src/gpu/GrPathRendering.cpp

   1 /*
   2  * Copyright 2014 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 "GrPathRendering.h"
   9 #include "SkDescriptor.h"
  10 #include "SkGlyph.h"
  11 #include "SkMatrix.h"
  12 #include "SkTypeface.h"
  13 #include "GrPathRange.h"
  14
  15 class GlyphGenerator : public GrPathRange::PathGenerator {
  16 public:
  17     GlyphGenerator(const SkTypeface& typeface, const SkDescriptor& desc)
  18         : fDesc(desc.copy()),
  19           fScalerContext(typeface.createScalerContext(fDesc)) {
  20         fFlipMatrix.setScale(1, -1);
  21     }
  22
  23     virtual ~GlyphGenerator() {
  24         SkDescriptor::Free(fDesc);
  25     }
  26
  27     int getNumPaths() override {
  28         return fScalerContext->getGlyphCount();
  29     }
  30
  31     void generatePath(int glyphID, SkPath* out) override {
  32         SkGlyph skGlyph;
  33         skGlyph.initWithGlyphID(glyphID);
  34         fScalerContext->getMetrics(&skGlyph);
  35
  36         fScalerContext->getPath(skGlyph, out);
  37         out->transform(fFlipMatrix); // Load glyphs with the inverted y-direction.
  38     }
  39
  40     bool isEqualTo(const SkDescriptor& desc) const override {
  41         return fDesc->equals(desc);
  42     }
  43
  44 private:
  45     SkDescriptor* const fDesc;
  46     const SkAutoTDelete<SkScalerContext> fScalerContext;
  47     SkMatrix fFlipMatrix;
  48 };
  49
  50 GrPathRange* GrPathRendering::createGlyphs(const SkTypeface* typeface,
  51                                            const SkDescriptor* desc,
  52                                            const SkStrokeRec& stroke) {
  53     if (NULL == typeface) {
  54         typeface = SkTypeface::GetDefaultTypeface();
  55         SkASSERT(NULL != typeface);
  56     }
  57
  58     if (desc) {
  59         SkAutoTUnref<GlyphGenerator> generator(SkNEW_ARGS(GlyphGenerator, (*typeface, *desc)));
  60         return this->createPathRange(generator, stroke);
  61     }
  62
  63     SkScalerContextRec rec;
  64     memset(&rec, 0, sizeof(rec));
  65     rec.fFontID = typeface->uniqueID();
  66     rec.fTextSize = SkPaint::kCanonicalTextSizeForPaths;
  67     rec.fPreScaleX = rec.fPost2x2[0][0] = rec.fPost2x2[1][1] = SK_Scalar1;
  68     // Don't bake stroke information into the glyphs, we'll let the GPU do the stroking.
  69
  70     SkAutoDescriptor ad(sizeof(rec) + SkDescriptor::ComputeOverhead(1));
  71     SkDescriptor*    genericDesc = ad.getDesc();
  72
  73     genericDesc->init();
  74     genericDesc->addEntry(kRec_SkDescriptorTag, sizeof(rec), &rec);
  75     genericDesc->computeChecksum();
  76
  77     SkAutoTUnref<GlyphGenerator> generator(SkNEW_ARGS(GlyphGenerator, (*typeface, *genericDesc)));
  78     return this->createPathRange(generator, stroke);
  79 }