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 "include/core/SkCanvas.h"
9 #include "include/core/SkSurface.h"
10 #include "include/gpu/GrDirectContext.h"
11 #include "src/gpu/GrCaps.h"
12 #include "src/gpu/GrDirectContextPriv.h"
13 #include "src/gpu/GrImageInfo.h"
14 #include "src/gpu/GrSurfaceContext.h"
15 #include "src/gpu/GrSurfaceDrawContext.h"
16 #include "src/gpu/SkGr.h"
17 #include "tests/Test.h"
18
19 // using anonymous namespace because these functions are used as template params.
20 namespace {
21 /** convert 0..1 srgb value to 0..1 linear */
srgb_to_linear(float srgb)22 float srgb_to_linear(float srgb) {
23 if (srgb <= 0.04045f) {
24 return srgb / 12.92f;
25 } else {
26 return powf((srgb + 0.055f) / 1.055f, 2.4f);
27 }
28 }
29
30 /** convert 0..1 linear value to 0..1 srgb */
linear_to_srgb(float linear)31 float linear_to_srgb(float linear) {
32 if (linear <= 0.0031308) {
33 return linear * 12.92f;
34 } else {
35 return 1.055f * powf(linear, 1.f / 2.4f) - 0.055f;
36 }
37 }
38 } // namespace
39
40 /** tests a conversion with an error tolerance */
check_conversion(uint32_t input,uint32_t output,float error)41 template <float (*CONVERT)(float)> static bool check_conversion(uint32_t input, uint32_t output,
42 float error) {
43 // alpha should always be exactly preserved.
44 if ((input & 0xff000000) != (output & 0xff000000)) {
45 return false;
46 }
47
48 for (int c = 0; c < 3; ++c) {
49 uint8_t inputComponent = (uint8_t) ((input & (0xff << (c*8))) >> (c*8));
50 float lower = std::max(0.f, (float) inputComponent - error);
51 float upper = std::min(255.f, (float) inputComponent + error);
52 lower = CONVERT(lower / 255.f);
53 upper = CONVERT(upper / 255.f);
54 SkASSERT(lower >= 0.f && lower <= 255.f);
55 SkASSERT(upper >= 0.f && upper <= 255.f);
56 uint8_t outputComponent = (output & (0xff << (c*8))) >> (c*8);
57 if (outputComponent < SkScalarFloorToInt(lower * 255.f) ||
58 outputComponent > SkScalarCeilToInt(upper * 255.f)) {
59 return false;
60 }
61 }
62 return true;
63 }
64
65 /** tests a forward and backward conversion with an error tolerance */
66 template <float (*FORWARD)(float), float (*BACKWARD)(float)>
check_double_conversion(uint32_t input,uint32_t output,float error)67 static bool check_double_conversion(uint32_t input, uint32_t output, float error) {
68 // alpha should always be exactly preserved.
69 if ((input & 0xff000000) != (output & 0xff000000)) {
70 return false;
71 }
72
73 for (int c = 0; c < 3; ++c) {
74 uint8_t inputComponent = (uint8_t) ((input & (0xff << (c*8))) >> (c*8));
75 float lower = std::max(0.f, (float) inputComponent - error);
76 float upper = std::min(255.f, (float) inputComponent + error);
77 lower = FORWARD(lower / 255.f);
78 upper = FORWARD(upper / 255.f);
79 SkASSERT(lower >= 0.f && lower <= 255.f);
80 SkASSERT(upper >= 0.f && upper <= 255.f);
81 uint8_t upperComponent = SkScalarCeilToInt(upper * 255.f);
82 uint8_t lowerComponent = SkScalarFloorToInt(lower * 255.f);
83 lower = std::max(0.f, (float) lowerComponent - error);
84 upper = std::min(255.f, (float) upperComponent + error);
85 lower = BACKWARD(lowerComponent / 255.f);
86 upper = BACKWARD(upperComponent / 255.f);
87 SkASSERT(lower >= 0.f && lower <= 255.f);
88 SkASSERT(upper >= 0.f && upper <= 255.f);
89 upperComponent = SkScalarCeilToInt(upper * 255.f);
90 lowerComponent = SkScalarFloorToInt(lower * 255.f);
91
92 uint8_t outputComponent = (output & (0xff << (c*8))) >> (c*8);
93 if (outputComponent < lowerComponent || outputComponent > upperComponent) {
