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 "src/gpu/text/GrTextContext.h"
9
10 #include "include/core/SkGraphics.h"
11 #include "include/gpu/GrContext.h"
12 #include "include/private/SkTo.h"
13 #include "src/core/SkDistanceFieldGen.h"
14 #include "src/core/SkDraw.h"
15 #include "src/core/SkDrawProcs.h"
16 #include "src/core/SkGlyphRun.h"
17 #include "src/core/SkMaskFilterBase.h"
18 #include "src/core/SkPaintPriv.h"
19 #include "src/gpu/GrCaps.h"
20 #include "src/gpu/GrRecordingContextPriv.h"
21 #include "src/gpu/SkGr.h"
22 #include "src/gpu/ops/GrMeshDrawOp.h"
23 #include "src/gpu/text/GrSDFMaskFilter.h"
24 #include "src/gpu/text/GrTextBlobCache.h"
25
26 // DF sizes and thresholds for usage of the small and medium sizes. For example, above
27 // kSmallDFFontLimit we will use the medium size. The large size is used up until the size at
28 // which we switch over to drawing as paths as controlled by Options.
29 static const int kSmallDFFontSize = 32;
30 static const int kSmallDFFontLimit = 32;
31 static const int kMediumDFFontSize = 72;
32 static const int kMediumDFFontLimit = 72;
33 static const int kLargeDFFontSize = 162;
34 #ifdef SK_BUILD_FOR_MAC
35 static const int kLargeDFFontLimit = 162;
36 static const int kExtraLargeDFFontSize = 256;
37 #endif
38
39 static const int kDefaultMinDistanceFieldFontSize = 18;
40 #if defined(SK_BUILD_FOR_ANDROID)
41 static const int kDefaultMaxDistanceFieldFontSize = 384;
42 #elif defined(SK_BUILD_FOR_MAC)
43 static const int kDefaultMaxDistanceFieldFontSize = kExtraLargeDFFontSize;
44 #else
45 static const int kDefaultMaxDistanceFieldFontSize = 2 * kLargeDFFontSize;
46 #endif
47
GrTextContext(const Options & options)48 GrTextContext::GrTextContext(const Options& options)
49 : fDistanceAdjustTable(new GrDistanceFieldAdjustTable), fOptions(options) {
50 SanitizeOptions(&fOptions);
51 }
52
Make(const Options & options)53 std::unique_ptr<GrTextContext> GrTextContext::Make(const Options& options) {
54 return std::unique_ptr<GrTextContext>(new GrTextContext(options));
55 }
56
ComputeCanonicalColor(const SkPaint & paint,bool lcd)57 SkColor GrTextContext::ComputeCanonicalColor(const SkPaint& paint, bool lcd) {
58 SkColor canonicalColor = SkPaintPriv::ComputeLuminanceColor(paint);
59 if (lcd) {
60 // This is the correct computation, but there are tons of cases where LCD can be overridden.
61 // For now we just regenerate if any run in a textblob has LCD.
62 // TODO figure out where all of these overrides are and see if we can incorporate that logic
63 // at a higher level *OR* use sRGB
64 SkASSERT(false);
65 //canonicalColor = SkMaskGamma::CanonicalColor(canonicalColor);
66 } else {
67 // A8, though can have mixed BMP text but it shouldn't matter because BMP text won't have
68 // gamma corrected masks anyways, nor color
69 U8CPU lum = SkComputeLuminance(SkColorGetR(canonicalColor),
70 SkColorGetG(canonicalColor),
71 SkColorGetB(canonicalColor));
72 // reduce to our finite number of bits
73 canonicalColor = SkMaskGamma::CanonicalColor(SkColorSetRGB(lum, lum, lum));
74 }
75 return canonicalColor;
76 }
77
ComputeScalerContextFlags(const GrColorInfo & colorInfo)78 SkScalerContextFlags GrTextContext::ComputeScalerContextFlags(const GrColorInfo& colorInfo) {
79 // If we're doing linear blending, then we can disable the gamma hacks.
80 // Otherwise, leave them on. In either case, we still want the contrast boost:
81 // TODO: Can we be even smarter about mask gamma based on the dest transfer function?
