1 /*
2  * Copyright 2015 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 "sk_tool_utils.h"
10 
11 #include "Resources.h"
12 #include "SkBlendModePriv.h"
13 #include "SkGradientShader.h"
14 
15 DEF_SIMPLE_GM(gamma, canvas, 850, 200) {
16     SkPaint p;
17     const SkScalar sz = 50.0f;
18     const int szInt = SkScalarTruncToInt(sz);
19     const SkScalar tx = sz + 15.0f;
20     const SkRect r = SkRect::MakeXYWH(0, 0, sz, sz);
21     SkShader::TileMode rpt = SkShader::kRepeat_TileMode;
22     auto srgbColorSpace = SkColorSpace::MakeSRGB();
23 
24     SkBitmap ditherBmp;
25     ditherBmp.allocN32Pixels(2, 2);
26     SkPMColor* pixels = reinterpret_cast<SkPMColor*>(ditherBmp.getPixels());
27     pixels[0] = pixels[3] = SkPackARGB32(0xFF, 0xFF, 0xFF, 0xFF);
28     pixels[1] = pixels[2] = SkPackARGB32(0xFF, 0, 0, 0);
29 
30     SkBitmap linearGreyBmp;
31     SkImageInfo linearGreyInfo = SkImageInfo::MakeN32(szInt, szInt, kOpaque_SkAlphaType, nullptr);
32     linearGreyBmp.allocPixels(linearGreyInfo);
33     linearGreyBmp.eraseARGB(0xFF, 0x7F, 0x7F, 0x7F);
34 
35     SkBitmap srgbGreyBmp;
36     SkImageInfo srgbGreyInfo = SkImageInfo::MakeN32(szInt, szInt, kOpaque_SkAlphaType,
37                                                     srgbColorSpace);
38     srgbGreyBmp.allocPixels(srgbGreyInfo);
39     // 0xBC = 255 * linear_to_srgb(0.5f)
40     srgbGreyBmp.eraseARGB(0xFF, 0xBC, 0xBC, 0xBC);
41 
42     SkBitmap mipmapBmp;
43     SkImageInfo mipmapInfo = SkImageInfo::Make(2, 2, kN32_SkColorType, kOpaque_SkAlphaType,
44                                                srgbColorSpace);
45     mipmapBmp.allocPixels(mipmapInfo);
46     SkPMColor* mipmapPixels = reinterpret_cast<SkPMColor*>(mipmapBmp.getPixels());
47     unsigned s25 = 0x89;    // 255 * linear_to_srgb(0.25f)
48     unsigned s75 = 0xE1;    // 255 * linear_to_srgb(0.75f)
49     mipmapPixels[0] = mipmapPixels[3] = SkPackARGB32(0xFF, s25, s25, s25);
50     mipmapPixels[1] = mipmapPixels[2] = SkPackARGB32(0xFF, s75, s75, s75);
51 
52     SkFont font(sk_tool_utils::create_portable_typeface());
53 
54     SkPaint textPaint;
55     textPaint.setAntiAlias(true);
56     textPaint.setColor(SK_ColorWHITE);
57 
58     // Helpers:
__anonb8714d360102() 59     auto advance = [&]() {
60         canvas->translate(tx, 0);
61         p.reset();
62     };
63 
__anonb8714d360202(const char str[], SkScalar x, SkScalar y) 64     auto drawString = [&](const char str[], SkScalar x, SkScalar y) {
65         canvas->drawSimpleText(str, strlen(str), kUTF8_SkTextEncoding, x, y, font, textPaint);
66     };
67 
__anonb8714d360302(const char* label, const char* label2) 68     auto nextRect = [&](const char* label, const char* label2) {
69         canvas->drawRect(r, p);
70         drawString(label, 0, sz + font.getSpacing());
71         if (label2) {
72             drawString(label2, 0, sz + 2 * font.getSpacing());
73         }
74         advance();
75     };
76 
__anonb8714d360402(const SkBitmap& bmp, const char* label) 77     auto nextBitmap = [&](const SkBitmap& bmp, const char* label) {
78         canvas->drawBitmap(bmp, 0, 0);
79         drawString(label, 0, sz + font.getSpacing());
80         advance();
81     };
82 
