gm/windowrectangles.cpp - platform/external/skqp - Gitiles

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #include "gm.h"
 #include "SkClipStack.h"
 #include "SkRRect.h"

 #if SK_SUPPORT_GPU
 #  include "GrAppliedClip.h"
 #  include "GrDrawContext.h"
 #  include "GrDrawContextPriv.h"
 #  include "GrFixedClip.h"
 #  include "GrReducedClip.h"
 #  include "GrRenderTargetPriv.h"
 #  include "GrResourceProvider.h"
 #  include "effects/GrTextureDomain.h"
 #endif

 constexpr static SkIRect kDeviceRect = {0, 0, 600, 600};
 constexpr static SkIRect kLayerRect = {25, 25, 575, 575};
 constexpr static SkIRect kCoverRect = {50, 50, 550, 550};

 namespace skiagm {

 ////////////////////////////////////////////////////////////////////////////////////////////////////

 class WindowRectanglesBaseGM : public GM {
 protected:
     virtual void onCoverClipStack(const SkClipStack&, SkCanvas*) = 0;

 private:
     SkISize onISize() override { return SkISize::Make(kDeviceRect.width(), kDeviceRect.height()); }
     void onDraw(SkCanvas*) final;
 };

 void WindowRectanglesBaseGM::onDraw(SkCanvas* canvas) {
     sk_tool_utils::draw_checkerboard(canvas, 0xffffffff, 0xffc6c3c6, 25);
     canvas->saveLayer(SkRect::Make(kLayerRect), nullptr);

     SkClipStack stack;
     stack.clipDevRect(SkRect::MakeXYWH(370.75, 80.25, 149, 100), SkRegion::kDifference_Op, false);
     stack.clipDevRect(SkRect::MakeXYWH(80.25, 420.75, 150, 100), SkRegion::kDifference_Op, true);
     stack.clipDevRRect(SkRRect::MakeRectXY(SkRect::MakeXYWH(200, 200, 200, 200), 60, 45),
                        SkRegion::kDifference_Op, true);

     SkRRect nine;
     nine.setNinePatch(SkRect::MakeXYWH(550 - 30.25 - 100, 370.75, 100, 150), 12, 35, 23, 20);
     stack.clipDevRRect(nine, SkRegion::kDifference_Op, true);

     SkRRect complx;
     SkVector complxRadii[4] = {{6, 4}, {8, 12}, {16, 24}, {48, 32}};
     complx.setRectRadii(SkRect::MakeXYWH(80.25, 80.75, 100, 149), complxRadii);
     stack.clipDevRRect(complx, SkRegion::kDifference_Op, false);

     this->onCoverClipStack(stack, canvas);

     canvas->restore();
 }

 ////////////////////////////////////////////////////////////////////////////////////////////////////

 /**
  * Draws a clip that will exercise window rectangles if they are supported.
  */
 class WindowRectanglesGM : public WindowRectanglesBaseGM {
 private:
     SkString onShortName() final { return SkString("windowrectangles"); }
     void onCoverClipStack(const SkClipStack&, SkCanvas*) final;
 };

 /**
  * This is a simple helper class for resetting a canvas's clip to our test’s SkClipStack.
  */
 class ReplayClipStackVisitor final : public SkCanvasClipVisitor {
 public:
     typedef SkRegion::Op Op;
     ReplayClipStackVisitor(SkCanvas* canvas) : fCanvas(canvas) {}
     void clipRect(const SkRect& r, Op op, bool aa) override { fCanvas->clipRect(r, op, aa); }
     void clipRRect(const SkRRect& rr, Op op, bool aa) override { fCanvas->clipRRect(rr, op, aa); }
     void clipPath(const SkPath&, Op, bool) override { SkFAIL("Not implemented"); }
 private:
     SkCanvas* const fCanvas;
 };

 void WindowRectanglesGM::onCoverClipStack(const SkClipStack& stack, SkCanvas* canvas) {
     SkPaint paint;
     paint.setColor(0xff00aa80);

     // Set up the canvas's clip to match our SkClipStack.
     ReplayClipStackVisitor visitor(canvas);
     SkClipStack::Iter iter(stack, SkClipStack::Iter::kBottom_IterStart);
     for (const SkClipStack::Element* element = iter.next(); element; element = iter.next()) {
         element->replay(&visitor);
     }

     canvas->drawRect(SkRect::Make(kCoverRect), paint);
 }

 DEF_GM( return new WindowRectanglesGM(); )