94 return false;
95 }
96 }
97 return true;
98 }
99
check_srgb_to_linear_conversion(uint32_t srgb,uint32_t linear,float error)100 static bool check_srgb_to_linear_conversion(uint32_t srgb, uint32_t linear, float error) {
101 return check_conversion<srgb_to_linear>(srgb, linear, error);
102 }
103
check_linear_to_srgb_conversion(uint32_t linear,uint32_t srgb,float error)104 static bool check_linear_to_srgb_conversion(uint32_t linear, uint32_t srgb, float error) {
105 return check_conversion<linear_to_srgb>(linear, srgb, error);
106 }
107
check_linear_to_srgb_to_linear_conversion(uint32_t input,uint32_t output,float error)108 static bool check_linear_to_srgb_to_linear_conversion(uint32_t input, uint32_t output, float error) {
109 return check_double_conversion<linear_to_srgb, srgb_to_linear>(input, output, error);
110 }
111
check_srgb_to_linear_to_srgb_conversion(uint32_t input,uint32_t output,float error)112 static bool check_srgb_to_linear_to_srgb_conversion(uint32_t input, uint32_t output, float error) {
113 return check_double_conversion<srgb_to_linear, linear_to_srgb>(input, output, error);
114 }
115
check_no_conversion(uint32_t input,uint32_t output,float error)116 static bool check_no_conversion(uint32_t input, uint32_t output, float error) {
117 // This is a bit of a hack to check identity transformations that may lose precision.
118 return check_srgb_to_linear_to_srgb_conversion(input, output, error);
119 }
120
121 typedef bool (*CheckFn) (uint32_t orig, uint32_t actual, float error);
122
read_and_check_pixels(skiatest::Reporter * reporter,GrDirectContext * dContext,GrSurfaceContext * sContext,uint32_t * origData,const SkImageInfo & dstInfo,CheckFn checker,float error,const char * subtestName)123 void read_and_check_pixels(skiatest::Reporter* reporter,
124 GrDirectContext* dContext,
125 GrSurfaceContext* sContext,
126 uint32_t* origData,
127 const SkImageInfo& dstInfo, CheckFn checker, float error,
128 const char* subtestName) {
129 auto [w, h] = dstInfo.dimensions();
130 GrPixmap readPM = GrPixmap::Allocate(dstInfo);
131 memset(readPM.addr(), 0, sizeof(uint32_t)*w*h);
132
133 if (!sContext->readPixels(dContext, readPM, {0, 0})) {
134 ERRORF(reporter, "Could not read pixels for %s.", subtestName);
135 return;
136 }
137
138 for (int j = 0; j < h; ++j) {
139 for (int i = 0; i < w; ++i) {
140 uint32_t orig = origData[j * w + i];
141 uint32_t read = static_cast<uint32_t*>(readPM.addr())[j * w + i];
142
143 if (!checker(orig, read, error)) {
144 ERRORF(reporter, "Original 0x%08x, read back as 0x%08x in %s at %d, %d).", orig,
145 read, subtestName, i, j);
146 return;
147 }
148 }
149 }
150 }
151
152 namespace {
153 enum class Encoding {
154 kUntagged,
155 kLinear,
156 kSRGB,
157 };
158 } // namespace
159
encoding_as_color_space(Encoding encoding)160 static sk_sp<SkColorSpace> encoding_as_color_space(Encoding encoding) {
161 switch (encoding) {
162 case Encoding::kUntagged: return nullptr;
163 case Encoding::kLinear: return SkColorSpace::MakeSRGBLinear();
164 case Encoding::kSRGB: return SkColorSpace::MakeSRGB();
165 }
166 return nullptr;
167 }
168
encoding_as_str(Encoding encoding)169 static const char* encoding_as_str(Encoding encoding) {
170 switch (encoding) {
171 case Encoding::kUntagged: return "untagged";
172 case Encoding::kLinear: return "linear";
173 case Encoding::kSRGB: return "sRGB";
174 }
175 return nullptr;
176 }
177
178 static constexpr int kW = 255;
179 static constexpr int kH = 255;
180
make_data()181 static std::unique_ptr<uint32_t[]> make_data() {
