1 /* 2 * Copyright 2019 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 "SkGradientShader.h" 10 #include "SkPaint.h" 11 #include "gm.h" 12 13 // This draws a hard stop gradient applied to a rectangle. The hard stops fall at half pixel 14 // boundaries in y. On some GPUs we've found that the winding of the two triangles that make up the 15 // rectangle can affect whether the interpolants for local coords wind up agreeing across a row. 16 // When they disagree the hard stop gradient appears jagged. We draw the rectangle four times: 17 // no-mirroring, mirror in x, mirror in y, and mirror in x and y. 18 DEF_SIMPLE_GM(crbug_938592, canvas, 500, 300) { 19 static constexpr SkPoint pts[] = {{0, 0}, {0, 30}}; 20 static constexpr SkScalar pos[] = {0.f, 9.f / 20, 9.f / 20, 11.f / 20, 11.f / 20, 20.f / 20}; 21 static constexpr SkColor c0 = SK_ColorBLUE; 22 static constexpr SkColor c1 = SK_ColorRED; 23 static constexpr SkColor c2 = SK_ColorGREEN; 24 static constexpr SkColor colors[] = {c0, c0, c1, c1, c2, c2}; 25 auto grad = SkGradientShader::MakeLinear(pts, colors, pos, 6, SkShader::kClamp_TileMode); 26 SkPaint paint; 27 paint.setShader(grad); 28 static constexpr int kMirrorX = 400; 29 static constexpr int kMirrorY = 200; 30 canvas->translate(50, 50); 31 for (int i = 0; i < 4; ++i) { 32 canvas->save(); 33 if (i & 0b01) { 34 canvas->translate(0, kMirrorY); 35 canvas->scale(1.f, -1.f); 36 } 37 if (i & 0b10) { 38 canvas->translate(kMirrorX, 0); 39 canvas->scale(-1.f, 1.f); 40 } 41 canvas->drawRect({0, 0, 150, 30}, paint); 42 canvas->restore(); 43 } 44 } 45