82 if (colorInfo.isLinearlyBlended()) {
83 return SkScalerContextFlags::kBoostContrast;
84 } else {
85 return SkScalerContextFlags::kFakeGammaAndBoostContrast;
86 }
87 }
88
SanitizeOptions(Options * options)89 void GrTextContext::SanitizeOptions(Options* options) {
90 if (options->fMaxDistanceFieldFontSize < 0.f) {
91 options->fMaxDistanceFieldFontSize = kDefaultMaxDistanceFieldFontSize;
92 }
93 if (options->fMinDistanceFieldFontSize < 0.f) {
94 options->fMinDistanceFieldFontSize = kDefaultMinDistanceFieldFontSize;
95 }
96 }
97
CanDrawAsDistanceFields(const SkPaint & paint,const SkFont & font,const SkMatrix & viewMatrix,const SkSurfaceProps & props,bool contextSupportsDistanceFieldText,const Options & options)98 bool GrTextContext::CanDrawAsDistanceFields(const SkPaint& paint, const SkFont& font,
99 const SkMatrix& viewMatrix,
100 const SkSurfaceProps& props,
101 bool contextSupportsDistanceFieldText,
102 const Options& options) {
103 // mask filters modify alpha, which doesn't translate well to distance
104 if (paint.getMaskFilter() || !contextSupportsDistanceFieldText) {
105 return false;
106 }
107
108 // TODO: add some stroking support
109 if (paint.getStyle() != SkPaint::kFill_Style) {
110 return false;
111 }
112
113 if (viewMatrix.hasPerspective()) {
114 if (!options.fDistanceFieldVerticesAlwaysHaveW) {
115 return false;
116 }
117 } else {
118 SkScalar maxScale = viewMatrix.getMaxScale();
119 SkScalar scaledTextSize = maxScale * font.getSize();
120 // Hinted text looks far better at small resolutions
121 // Scaling up beyond 2x yields undesireable artifacts
122 if (scaledTextSize < options.fMinDistanceFieldFontSize ||
123 scaledTextSize > options.fMaxDistanceFieldFontSize) {
124 return false;
125 }
126
127 bool useDFT = props.isUseDeviceIndependentFonts();
128 #if SK_FORCE_DISTANCE_FIELD_TEXT
129 useDFT = true;
130 #endif
131
132 if (!useDFT && scaledTextSize < kLargeDFFontSize) {
133 return false;
134 }
135 }
136
137 return true;
138 }
139
scaled_text_size(const SkScalar textSize,const SkMatrix & viewMatrix)140 SkScalar scaled_text_size(const SkScalar textSize, const SkMatrix& viewMatrix) {
141 SkScalar scaledTextSize = textSize;
142
143 if (viewMatrix.hasPerspective()) {
144 // for perspective, we simply force to the medium size
145 // TODO: compute a size based on approximate screen area
146 scaledTextSize = kMediumDFFontLimit;
147 } else {
148 SkScalar maxScale = viewMatrix.getMaxScale();
149 // if we have non-unity scale, we need to choose our base text size
150 // based on the SkPaint's text size multiplied by the max scale factor
151 // TODO: do we need to do this if we're scaling down (i.e. maxScale < 1)?
152 if (maxScale > 0 && !SkScalarNearlyEqual(maxScale, SK_Scalar1)) {
153 scaledTextSize *= maxScale;
154 }
155 }
156
157 return scaledTextSize;
158 }
159
InitDistanceFieldFont(const SkFont & font,const SkMatrix & viewMatrix,const Options & options,SkScalar * textRatio)160 SkFont GrTextContext::InitDistanceFieldFont(const SkFont& font,
161 const SkMatrix& viewMatrix,
162 const Options& options,
163 SkScalar* textRatio) {
164 SkScalar textSize = font.getSize();
165 SkScalar scaledTextSize = scaled_text_size(textSize, viewMatrix);
166
167 SkFont dfFont{font};
168
169 if (scaledTextSize <= kSmallDFFontLimit) {
170 *textRatio = textSize / kSmallDFFontSize;
171 dfFont.setSize(SkIntToScalar(kSmallDFFontSize));
172 } else if (scaledTextSize <= kMediumDFFontLimit) {
173 *textRatio = textSize / kMediumDFFontSize;
174 dfFont.setSize(SkIntToScalar(kMediumDFFontSize));
175 #ifdef SK_BUILD_FOR_MAC
176 } else if (scaledTextSize <= kLargeDFFontLimit) {
177 *textRatio = textSize / kLargeDFFontSize;
178 dfFont.setSize(SkIntToScalar(kLargeDFFontSize));
179 } else {
180 *textRatio = textSize / kExtraLargeDFFontSize;
181 dfFont.setSize(SkIntToScalar(kExtraLargeDFFontSize));
182 }
183 #else
184 } else {
185 *textRatio = textSize / kLargeDFFontSize;
186 dfFont.setSize(SkIntToScalar(kLargeDFFontSize));
187 }
188 #endif
189
190 dfFont.setEdging(SkFont::Edging::kAntiAlias);
191 dfFont.setForceAutoHinting(false);
192 dfFont.setHinting(SkFontHinting::kNormal);
193
194 // The sub-pixel position will always happen when transforming to the screen.
