2 * Copyright 2019 Google Inc.
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
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"
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);
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) {
39 canvas->translate(0, kMirrorY);
40 canvas->scale(1.f, -1.f);
43 canvas->translate(kMirrorX, 0);
44 canvas->scale(-1.f, 1.f);
46 canvas->drawRect({0, 0, 150, 30}, paint);