 ////////////////////////////////////////////////////////////////////////////////////////////////////

 #if SK_SUPPORT_GPU

 constexpr static int kNumWindows = 8;

 /**
  * Visualizes the mask (alpha or stencil) for a clip with several window rectangles. The purpose of
  * this test is to verify that window rectangles are being used during clip mask generation, and to
  * visualize where the window rectangles are placed.
  *
  * We use window rectangles when generating the clip mask because there is no need to invest time
  * defining those regions where window rectangles will be in effect during the actual draw anyway.
  *
  * This test works by filling the entire clip mask with a small checkerboard pattern before drawing
  * it, and then covering the mask with a solid color once it has been generated. The regions inside
  * window rectangles or outside the scissor should still have the initial checkerboard intact.
  */
 class WindowRectanglesMaskGM : public WindowRectanglesBaseGM {
 private:
     constexpr static int kMaskCheckerSize = 5;
     SkString onShortName() final { return SkString("windowrectangles_mask"); }
     void onCoverClipStack(const SkClipStack&, SkCanvas*) final;
     void visualizeAlphaMask(GrContext*, GrDrawContext*, const GrReducedClip&, const GrPaint&);
     void visualizeStencilMask(GrContext*, GrDrawContext*, const GrReducedClip&, const GrPaint&);
     void stencilCheckerboard(GrDrawContext*, bool flip);
     void fail(SkCanvas*);
 };

 /**
  * Base class for GrClips that visualize a clip mask.
  */
 class MaskOnlyClipBase : public GrClip {
 private:
     bool quickContains(const SkRect&) const final { return false; }
     bool isRRect(const SkRect& rtBounds, SkRRect* rr, bool* aa) const final { return false; }
     void getConservativeBounds(int width, int height, SkIRect* rect, bool* iior) const final {
         rect->set(0, 0, width, height);
         if (iior) {
             *iior = false;
         }
     }
 };

 /**
  * This class clips a cover by an alpha mask. We use it to visualize the alpha clip mask.
  */
 class AlphaOnlyClip final : public MaskOnlyClipBase {
 public:
     AlphaOnlyClip(GrTexture* mask, int x, int y) {
         int w = mask->width(), h = mask->height();
         SkMatrix mat = SkMatrix::MakeScale(1.f / SkIntToScalar(w), 1.f / SkIntToScalar(h));
         mat.preTranslate(SkIntToScalar(-x), SkIntToScalar(-y));
         fFP = GrTextureDomainEffect::Make(
                   mask, nullptr, mat,
                   GrTextureDomain::MakeTexelDomain(mask, SkIRect::MakeWH(w, h)),
                   GrTextureDomain::kDecal_Mode, GrTextureParams::kNone_FilterMode,
                   kDevice_GrCoordSet);

     }
 private:
     bool apply(GrContext*, GrDrawContext*, bool, bool, GrAppliedClip* out) const override {
         out->addCoverageFP(fFP);
         return true;
     }
     sk_sp<GrFragmentProcessor> fFP;
 };

 /**
  * This class clips a cover by the stencil clip bit. We use it to visualize the stencil mask.
  */
 class StencilOnlyClip final : public MaskOnlyClipBase {
 private:
     bool apply(GrContext*, GrDrawContext*, bool, bool, GrAppliedClip* out) const override {
         out->addStencilClip();
         return true;
     }
 };

 void WindowRectanglesMaskGM::onCoverClipStack(const SkClipStack& stack, SkCanvas* canvas) {
     GrContext* ctx = canvas->getGrContext();
     GrDrawContext* dc = canvas->internal_private_accessTopLayerDrawContext();

     if (!ctx || !dc ||
         dc->accessRenderTarget()->renderTargetPriv().maxWindowRectangles() < kNumWindows) {
         this->fail(canvas);
         return;
     }

     const GrReducedClip reducedClip(stack, SkRect::Make(kCoverRect), kNumWindows);

     GrPaint paint;
     paint.setAntiAlias(true);
     if (!dc->isStencilBufferMultisampled()) {
         paint.setColor4f(GrColor4f(0, 0.25f, 1, 1));
         this->visualizeAlphaMask(ctx, dc, reducedClip, paint);
     } else {
         paint.setColor4f(GrColor4f(1, 0.25f, 0.25f, 1));
         this->visualizeStencilMask(ctx, dc, reducedClip, paint);
     }
 }

 void WindowRectanglesMaskGM::visualizeAlphaMask(GrContext* ctx, GrDrawContext* dc,
                                                 const GrReducedClip& reducedClip,
                                                 const GrPaint& paint) {
     sk_sp<GrDrawContext> maskDC(
         ctx->makeDrawContextWithFallback(SkBackingFit::kExact, kLayerRect.width(),
                                          kLayerRect.height(), kAlpha_8_GrPixelConfig, nullptr));
     if (!maskDC ||
         !ctx->resourceProvider()->attachStencilAttachment(maskDC->accessRenderTarget())) {
         return;
     }

