src/utils/SkGatherPixelRefsAndRects.h - platform/external/skqp - Gitiles

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #ifndef SkGatherPixelRefsAndRects_DEFINED
 #define SkGatherPixelRefsAndRects_DEFINED

 #include "SkBitmap.h"
 #include "SkDevice.h"
 #include "SkDraw.h"
 #include "SkPictureUtils.h"
 #include "SkRasterClip.h"
 #include "SkRefCnt.h"
 #include "SkRRect.h"
 #include "SkTypes.h"

 // This GatherPixelRefs device passes all discovered pixel refs and their
 // device bounds to the user provided SkPixelRefContainer-derived object
 class SkGatherPixelRefsAndRectsDevice : public SkBaseDevice {
 public:
     SK_DECLARE_INST_COUNT(SkGatherPixelRefsAndRectsDevice)

     SkGatherPixelRefsAndRectsDevice(int width, int height,
                                     SkPictureUtils::SkPixelRefContainer* prCont) {
         fSize.set(width, height);
         fPRCont = prCont;
         SkSafeRef(fPRCont);
         fEmptyBitmap.setInfo(SkImageInfo::MakeUnknown(width, height));
     }

     virtual ~SkGatherPixelRefsAndRectsDevice() {
         SkSafeUnref(fPRCont);
     }

     virtual SkImageInfo imageInfo() const SK_OVERRIDE {
         return fEmptyBitmap.info();
     }

 protected:
     virtual void clear(SkColor color) SK_OVERRIDE {
         NothingToDo();
     }
     virtual void drawPaint(const SkDraw& draw, const SkPaint& paint) SK_OVERRIDE {
         SkBitmap bm;

         if (GetBitmapFromPaint(paint, &bm)) {
             SkRect clipRect = SkRect::Make(draw.fRC->getBounds());
             fPRCont->add(bm.pixelRef(), clipRect);
         }
     }
     virtual void drawPoints(const SkDraw& draw, SkCanvas::PointMode mode, size_t count,
                             const SkPoint points[], const SkPaint& paint) SK_OVERRIDE {
         SkBitmap bm;
         if (!GetBitmapFromPaint(paint, &bm)) {
             return;
         }

         if (0 == count) {
             return;
         }

         SkPoint min = points[0];
         SkPoint max = points[0];
         for (size_t i = 1; i < count; ++i) {
             const SkPoint& point = points[i];

             min.set(SkMinScalar(min.x(), point.x()), SkMinScalar(min.y(), point.y()));
             max.set(SkMaxScalar(max.x(), point.x()), SkMaxScalar(max.y(), point.y()));
         }

         SkRect bounds = SkRect::MakeLTRB(min.x(), min.y(), max.x()+1, max.y()+1);

         this->drawRect(draw, bounds, paint);
     }
     virtual void drawRect(const SkDraw& draw, const SkRect& rect,
                           const SkPaint& paint) SK_OVERRIDE {
         SkBitmap bm;
         if (GetBitmapFromPaint(paint, &bm)) {
             SkRect mappedRect;
             draw.fMatrix->mapRect(&mappedRect, rect);
             SkRect clipRect = SkRect::Make(draw.fRC->getBounds());
             mappedRect.intersect(clipRect);
             fPRCont->add(bm.pixelRef(), mappedRect);
         }
     }
     virtual void drawOval(const SkDraw& draw, const SkRect& rect,
                           const SkPaint& paint) SK_OVERRIDE {
         this->drawRect(draw, rect, paint);
     }
     virtual void drawRRect(const SkDraw& draw, const SkRRect& rrect,
                            const SkPaint& paint) SK_OVERRIDE {
         this->drawRect(draw, rrect.rect(), paint);
     }
     virtual void drawPath(const SkDraw& draw, const SkPath& path,
                           const SkPaint& paint, const SkMatrix* prePathMatrix,
                           bool pathIsMutable) SK_OVERRIDE {
         SkBitmap bm;
         if (!GetBitmapFromPaint(paint, &bm)) {
             return;
         }

         SkRect pathBounds = path.getBounds();
         if (NULL != prePathMatrix) {
             prePathMatrix->mapRect(&pathBounds);
         }

         this->drawRect(draw, pathBounds, paint);
     }
     virtual void drawBitmap(const SkDraw& draw, const SkBitmap& bitmap,
                             const SkMatrix& matrix, const SkPaint& paint) SK_OVERRIDE {
         SkMatrix totMatrix;
         totMatrix.setConcat(*draw.fMatrix, matrix);

