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* 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/gm.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkClipOp.h"
#include "include/core/SkColorSpace.h"
#include "include/core/SkImageInfo.h"
#include "include/core/SkMatrix.h"
#include "include/core/SkPaint.h"
#include "include/core/SkPoint.h"
#include "include/core/SkRRect.h"
#include "include/core/SkRect.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkRegion.h"
#include "include/core/SkSize.h"
#include "include/core/SkString.h"
#include "include/core/SkTypes.h"
#include "include/gpu/GrBackendSurface.h"
#include "include/gpu/GrRecordingContext.h"
#include "include/private/GrTypesPriv.h"
#include "include/private/SkColorData.h"
#include "src/core/SkClipOpPriv.h"
#include "src/core/SkClipStack.h"
#include "src/gpu/GrAppliedClip.h"
#include "src/gpu/GrCaps.h"
#include "src/gpu/GrClip.h"
#include "src/gpu/GrFragmentProcessor.h"
#include "src/gpu/GrPaint.h"
#include "src/gpu/GrRecordingContextPriv.h"
#include "src/gpu/GrReducedClip.h"
#include "src/gpu/GrRenderTargetContext.h"
#include "src/gpu/GrRenderTargetContextPriv.h"
#include "src/gpu/GrStencilClip.h"
#include "src/gpu/GrTextureProxy.h"
#include "src/gpu/GrUserStencilSettings.h"
#include "src/gpu/effects/generated/GrDeviceSpaceEffect.h"
#include "tools/ToolUtils.h"
#include <utility>
class GrRecordingContext;
constexpr static SkIRect kDeviceRect = {0, 0, 600, 600};
constexpr static SkIRect kCoverRect = {50, 50, 550, 550};
namespace skiagm {
class WindowRectanglesBaseGM : public GM {
virtual DrawResult onCoverClipStack(const SkClipStack&, SkCanvas*, SkString* errorMsg) = 0;
SkISize onISize() override { return SkISize::Make(kDeviceRect.width(), kDeviceRect.height()); }
DrawResult onDraw(SkCanvas*, SkString* errorMsg) final;
DrawResult WindowRectanglesBaseGM::onDraw(SkCanvas* canvas, SkString* errorMsg) {
ToolUtils::draw_checkerboard(canvas, 0xffffffff, 0xffc6c3c6, 25);
SkClipStack stack;
stack.clipRect(SkRect::MakeXYWH(370.75, 80.25, 149, 100), SkMatrix::I(),
kDifference_SkClipOp, false);
stack.clipRect(SkRect::MakeXYWH(80.25, 420.75, 150, 100), SkMatrix::I(),
kDifference_SkClipOp, true);
stack.clipRRect(SkRRect::MakeRectXY(SkRect::MakeXYWH(200, 200, 200, 200), 60, 45),
SkMatrix::I(), kDifference_SkClipOp, true);
SkRRect nine;
nine.setNinePatch(SkRect::MakeXYWH(550 - 30.25 - 100, 370.75, 100, 150), 12, 35, 23, 20);
stack.clipRRect(nine, SkMatrix::I(), kDifference_SkClipOp, 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.clipRRect(complx, SkMatrix::I(), kDifference_SkClipOp, false);
return this->onCoverClipStack(stack, canvas, errorMsg);
* Draws a clip that will exercise window rectangles if they are supported.
class WindowRectanglesGM : public WindowRectanglesBaseGM {
SkString onShortName() final { return SkString("windowrectangles"); }
DrawResult onCoverClipStack(const SkClipStack&, SkCanvas*, SkString* errorMsg) final;
DrawResult WindowRectanglesGM::onCoverClipStack(const SkClipStack& stack, SkCanvas* canvas,
SkString* errorMsg) {
SkPaint paint;
// Set up the canvas's clip to match our SkClipStack.
