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- /*
- * Copyright 2017 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/SkFilterQuality.h"
- #include "include/core/SkImage.h"
- #include "include/core/SkMatrix.h"
- #include "include/core/SkPaint.h"
- #include "include/core/SkRect.h"
- #include "include/core/SkRefCnt.h"
- #include "include/core/SkShader.h"
- #include "include/core/SkSurface.h"
- #include "include/core/SkTileMode.h"
- // This GM reproduces skia:6783, which demonstrated a bug in repeat and mirror
- // image sampling tiling modes as implemented in software. We want to tile to
- // [0,limit), and the old incorrect logic was:
- //
- // limit = ulp_before(limit)
- // val = val - floor(val/limit)*limit (This is repeat; mirror is similar.)
- //
- // while the correct logic is more like:
- //
- // val = val - floor(val/limit)*limit
- // val = min(val, ulp_before(limit))
- //
- // You would see ugly jaggies on the blue/yellow edge near the bottom left if
- // the bug were still present. All stripes should now look roughly the same.
- DEF_SIMPLE_GM(bug6783, canvas, 500, 500) {
- sk_sp<SkSurface> surface = SkSurface::MakeRasterN32Premul(100, 100);
- SkPaint p;
- p.setColor(SK_ColorYELLOW);
- surface->getCanvas()->drawPaint(p);
- p.setColor(SK_ColorBLUE);
- surface->getCanvas()->drawRect(SkRect::MakeWH(50, 100), p);
- sk_sp<SkImage> img = surface->makeImageSnapshot();
- SkMatrix m = SkMatrix::Concat(SkMatrix::MakeTrans(25, 214),
- SkMatrix::MakeScale(2, 2));
- m.preSkew(0.5f, 0.5f);
- // The bug was present at all filter levels, but you might not notice it at kNone.
- p.setFilterQuality(kLow_SkFilterQuality);
- // It's only important to repeat or mirror in x to show off the bug.
- p.setShader(img->makeShader(SkTileMode::kRepeat, SkTileMode::kClamp, &m));
- canvas->drawPaint(p);
- }
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