         SkRect bitmapRect = SkRect::MakeWH(SkIntToScalar(bitmap.width()),
                                            SkIntToScalar(bitmap.height()));
         SkRect mappedRect;
         totMatrix.mapRect(&mappedRect, bitmapRect);
         fPRCont->add(bitmap.pixelRef(), mappedRect);

         SkBitmap paintBitmap;
         if (GetBitmapFromPaint(paint, &paintBitmap)) {
             fPRCont->add(paintBitmap.pixelRef(), mappedRect);
         }
     }
     virtual void drawSprite(const SkDraw&, const SkBitmap& bitmap,
                             int x, int y, const SkPaint& paint) SK_OVERRIDE {
         // Sprites aren't affected by current matrix, so we can't reuse drawRect.
         SkMatrix matrix;
         matrix.setTranslate(SkIntToScalar(x), SkIntToScalar(y));

         SkRect bitmapRect = SkRect::MakeWH(SkIntToScalar(bitmap.width()),
                                            SkIntToScalar(bitmap.height()));
         SkRect mappedRect;
         matrix.mapRect(&mappedRect, bitmapRect);
         fPRCont->add(bitmap.pixelRef(), mappedRect);

         SkBitmap paintBitmap;
         if (GetBitmapFromPaint(paint, &paintBitmap)) {
             fPRCont->add(paintBitmap.pixelRef(), mappedRect);
         }
     }
     virtual void drawBitmapRect(const SkDraw& draw, const SkBitmap& bitmap,
                                 const SkRect* srcOrNull, const SkRect& dst,
                                 const SkPaint& paint,
                                 SkCanvas::DrawBitmapRectFlags flags) SK_OVERRIDE {
         SkRect bitmapRect = SkRect::MakeWH(SkIntToScalar(bitmap.width()),
                                            SkIntToScalar(bitmap.height()));
         SkMatrix matrix;
         matrix.setRectToRect(bitmapRect, dst, SkMatrix::kFill_ScaleToFit);
         this->drawBitmap(draw, bitmap, matrix, paint);
     }
     virtual void drawText(const SkDraw& draw, const void* text, size_t len,
                           SkScalar x, SkScalar y,
                           const SkPaint& paint) SK_OVERRIDE {
         SkBitmap bitmap;
         if (!GetBitmapFromPaint(paint, &bitmap)) {
             return;
         }

         // Math is borrowed from SkBBoxRecord
         SkRect bounds;
         paint.measureText(text, len, &bounds);
         SkPaint::FontMetrics metrics;
         paint.getFontMetrics(&metrics);

         if (paint.isVerticalText()) {
             SkScalar h = bounds.fBottom - bounds.fTop;
             if (paint.getTextAlign() == SkPaint::kCenter_Align) {
                 bounds.fTop -= h / 2;
                 bounds.fBottom -= h / 2;
             }
             bounds.fBottom += metrics.fBottom;
             bounds.fTop += metrics.fTop;
         } else {
             SkScalar w = bounds.fRight - bounds.fLeft;
             if (paint.getTextAlign() == SkPaint::kCenter_Align) {
                 bounds.fLeft -= w / 2;
                 bounds.fRight -= w / 2;
             } else if (paint.getTextAlign() == SkPaint::kRight_Align) {
                 bounds.fLeft -= w;
                 bounds.fRight -= w;
             }
             bounds.fTop = metrics.fTop;
             bounds.fBottom = metrics.fBottom;
         }

         SkScalar pad = (metrics.fBottom - metrics.fTop) / 2;
         bounds.fLeft -= pad;
         bounds.fRight += pad;
         bounds.offset(x, y);

         this->drawRect(draw, bounds, paint);
     }
     virtual void drawPosText(const SkDraw& draw, const void* text, size_t len,
                              const SkScalar pos[], SkScalar constY,
                              int scalarsPerPos, const SkPaint& paint) SK_OVERRIDE {
         SkBitmap bitmap;
         if (!GetBitmapFromPaint(paint, &bitmap)) {
             return;
         }

         if (0 == len) {
             return;
         }

         // Similar to SkDraw asserts.
         SkASSERT(scalarsPerPos == 1 || scalarsPerPos == 2);

         SkScalar y = scalarsPerPos == 1 ? constY : constY + pos[1];

