Add GM to test non-AA pixel snapping for points, lines, rects.
Review URL: https://codereview.chromium.org/1070213003
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gm/pixelsnap.cpp
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191
gm/pixelsnap.cpp
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/*
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* Copyright 2015 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.h"
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#include "SkShader.h"
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// This class of GMs test how edges/verts snap near rounding boundaries in device space without
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// anti-aliaing.
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class PixelSnapGM : public skiagm::GM {
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public:
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PixelSnapGM() {}
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protected:
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// kTrans should be even or checkboards wont agree in different test cases.
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static const int kTrans = 14;
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static const int kLabelPad = 4;
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// The inverse of this value should be a perfect SkScalar.
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static const int kSubPixelSteps = 8;
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static const int kLabelTextSize = 9;
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SkISize onISize() override {
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SkPaint labelPaint;
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labelPaint.setAntiAlias(true);
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labelPaint.setColor(SK_ColorWHITE);
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labelPaint.setTextSize(SkIntToScalar(kLabelTextSize));
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// Assert that we only render double digit labels
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SkASSERT(kSubPixelSteps < 99);
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// Pick 88 as widest possible label rendered (?)
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int xoffset = SkScalarCeilToInt(labelPaint.measureText("88", 2));
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int yoffset = SkScalarCeilToInt(labelPaint.getTextSize());
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return SkISize::Make(kLabelPad + (kSubPixelSteps + 1) * kTrans + xoffset,
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kLabelPad + (kSubPixelSteps + 1) * kTrans + yoffset);
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}
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void onDraw(SkCanvas* canvas) override {
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SkPaint bgPaint;
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bgPaint.setShader(
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sk_tool_utils::create_checkerboard_shader(0xFFAAAAAA, 0xFF777777, 1))->unref();
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canvas->drawPaint(bgPaint);
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SkString offset;
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SkPaint labelPaint;
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labelPaint.setAntiAlias(true);
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labelPaint.setColor(SK_ColorWHITE);
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labelPaint.setTextSize(SkIntToScalar(kLabelTextSize));
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SkPaint linePaint;
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linePaint.setColor(SK_ColorWHITE);
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// Draw row labels
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static const SkScalar labelOffsetY = labelPaint.getTextSize() + kLabelPad;
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SkScalar labelOffsetX = 0;
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canvas->save();
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canvas->translate(0, labelOffsetY);
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for (int i = 0; i <= kSubPixelSteps; ++i) {
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offset.printf("%d", i);
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canvas->drawText(offset.c_str(), offset.size(),
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0, i * kTrans + labelPaint.getTextSize(),
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labelPaint);
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labelOffsetX = SkTMax(labelPaint.measureText(offset.c_str(), offset.size()),
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labelOffsetX);
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}
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canvas->restore();
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labelOffsetX += kLabelPad;
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labelOffsetX = SkScalarCeilToScalar(labelOffsetX);
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// Draw col labels
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canvas->save();
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canvas->translate(labelOffsetX, 0);
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for (int i = 0; i <= kSubPixelSteps; ++i) {
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offset.printf("%d", i);
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canvas->drawText(offset.c_str(), offset.size(),
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i * SkIntToScalar(kTrans), labelPaint.getTextSize(),
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labelPaint);
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}
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canvas->restore();
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canvas->translate(labelOffsetX, labelOffsetY);
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SkASSERT((SkScalar)(int)labelOffsetX == labelOffsetX);
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SkASSERT((SkScalar)(int)labelOffsetY == labelOffsetY);
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// Draw test case grid lines (Draw them all at pixel centers to hopefully avoid any
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// snapping issues).
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for (int i = 0; i <= kSubPixelSteps + 1; ++i) {
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canvas->drawLine(0.5f,
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i * SkIntToScalar(kTrans) + 0.5f,
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SkIntToScalar(kTrans) * (kSubPixelSteps + 1) + 0.5f,
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i * SkIntToScalar(kTrans) + 0.5f,
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linePaint);
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canvas->drawLine(i * SkIntToScalar(kTrans) + 0.5f,
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0.5f,
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i * SkIntToScalar(kTrans) + 0.5f,
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SkIntToScalar(kTrans) * (kSubPixelSteps + 1) + 0.5f,
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linePaint);
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}
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for (int i = 0; i <= kSubPixelSteps; ++i) {
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for (int j = 0; j <= kSubPixelSteps; ++j) {
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canvas->save();
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// +1's account for the grid lines around each test case.