     // Draw a checker pattern into the alpha mask so we can visualize the regions left untouched by
     // the clip mask generation.
     this->stencilCheckerboard(maskDC.get(), true);
     maskDC->clear(nullptr, GrColorPackA4(0xff), true);
     maskDC->drawContextPriv().drawAndStencilRect(StencilOnlyClip(), &GrUserStencilSettings::kUnused,
                                                  SkRegion::kDifference_Op, false, false,
                                                  SkMatrix::I(),
                                                  SkRect::MakeIWH(maskDC->width(), maskDC->height()));
     reducedClip.drawAlphaClipMask(maskDC.get());
     sk_sp<GrTexture> mask(maskDC->asTexture());

     int x = kCoverRect.x() - kLayerRect.x(),
         y = kCoverRect.y() - kLayerRect.y();

     // Now visualize the alpha mask by drawing a rect over the area where it is defined. The regions
     // inside window rectangles or outside the scissor should still have the initial checkerboard
     // intact. (This verifies we didn't spend any time modifying those pixels in the mask.)
     AlphaOnlyClip clip(mask.get(), x, y);
     dc->drawRect(clip, paint, SkMatrix::I(),
                  SkRect::Make(SkIRect::MakeXYWH(x, y, mask->width(), mask->height())));
 }

 void WindowRectanglesMaskGM::visualizeStencilMask(GrContext* ctx, GrDrawContext* dc,
                                                   const GrReducedClip& reducedClip,
                                                   const GrPaint& paint) {
     if (!ctx->resourceProvider()->attachStencilAttachment(dc->accessRenderTarget())) {
         return;
     }

     // Draw a checker pattern into the stencil buffer so we can visualize the regions left untouched
     // by the clip mask generation.
     this->stencilCheckerboard(dc, false);
     reducedClip.drawStencilClipMask(ctx, dc, {kLayerRect.x(), kLayerRect.y()});

     // Now visualize the stencil mask by covering the entire render target. The regions inside
     // window rectangless or outside the scissor should still have the initial checkerboard intact.
     // (This verifies we didn't spend any time modifying those pixels in the mask.)
     dc->drawPaint(StencilOnlyClip(), paint, SkMatrix::I());
 }

 void WindowRectanglesMaskGM::stencilCheckerboard(GrDrawContext* dc, bool flip) {
     constexpr static GrUserStencilSettings kSetClip(
         GrUserStencilSettings::StaticInit<
         0,
         GrUserStencilTest::kAlways,
         0,
         GrUserStencilOp::kSetClipBit,
         GrUserStencilOp::kKeep,
         0>()
     );

     dc->drawContextPriv().clearStencilClip(GrFixedClip::Disabled(), false);

     for (int y = 0; y < kLayerRect.height(); y += kMaskCheckerSize) {
         for (int x = (y & 1) == flip ? 0 : kMaskCheckerSize;
              x < kLayerRect.width(); x += 2 * kMaskCheckerSize) {
             SkIRect checker = SkIRect::MakeXYWH(x, y, kMaskCheckerSize, kMaskCheckerSize);
             dc->drawContextPriv().stencilRect(GrNoClip(), &kSetClip, false, SkMatrix::I(),
                                               SkRect::Make(checker));
         }
     }
 }

 void WindowRectanglesMaskGM::fail(SkCanvas* canvas) {
     SkPaint paint;
     paint.setAntiAlias(true);
     paint.setTextAlign(SkPaint::kCenter_Align);
     paint.setTextSize(20);
     sk_tool_utils::set_portable_typeface(&paint);

     SkString errorMsg;
     errorMsg.printf("Requires GPU with %i window rectangles", kNumWindows);

     canvas->clipRect(SkRect::Make(kCoverRect));
     canvas->clear(SK_ColorWHITE);
     canvas->drawText(errorMsg.c_str(), errorMsg.size(), SkIntToScalar(kCoverRect.centerX()),
                      SkIntToScalar(kCoverRect.centerY() - 10), paint);
 }