__anonb8714d360502(SkColor srcColor, SkBlendMode mode, SkColor dstColor) 83     auto nextXferRect = [&](SkColor srcColor, SkBlendMode mode, SkColor dstColor) {
84         p.setColor(dstColor);
85         canvas->drawRect(r, p);
86         p.setColor(srcColor);
87         p.setBlendMode(mode);
88         canvas->drawRect(r, p);
89 
90         SkString srcText = SkStringPrintf("%08X", srcColor);
91         SkString dstText = SkStringPrintf("%08X", dstColor);
92         drawString(srcText.c_str(), 0, sz + font.getSpacing());
93         const char* modeName = SkBlendMode_Name(mode);
94         drawString(modeName, 0, sz + 2 * font.getSpacing());
95         drawString(dstText.c_str(), 0, sz + 3 * font.getSpacing());
96         advance();
97     };
98 
99     // Necessary for certain Xfermode tests to work (ie some of them output white @ 50% alpha):
100     canvas->clear(SK_ColorBLACK);
101 
102     // *Everything* should be perceptually 50% grey. Only the first rectangle
103     // is guaranteed to draw that way, though.
104     canvas->save();
105 
106     // Black/white dither, pixel perfect. This is ground truth.
107     p.setShader(SkShader::MakeBitmapShader(ditherBmp, rpt, rpt));
108     p.setFilterQuality(SkFilterQuality::kNone_SkFilterQuality);
109     nextRect("Dither", "Reference");
110 
111     // Black/white dither, sampled at half-texel offset. Tests bilerp.
112     // NOTE: We need to apply a non-identity scale and/or rotation to trick
113     // the raster pipeline into *not* snapping to nearest.
114     SkMatrix offsetMatrix = SkMatrix::Concat(
115         SkMatrix::MakeScale(-1.0f), SkMatrix::MakeTrans(0.5f, 0.0f));
116     p.setShader(SkShader::MakeBitmapShader(ditherBmp, rpt, rpt, &offsetMatrix));
117     p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
118     nextRect("Dither", "Bilerp");
119 
120     // Black/white dither, scaled down by 2x. Tests minification.
121     SkMatrix scaleMatrix = SkMatrix::MakeScale(0.5f);
122     p.setShader(SkShader::MakeBitmapShader(ditherBmp, rpt, rpt, &scaleMatrix));
123     p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
124     nextRect("Dither", "Scale");
125 
126     // 25%/75% dither, scaled down by 2x. Tests ALL aspects of minification. Specifically, are
127     // sRGB sources decoded to linear before computing mipmaps?
128     p.setShader(SkShader::MakeBitmapShader(mipmapBmp, rpt, rpt, &scaleMatrix));
129     p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
130     nextRect("MipMaps", nullptr);
131 
132     // 50% grey via paint color. Paint color (SkColor) is specified to be sRGB!
133     p.setColor(0xffbcbcbc);
134     nextRect("Color", nullptr);
135 
136     {
137         // Black -> White gradient, scaled to sample just the middle.
138         // Tests gradient interpolation.
139         SkPoint points[2] = {
140             SkPoint::Make(0 - (sz * 10), 0),
141             SkPoint::Make(sz + (sz * 10), 0)
142         };
143         SkColor colors[2] = { SK_ColorBLACK, SK_ColorWHITE };
144         p.setShader(SkGradientShader::MakeLinear(points, colors, nullptr, 2,
145                                                  SkShader::kClamp_TileMode));
146         nextRect("Gradient", "Interpolation");
147     }
148 
149     {
150         // Shallow gradient around 50% (perceptual) gray. Endpoints are SkColor, so sRGB.
