gecko-dev/gfx/layers/RotatedBuffer.h

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/* -*- 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()
{
UnlockBuffers();
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) {}
virtual bool LockBuffers() { return true; }
virtual void UnlockBuffers() {}
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_ */