 DEF_GM( return new WindowRectanglesMaskGM(); )

 #endif

 }
	/*
	* Copyright 2016 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#include "gm.h"
	#include "SkClipStack.h"
	#include "SkRRect.h"

	#if SK_SUPPORT_GPU
	# include "GrAppliedClip.h"
	# include "GrDrawContext.h"
	# include "GrDrawContextPriv.h"
	# include "GrFixedClip.h"
	# include "GrReducedClip.h"
	# include "GrRenderTargetPriv.h"
	# include "GrResourceProvider.h"
	# include "effects/GrTextureDomain.h"
	#endif

	constexpr static SkIRect kDeviceRect = {0, 0, 600, 600};
	constexpr static SkIRect kLayerRect = {25, 25, 575, 575};
	constexpr static SkIRect kCoverRect = {50, 50, 550, 550};

	namespace skiagm {

	////////////////////////////////////////////////////////////////////////////////////////////////////

	class WindowRectanglesBaseGM : public GM {
	protected:
	virtual void onCoverClipStack(const SkClipStack&, SkCanvas*) = 0;

	private:
	SkISize onISize() override { return SkISize::Make(kDeviceRect.width(), kDeviceRect.height()); }
	void onDraw(SkCanvas*) final;
	};

	void WindowRectanglesBaseGM::onDraw(SkCanvas* canvas) {
	sk_tool_utils::draw_checkerboard(canvas, 0xffffffff, 0xffc6c3c6, 25);
	canvas->saveLayer(SkRect::Make(kLayerRect), nullptr);

	SkClipStack stack;
	stack.clipDevRect(SkRect::MakeXYWH(370.75, 80.25, 149, 100), SkRegion::kDifference_Op, false);
	stack.clipDevRect(SkRect::MakeXYWH(80.25, 420.75, 150, 100), SkRegion::kDifference_Op, true);
	stack.clipDevRRect(SkRRect::MakeRectXY(SkRect::MakeXYWH(200, 200, 200, 200), 60, 45),
	SkRegion::kDifference_Op, true);

	SkRRect nine;
	nine.setNinePatch(SkRect::MakeXYWH(550 - 30.25 - 100, 370.75, 100, 150), 12, 35, 23, 20);
	stack.clipDevRRect(nine, SkRegion::kDifference_Op, true);

	SkRRect complx;
	SkVector complxRadii[4] = {{6, 4}, {8, 12}, {16, 24}, {48, 32}};
	complx.setRectRadii(SkRect::MakeXYWH(80.25, 80.75, 100, 149), complxRadii);
	stack.clipDevRRect(complx, SkRegion::kDifference_Op, false);

	this->onCoverClipStack(stack, canvas);

	canvas->restore();
	}

	////////////////////////////////////////////////////////////////////////////////////////////////////

	/**
	* Draws a clip that will exercise window rectangles if they are supported.
	*/
	class WindowRectanglesGM : public WindowRectanglesBaseGM {
	private:
	SkString onShortName() final { return SkString("windowrectangles"); }
	void onCoverClipStack(const SkClipStack&, SkCanvas*) final;
	};

	/**
	* This is a simple helper class for resetting a canvas's clip to our test’s SkClipStack.
	*/
	class ReplayClipStackVisitor final : public SkCanvasClipVisitor {
	public:
	typedef SkRegion::Op Op;
	ReplayClipStackVisitor(SkCanvas* canvas) : fCanvas(canvas) {}
	void clipRect(const SkRect& r, Op op, bool aa) override { fCanvas->clipRect(r, op, aa); }
	void clipRRect(const SkRRect& rr, Op op, bool aa) override { fCanvas->clipRRect(rr, op, aa); }
	void clipPath(const SkPath&, Op, bool) override { SkFAIL("Not implemented"); }
	private:
	SkCanvas* const fCanvas;
	};

	void WindowRectanglesGM::onCoverClipStack(const SkClipStack& stack, SkCanvas* canvas) {
	SkPaint paint;
	paint.setColor(0xff00aa80);

	// Set up the canvas's clip to match our SkClipStack.
	ReplayClipStackVisitor visitor(canvas);
	SkClipStack::Iter iter(stack, SkClipStack::Iter::kBottom_IterStart);
	for (const SkClipStack::Element* element = iter.next(); element; element = iter.next()) {
	element->replay(&visitor);
	}

	canvas->drawRect(SkRect::Make(kCoverRect), paint);
	}

	DEF_GM( return new WindowRectanglesGM(); )

