1/*
2 * Copyright 2017 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#include "gm.h"
9#include "SkCanvas.h"
10#include "SkPath.h"
11
12namespace {
13// Test thin stroked rect (stroked "by hand", not by stroking).
14void draw_thin_stroked_rect(SkCanvas* canvas, const SkPaint& paint, SkScalar width) {
15    SkPath path;
16    path.moveTo(10 + width, 10 + width);
17    path.lineTo(40,         10 + width);
18    path.lineTo(40,         20);
19    path.lineTo(10 + width, 20);
20    path.moveTo(10,         10);
21    path.lineTo(10,         20 + width);
22    path.lineTo(40 + width, 20 + width);
23    path.lineTo(40 + width, 10);
24    canvas->drawPath(path, paint);
25}
26
27void draw_thin_right_angle(SkCanvas* canvas, const SkPaint& paint, SkScalar width) {
28    SkPath path;
29    path.moveTo(10 + width, 10 + width);
30    path.lineTo(40,         10 + width);
31    path.lineTo(40,         20);
32    path.lineTo(40 + width, 20 + width);
33    path.lineTo(40 + width, 10);
34    path.lineTo(10,         10);
35    canvas->drawPath(path, paint);
36}
37
38// Test thin horizontal line (<1 pixel) which should give lower alpha.
39void draw_golf_club(SkCanvas* canvas, const SkPaint& paint, SkScalar width) {
40    SkPath path;
41    path.moveTo(20, 10);
42    path.lineTo(80, 10);
43    path.lineTo(80, 10 + width);
44    path.lineTo(30, 10 + width);
45    path.lineTo(30, 20);
46    path.lineTo(20, 20);
47    canvas->drawPath(path, paint);
48}
49
50// Test thin lines between two filled regions. The outer edges overlap, but
51// there are no inverted edges to fix.
52void draw_barbell(SkCanvas* canvas, const SkPaint& paint, SkScalar width) {
53    SkScalar offset = width * 0.5f;
54    SkPath path;
55    path.moveTo(30,  5);
56    path.lineTo(40 - offset, 15 - offset);
57    path.lineTo(60 + offset, 15 - offset);
58    path.lineTo(70,  5);
59    path.lineTo(70, 25);
60    path.lineTo(60 + offset, 15 + offset);
61    path.lineTo(40 - offset, 15 + offset);
62    path.lineTo(30, 25);
63    canvas->drawPath(path, paint);
64}
65
66// Test a thin rectangle and triangle. The top and bottom inner edges of the
67// rectangle and all inner edges of the triangle invert on stroking.
68void draw_thin_rect_and_triangle(SkCanvas* canvas, const SkPaint& paint, SkScalar width) {
69    SkPath path;
70    path.moveTo(30,  5);
71    path.lineTo(30 + width,  5);
72    path.lineTo(30 + width,  25);
73    path.lineTo(30,  25);
74    path.moveTo(40,  5);
75    path.lineTo(40 + width,  5);
76    path.lineTo(40,  25);
77    canvas->drawPath(path, paint);
78}
79
80// Two triangles joined by a very thin bridge. The tiny triangle formed
81// by the inner edges at the bridge is inverted.
82// (These are actually now more phat pants than hipster pants.)
83void draw_hipster_pants(SkCanvas* canvas, const SkPaint& paint, SkScalar width) {
84    SkPath path;
85    path.moveTo(10, 10);
86    path.lineTo(10, 20);
87    path.lineTo(50, 10 + width);
88    path.lineTo(90, 20);
89    path.lineTo(90, 10);
90    canvas->drawPath(path, paint);
91}
92
93// A thin z-shape whose interior inverts on stroking. The top and bottom inner edges invert, and
94// the connector edges at the "elbows" intersect the inner edges.
95void draw_skinny_snake(SkCanvas* canvas, const SkPaint& paint, SkScalar width) {
96    SkPath path;
97    path.moveTo(20 + width, 10);
98    path.lineTo(20 + width, 20);
99    path.lineTo(10 + width, 30);
100    path.lineTo(10 + width, 40);
101    path.lineTo(10 - width, 40);
102    path.lineTo(10 - width, 30);
103    path.lineTo(20 - width, 20);
104    path.lineTo(20 - width, 10);
105    canvas->drawPath(path, paint);
106}
107
108// Test pointy features whose outer edges extend far to the right on stroking.
109void draw_pointy_golf_club(SkCanvas* canvas, const SkPaint& paint, SkScalar width) {
110    SkPath path;
111    path.moveTo(20, 10);
112    path.lineTo(80, 10 + width * 0.5);
113    path.lineTo(30, 10 + width);
114    path.lineTo(30, 20);
115    path.lineTo(20, 20);
116    canvas->drawPath(path, paint);
117}
118
119};
120
121DEF_SIMPLE_GM(thinconcavepaths, canvas, 550, 400) {
122    SkPaint paint;
123
124    paint.setAntiAlias(true);
125    paint.setStyle(SkPaint::kFill_Style);
126
127    canvas->save();
128    for (SkScalar width = 0.5f; width < 2.05f; width += 0.25f) {
129        draw_thin_stroked_rect(canvas, paint, width);
130        canvas->translate(0, 25);
131    }
132    canvas->restore();
133    canvas->translate(50, 0);
134    canvas->save();
135    for (SkScalar width = 0.5f; width < 2.05f; width += 0.25f) {
136        draw_thin_right_angle(canvas, paint, width);
137        canvas->translate(0, 25);
138    }
139    canvas->restore();
140    canvas->translate(40, 0);
141    canvas->save();
142    for (SkScalar width = 0.2f; width < 2.1f; width += 0.2f) {
143        draw_golf_club(canvas, paint, width);
144        canvas->translate(0, 30);
145    }
146    canvas->restore();
147    canvas->translate(70, 0);
148    canvas->save();
149    for (SkScalar width = 0.2f; width < 2.1f; width += 0.2f) {
150        draw_thin_rect_and_triangle(canvas, paint, width);
151        canvas->translate(0, 30);
152    }
153    canvas->restore();
154    canvas->translate(30, 0);
155    canvas->save();
156
157    for (SkScalar width = 0.2f; width < 2.1f; width += 0.2f) {
158        draw_barbell(canvas, paint, width);
159        canvas->translate(0, 30);
160    }
161    canvas->restore();
162    canvas->translate(80, 0);
163    canvas->save();
164    for (SkScalar width = 0.2f; width < 2.1f; width += 0.2f) {
165        draw_hipster_pants(canvas, paint, width);
166        canvas->translate(0, 30);
167    }
168    canvas->restore();
169    canvas->translate(100, 0);
170    canvas->save();
171    for (SkScalar width = 0.2f; width < 2.1f; width += 0.2f) {
172        draw_skinny_snake(canvas, paint, width);
173        canvas->translate(0, 30);
174    }
175    canvas->restore();
176    canvas->translate(30, 0);
177    canvas->save();
178    for (SkScalar width = 0.2f; width < 2.1f; width += 0.2f) {
179        draw_pointy_golf_club(canvas, paint, width);
180        canvas->translate(0, 30);
181    }
182    canvas->restore();
183    canvas->translate(100, 0);
184}
185