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/gm.h"
40 #include "include/core/SkCanvas.h"
41 #include "include/core/SkColor.h"
42 #include "include/core/SkPaint.h"
43 #include "include/core/SkPoint.h"
44 #include "include/core/SkRect.h"
45 #include "include/core/SkRefCnt.h"
46 #include "include/core/SkScalar.h"
47 #include "include/core/SkShader.h"
48 #include "include/core/SkSize.h"
49 #include "include/core/SkString.h"
50 #include "include/core/SkTileMode.h"
51 #include "include/effects/SkGradientShader.h"
52
53 const int WIDTH = 500;
54 const int HEIGHT = 500;
55
56 const int NUM_ROWS = 8;
57 const int NUM_COLS = 3;
58
59 const int CELL_WIDTH = WIDTH / NUM_COLS;
60 const int CELL_HEIGHT = HEIGHT / NUM_ROWS;
61
62 const int PAD_WIDTH = 3;
63 const int PAD_HEIGHT = 3;
64
65 const int RECT_WIDTH = CELL_WIDTH - (2 * PAD_WIDTH);
66 const int RECT_HEIGHT = CELL_HEIGHT - (2 * PAD_HEIGHT);
67
shade_rect(SkCanvas * canvas,sk_sp<SkShader> shader,int cellRow,int cellCol)68 static void shade_rect(SkCanvas* canvas, sk_sp<SkShader> shader, int cellRow, int cellCol) {
69 SkPaint paint;
70 paint.setShader(shader);
71
72 SkRect rect = SkRect::MakeXYWH(SkIntToScalar(cellCol * CELL_WIDTH + PAD_WIDTH),
73 SkIntToScalar(cellRow * CELL_HEIGHT + PAD_HEIGHT),
74 SkIntToScalar(RECT_WIDTH),
75 SkIntToScalar(RECT_HEIGHT));
76
77 canvas->drawRect(rect, paint);
78 }
79
create_gradient_points(int cellRow,int cellCol,SkPoint points[2])80 static void create_gradient_points(int cellRow, int cellCol, SkPoint points[2]) {
81 const int X_OFFSET = 30;
82
83 auto x0 = SkIntToScalar(cellCol * CELL_WIDTH + PAD_WIDTH + X_OFFSET);
84 auto x1 = SkIntToScalar((cellCol+1) * CELL_WIDTH - PAD_WIDTH - X_OFFSET);
85 auto y = SkIntToScalar(cellRow * CELL_HEIGHT + PAD_HEIGHT + RECT_HEIGHT/2);
86
87 points[0] = SkPoint::Make(x0, y);
88 points[1] = SkPoint::Make(x1, y);
89 }
90
91 class HardstopGradientShaderGM : public skiagm::GM {
92 public:
HardstopGradientShaderGM()93 HardstopGradientShaderGM() {
94
95 }
96
97 protected:
onShortName()98 SkString onShortName() override {
99 return SkString("hardstop_gradients");
100 }
101
onISize()102 SkISize onISize() override {
103 return SkISize::Make(512, 512);
104 }
105
onDraw(SkCanvas * canvas)106 void onDraw(SkCanvas* canvas) override {
107 SkPoint points[2];
108
109 SkColor colors[] = {
110 SK_ColorRED,
111 SK_ColorGREEN,
112 SK_ColorBLUE,
113 SK_ColorYELLOW,
114 SK_ColorMAGENTA,
115 };
116
117 SkScalar row3[] = {0.00f, 0.25f, 1.00f};
118 SkScalar row4[] = {0.00f, 0.25f, 0.50f, 0.50f, 1.00f};
119 SkScalar row5[] = {0.00f, 0.50f, 0.50f, 1.00f};
120 SkScalar row6[] = {0.00f, 0.00f, 1.00f};
121 SkScalar row7[] = {0.00f, 1.00f, 1.00f};
122 SkScalar row8[] = {0.00f, 0.30f, 0.30f, 1.00f};
123
124 SkScalar* positions[NUM_ROWS] = {
125 nullptr,
126 nullptr,
127 row3,
128 row4,
129 row5,
130 row6,
131 row7,
132 row8,
133 };
134
135 int numGradientColors[NUM_ROWS] = {
136 2,
137 3,
138 3,
139 5,
140 4,
141 3,
142 3,
143 4,
144 };
145
146 SkTileMode tilemodes[NUM_COLS] = {
147 SkTileMode::kClamp,
148 SkTileMode::kRepeat,
149 SkTileMode::kMirror,
150 };
151
152 for (int cellRow = 0; cellRow < NUM_ROWS; cellRow++) {
153 for (int cellCol = 0; cellCol < NUM_COLS; cellCol++) {
154 create_gradient_points(cellRow, cellCol, points);
155
156 auto shader = SkGradientShader::MakeLinear(
157 points,
158 colors,
159 positions[cellRow],
160 numGradientColors[cellRow],
161 tilemodes[cellCol],
162 0,
163 nullptr);
164
165 shade_rect(canvas, shader, cellRow, cellCol);
166 }
167 }
168 }
169
170 private:
171 using INHERITED = skiagm::GM;
172 };
173
174 DEF_GM(return new HardstopGradientShaderGM;)
175