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 "gm/gm.h" 9 #include "include/core/SkCanvas.h" 10 #include "include/core/SkColor.h" 11 #include "include/core/SkPaint.h" 12 #include "include/core/SkPoint.h" 13 #include "include/core/SkScalar.h" 14 #include "include/core/SkShader.h" 15 #include "include/core/SkTileMode.h" 16 #include "include/effects/SkGradientShader.h" 17 18 // This draws a hard stop gradient applied to a rectangle. The hard stops fall at half pixel 19 // boundaries in y. On some GPUs we've found that the winding of the two triangles that make up the 20 // rectangle can affect whether the interpolants for local coords wind up agreeing across a row. 21 // When they disagree the hard stop gradient appears jagged. We draw the rectangle four times: 22 // no-mirroring, mirror in x, mirror in y, and mirror in x and y. 23 DEF_SIMPLE_GM(crbug_938592, canvas, 500, 300) { 24 static constexpr SkPoint pts[] = {{0, 0}, {0, 30}}; 25 static constexpr SkScalar pos[] = {0.f, 9.f / 20, 9.f / 20, 11.f / 20, 11.f / 20, 20.f / 20}; 26 static constexpr SkColor c0 = SK_ColorBLUE; 27 static constexpr SkColor c1 = SK_ColorRED; 28 static constexpr SkColor c2 = SK_ColorGREEN; 29 static constexpr SkColor colors[] = {c0, c0, c1, c1, c2, c2}; 30 auto grad = SkGradientShader::MakeLinear(pts, colors, pos, 6, SkTileMode::kClamp); 31 SkPaint paint; 32 paint.setShader(grad); 33 static constexpr int kMirrorX = 400; 34 static constexpr int kMirrorY = 200; 35 canvas->translate(50, 50); 36 for (int i = 0; i < 4; ++i) { 37 canvas->save(); 38 if (i & 0b01) { 39 canvas->translate(0, kMirrorY); 40 canvas->scale(1.f, -1.f); 41 } 42 if (i & 0b10) { 43 canvas->translate(kMirrorX, 0); 44 canvas->scale(-1.f, 1.f); 45 } 46 canvas->drawRect({0, 0, 150, 30}, paint); 47 canvas->restore(); 48 } 49 } 50