prototype for kerning api

include/core/SkTypeface.h

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkTypeface_DEFINED
@@ skipping 207 matching lines @@
      */
     size_t getTableData(SkFontTableTag tag, size_t offset, size_t length,
                         void* data) const;
 
     /**
      *  Return the units-per-em value for this typeface, or zero if there is an
      *  error.
      */
     int getUnitsPerEm() const;
 
+    /**
+     *  Given a run of glyphs, return the associated horizontal adjustments.
+     *  Adjustments are in "design units", which are integers relative to the
+     *  typeface's units per em (see getUnitsPerEm).
+     *
+     *  Some typefaces are known to never support kerning. Calling this method
+     *  with all zeros (e.g. getKerningPairAdustments(NULL, 0, NULL)) returns
+     *  a boolean indicating if the typeface might support kerning. If it
+     *  returns false, then it will always return false (no kerning) for all
+     *  possible glyph runs. If it returns true, then it *may* return true for
+     *  somne glyph runs.
+     *
+     *  If count is non-zero, then the glyphs parameter must point to at least
+     *  [count] valid glyph IDs, and the adjustments parameter must be
+     *  sized to at least [count - 1] entries. If the method returns true, then
+     *  [count-1] entries in the adjustments array will be set. If the method
+     *  returns false, then no kerning should be applied, and the adjustments
+     *  array will be in an undefined state (possibly some values may have been
+     *  written, but none of them should be interpreted as valid values).
+     */
+    bool getKerningPairAdjustments(const uint16_t glyphs[], int count,
+                                   int32_t adjustments[]) const;
+
     struct LocalizedString {
         SkString fString;
         SkString fLanguage;
     };
     class LocalizedStrings : ::SkNoncopyable {
     public:
         virtual ~LocalizedStrings() { }
         virtual bool next(LocalizedString* localizedString) = 0;
         void unref() { SkDELETE(this); }
     };
@@ skipping 58 matching lines @@
 
     friend class SkScalerContext;
     static SkTypeface* GetDefaultTypeface(Style style = SkTypeface::kNormal);
 
     virtual SkScalerContext* onCreateScalerContext(const SkDescriptor*) const = 0;
     virtual void onFilterRec(SkScalerContextRec*) const = 0;
     virtual SkAdvancedTypefaceMetrics* onGetAdvancedTypefaceMetrics(
                         SkAdvancedTypefaceMetrics::PerGlyphInfo perGlyphInfo,
                         const uint32_t* glyphIDs,
                         uint32_t glyphIDsCount) const = 0;
+
     virtual SkStream* onOpenStream(int* ttcIndex) const = 0;
     virtual void onGetFontDescriptor(SkFontDescriptor*, bool* isLocal) const = 0;
 
     virtual int onCharsToGlyphs(const void* chars, Encoding, uint16_t glyphs[],
                                 int glyphCount) const = 0;
     virtual int onCountGlyphs() const = 0;
 
     virtual int onGetUPEM() const = 0;
+    virtual bool onGetKerningPairAdjustments(const uint16_t glyphs[], int count,
+                                             int32_t adjustments[]) const;
 
     virtual LocalizedStrings* onCreateFamilyNameIterator() const = 0;
 
     virtual int onGetTableTags(SkFontTableTag tags[]) const = 0;
     virtual size_t onGetTableData(SkFontTableTag, size_t offset,
                                   size_t length, void* data) const = 0;
 
     virtual SkTypeface* onRefMatchingStyle(Style styleBits) const = 0;
 
 private:
     SkFontID    fUniqueID;
     Style       fStyle;
     bool        fIsFixedPitch;
 
     friend class SkPaint;
     friend class SkGlyphCache;  // GetDefaultTypeface
     // just so deprecated fonthost can call protected methods
     friend class SkFontHost;
 
     typedef SkWeakRefCnt INHERITED;
 };
 
 #endif