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      1 /*
      2  * Copyright 2013 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #include "SkCanvas.h"
      9 #include "SkColor.h"
     10 #include "SkGradientShader.h"
     11 #include "SkMatrix.h"
     12 #include "SkPaint.h"
     13 #include "SkPoint.h"
     14 #include "SkRect.h"
     15 #include "SkRefCnt.h"
     16 #include "SkScalar.h"
     17 #include "SkSize.h"
     18 #include "SkString.h"
     19 
     20 #include "gm.h"
     21 
     22 static const SkColor gColors[] = {
     23     SK_ColorRED, SK_ColorYELLOW
     24 };
     25 
     26 // These annoying defines are necessary, because the only other alternative
     27 // is to use SkIntToScalar(...) everywhere.
     28 static const SkScalar sZero = 0;
     29 static const SkScalar sHalf = SK_ScalarHalf;
     30 static const SkScalar sOne = SK_Scalar1;
     31 
     32 // These arrays define the gradient stop points
     33 // as x1, y1, x2, y2 per gradient to draw.
     34 static const SkPoint linearPts[][2] = {
     35     {{sZero, sZero}, {sOne,  sZero}},
     36     {{sZero, sZero}, {sZero, sOne}},
     37     {{sOne,  sZero}, {sZero, sZero}},
     38     {{sZero, sOne},  {sZero, sZero}},
     39 
     40     {{sZero, sZero}, {sOne,  sOne}},
     41     {{sOne,  sOne},  {sZero, sZero}},
     42     {{sOne,  sZero}, {sZero, sOne}},
     43     {{sZero, sOne},  {sOne,  sZero}}
     44 };
     45 
     46 static const SkPoint radialPts[][2] = {
     47     {{sZero, sHalf}, {sOne,  sHalf}},
     48     {{sHalf, sZero}, {sHalf, sOne}},
     49     {{sOne,  sHalf}, {sZero, sHalf}},
     50     {{sHalf, sOne},  {sHalf, sZero}},
     51 
     52     {{sZero, sZero}, {sOne,  sOne}},
     53     {{sOne,  sOne},  {sZero, sZero}},
     54     {{sOne,  sZero}, {sZero, sOne}},
     55     {{sZero, sOne},  {sOne,  sZero}}
     56 };
     57 
     58 // These define the pixels allocated to each gradient image.
     59 static const SkScalar TESTGRID_X = SkIntToScalar(200);
     60 static const SkScalar TESTGRID_Y = SkIntToScalar(200);
     61 
     62 static const int IMAGES_X = 4;             // number of images per row
     63 
     64 static SkShader* make_linear_gradient(const SkPoint pts[2], const SkMatrix& localMatrix) {
     65     return SkGradientShader::CreateLinear(pts, gColors, nullptr, SK_ARRAY_COUNT(gColors),
     66                                           SkShader::kClamp_TileMode, 0, &localMatrix);
     67 }
     68 
     69 static SkShader* make_radial_gradient(const SkPoint pts[2], const SkMatrix& localMatrix) {
     70     SkPoint center;
     71     center.set(SkScalarAve(pts[0].fX, pts[1].fX),
     72                SkScalarAve(pts[0].fY, pts[1].fY));
     73     float radius = (center - pts[0]).length();
     74     return SkGradientShader::CreateRadial(center, radius, gColors, nullptr, SK_ARRAY_COUNT(gColors),
     75                                           SkShader::kClamp_TileMode, 0, &localMatrix);
     76 }
     77 
     78 static void draw_gradients(SkCanvas* canvas,
     79                            SkShader* (*makeShader)(const SkPoint[2], const SkMatrix&),
     80                            const SkPoint ptsArray[][2], int numImages) {
     81     // Use some nice prime numbers for the rectangle and matrix with
     82     // different scaling along the x and y axes (which is the bug this
     83     // test addresses, where incorrect order of operations mixed up the axes)
     84     SkRect rectGrad = {
     85         SkIntToScalar(43),  SkIntToScalar(61),
     86         SkIntToScalar(181), SkIntToScalar(167) };
     87     SkMatrix shaderMat;
     88     shaderMat.setScale(rectGrad.width(), rectGrad.height());
     89     shaderMat.postTranslate(rectGrad.left(), rectGrad.top());
     90 
     91     canvas->save();
     92     for (int i = 0; i < numImages; i++) {
     93         // Advance line downwards if necessary.
     94         if (i % IMAGES_X == 0 && i != 0) {
     95             canvas->restore();
     96             canvas->translate(0, TESTGRID_Y);
     97             canvas->save();
     98         }
     99 
    100         // Setup shader and draw.
    101         SkAutoTUnref<SkShader> shader(makeShader(*ptsArray, shaderMat));
    102 
    103         SkPaint paint;
    104         paint.setShader(shader);
    105         canvas->drawRect(rectGrad, paint);
    106 
    107         // Advance to next position.
    108         canvas->translate(TESTGRID_X, 0);
    109         ptsArray++;
    110     }
    111     canvas->restore();
    112 }
    113 
    114 DEF_SIMPLE_GM_BG(gradient_matrix, canvas, 800, 800,
    115                  sk_tool_utils::color_to_565(0xFFDDDDDD)) {
    116         draw_gradients(canvas, &make_linear_gradient,
    117                       linearPts, SK_ARRAY_COUNT(linearPts));
    118 
    119         canvas->translate(0, TESTGRID_Y);
    120 
    121         draw_gradients(canvas, &make_radial_gradient,
    122                       radialPts, SK_ARRAY_COUNT(radialPts));
    123 }
    124