	////////////////////////////////////////////////////////////////////////////////////////////////////

	#if SK_SUPPORT_GPU

	constexpr static int kNumWindows = 8;

	/**
	* Visualizes the mask (alpha or stencil) for a clip with several window rectangles. The purpose of
	* this test is to verify that window rectangles are being used during clip mask generation, and to
	* visualize where the window rectangles are placed.
	*
	* We use window rectangles when generating the clip mask because there is no need to invest time
	* defining those regions where window rectangles will be in effect during the actual draw anyway.
	*
	* This test works by filling the entire clip mask with a small checkerboard pattern before drawing
	* it, and then covering the mask with a solid color once it has been generated. The regions inside
	* window rectangles or outside the scissor should still have the initial checkerboard intact.
	*/
	class WindowRectanglesMaskGM : public WindowRectanglesBaseGM {
	private:
	constexpr static int kMaskCheckerSize = 5;
	SkString onShortName() final { return SkString("windowrectangles_mask"); }
	void onCoverClipStack(const SkClipStack&, SkCanvas*) final;
	void visualizeAlphaMask(GrContext, GrDrawContext, const GrReducedClip&, const GrPaint&);
	void visualizeStencilMask(GrContext, GrDrawContext, const GrReducedClip&, const GrPaint&);
	void stencilCheckerboard(GrDrawContext*, bool flip);
	void fail(SkCanvas*);
	};

	/**
	* Base class for GrClips that visualize a clip mask.
	*/
	class MaskOnlyClipBase : public GrClip {
	private:
	bool quickContains(const SkRect&) const final { return false; }
	bool isRRect(const SkRect& rtBounds, SkRRect* rr, bool* aa) const final { return false; }
	void getConservativeBounds(int width, int height, SkIRect* rect, bool* iior) const final {
	rect->set(0, 0, width, height);
	if (iior) {
	*iior = false;
	}
	}
	};

	/**
	* This class clips a cover by an alpha mask. We use it to visualize the alpha clip mask.
	*/
	class AlphaOnlyClip final : public MaskOnlyClipBase {
	public:
	AlphaOnlyClip(GrTexture* mask, int x, int y) {
	int w = mask->width(), h = mask->height();
	SkMatrix mat = SkMatrix::MakeScale(1.f / SkIntToScalar(w), 1.f / SkIntToScalar(h));
	mat.preTranslate(SkIntToScalar(-x), SkIntToScalar(-y));
	fFP = GrTextureDomainEffect::Make(
	mask, nullptr, mat,
	GrTextureDomain::MakeTexelDomain(mask, SkIRect::MakeWH(w, h)),
	GrTextureDomain::kDecal_Mode, GrTextureParams::kNone_FilterMode,
	kDevice_GrCoordSet);

	}
	private:
	bool apply(GrContext, GrDrawContext, bool, bool, GrAppliedClip* out) const override {
	out->addCoverageFP(fFP);
	return true;
	}
	sk_sp<GrFragmentProcessor> fFP;
	};

	/**
	* This class clips a cover by the stencil clip bit. We use it to visualize the stencil mask.
	*/
	class StencilOnlyClip final : public MaskOnlyClipBase {
	private:
	bool apply(GrContext, GrDrawContext, bool, bool, GrAppliedClip* out) const override {
	out->addStencilClip();
	return true;
	}
	};

	void WindowRectanglesMaskGM::onCoverClipStack(const SkClipStack& stack, SkCanvas* canvas) {
	GrContext* ctx = canvas->getGrContext();
	GrDrawContext* dc = canvas->internal_private_accessTopLayerDrawContext();

	if (!ctx \|\| !dc \|\|
	dc->accessRenderTarget()->renderTargetPriv().maxWindowRectangles() < kNumWindows) {
	this->fail(canvas);
	return;
	}

	const GrReducedClip reducedClip(stack, SkRect::Make(kCoverRect), kNumWindows);

	GrPaint paint;
	paint.setAntiAlias(true);
	if (!dc->isStencilBufferMultisampled()) {
	paint.setColor4f(GrColor4f(0, 0.25f, 1, 1));
	this->visualizeAlphaMask(ctx, dc, reducedClip, paint);
	} else {
	paint.setColor4f(GrColor4f(1, 0.25f, 0.25f, 1));
	this->visualizeStencilMask(ctx, dc, reducedClip, paint);
	}
	}

	void WindowRectanglesMaskGM::visualizeAlphaMask(GrContext* ctx, GrDrawContext* dc,
	const GrReducedClip& reducedClip,
	const GrPaint& paint) {
	sk_sp<GrDrawContext> maskDC(
	ctx->makeDrawContextWithFallback(SkBackingFit::kExact, kLayerRect.width(),
	kLayerRect.height(), kAlpha_8_GrPixelConfig, nullptr));
	if (!maskDC \|\|
	!ctx->resourceProvider()->attachStencilAttachment(maskDC->accessRenderTarget())) {
	return;
	}

