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