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* Copyright 2013 Google Inc.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#include "SkCanvas.h"
#include "SkColor.h"
#include "SkGradientShader.h"
#include "SkMatrix.h"
#include "SkPaint.h"
#include "SkPoint.h"
#include "SkRect.h"
#include "SkRefCnt.h"
#include "SkScalar.h"
#include "SkSize.h"
#include "SkString.h"
#include "gm.h"
static const SkColor gColors[] = {
// These annoying defines are necessary, because the only other alternative
// is to use SkIntToScalar(...) everywhere.
static const SkScalar sZero = 0;
static const SkScalar sHalf = SK_ScalarHalf;
static const SkScalar sOne = SK_Scalar1;
// These arrays define the gradient stop points
// as x1, y1, x2, y2 per gradient to draw.
static const SkPoint linearPts[][2] = {
{{sZero, sZero}, {sOne, sZero}},
{{sZero, sZero}, {sZero, sOne}},
{{sOne, sZero}, {sZero, sZero}},
{{sZero, sOne}, {sZero, sZero}},
{{sZero, sZero}, {sOne, sOne}},
{{sOne, sOne}, {sZero, sZero}},
{{sOne, sZero}, {sZero, sOne}},
{{sZero, sOne}, {sOne, sZero}}
static const SkPoint radialPts[][2] = {
{{sZero, sHalf}, {sOne, sHalf}},
{{sHalf, sZero}, {sHalf, sOne}},
{{sOne, sHalf}, {sZero, sHalf}},
{{sHalf, sOne}, {sHalf, sZero}},
{{sZero, sZero}, {sOne, sOne}},
{{sOne, sOne}, {sZero, sZero}},
{{sOne, sZero}, {sZero, sOne}},
{{sZero, sOne}, {sOne, sZero}}
// These define the pixels allocated to each gradient image.
static const SkScalar TESTGRID_X = SkIntToScalar(200);
static const SkScalar TESTGRID_Y = SkIntToScalar(200);
static const int IMAGES_X = 4; // number of images per row
static SkShader* make_linear_gradient(const SkPoint pts[2], const SkMatrix& localMatrix) {
return SkGradientShader::CreateLinear(pts, gColors, NULL, SK_ARRAY_COUNT(gColors),
SkShader::kClamp_TileMode, 0, &localMatrix);
static SkShader* make_radial_gradient(const SkPoint pts[2], const SkMatrix& localMatrix) {
SkPoint center;
center.set(SkScalarAve(pts[0].fX, pts[1].fX),
SkScalarAve(pts[0].fY, pts[1].fY));
float radius = (center - pts[0]).length();
return SkGradientShader::CreateRadial(center, radius, gColors, NULL, SK_ARRAY_COUNT(gColors),
SkShader::kClamp_TileMode, 0, &localMatrix);
static void draw_gradients(SkCanvas* canvas,
SkShader* (*makeShader)(const SkPoint[2], const SkMatrix&),
const SkPoint ptsArray[][2], int numImages) {
// Use some nice prime numbers for the rectangle and matrix with
// different scaling along the x and y axes (which is the bug this
// test addresses, where incorrect order of operations mixed up the axes)
SkRect rectGrad = {
SkIntToScalar(43), SkIntToScalar(61),
SkIntToScalar(181), SkIntToScalar(167) };
SkMatrix shaderMat;
shaderMat.setScale(rectGrad.width(), rectGrad.height());
for (int i = 0; i < numImages; i++) {
// Advance line downwards if necessary.
if (i % IMAGES_X == 0 && i != 0) {
canvas->translate(0, TESTGRID_Y);
// Setup shader and draw.
SkAutoTUnref<SkShader> shader(makeShader(*ptsArray, shaderMat));
SkPaint paint;
canvas->drawRect(rectGrad, paint);
// Advance to next position.
canvas->translate(TESTGRID_X, 0);
namespace skiagm {
class GradientMatrixGM : public GM {
GradientMatrixGM() {
uint32_t onGetFlags() const SK_OVERRIDE {
return kSkipTiled_Flag;
SkString onShortName() SK_OVERRIDE {
return SkString("gradient_matrix");
SkISize onISize() SK_OVERRIDE {
return SkISize::Make(800, 800);
void onDraw(SkCanvas* canvas) SK_OVERRIDE {
draw_gradients(canvas, &make_linear_gradient,
linearPts, SK_ARRAY_COUNT(linearPts));
canvas->translate(0, TESTGRID_Y);
draw_gradients(canvas, &make_radial_gradient,
radialPts, SK_ARRAY_COUNT(radialPts));
DEF_GM( return new GradientMatrixGM; )