         SkPoint min, max;
         min.set(pos[0], y);
         max.set(pos[0], y);

         for (size_t i = 1; i < len; ++i) {
             SkScalar x = pos[i * scalarsPerPos];
             SkScalar y = constY;
             if (2 == scalarsPerPos) {
                 y += pos[i * scalarsPerPos + 1];
             }

             min.set(SkMinScalar(x, min.x()), SkMinScalar(y, min.y()));
             max.set(SkMaxScalar(x, max.x()), SkMaxScalar(y, max.y()));
         }

         SkRect bounds = SkRect::MakeLTRB(min.x(), min.y(), max.x(), max.y());

         // Math is borrowed from SkBBoxRecord
         SkPaint::FontMetrics metrics;
         paint.getFontMetrics(&metrics);

         bounds.fTop += metrics.fTop;
         bounds.fBottom += metrics.fBottom;

         SkScalar pad = (metrics.fTop - metrics.fBottom) / 2;
         bounds.fLeft -= pad;
         bounds.fRight += pad;

         this->drawRect(draw, bounds, paint);
     }
     virtual void drawTextOnPath(const SkDraw& draw, const void* text, size_t len,
                                 const SkPath& path, const SkMatrix* matrix,
                                 const SkPaint& paint) SK_OVERRIDE {
         SkBitmap bitmap;
         if (!GetBitmapFromPaint(paint, &bitmap)) {
             return;
         }

         // Math is borrowed from SkBBoxRecord
         SkRect bounds = path.getBounds();
         SkPaint::FontMetrics metrics;
         paint.getFontMetrics(&metrics);

         SkScalar pad = metrics.fTop;
         // TODO: inset?!
         bounds.fLeft += pad;
         bounds.fRight -= pad;
         bounds.fTop += pad;
         bounds.fBottom -= pad;

         this->drawRect(draw, bounds, paint);
     }
     virtual void drawVertices(const SkDraw& draw, SkCanvas::VertexMode, int vertexCount,
                               const SkPoint verts[], const SkPoint texs[],
                               const SkColor colors[], SkXfermode* xmode,
                               const uint16_t indices[], int indexCount,
                               const SkPaint& paint) SK_OVERRIDE {
         this->drawPoints(draw, SkCanvas::kPolygon_PointMode, vertexCount, verts, paint);
     }
     virtual void drawDevice(const SkDraw&, SkBaseDevice*, int x, int y,
                             const SkPaint&) SK_OVERRIDE {
         NothingToDo();
     }
     // TODO: allow this call to return failure, or move to SkBitmapDevice only.
     virtual const SkBitmap& onAccessBitmap() SK_OVERRIDE {
         return fEmptyBitmap;
     }
     virtual void lockPixels() SK_OVERRIDE { NothingToDo(); }
     virtual void unlockPixels() SK_OVERRIDE { NothingToDo(); }
     virtual bool allowImageFilter(const SkImageFilter*) SK_OVERRIDE { return false; }
     virtual bool canHandleImageFilter(const SkImageFilter*) SK_OVERRIDE { return false; }
     virtual bool filterImage(const SkImageFilter*, const SkBitmap&, const SkImageFilter::Context&,
                              SkBitmap* result, SkIPoint* offset) SK_OVERRIDE {
         return false;
     }

 private:
     SkPictureUtils::SkPixelRefContainer* fPRCont;
     SkISize                              fSize;

     SkBitmap                             fEmptyBitmap; // legacy -- need to remove

     static bool GetBitmapFromPaint(const SkPaint &paint, SkBitmap* bitmap) {
         SkShader* shader = paint.getShader();
         if (NULL != shader) {
             if (SkShader::kNone_GradientType == shader->asAGradient(NULL)) {
                 return SkShader::kNone_BitmapType != shader->asABitmap(bitmap, NULL, NULL);
             }
         }
         return false;
     }

     virtual void replaceBitmapBackendForRasterSurface(const SkBitmap&) SK_OVERRIDE {
         NotSupported();
     }

     virtual SkBaseDevice* onCreateDevice(const SkImageInfo& info, Usage usage) SK_OVERRIDE {
         // we expect to only get called via savelayer, in which case it is fine.
         SkASSERT(kSaveLayer_Usage == usage);
         return SkNEW_ARGS(SkGatherPixelRefsAndRectsDevice,
                           (info.width(), info.height(), fPRCont));
     }

     static void NotSupported() {
         SkDEBUGFAIL("this method should never be called");
     }

     static void NothingToDo() {}

     typedef SkBaseDevice INHERITED;
 };

