skia2/gm/bug12866.cpp
Brian Osman e09d7500c5 Add GM to demonstate skbug.com/12866
The original drew text with a specific perspective matrix. After
minification, the real problem is the stroker, where having a large
enough resScale creates an incorrect filled version of the path.

Bug: skia:12866
Change-Id: I41a104edf932f54c2db40cd6a913d303cfaa9ba3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/500377
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
2022-01-27 15:24:21 +00:00

65 lines
2.4 KiB
C++

/*
* Copyright 2022 Google LLC
*
* 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/SkPath.h"
static SkPath get_path() {
SkPath path;
path.setFillType(SkPathFillType::kWinding);
path.moveTo(SkBits2Float(0x45034ec4), SkBits2Float(0x42e7fb80)); // 2100.92f, 115.991f
path.quadTo(SkBits2Float(0x4500f46c),
SkBits2Float(0x43333300),
SkBits2Float(0x4500f46c),
SkBits2Float(0x431f0ec0)); // 2063.28f, 179.199f, 2063.28f, 159.058f
path.quadTo(SkBits2Float(0x4500f46c),
SkBits2Float(0x430ad7c0),
SkBits2Float(0x45019462),
SkBits2Float(0x42fed580)); // 2063.28f, 138.843f, 2073.27f, 127.417f
path.quadTo(SkBits2Float(0x45023458),
SkBits2Float(0x42e7fb80),
SkBits2Float(0x45034ec4),
SkBits2Float(0x42e7fb80)); // 2083.27f, 115.991f, 2100.92f, 115.991f
path.close();
return path;
}
// Reproduces the underlying problem from skbug.com/12866.
// The path (part of a glyph) was being drawn stroked, and with a perspective matrix.
// The perspective matrix forces a very large resScale when stroking the path.
// The resulting filled path is incorrect. Note that stroking with a smaller resScale works fine.
DEF_SIMPLE_GM(bug12866, canvas, 128, 64) {
SkPaint strokePaint;
strokePaint.setAntiAlias(true);
strokePaint.setStyle(SkPaint::kStroke_Style);
strokePaint.setStrokeWidth(3);
SkPaint fillPaint;
fillPaint.setAntiAlias(true);
SkPath strokePath = get_path();
SkPath fillPath;
strokePaint.getFillPath(strokePath, &fillPath, nullptr, 1200.0f);
SkRect strokeBounds = strokePath.getBounds();
SkRect fillBounds = fillPath.getBounds();
// Draw the stroked path. This (internally) uses a resScale of 1.0, and looks good.
canvas->save();
canvas->translate(10 - strokeBounds.fLeft, 10 - strokeBounds.fTop);
canvas->drawPath(strokePath, strokePaint);
canvas->restore();
// With a perspective CTM, it's possible for resScale to become large. Draw the filled
// path produced by the stroker in that situation, which ends up being incorrect.
canvas->save();
canvas->translate(74 - fillBounds.fLeft, 10 - fillBounds.fTop);
canvas->drawPath(fillPath, fillPaint);
canvas->restore();
}