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- /*
- * Copyright 2019 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
- #include "gm/gm.h"
- #include "include/core/SkCanvas.h"
- #include "include/core/SkColor.h"
- #include "include/core/SkPaint.h"
- #include "include/core/SkPoint.h"
- #include "include/core/SkScalar.h"
- #include "include/core/SkShader.h"
- #include "include/core/SkTileMode.h"
- #include "include/effects/SkGradientShader.h"
- // This draws a hard stop gradient applied to a rectangle. The hard stops fall at half pixel
- // boundaries in y. On some GPUs we've found that the winding of the two triangles that make up the
- // rectangle can affect whether the interpolants for local coords wind up agreeing across a row.
- // When they disagree the hard stop gradient appears jagged. We draw the rectangle four times:
- // no-mirroring, mirror in x, mirror in y, and mirror in x and y.
- DEF_SIMPLE_GM(crbug_938592, canvas, 500, 300) {
- static constexpr SkPoint pts[] = {{0, 0}, {0, 30}};
- static constexpr SkScalar pos[] = {0.f, 9.f / 20, 9.f / 20, 11.f / 20, 11.f / 20, 20.f / 20};
- static constexpr SkColor c0 = SK_ColorBLUE;
- static constexpr SkColor c1 = SK_ColorRED;
- static constexpr SkColor c2 = SK_ColorGREEN;
- static constexpr SkColor colors[] = {c0, c0, c1, c1, c2, c2};
- auto grad = SkGradientShader::MakeLinear(pts, colors, pos, 6, SkTileMode::kClamp);
- SkPaint paint;
- paint.setShader(grad);
- static constexpr int kMirrorX = 400;
- static constexpr int kMirrorY = 200;
- canvas->translate(50, 50);
- for (int i = 0; i < 4; ++i) {
- canvas->save();
- if (i & 0b01) {
- canvas->translate(0, kMirrorY);
- canvas->scale(1.f, -1.f);
- }
- if (i & 0b10) {
- canvas->translate(kMirrorX, 0);
- canvas->scale(-1.f, 1.f);
- }
- canvas->drawRect({0, 0, 150, 30}, paint);
- canvas->restore();
- }
- }
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