195 dfFont.setSubpixel(false);
196 return dfFont;
197 }
198
InitDistanceFieldMinMaxScale(SkScalar textSize,const SkMatrix & viewMatrix,const GrTextContext::Options & options)199 std::pair<SkScalar, SkScalar> GrTextContext::InitDistanceFieldMinMaxScale(
200 SkScalar textSize,
201 const SkMatrix& viewMatrix,
202 const GrTextContext::Options& options) {
203
204 SkScalar scaledTextSize = scaled_text_size(textSize, viewMatrix);
205
206 // We have three sizes of distance field text, and within each size 'bucket' there is a floor
207 // and ceiling. A scale outside of this range would require regenerating the distance fields
208 SkScalar dfMaskScaleFloor;
209 SkScalar dfMaskScaleCeil;
210 if (scaledTextSize <= kSmallDFFontLimit) {
211 dfMaskScaleFloor = options.fMinDistanceFieldFontSize;
212 dfMaskScaleCeil = kSmallDFFontLimit;
213 } else if (scaledTextSize <= kMediumDFFontLimit) {
214 dfMaskScaleFloor = kSmallDFFontLimit;
215 dfMaskScaleCeil = kMediumDFFontLimit;
216 } else {
217 dfMaskScaleFloor = kMediumDFFontLimit;
218 dfMaskScaleCeil = options.fMaxDistanceFieldFontSize;
219 }
220
221 // Because there can be multiple runs in the blob, we want the overall maxMinScale, and
222 // minMaxScale to make regeneration decisions. Specifically, we want the maximum minimum scale
223 // we can tolerate before we'd drop to a lower mip size, and the minimum maximum scale we can
224 // tolerate before we'd have to move to a large mip size. When we actually test these values
225 // we look at the delta in scale between the new viewmatrix and the old viewmatrix, and test
226 // against these values to decide if we can reuse or not(ie, will a given scale change our mip
227 // level)
228 SkASSERT(dfMaskScaleFloor <= scaledTextSize && scaledTextSize <= dfMaskScaleCeil);
229
230 return std::make_pair(dfMaskScaleFloor / scaledTextSize, dfMaskScaleCeil / scaledTextSize);
231 }
232
InitDistanceFieldPaint(const SkPaint & paint)233 SkPaint GrTextContext::InitDistanceFieldPaint(const SkPaint& paint) {
234 SkPaint dfPaint{paint};
235 dfPaint.setMaskFilter(GrSDFMaskFilter::Make());
236 return dfPaint;
237 }
238
239 ///////////////////////////////////////////////////////////////////////////////////////////////////
240
241 #if GR_TEST_UTILS
242
243 #include "src/gpu/GrRenderTargetContext.h"
244
GR_DRAW_OP_TEST_DEFINE(GrAtlasTextOp)245 GR_DRAW_OP_TEST_DEFINE(GrAtlasTextOp) {
246 static uint32_t gContextID = SK_InvalidGenID;
247 static std::unique_ptr<GrTextContext> gTextContext;
248 static SkSurfaceProps gSurfaceProps(SkSurfaceProps::kLegacyFontHost_InitType);
249
250 if (context->priv().contextID() != gContextID) {
251 gContextID = context->priv().contextID();
252 gTextContext = GrTextContext::Make(GrTextContext::Options());
253 }
254
255 // Setup dummy SkPaint / GrPaint / GrRenderTargetContext
256 auto rtc = GrRenderTargetContext::Make(
257 context, GrColorType::kRGBA_8888, nullptr, SkBackingFit::kApprox, {1024, 1024});
258
259 SkMatrix viewMatrix = GrTest::TestMatrixInvertible(random);
260
261 SkPaint skPaint;
262 skPaint.setColor(random->nextU());
263
264 SkFont font;
265 if (random->nextBool()) {
266 font.setEdging(SkFont::Edging::kSubpixelAntiAlias);
267 } else {
268 font.setEdging(random->nextBool() ? SkFont::Edging::kAntiAlias : SkFont::Edging::kAlias);
269 }
270 font.setSubpixel(random->nextBool());
271
272 const char* text = "The quick brown fox jumps over the lazy dog.";
273
274 // create some random x/y offsets, including negative offsets
275 static const int kMaxTrans = 1024;
276 int xPos = (random->nextU() % 2) * 2 - 1;
277 int yPos = (random->nextU() % 2) * 2 - 1;
278 int xInt = (random->nextU() % kMaxTrans) * xPos;
279 int yInt = (random->nextU() % kMaxTrans) * yPos;
280
281 return gTextContext->createOp_TestingOnly(context, gTextContext.get(), rtc.get(),
282 skPaint, font, viewMatrix, text, xInt, yInt);
283 }
284
285 #endif
286