182 std::unique_ptr<uint32_t[]> data(new uint32_t[kW * kH]);
183 for (int j = 0; j < kH; ++j) {
184 for (int i = 0; i < kW; ++i) {
185 data[j * kW + i] = (0xFF << 24) | (i << 16) | (i << 8) | i;
186 }
187 }
188 return data;
189 }
190
make_surface_context(Encoding contextEncoding,GrRecordingContext * rContext,skiatest::Reporter * reporter)191 static std::unique_ptr<GrSurfaceContext> make_surface_context(Encoding contextEncoding,
192 GrRecordingContext* rContext,
193 skiatest::Reporter* reporter) {
194 auto surfaceContext = GrSurfaceDrawContext::Make(
195 rContext, GrColorType::kRGBA_8888, encoding_as_color_space(contextEncoding),
196 SkBackingFit::kExact, {kW, kH}, SkSurfaceProps(), 1, GrMipmapped::kNo, GrProtected::kNo,
197 kBottomLeft_GrSurfaceOrigin, SkBudgeted::kNo);
198 if (!surfaceContext) {
199 ERRORF(reporter, "Could not create %s surface context.", encoding_as_str(contextEncoding));
200 }
201 return std::move(surfaceContext);
202 }
203
test_write_read(Encoding contextEncoding,Encoding writeEncoding,Encoding readEncoding,float error,CheckFn check,GrDirectContext * dContext,skiatest::Reporter * reporter)204 static void test_write_read(Encoding contextEncoding, Encoding writeEncoding, Encoding readEncoding,
205 float error, CheckFn check, GrDirectContext* dContext,
206 skiatest::Reporter* reporter) {
207 auto surfaceContext = make_surface_context(contextEncoding, dContext, reporter);
208 if (!surfaceContext) {
209 return;
210 }
211 auto writeII = SkImageInfo::Make(kW, kH, kRGBA_8888_SkColorType, kPremul_SkAlphaType,
212 encoding_as_color_space(writeEncoding));
213 auto data = make_data();
214 GrCPixmap dataPM(writeII, data.get(), kW*sizeof(uint32_t));
215 if (!surfaceContext->writePixels(dContext, dataPM, {0, 0})) {
216 ERRORF(reporter, "Could not write %s to %s surface context.",
217 encoding_as_str(writeEncoding), encoding_as_str(contextEncoding));
218 return;
219 }
220
221 auto readII = SkImageInfo::Make(kW, kH, kRGBA_8888_SkColorType, kPremul_SkAlphaType,
222 encoding_as_color_space(readEncoding));
223 SkString testName;
224 testName.printf("write %s data to a %s context and read as %s.", encoding_as_str(writeEncoding),
225 encoding_as_str(contextEncoding), encoding_as_str(readEncoding));
226 read_and_check_pixels(reporter, dContext, surfaceContext.get(), data.get(), readII, check,
227 error, testName.c_str());
228 }
229
230 // Test all combinations of writePixels/readPixels where the surface context/write source/read dst
231 // are sRGB, linear, or untagged RGBA_8888.
DEF_GPUTEST_FOR_RENDERING_CONTEXTS(SRGBReadWritePixels,reporter,ctxInfo)232 DEF_GPUTEST_FOR_RENDERING_CONTEXTS(SRGBReadWritePixels, reporter, ctxInfo) {
233 auto context = ctxInfo.directContext();
234 if (!context->priv().caps()->getDefaultBackendFormat(GrColorType::kRGBA_8888_SRGB,
235 GrRenderable::kNo).isValid()) {
236 return;
237 }
238 // We allow more error on GPUs with lower precision shader variables.
239 float error = context->priv().caps()->shaderCaps()->halfIs32Bits() ? 0.5f : 1.2f;
240 // For the all-sRGB case, we allow a small error only for devices that have
241 // precision variation because the sRGB data gets converted to linear and back in
242 // the shader.
243 float smallError = context->priv().caps()->shaderCaps()->halfIs32Bits() ? 0.0f : 1.f;
244
245 ///////////////////////////////////////////////////////////////////////////////////////////////
246 // Write sRGB data to a sRGB context - no conversion on the write.
247
248 // back to sRGB - no conversion.