	// Draw a checker pattern into the alpha mask so we can visualize the regions left untouched by
	// the clip mask generation.
	this->stencilCheckerboard(maskDC.get(), true);
	maskDC->clear(nullptr, GrColorPackA4(0xff), true);
	maskDC->drawContextPriv().drawAndStencilRect(StencilOnlyClip(), &GrUserStencilSettings::kUnused,
	SkRegion::kDifference_Op, false, false,
	SkMatrix::I(),
	SkRect::MakeIWH(maskDC->width(), maskDC->height()));
	reducedClip.drawAlphaClipMask(maskDC.get());
	sk_sp<GrTexture> mask(maskDC->asTexture());

	int x = kCoverRect.x() - kLayerRect.x(),
	y = kCoverRect.y() - kLayerRect.y();

	// Now visualize the alpha mask by drawing a rect over the area where it is defined. The regions
	// inside window rectangles or outside the scissor should still have the initial checkerboard
	// intact. (This verifies we didn't spend any time modifying those pixels in the mask.)
	AlphaOnlyClip clip(mask.get(), x, y);
	dc->drawRect(clip, paint, SkMatrix::I(),
	SkRect::Make(SkIRect::MakeXYWH(x, y, mask->width(), mask->height())));
	}

	void WindowRectanglesMaskGM::visualizeStencilMask(GrContext* ctx, GrDrawContext* dc,
	const GrReducedClip& reducedClip,
	const GrPaint& paint) {
	if (!ctx->resourceProvider()->attachStencilAttachment(dc->accessRenderTarget())) {
	return;
	}

	// Draw a checker pattern into the stencil buffer so we can visualize the regions left untouched
	// by the clip mask generation.
	this->stencilCheckerboard(dc, false);
	reducedClip.drawStencilClipMask(ctx, dc, {kLayerRect.x(), kLayerRect.y()});

	// Now visualize the stencil mask by covering the entire render target. The regions inside
	// window rectangless or outside the scissor should still have the initial checkerboard intact.
	// (This verifies we didn't spend any time modifying those pixels in the mask.)
	dc->drawPaint(StencilOnlyClip(), paint, SkMatrix::I());
	}

	void WindowRectanglesMaskGM::stencilCheckerboard(GrDrawContext* dc, bool flip) {
	constexpr static GrUserStencilSettings kSetClip(
	GrUserStencilSettings::StaticInit<
	0,
	GrUserStencilTest::kAlways,
	0,
	GrUserStencilOp::kSetClipBit,
	GrUserStencilOp::kKeep,
	0>()
	);

	dc->drawContextPriv().clearStencilClip(GrFixedClip::Disabled(), false);

	for (int y = 0; y < kLayerRect.height(); y += kMaskCheckerSize) {
	for (int x = (y & 1) == flip ? 0 : kMaskCheckerSize;
	x < kLayerRect.width(); x += 2 * kMaskCheckerSize) {
	SkIRect checker = SkIRect::MakeXYWH(x, y, kMaskCheckerSize, kMaskCheckerSize);
	dc->drawContextPriv().stencilRect(GrNoClip(), &kSetClip, false, SkMatrix::I(),
	SkRect::Make(checker));
	}
	}
	}

	void WindowRectanglesMaskGM::fail(SkCanvas* canvas) {
	SkPaint paint;
	paint.setAntiAlias(true);
	paint.setTextAlign(SkPaint::kCenter_Align);
	paint.setTextSize(20);
	sk_tool_utils::set_portable_typeface(&paint);

	SkString errorMsg;
	errorMsg.printf("Requires GPU with %i window rectangles", kNumWindows);

	canvas->clipRect(SkRect::Make(kCoverRect));
	canvas->clear(SK_ColorWHITE);
	canvas->drawText(errorMsg.c_str(), errorMsg.size(), SkIntToScalar(kCoverRect.centerX()),
	SkIntToScalar(kCoverRect.centerY() - 10), paint);
	}

	DEF_GM( return new WindowRectanglesMaskGM(); )

	#endif

	}