151         // Tests gamma-correction of gradient stops before interpolation in two-stop case
152         SkPoint points[2] = {
153             SkPoint::Make(0, 0),
154             SkPoint::Make(sz, 0)
155         };
156         SkColor colors[2] = { 0xffbbbbbb, 0xffbdbdbd };
157         p.setShader(SkGradientShader::MakeLinear(points, colors, nullptr, 2,
158                                                  SkShader::kClamp_TileMode));
159         nextRect("Gradient", "Endpoints");
160     }
161 
162     {
163         // Shallow 3-stop gradient around 50% (perceptual) gray. Endpoints are SkColor, so sRGB.
164         // Tests gamma-correction of gradient stops before interpolation in three-stop case
165         SkPoint points[2] = {
166             SkPoint::Make(0, 0),
167             SkPoint::Make(sz, 0)
168         };
169         SkColor colors[3] = { 0xffbbbbbb, 0xffbdbdbd, 0xffbbbbbb };
170         p.setShader(SkGradientShader::MakeLinear(points, colors, nullptr, 3,
171                                                  SkShader::kClamp_TileMode));
172         nextRect("Gradient", "3-Stop");
173     }
174 
175     {
176         // Shallow N-stop gradient around 50% (perceptual) gray. Endpoints are SkColor, so sRGB.
177         // Tests gamma-correction of gradient stops before interpolation in texture implementation
178         SkPoint points[2] = {
179             SkPoint::Make(0, 0),
180             SkPoint::Make(sz, 0)
181         };
182         SkColor colors[5] = { 0xffbbbbbb, 0xffbdbdbd, 0xffbbbbbb, 0xffbdbdbd, 0xffbbbbbb };
183         p.setShader(SkGradientShader::MakeLinear(points, colors, nullptr, 5,
184                                                  SkShader::kClamp_TileMode));
185         nextRect("Gradient", "Texture");
186     }
187 
188     // 50% grey from linear bitmap, with drawBitmap
189     nextBitmap(linearGreyBmp, "Lnr BMP");
190 
191     // 50% grey from sRGB bitmap, with drawBitmap
192     nextBitmap(srgbGreyBmp, "sRGB BMP");
193 
194     // Bitmap wrapped in a shader (linear):
195     p.setShader(SkShader::MakeBitmapShader(linearGreyBmp, rpt, rpt));
196     p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
197     nextRect("Lnr BMP", "Shader");
198 
199     // Bitmap wrapped in a shader (sRGB):
200     p.setShader(SkShader::MakeBitmapShader(srgbGreyBmp, rpt, rpt));
201     p.setFilterQuality(SkFilterQuality::kMedium_SkFilterQuality);
202     nextRect("sRGB BMP", "Shader");
203 
204     // Carriage return.
205     canvas->restore();
206     canvas->translate(0, 2 * sz);
207 
208     // Xfermode tests, all done off-screen so certain modes work...
209 
210     canvas->saveLayer(nullptr, nullptr);
211 
212     nextXferRect(0x7fffffff, SkBlendMode::kSrcOver, SK_ColorBLACK);
213     nextXferRect(0x7f000000, SkBlendMode::kSrcOver, SK_ColorWHITE);
214 
215     nextXferRect(SK_ColorBLACK, SkBlendMode::kDstOver, 0x7fffffff);
216     nextXferRect(SK_ColorWHITE, SkBlendMode::kSrcIn, 0x7fff00ff);
217     nextXferRect(0x7fff00ff, SkBlendMode::kDstIn, SK_ColorWHITE);
218 
219     // 0x89 = 255 * linear_to_srgb(0.25)
220     nextXferRect(0xff898989, SkBlendMode::kPlus, 0xff898989);
221 
222     // 0xDB = 255 * linear_to_srgb(sqrt(0.5))
223     nextXferRect(0xffdbdbdb, SkBlendMode::kModulate, 0xffdbdbdb);
224 
225     canvas->restore();
226 }
227