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canvas->translate(j * (kTrans + 1.f/kSubPixelSteps) + 1,
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i * (kTrans + 1.f/kSubPixelSteps) + 1);
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this->drawElement(canvas);
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canvas->restore();
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}
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}
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}
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virtual void drawElement(SkCanvas*) = 0;
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private:
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typedef skiagm::GM INHERITED;
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};
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class PointSnapGM : public PixelSnapGM {
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protected:
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SkString onShortName() override { return SkString("pixel_snap_point"); }
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void drawElement(SkCanvas* canvas) override { canvas->drawPoint(1, 1, SK_ColorBLUE); }
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private:
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typedef PixelSnapGM INHERITED;
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};
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class LineSnapGM : public PixelSnapGM {
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protected:
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SkString onShortName() override { return SkString("pixel_snap_line"); }
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void drawElement(SkCanvas* canvas) override {
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SkPaint paint;
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paint.setColor(SK_ColorGREEN);
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// Draw a horizontal and vertical line, each length 3.
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canvas->drawLine(1, 1, 4, 1, paint);
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canvas->drawLine(6, 1, 6, 4, paint);
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}
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private:
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typedef PixelSnapGM INHERITED;
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};
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class RectSnapGM : public PixelSnapGM {
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protected:
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SkString onShortName() override { return SkString("pixel_snap_rect"); }
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void drawElement(SkCanvas* canvas) override {
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SkPaint paint;
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paint.setColor(SK_ColorRED);
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canvas->drawRect(SkRect::MakeXYWH(1, 1, 3, 3), paint);
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}
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private:
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typedef PixelSnapGM INHERITED;
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};
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class ComboSnapGM : public PixelSnapGM {
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protected:
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SkString onShortName() override { return SkString("pixel_snap_combo"); }
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void drawElement(SkCanvas* canvas) override {
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SkPaint paint;
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paint.setAntiAlias(false);
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// A rectangle that exactly covers a pixel, a point at each corner, 8 horiz/vert lines
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// at rect corners (two at each corner, extending away from rect). They are drawn in this
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// order lines (green), points (blue), rect(red).
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SkRect rect = SkRect::MakeXYWH(3, 3, 1, 1);
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paint.setColor(SK_ColorGREEN);
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canvas->drawLine(3, 3, 0, 3, paint);
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canvas->drawLine(3, 3, 3, 0, paint);
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canvas->drawLine(4, 3, 7, 3, paint);
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canvas->drawLine(4, 3, 4, 0, paint);
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canvas->drawLine(3, 4, 0, 4, paint);
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canvas->drawLine(3, 4, 3, 7, paint);
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canvas->drawLine(4, 4, 7, 4, paint);
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canvas->drawLine(4, 4, 4, 7, paint);
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canvas->drawPoint(4, 3, SK_ColorBLUE);
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canvas->drawPoint(4, 4, SK_ColorBLUE);
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canvas->drawPoint(3, 3, SK_ColorBLUE);
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canvas->drawPoint(3, 4, SK_ColorBLUE);
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paint.setColor(SK_ColorRED);
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canvas->drawRect(rect, paint);
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}
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private:
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typedef PixelSnapGM INHERITED;
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};
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//////////////////////////////////////////////////////////////////////////////
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DEF_GM( return SkNEW(PointSnapGM); )
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DEF_GM( return SkNEW(LineSnapGM); )
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DEF_GM( return SkNEW(RectSnapGM); )
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DEF_GM( return SkNEW(ComboSnapGM); )
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@ -173,6 +173,7 @@
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'../gm/pictureimagefilter.cpp',
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'../gm/pictureshader.cpp',
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'../gm/pictureshadertile.cpp',
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'../gm/pixelsnap.cpp',
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'../gm/points.cpp',
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'../gm/poly2poly.cpp',
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'../gm/polygons.cpp',
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