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228 lines
8.1 KiB
C++
228 lines
8.1 KiB
C++
/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is Mozilla Corporation code.
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*
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* The Initial Developer of the Original Code is Mozilla Foundation.
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* Portions created by the Initial Developer are Copyright (C) 2010
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Robert O'Callahan <robert@ocallahan.org>
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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#ifndef THEBESLAYERBUFFER_H_
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#define THEBESLAYERBUFFER_H_
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#include "gfxContext.h"
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#include "gfxASurface.h"
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#include "nsRegion.h"
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namespace mozilla {
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namespace layers {
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class ThebesLayer;
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/**
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* This class encapsulates the buffer used to retain ThebesLayer contents,
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* i.e., the contents of the layer's GetVisibleRegion().
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*
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* This is a cairo/Thebes surface, but with a literal twist. Scrolling
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* causes the layer's visible region to move. We want to keep
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* reusing the same surface if the region size hasn't changed, but we don't
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* want to keep moving the contents of the surface around in memory. So
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* we use a trick.
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* Consider just the vertical case, and suppose the buffer is H pixels
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* high and we're scrolling down by N pixels. Instead of copying the
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* buffer contents up by N pixels, we leave the buffer contents in place,
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* and paint content rows H to H+N-1 into rows 0 to N-1 of the buffer.
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* Then we can refresh the screen by painting rows N to H-1 of the buffer
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* at row 0 on the screen, and then painting rows 0 to N-1 of the buffer
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* at row H-N on the screen.
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* mBufferRotation.y would be N in this example.
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*/
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class ThebesLayerBuffer {
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public:
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typedef gfxASurface::gfxContentType ContentType;
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/**
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* Controls the size of the backing buffer of this.
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* - SizedToVisibleBounds: the backing buffer is exactly the same
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* size as the bounds of ThebesLayer's visible region
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* - ContainsVisibleBounds: the backing buffer is large enough to
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* fit visible bounds. May be larger.
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*/
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enum BufferSizePolicy {
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SizedToVisibleBounds,
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ContainsVisibleBounds
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};
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ThebesLayerBuffer(BufferSizePolicy aBufferSizePolicy)
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: mBufferDims(0,0)
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, mBufferRotation(0,0)
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, mBufferSizePolicy(aBufferSizePolicy)
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{
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MOZ_COUNT_CTOR(ThebesLayerBuffer);
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}
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virtual ~ThebesLayerBuffer()
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{
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MOZ_COUNT_DTOR(ThebesLayerBuffer);
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}
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/**
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* Wipe out all retained contents. Call this when the entire
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* buffer becomes invalid.
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*/
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void Clear()
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{
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mBuffer = nsnull;
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mBufferDims.SizeTo(0, 0);
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mBufferRect.Empty();
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}
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/**
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* This is returned by BeginPaint. The caller should draw into mContext.
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* mRegionToDraw must be drawn. mRegionToInvalidate has been invalidated
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* by ThebesLayerBuffer and must be redrawn on the screen.
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* mRegionToInvalidate is set when the buffer has changed from
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* opaque to transparent or vice versa, since the details of rendering can
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* depend on the buffer type.
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*/
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struct PaintState {
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nsRefPtr<gfxContext> mContext;
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nsIntRegion mRegionToDraw;
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nsIntRegion mRegionToInvalidate;
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};
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/**
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* Start a drawing operation. This returns a PaintState describing what
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* needs to be drawn to bring the buffer up to date in the visible region.
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* This queries aLayer to get the currently valid and visible regions.
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* The returned mContext may be null if mRegionToDraw is empty.
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* Otherwise it must not be null.
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* mRegionToInvalidate will contain mRegionToDraw.
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*/
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PaintState BeginPaint(ThebesLayer* aLayer, ContentType aContentType,
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float aXResolution, float aYResolution);
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/**
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* Return a new surface of |aSize| and |aType|.
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*/
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virtual already_AddRefed<gfxASurface>
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CreateBuffer(ContentType aType, const nsIntSize& aSize) = 0;
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/**
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* Get the underlying buffer, if any. This is useful because we can pass
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* in the buffer as the default "reference surface" if there is one.
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* Don't use it for anything else!
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*/
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gfxASurface* GetBuffer() { return mBuffer; }
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protected:
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enum XSide {
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LEFT, RIGHT
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};
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enum YSide {
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TOP, BOTTOM
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};
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nsIntRect GetQuadrantRectangle(XSide aXSide, YSide aYSide);
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void DrawBufferQuadrant(gfxContext* aTarget, XSide aXSide, YSide aYSide,
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float aOpacity, float aXRes, float aYRes);
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void DrawBufferWithRotation(gfxContext* aTarget, float aOpacity,
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float aXRes, float aYRes);
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/**
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* |BufferRect()| is the rect of device pixels that this
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* ThebesLayerBuffer covers. That is what DrawBufferWithRotation()
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* will paint when it's called.
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*
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* |BufferDims()| is the actual dimensions of the underlying surface
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* maintained by this, also in device pixels. It is *not*
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* necessarily true that |BufferRect().Size() == BufferDims()|.
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* They may differ if a ThebesLayer is drawn at a non-1.0
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* resolution.
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*/
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const nsIntSize& BufferDims() const { return mBufferDims; }
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const nsIntRect& BufferRect() const { return mBufferRect; }
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const nsIntPoint& BufferRotation() const { return mBufferRotation; }
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already_AddRefed<gfxASurface>
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SetBuffer(gfxASurface* aBuffer, const nsIntSize& aBufferDims,
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const nsIntRect& aBufferRect, const nsIntPoint& aBufferRotation)
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{
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nsRefPtr<gfxASurface> tmp = mBuffer.forget();
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mBuffer = aBuffer;
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mBufferDims = aBufferDims;
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mBufferRect = aBufferRect;
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mBufferRotation = aBufferRotation;
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return tmp.forget();
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}
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/**
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* Get a context at the specified resolution for updating |aBounds|,
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* which must be contained within a single quadrant.
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*/
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already_AddRefed<gfxContext>
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GetContextForQuadrantUpdate(const nsIntRect& aBounds,
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float aXResolution, float aYResolution);
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private:
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PRBool BufferSizeOkFor(const nsIntSize& aSize)
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{
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return (aSize == mBufferDims ||
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(SizedToVisibleBounds != mBufferSizePolicy &&
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aSize < mBufferDims));
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}
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nsRefPtr<gfxASurface> mBuffer;
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/**
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* The actual dimensions of mBuffer. For the ContainsVisibleBounds
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* policy or with resolution-scaled drawing, mBufferDims might be
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* different than mBufferRect.Size().
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*/
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nsIntSize mBufferDims;
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/** The area of the ThebesLayer that is covered by the buffer as a whole */
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nsIntRect mBufferRect;
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/**
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* The x and y rotation of the buffer. Conceptually the buffer
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* has its origin translated to mBufferRect.TopLeft() - mBufferRotation,
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* is tiled to fill the plane, and the result is clipped to mBufferRect.
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* So the pixel at mBufferRotation within the buffer is what gets painted at
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* mBufferRect.TopLeft().
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* This is "rotation" in the sense of rotating items in a linear buffer,
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* where items falling off the end of the buffer are returned to the
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* buffer at the other end, not 2D rotation!
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*/
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nsIntPoint mBufferRotation;
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BufferSizePolicy mBufferSizePolicy;
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};
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}
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}
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#endif /* THEBESLAYERBUFFER_H_ */
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