1 /*
2 * Copyright 2016 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 /*
9 * This GM presents a variety of different gradients with different
10 * tile modes. Each entry in the table is a rectangle with a linear
11 * gradient that spans from its left edge to its right edge. The rows
12 * in the table represent different color/position configurations,
13 * while the columns in the table represent different tile modes. In
14 * order to highlight the differences between tile modes, the gradient
15 * starts and ends at 30 pixel inset from either side of the rectangle.
16 *
17 * | Clamp Repeat Mirror
18 * _____________________________|___________________________________________
19 * 2-color | rect00 rect01 rect02
20 * 3-color even | rect10 rect11 rect12
21 * 3-color texture | rect20 rect21 rect22
22 * 5-color hard stop | rect30 rect31 rect32
23 * 4-color hard stop centered | rect40 rect41 rect42
24 * 3-color hard stop 001 | rect50 rect51 rect52
25 * 3-color hard stop 011 | rect60 rect61 rect62
26 * 4-color hard stop off-center | rect70 rect71 rect72
27 *
28 * The first three rows are cases covered by pre-hard-stop code; simple
29 * 2-color gradients, 3-color gradients with the middle color centered,
30 * and general gradients that are rendered from a texture atlas.
31 *
32 * The next four rows all deal with hard stop gradients. The fourth row
33 * is a generic hard stop gradient, while the three subsequent rows deal
34 * with special cases of hard stop gradients; centered hard stop gradients
35 * (with t-values 0, 0.5, 0.5, 1), and two edge cases (with t-values
36 * 0, 0, 1 and 0, 1, 1). The final row has a single off-center hard stop.
37 */
38
39 #include "gm.h"
40
41 #include "SkGradientShader.h"
42
43 const int WIDTH = 500;
44 const int HEIGHT = 500;
45
46 const int NUM_ROWS = 8;
47 const int NUM_COLS = 3;
48
49 const int CELL_WIDTH = WIDTH / NUM_COLS;
50 const int CELL_HEIGHT = HEIGHT / NUM_ROWS;
51
52 const int PAD_WIDTH = 3;
53 const int PAD_HEIGHT = 3;
54
55 const int RECT_WIDTH = CELL_WIDTH - (2 * PAD_WIDTH);
56 const int RECT_HEIGHT = CELL_HEIGHT - (2 * PAD_HEIGHT);
57
shade_rect(SkCanvas * canvas,sk_sp<SkShader> shader,int cellRow,int cellCol)58 static void shade_rect(SkCanvas* canvas, sk_sp<SkShader> shader, int cellRow, int cellCol) {
59 SkPaint paint;
60 paint.setShader(shader);
61
62 SkRect rect = SkRect::MakeXYWH(SkIntToScalar(cellCol * CELL_WIDTH + PAD_WIDTH),
63 SkIntToScalar(cellRow * CELL_HEIGHT + PAD_HEIGHT),
64 SkIntToScalar(RECT_WIDTH),
65 SkIntToScalar(RECT_HEIGHT));
66
67 canvas->drawRect(rect, paint);
68 }
69
create_gradient_points(int cellRow,int cellCol,SkPoint points[2])70 static void create_gradient_points(int cellRow, int cellCol, SkPoint points[2]) {
71 const int X_OFFSET = 30;
72
73 auto x0 = SkIntToScalar(cellCol * CELL_WIDTH + PAD_WIDTH + X_OFFSET);
74 auto x1 = SkIntToScalar((cellCol+1) * CELL_WIDTH - PAD_WIDTH - X_OFFSET);
75 auto y = SkIntToScalar(cellRow * CELL_HEIGHT + PAD_HEIGHT + RECT_HEIGHT/2);
76
77 points[0] = SkPoint::Make(x0, y);
78 points[1] = SkPoint::Make(x1, y);
79 }
80
81 class HardstopGradientShaderGM : public skiagm::GM {
82 public:
HardstopGradientShaderGM()83 HardstopGradientShaderGM() {
84
85 }
86
87 protected:
onShortName()88 SkString onShortName() override {
89 return SkString("hardstop_gradients");
90 }
91
onISize()92 SkISize onISize() override {
93 return SkISize::Make(512, 512);
94 }
95
onDraw(SkCanvas * canvas)96 void onDraw(SkCanvas* canvas) override {
97 SkPoint points[2];
98
99 SkColor colors[] = {
100 SK_ColorRED,
101 SK_ColorGREEN,
102 SK_ColorBLUE,
103 SK_ColorYELLOW,
104 SK_ColorMAGENTA,
105 };
106
107 SkScalar row3[] = {0.00f, 0.25f, 1.00f};
108 SkScalar row4[] = {0.00f, 0.25f, 0.50f, 0.50f, 1.00f};
109 SkScalar row5[] = {0.00f, 0.50f, 0.50f, 1.00f};
110 SkScalar row6[] = {0.00f, 0.00f, 1.00f};
111 SkScalar row7[] = {0.00f, 1.00f, 1.00f};
112 SkScalar row8[] = {0.00f, 0.30f, 0.30f, 1.00f};
113
114 SkScalar* positions[NUM_ROWS] = {
115 nullptr,
116 nullptr,
117 row3,
118 row4,
119 row5,
120 row6,
121 row7,
122 row8,
123 };
124
125 int numGradientColors[NUM_ROWS] = {
126 2,
127 3,
128 3,
129 5,
130 4,
131 3,
132 3,
133 4,
134 };
135
136 SkShader::TileMode tilemodes[NUM_COLS] = {
137 SkShader::kClamp_TileMode,
138 SkShader::kRepeat_TileMode,
139 SkShader::kMirror_TileMode,
140 };
141
142 for (int cellRow = 0; cellRow < NUM_ROWS; cellRow++) {
143 for (int cellCol = 0; cellCol < NUM_COLS; cellCol++) {
144 create_gradient_points(cellRow, cellCol, points);
145
146 auto shader = SkGradientShader::MakeLinear(
147 points,
148 colors,
149 positions[cellRow],
150 numGradientColors[cellRow],
151 tilemodes[cellCol],
152 0,
153 nullptr);
154
155 shade_rect(canvas, shader, cellRow, cellCol);
156 }
157 }
158 }
159
160 private:
161 typedef skiagm::GM INHERITED;
162 };
163
164 DEF_GM(return new HardstopGradientShaderGM;)
165