249 test_write_read(Encoding::kSRGB, Encoding::kSRGB, Encoding::kSRGB, smallError,
250 check_no_conversion, context, reporter);
251 // Reading back to untagged should be a pass through with no conversion.
252 test_write_read(Encoding::kSRGB, Encoding::kSRGB, Encoding::kUntagged, error,
253 check_no_conversion, context, reporter);
254
255 // Converts back to linear
256 test_write_read(Encoding::kSRGB, Encoding::kSRGB, Encoding::kLinear, error,
257 check_srgb_to_linear_conversion, context, reporter);
258
259 // Untagged source data should be interpreted as sRGB.
260 test_write_read(Encoding::kSRGB, Encoding::kUntagged, Encoding::kSRGB, smallError,
261 check_no_conversion, context, reporter);
262
263 ///////////////////////////////////////////////////////////////////////////////////////////////
264 // Write linear data to a sRGB context. It gets converted to sRGB on write. The reads
265 // are all the same as the above cases where the original data was untagged.
266 test_write_read(Encoding::kSRGB, Encoding::kLinear, Encoding::kSRGB, error,
267 check_linear_to_srgb_conversion, context, reporter);
268 // When the dst buffer is untagged there should be no conversion on the read.
269 test_write_read(Encoding::kSRGB, Encoding::kLinear, Encoding::kUntagged, error,
270 check_linear_to_srgb_conversion, context, reporter);
271 test_write_read(Encoding::kSRGB, Encoding::kLinear, Encoding::kLinear, error,
272 check_linear_to_srgb_to_linear_conversion, context, reporter);
273
274 ///////////////////////////////////////////////////////////////////////////////////////////////
275 // Write data to an untagged context. The write does no conversion no matter what encoding the
276 // src data has.
277 for (auto writeEncoding : {Encoding::kSRGB, Encoding::kUntagged, Encoding::kLinear}) {
278 // The read from untagged to sRGB also does no conversion.
279 test_write_read(Encoding::kUntagged, writeEncoding, Encoding::kSRGB, error,
280 check_no_conversion, context, reporter);
281 // Reading untagged back as untagged should do no conversion.
282 test_write_read(Encoding::kUntagged, writeEncoding, Encoding::kUntagged, error,
283 check_no_conversion, context, reporter);
284 // Reading untagged back as linear does convert (context is source, so treated as sRGB),
285 // dst is tagged.
286 test_write_read(Encoding::kUntagged, writeEncoding, Encoding::kLinear, error,
287 check_srgb_to_linear_conversion, context, reporter);
288 }
289
290 ///////////////////////////////////////////////////////////////////////////////////////////////
291 // Write sRGB data to a linear context - converts to sRGB on the write.
292
293 // converts back to sRGB on read.
294 test_write_read(Encoding::kLinear, Encoding::kSRGB, Encoding::kSRGB, error,
295 check_srgb_to_linear_to_srgb_conversion, context, reporter);
296 // Reading untagged data from linear currently does no conversion.
297 test_write_read(Encoding::kLinear, Encoding::kSRGB, Encoding::kUntagged, error,
298 check_srgb_to_linear_conversion, context, reporter);
299 // Stays linear when read.
300 test_write_read(Encoding::kLinear, Encoding::kSRGB, Encoding::kLinear, error,
301 check_srgb_to_linear_conversion, context, reporter);
302
303 // Untagged source data should be interpreted as sRGB.
304 test_write_read(Encoding::kLinear, Encoding::kUntagged, Encoding::kSRGB, error,
305 check_srgb_to_linear_to_srgb_conversion, context, reporter);
306
307 ///////////////////////////////////////////////////////////////////////////////////////////////
308 // Write linear data to a linear context. Does no conversion.
309
310 // Reading to sRGB does a conversion.
311 test_write_read(Encoding::kLinear, Encoding::kLinear, Encoding::kSRGB, error,
312 check_linear_to_srgb_conversion, context, reporter);
313 // Reading to untagged does no conversion.
314 test_write_read(Encoding::kLinear, Encoding::kLinear, Encoding::kUntagged, error,
315 check_no_conversion, context, reporter);
316 // Stays linear when read.
317 test_write_read(Encoding::kLinear, Encoding::kLinear, Encoding::kLinear, error,
318 check_no_conversion, context, reporter);
319 }
320