SkClipStack::Iter iter(stack, SkClipStack::Iter::kBottom_IterStart);
for (const SkClipStack::Element* element =; element; element = {
SkClipOp op = element->getOp();
bool isAA = element->isAA();
switch (element->getDeviceSpaceType()) {
case SkClipStack::Element::DeviceSpaceType::kShader:
canvas->clipShader(element->refShader(), op);
case SkClipStack::Element::DeviceSpaceType::kPath:
canvas->clipPath(element->getDeviceSpacePath(), op, isAA);
case SkClipStack::Element::DeviceSpaceType::kRRect:
canvas->clipRRect(element->getDeviceSpaceRRect(), op, isAA);
case SkClipStack::Element::DeviceSpaceType::kRect:
canvas->clipRect(element->getDeviceSpaceRect(), op, isAA);
case SkClipStack::Element::DeviceSpaceType::kEmpty:
canvas->clipRect({ 0, 0, 0, 0 }, kIntersect_SkClipOp, false);
canvas->drawRect(SkRect::Make(kCoverRect), paint);
return DrawResult::kOk;
DEF_GM( return new WindowRectanglesGM(); )
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 {
constexpr static int kMaskCheckerSize = 5;
SkString onShortName() final { return SkString("windowrectangles_mask"); }
DrawResult onCoverClipStack(const SkClipStack&, SkCanvas*, SkString* errorMsg) final;
void visualizeAlphaMask(GrRecordingContext*, GrRenderTargetContext*,
const GrReducedClip&, GrPaint&&);
void visualizeStencilMask(GrRecordingContext*, GrRenderTargetContext*,
const GrReducedClip&, GrPaint&&);
void stencilCheckerboard(GrRenderTargetContext*, bool flip);
* This class clips a cover by an alpha mask. We use it to visualize the alpha clip mask.
class AlphaOnlyClip final : public GrClip {
AlphaOnlyClip(GrSurfaceProxyView mask, int x, int y) : fMask(std::move(mask)), fX(x), fY(y) {}
SkIRect getConservativeBounds() const final {
return SkIRect::MakeXYWH(fX, fY, fMask.width(), fMask.height());
Effect apply(GrRecordingContext* ctx, GrRenderTargetContext*, GrAAType, bool,
GrAppliedClip* out, SkRect* bounds) const override {
GrSamplerState samplerState(GrSamplerState::WrapMode::kClampToBorder,
auto m = SkMatrix::Translate(-fX, -fY);
auto subset = SkRect::Make(fMask.dimensions());
auto domain = bounds->makeOffset(-fX, -fY).makeInset(0.5, 0.5);
auto fp = GrTextureEffect::MakeSubset(fMask, kPremul_SkAlphaType, m, samplerState, subset,
domain, *ctx->priv().caps());
fp = GrDeviceSpaceEffect::Make(std::move(fp));
return Effect::kClipped;
GrSurfaceProxyView fMask;
int fX;
int fY;
* Makes a clip object that enforces the stencil clip bit. Used to visualize the stencil mask.