 #endif // SkGatherPixelRefsAndRects_DEFINED
	/*
	* Copyright 2014 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#ifndef SkGatherPixelRefsAndRects_DEFINED
	#define SkGatherPixelRefsAndRects_DEFINED

	#include "SkBitmap.h"
	#include "SkDevice.h"
	#include "SkDraw.h"
	#include "SkPictureUtils.h"
	#include "SkRasterClip.h"
	#include "SkRefCnt.h"
	#include "SkRRect.h"
	#include "SkTypes.h"

	// This GatherPixelRefs device passes all discovered pixel refs and their
	// device bounds to the user provided SkPixelRefContainer-derived object
	class SkGatherPixelRefsAndRectsDevice : public SkBaseDevice {
	public:
	SK_DECLARE_INST_COUNT(SkGatherPixelRefsAndRectsDevice)

	SkGatherPixelRefsAndRectsDevice(int width, int height,
	SkPictureUtils::SkPixelRefContainer* prCont) {
	fSize.set(width, height);
	fPRCont = prCont;
	SkSafeRef(fPRCont);
	fEmptyBitmap.setInfo(SkImageInfo::MakeUnknown(width, height));
	}

	virtual ~SkGatherPixelRefsAndRectsDevice() {
	SkSafeUnref(fPRCont);
	}

	virtual SkImageInfo imageInfo() const SK_OVERRIDE {
	return fEmptyBitmap.info();
	}

	protected:
	virtual void clear(SkColor color) SK_OVERRIDE {
	NothingToDo();
	}
	virtual void drawPaint(const SkDraw& draw, const SkPaint& paint) SK_OVERRIDE {
	SkBitmap bm;

	if (GetBitmapFromPaint(paint, &bm)) {
	SkRect clipRect = SkRect::Make(draw.fRC->getBounds());
	fPRCont->add(bm.pixelRef(), clipRect);
	}
	}
	virtual void drawPoints(const SkDraw& draw, SkCanvas::PointMode mode, size_t count,
	const SkPoint points[], const SkPaint& paint) SK_OVERRIDE {
	SkBitmap bm;
	if (!GetBitmapFromPaint(paint, &bm)) {
	return;
	}

	if (0 == count) {
	return;
	}

	SkPoint min = points[0];
	SkPoint max = points[0];
	for (size_t i = 1; i < count; ++i) {
	const SkPoint& point = points[i];

	min.set(SkMinScalar(min.x(), point.x()), SkMinScalar(min.y(), point.y()));
	max.set(SkMaxScalar(max.x(), point.x()), SkMaxScalar(max.y(), point.y()));
	}

	SkRect bounds = SkRect::MakeLTRB(min.x(), min.y(), max.x()+1, max.y()+1);

	this->drawRect(draw, bounds, paint);
	}
	virtual void drawRect(const SkDraw& draw, const SkRect& rect,
	const SkPaint& paint) SK_OVERRIDE {
	SkBitmap bm;
	if (GetBitmapFromPaint(paint, &bm)) {
	SkRect mappedRect;
	draw.fMatrix->mapRect(&mappedRect, rect);
	SkRect clipRect = SkRect::Make(draw.fRC->getBounds());
	mappedRect.intersect(clipRect);
	fPRCont->add(bm.pixelRef(), mappedRect);
	}
	}
	virtual void drawOval(const SkDraw& draw, const SkRect& rect,
	const SkPaint& paint) SK_OVERRIDE {
	this->drawRect(draw, rect, paint);
	}
	virtual void drawRRect(const SkDraw& draw, const SkRRect& rrect,
	const SkPaint& paint) SK_OVERRIDE {
	this->drawRect(draw, rrect.rect(), paint);
	}
	virtual void drawPath(const SkDraw& draw, const SkPath& path,
	const SkPaint& paint, const SkMatrix* prePathMatrix,
	bool pathIsMutable) SK_OVERRIDE {
	SkBitmap bm;
	if (!GetBitmapFromPaint(paint, &bm)) {
	return;
	}

	SkRect pathBounds = path.getBounds();
	if (NULL != prePathMatrix) {
	prePathMatrix->mapRect(&pathBounds);
	}

	this->drawRect(draw, pathBounds, paint);
	}
	virtual void drawBitmap(const SkDraw& draw, const SkBitmap& bitmap,
	const SkMatrix& matrix, const SkPaint& paint) SK_OVERRIDE {
	SkMatrix totMatrix;
	totMatrix.setConcat(*draw.fMatrix, matrix);

