default "reference surface" if there is one.
+   * Don't use it for anything else!
+   */
+  gfx::DrawTarget* GetDTBuffer() { return mDTBuffer; }
+  gfx::DrawTarget* GetDTBufferOnWhite() { return mDTBufferOnWhite; }
+
+  virtual already_AddRefed<gfx::SourceSurface> GetSourceSurface(ContextSource aSource) const;
+
+  /**
+   * Complete the drawing operation. The region to draw must have been
+   * drawn before this is called. The contents of the buffer are drawn
+   * to aTarget.
+   */
+  void DrawTo(PaintedLayer* aLayer,
+              gfx::DrawTarget* aTarget,
+              float aOpacity,
+              gfx::CompositionOp aOp,
+              gfx::SourceSurface* aMask,
+              const gfx::Matrix* aMaskTransform);
+
+protected:
+  // new texture client versions
+  void SetBufferProvider(TextureClient* aClient)
+  {
+    // Only this buffer provider can give us a buffer.  If we
+    // already have one, something has gone wrong.
+    MOZ_ASSERT(!aClient || !mDTBuffer || !mDTBuffer->IsValid());
+
+    mBufferProvider = aClient;
+    if (!mBufferProvider) {
+      mDTBuffer = nullptr;
+    }
+  }
+
+  void SetBufferProviderOnWhite(TextureClient* aClient)
+  {
+    // Only this buffer provider can give us a buffer.  If we
+    // already have one, something has gone wrong.
+    MOZ_ASSERT(!aClient || !mDTBufferOnWhite || !mDTBufferOnWhite->IsValid());
+
+    mBufferProviderOnWhite = aClient;
+    if (!mBufferProviderOnWhite) {
+      mDTBufferOnWhite = nullptr;
+    }
+  }
+
+  /**
+   * Get a draw target at the specified resolution for updating |aBounds|,
+   * which must be contained within a single quadrant.
+   *
+   * The result should only be held temporarily by the caller (it will be kept
+   * alive by this). Once used it should be returned using ReturnDrawTarget.
+   * BorrowDrawTargetForQuadrantUpdate may not be called more than once without
+   * first calling ReturnDrawTarget.
+   *
+   * ReturnDrawTarget will restore the transform on the draw target. But it is
+   * the callers responsibility to restore the clip. The caller should flush the
+   * draw target, if necessary.
+   */
+  gfx::DrawTarget*
+  BorrowDrawTargetForQuadrantUpdate(const gfx::IntRect& aBounds,
+                                    ContextSource aSource,
+                                    DrawIterator* aIter);
+
+  static bool IsClippingCheap(gfx::DrawTarget* aTarget, const nsIntRegion& aRegion);
+
+protected:
+  /**
+   * Return the buffer's content type.  Requires a valid buffer or
+   * buffer provider.
+   */
+  gfxContentType BufferContentType();
+  bool BufferSizeOkFor(const gfx::IntSize& aSize);
+  /**
+   * If the buffer hasn't been mapped, map it.
+   */
+  bool EnsureBuffer();
+  bool EnsureBufferOnWhite();
+
+  // Flush our buffers if they are mapped.
+  void FlushBuffers();
+
+  /**
+   * True if we have a buffer where we can get it (but not necessarily
+   * mapped currently).
+   */
+  virtual bool HaveBuffer() const;
+  virtual bool HaveBufferOnWhite() const;
+
+  /**
+   * Any actions that should be performed at the last moment before we begin
+   * rendering the next frame. I.e., after we calculate what we will draw,
+   * but before we rotate the buffer and possibly create new buffers.
+   * aRegionToDraw is the region which is guaranteed to be overwritten when
+   * drawing the next frame.
+   */
+  virtual void FinalizeFrame(const nsIntRegion& aRegionToDraw) {}
+
+  RefPtr<gfx::DrawTarget> mDTBuffer;
+  RefPtr<gfx::DrawTarget> mDTBufferOnWhite;
+
+  /**
+   * These members are only set transiently.  They're used to map mDTBuffer
+   * when we're using surfaces that require explicit map/unmap. Only one
+   * may be used at a time.
+   */
+  TextureClient* mBufferProvider;
+  TextureClient* mBufferProviderOnWhite;
+
+  BufferSizePolicy      mBufferSizePolicy;
+};
+
+} // namespace layers
+} // namespace mozilla
+
+#endif /* ROTATEDBUFFER_H_ */