static GrStencilClip make_stencil_only_clip(GrRenderTargetContext* rtc) {
return GrStencilClip(rtc->dimensions(), SkClipStack::kEmptyGenID);
DrawResult WindowRectanglesMaskGM::onCoverClipStack(const SkClipStack& stack, SkCanvas* canvas,
SkString* errorMsg) {
auto ctx = canvas->recordingContext();
GrRenderTargetContext* rtc = canvas->internal_private_accessTopLayerRenderTargetContext();
if (!ctx || !rtc) {
*errorMsg = kErrorMsg_DrawSkippedGpuOnly;
return DrawResult::kSkip;
if (rtc->priv().maxWindowRectangles() < kNumWindows) {
*errorMsg = "Requires at least 8 window rectangles. "
"(Are you off FBO 0? Use sRGB to force offscreen rendering.)";
return DrawResult::kSkip;
const GrReducedClip reducedClip(stack, SkRect::Make(kCoverRect), rtc->caps(), kNumWindows);
GrPaint paint;
if (rtc->numSamples() <= 1) {
paint.setColor4f({ 0, 0.25f, 1, 1 });
this->visualizeAlphaMask(ctx, rtc, reducedClip, std::move(paint));
} else {
paint.setColor4f({ 1, 0.25f, 0.25f, 1 });
this->visualizeStencilMask(ctx, rtc, reducedClip, std::move(paint));
return DrawResult::kOk;
void WindowRectanglesMaskGM::visualizeAlphaMask(GrRecordingContext* ctx, GrRenderTargetContext* rtc,
const GrReducedClip& reducedClip, GrPaint&& paint) {
const int padRight = (kDeviceRect.right() - kCoverRect.right()) / 2;
const int padBottom = (kDeviceRect.bottom() - kCoverRect.bottom()) / 2;
auto maskRTC = GrRenderTargetContext::MakeWithFallback(
ctx, GrColorType::kAlpha_8, nullptr, SkBackingFit::kExact,
{kCoverRect.width() + padRight, kCoverRect.height() + padBottom});
if (!maskRTC) {
// Draw a checker pattern into the alpha mask so we can visualize the regions left untouched by
// the clip mask generation.
this->stencilCheckerboard(maskRTC.get(), true);
GrPaint stencilPaint;
stencilPaint.setCoverageSetOpXPFactory(SkRegion::kDifference_Op, false);
GrStencilClip stencilClip = make_stencil_only_clip(maskRTC.get());
maskRTC->priv().stencilRect(&stencilClip, &GrUserStencilSettings::kUnused,
std::move(stencilPaint), GrAA::kNo, SkMatrix::I(),
int x = kCoverRect.x() - kDeviceRect.x(),
y = kCoverRect.y() - kDeviceRect.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 alphaClip(maskRTC->readSurfaceView(), x, y);
rtc->drawRect(&alphaClip, std::move(paint), GrAA::kYes, SkMatrix::I(),
SkRect::Make(SkIRect::MakeXYWH(x, y, maskRTC->width(), maskRTC->height())));
void WindowRectanglesMaskGM::visualizeStencilMask(GrRecordingContext* ctx,
GrRenderTargetContext* rtc,
const GrReducedClip& reducedClip,
GrPaint&& paint) {
if (ctx->abandoned()) {
// GrReducedClip assumes the context hasn't been abandoned, which is reasonable since it is
// only ever used if a draw op is made. Since this GM calls it directly, it has to be taken
// into account.
// Draw a checker pattern into the stencil buffer so we can visualize the regions left untouched
// by the clip mask generation.
this->stencilCheckerboard(rtc, false);
reducedClip.drawStencilClipMask(ctx, rtc);
// Now visualize the stencil mask by covering the entire render target. 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.)
GrStencilClip clip = make_stencil_only_clip(rtc);
rtc->drawPaint(&clip, std::move(paint), SkMatrix::I());
void WindowRectanglesMaskGM::stencilCheckerboard(GrRenderTargetContext* rtc, bool flip) {
constexpr static GrUserStencilSettings kSetClip(
rtc->priv().clearStencilClip(SkIRect::MakeSize(rtc->dimensions()), false);
for (int y = 0; y < kDeviceRect.height(); y += kMaskCheckerSize) {
for (int x = (y & 1) == flip ? 0 : kMaskCheckerSize;
x < kDeviceRect.width(); x += 2 * kMaskCheckerSize) {
SkIRect checker = SkIRect::MakeXYWH(x, y, kMaskCheckerSize, kMaskCheckerSize);
GrPaint paint;
rtc->priv().stencilRect(nullptr, &kSetClip, std::move(paint), GrAA::kNo,
SkMatrix::I(), SkRect::Make(checker));
DEF_GM( return new WindowRectanglesMaskGM(); )
} // namespace skiagm