	SkRect bitmapRect = SkRect::MakeWH(SkIntToScalar(bitmap.width()),
	SkIntToScalar(bitmap.height()));
	SkRect mappedRect;
	totMatrix.mapRect(&mappedRect, bitmapRect);
	fPRCont->add(bitmap.pixelRef(), mappedRect);

	SkBitmap paintBitmap;
	if (GetBitmapFromPaint(paint, &paintBitmap)) {
	fPRCont->add(paintBitmap.pixelRef(), mappedRect);
	}
	}
	virtual void drawSprite(const SkDraw&, const SkBitmap& bitmap,
	int x, int y, const SkPaint& paint) SK_OVERRIDE {
	// Sprites aren't affected by current matrix, so we can't reuse drawRect.
	SkMatrix matrix;
	matrix.setTranslate(SkIntToScalar(x), SkIntToScalar(y));

	SkRect bitmapRect = SkRect::MakeWH(SkIntToScalar(bitmap.width()),
	SkIntToScalar(bitmap.height()));
	SkRect mappedRect;
	matrix.mapRect(&mappedRect, bitmapRect);
	fPRCont->add(bitmap.pixelRef(), mappedRect);

	SkBitmap paintBitmap;
	if (GetBitmapFromPaint(paint, &paintBitmap)) {
	fPRCont->add(paintBitmap.pixelRef(), mappedRect);
	}
	}
	virtual void drawBitmapRect(const SkDraw& draw, const SkBitmap& bitmap,
	const SkRect* srcOrNull, const SkRect& dst,
	const SkPaint& paint,
	SkCanvas::DrawBitmapRectFlags flags) SK_OVERRIDE {
	SkRect bitmapRect = SkRect::MakeWH(SkIntToScalar(bitmap.width()),
	SkIntToScalar(bitmap.height()));
	SkMatrix matrix;
	matrix.setRectToRect(bitmapRect, dst, SkMatrix::kFill_ScaleToFit);
	this->drawBitmap(draw, bitmap, matrix, paint);
	}
	virtual void drawText(const SkDraw& draw, const void* text, size_t len,
	SkScalar x, SkScalar y,
	const SkPaint& paint) SK_OVERRIDE {
	SkBitmap bitmap;
	if (!GetBitmapFromPaint(paint, &bitmap)) {
	return;
	}

	// Math is borrowed from SkBBoxRecord
	SkRect bounds;
	paint.measureText(text, len, &bounds);
	SkPaint::FontMetrics metrics;
	paint.getFontMetrics(&metrics);

	if (paint.isVerticalText()) {
	SkScalar h = bounds.fBottom - bounds.fTop;
	if (paint.getTextAlign() == SkPaint::kCenter_Align) {
	bounds.fTop -= h / 2;
	bounds.fBottom -= h / 2;
	}
	bounds.fBottom += metrics.fBottom;
	bounds.fTop += metrics.fTop;
	} else {
	SkScalar w = bounds.fRight - bounds.fLeft;
	if (paint.getTextAlign() == SkPaint::kCenter_Align) {
	bounds.fLeft -= w / 2;
	bounds.fRight -= w / 2;
	} else if (paint.getTextAlign() == SkPaint::kRight_Align) {
	bounds.fLeft -= w;
	bounds.fRight -= w;
	}
	bounds.fTop = metrics.fTop;
	bounds.fBottom = metrics.fBottom;
	}

	SkScalar pad = (metrics.fBottom - metrics.fTop) / 2;
	bounds.fLeft -= pad;
	bounds.fRight += pad;
	bounds.offset(x, y);

	this->drawRect(draw, bounds, paint);
	}
	virtual void drawPosText(const SkDraw& draw, const void* text, size_t len,
	const SkScalar pos[], SkScalar constY,
	int scalarsPerPos, const SkPaint& paint) SK_OVERRIDE {
	SkBitmap bitmap;
	if (!GetBitmapFromPaint(paint, &bitmap)) {
	return;
	}

	if (0 == len) {
	return;
	}

	// Similar to SkDraw asserts.
	SkASSERT(scalarsPerPos == 1 \|\| scalarsPerPos == 2);

	SkScalar y = scalarsPerPos == 1 ? constY : constY + pos[1];

