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      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 #ifndef GrStencilAndCoverTextContext_DEFINED
      9 #define GrStencilAndCoverTextContext_DEFINED
     10 
     11 #include "GrTextContext.h"
     12 #include "GrDrawState.h"
     13 #include "GrDrawTarget.h"
     14 #include "SkStrokeRec.h"
     15 
     16 class GrTextStrike;
     17 class GrPath;
     18 class GrPathRange;
     19 
     20 /*
     21  * This class implements text rendering using stencil and cover path rendering
     22  * (by the means of GrDrawTarget::drawPath).
     23  * This class exposes the functionality through GrTextContext interface.
     24  */
     25 class GrStencilAndCoverTextContext : public GrTextContext {
     26 public:
     27     GrStencilAndCoverTextContext(GrContext*, const SkDeviceProperties&);
     28     virtual ~GrStencilAndCoverTextContext();
     29 
     30     virtual void drawText(const GrPaint&, const SkPaint&, const char text[],
     31                           size_t byteLength,
     32                           SkScalar x, SkScalar y) SK_OVERRIDE;
     33     virtual void drawPosText(const GrPaint&, const SkPaint&,
     34                              const char text[], size_t byteLength,
     35                              const SkScalar pos[], SkScalar constY,
     36                              int scalarsPerPosition) SK_OVERRIDE;
     37 
     38     virtual bool canDraw(const SkPaint& paint) SK_OVERRIDE;
     39 
     40 private:
     41     static const int kGlyphBufferSize = 1024;
     42 
     43     enum RenderMode {
     44         /**
     45          * This is the render mode used by drawText(), which is mainly used by
     46          * the Skia unit tests. It tries match the other text backends exactly,
     47          * with the exception of not implementing LCD text, and doing anti-
     48          * aliasing with the built-in MSAA.
     49          */
     50         kMaxAccuracy_RenderMode,
     51 
     52         /**
     53          * This is the render mode used by drawPosText(). It ignores hinting and
     54          * LCD text, even if the client provided positions for hinted glyphs,
     55          * and renders from a canonically-sized, generic set of paths for the
     56          * given typeface. In the future we should work out a system for the
     57          * client to know it should not provide hinted glyph positions. This
     58          * render mode also tries to use GPU stroking for fake bold, even when
     59          * SK_USE_FREETYPE_EMBOLDEN is set.
     60          */
     61         kMaxPerformance_RenderMode,
     62     };
     63 
     64     void init(const GrPaint&, const SkPaint&, size_t textByteLength,
     65               RenderMode, SkScalar textTranslateY = 0);
     66     void initGlyphs(SkGlyphCache* cache);
     67     void appendGlyph(uint16_t glyphID, float x);
     68     void appendGlyph(uint16_t glyphID, float x, float y);
     69     void flush();
     70     void finish();
     71 
     72     GrDrawState::AutoRestoreEffects fStateRestore;
     73     SkScalar fTextRatio;
     74     float fTextInverseRatio;
     75     SkGlyphCache* fGlyphCache;
     76     GrPathRange* fGlyphs;
     77     uint32_t fIndexBuffer[kGlyphBufferSize];
     78     float fTransformBuffer[2 * kGlyphBufferSize];
     79     GrDrawTarget::PathTransformType fTransformType;
     80     int fPendingGlyphCount;
     81     SkMatrix fContextInitialMatrix;
     82     bool fNeedsDeviceSpaceGlyphs;
     83 };
     84 
     85 #endif
     86