labyrinth.cpp File Reference

#include "gm/gm.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkPaint.h"
#include "include/core/SkPathBuilder.h"

Go to the source code of this file.

Functions
static void	draw_labyrinth (SkCanvas *canvas, SkPaint::Cap cap)
	DEF_SIMPLE_GM (labyrinth_square, canvas, kWidth, kHeight)
	DEF_SIMPLE_GM (labyrinth_round, canvas, kWidth, kHeight)
	DEF_SIMPLE_GM (labyrinth_butt, canvas, kWidth, kHeight)

Variables
static constexpr int	kWidth = 500
static constexpr int	kHeight = 420

Function Documentation

DEF_SIMPLE_GM() [1/3]

DEF_SIMPLE_GM	(	labyrinth_butt	,
		canvas	,
		kWidth	,
		kHeight
	)

Definition at line 96 of file labyrinth.cpp.

                                                       {
    draw_labyrinth(canvas, SkPaint::kButt_Cap);
}

DEF_SIMPLE_GM() [2/3]

DEF_SIMPLE_GM	(	labyrinth_round	,
		canvas	,
		kWidth	,
		kHeight
	)

Definition at line 92 of file labyrinth.cpp.

                                                        {
    draw_labyrinth(canvas, SkPaint::kRound_Cap);
}

DEF_SIMPLE_GM() [3/3]

DEF_SIMPLE_GM	(	labyrinth_square	,
		canvas	,
		kWidth	,
		kHeight
	)

Definition at line 88 of file labyrinth.cpp.

                                                         {
    draw_labyrinth(canvas, SkPaint::kSquare_Cap);
}

draw_labyrinth()

static void draw_labyrinth ( SkCanvas *  canvas, SkPaint::Cap  cap  )

static

Repro case for https://bugs.chromium.org/p/chromium/issues/detail?id=913223

The original bug was filed against square caps, but here we also draw the labyrinth using round and butt caps.

Square and round caps expose over-coverage on overlaps when using coverage counting.

Butt caps expose under-coverage on abutted strokes when using a 'max()' coverage function.

Definition at line 24 of file labyrinth.cpp.

                                                             {
    constexpr static bool kRows[11][12] = {
        {1,1,1,1,1,1,1,1,1,1,1,1},
        {0,1,0,1,0,1,0,0,0,0,1,1},
        {0,0,0,0,1,0,0,0,0,1,1,1},
        {1,0,1,0,0,0,0,1,0,0,0,0},
        {0,1,1,0,0,0,0,0,0,1,1,1},
        {1,0,0,1,0,0,0,0,1,1,1,0},
        {0,1,0,1,1,1,0,0,1,1,1,0},
        {1,0,1,0,1,1,1,1,0,1,1,1},
        {0,0,1,0,0,1,0,0,0,0,0,1},
        {0,1,1,1,0,0,1,1,1,1,0,0},
        {1,1,1,1,1,1,1,1,1,1,1,1},
    };
 
    constexpr static bool kCols[13][10] = {
        {1,1,1,1,0,1,1,1,1,1},
        {0,0,1,0,0,0,1,1,1,0},
        {0,1,1,0,1,1,1,0,0,1},
        {1,1,0,0,0,0,1,0,1,0},
        {0,0,1,0,1,0,0,0,0,1},
        {0,0,1,1,1,0,0,0,1,0},
        {0,1,0,1,1,1,0,0,0,0},
        {1,1,1,0,1,1,1,0,1,0},
        {1,1,0,1,1,0,0,0,1,0},
        {0,0,1,0,0,0,0,0,0,1},
        {0,0,1,1,0,0,0,0,1,0},
        {0,0,0,0,0,0,1,0,0,1},
        {1,1,1,1,1,1,0,1,1,1},
    };
 
    SkPathBuilder maze;
    for (size_t y = 0; y < std::size(kRows); ++y) {
        for (size_t x = 0; x < std::size(kRows[0]); ++x) {
            if (kRows[y][x]) {
                maze.moveTo(x, y);
                maze.lineTo(x+1, y);
            }
        }
    }
    for (size_t x = 0; x < std::size(kCols); ++x) {
        for (size_t y = 0; y < std::size(kCols[0]); ++y) {
            if (kCols[x][y]) {
                maze.moveTo(x, y);
                maze.lineTo(x, y+1);
            }
        }
    }
 
    SkPaint paint;
    paint.setStyle(SkPaint::kStroke_Style);
    paint.setStrokeWidth(.1f);
    paint.setColor(0xff406060);
    paint.setAntiAlias(true);
    paint.setStrokeCap(cap);
 
    canvas->translate(10.5, 10.5);
    canvas->scale(40, 40);
    canvas->drawPath(maze.detach(), paint);
}

Variable Documentation

kHeight

constexpr int kHeight = 420

staticconstexpr

Definition at line 86 of file labyrinth.cpp.

kWidth

constexpr int kWidth = 500

staticconstexpr

Definition at line 85 of file labyrinth.cpp.