	SkPoint min, max;
	min.set(pos[0], y);
	max.set(pos[0], y);

	for (size_t i = 1; i < len; ++i) {
	SkScalar x = pos[i * scalarsPerPos];
	SkScalar y = constY;
	if (2 == scalarsPerPos) {
	y += pos[i * scalarsPerPos + 1];
	}

	min.set(SkMinScalar(x, min.x()), SkMinScalar(y, min.y()));
	max.set(SkMaxScalar(x, max.x()), SkMaxScalar(y, max.y()));
	}

	SkRect bounds = SkRect::MakeLTRB(min.x(), min.y(), max.x(), max.y());

	// Math is borrowed from SkBBoxRecord
	SkPaint::FontMetrics metrics;
	paint.getFontMetrics(&metrics);

	bounds.fTop += metrics.fTop;
	bounds.fBottom += metrics.fBottom;

	SkScalar pad = (metrics.fTop - metrics.fBottom) / 2;
	bounds.fLeft -= pad;
	bounds.fRight += pad;

	this->drawRect(draw, bounds, paint);
	}
	virtual void drawTextOnPath(const SkDraw& draw, const void* text, size_t len,
	const SkPath& path, const SkMatrix* matrix,
	const SkPaint& paint) SK_OVERRIDE {
	SkBitmap bitmap;
	if (!GetBitmapFromPaint(paint, &bitmap)) {
	return;
	}

	// Math is borrowed from SkBBoxRecord
	SkRect bounds = path.getBounds();
	SkPaint::FontMetrics metrics;
	paint.getFontMetrics(&metrics);

	SkScalar pad = metrics.fTop;
	// TODO: inset?!
	bounds.fLeft += pad;
	bounds.fRight -= pad;
	bounds.fTop += pad;
	bounds.fBottom -= pad;

	this->drawRect(draw, bounds, paint);
	}
	virtual void drawVertices(const SkDraw& draw, SkCanvas::VertexMode, int vertexCount,
	const SkPoint verts[], const SkPoint texs[],
	const SkColor colors[], SkXfermode* xmode,
	const uint16_t indices[], int indexCount,
	const SkPaint& paint) SK_OVERRIDE {
	this->drawPoints(draw, SkCanvas::kPolygon_PointMode, vertexCount, verts, paint);
	}
	virtual void drawDevice(const SkDraw&, SkBaseDevice*, int x, int y,
	const SkPaint&) SK_OVERRIDE {
	NothingToDo();
	}
	// TODO: allow this call to return failure, or move to SkBitmapDevice only.
	virtual const SkBitmap& onAccessBitmap() SK_OVERRIDE {
	return fEmptyBitmap;
	}
	virtual void lockPixels() SK_OVERRIDE { NothingToDo(); }
	virtual void unlockPixels() SK_OVERRIDE { NothingToDo(); }
	virtual bool allowImageFilter(const SkImageFilter*) SK_OVERRIDE { return false; }
	virtual bool canHandleImageFilter(const SkImageFilter*) SK_OVERRIDE { return false; }
	virtual bool filterImage(const SkImageFilter*, const SkBitmap&, const SkImageFilter::Context&,
	SkBitmap* result, SkIPoint* offset) SK_OVERRIDE {
	return false;
	}

	private:
	SkPictureUtils::SkPixelRefContainer* fPRCont;
	SkISize fSize;

	SkBitmap fEmptyBitmap; // legacy -- need to remove

	static bool GetBitmapFromPaint(const SkPaint &paint, SkBitmap* bitmap) {
	SkShader* shader = paint.getShader();
	if (NULL != shader) {
	if (SkShader::kNone_GradientType == shader->asAGradient(NULL)) {
	return SkShader::kNone_BitmapType != shader->asABitmap(bitmap, NULL, NULL);
	}
	}
	return false;
	}

	virtual void replaceBitmapBackendForRasterSurface(const SkBitmap&) SK_OVERRIDE {
	NotSupported();
	}

	virtual SkBaseDevice* onCreateDevice(const SkImageInfo& info, Usage usage) SK_OVERRIDE {
	// we expect to only get called via savelayer, in which case it is fine.
	SkASSERT(kSaveLayer_Usage == usage);
	return SkNEW_ARGS(SkGatherPixelRefsAndRectsDevice,
	(info.width(), info.height(), fPRCont));
	}

	static void NotSupported() {
	SkDEBUGFAIL("this method should never be called");
	}

	static void NothingToDo() {}

	typedef SkBaseDevice INHERITED;
	};

	#endif // SkGatherPixelRefsAndRects_DEFINED