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 /*

  * 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 SkScalerContext_DEFINED

 #define SkScalerContext_DEFINED

 #include "SkMask.h"

 #include "SkMaskGamma.h"

 #include "SkMatrix.h"

 #include "SkPaint.h"

 #include "SkTypeface.h"

 #ifdef SK_BUILD_FOR_ANDROID

     #include "SkPaintOptionsAndroid.h"

 #endif

 struct SkGlyph;

 class SkDescriptor;

 class SkMaskFilter;

 class SkPathEffect;

 class SkRasterizer;

 /*

  *  To allow this to be forward-declared, it must be its own typename, rather

  *  than a nested struct inside SkScalerContext (where it started).

  */

 struct SkScalerContextRec {

     uint32_t    fOrigFontID;

     uint32_t    fFontID;

     SkScalar    fTextSize, fPreScaleX, fPreSkewX;

     SkScalar    fPost2x2[2][2];

     SkScalar    fFrameWidth, fMiterLimit;

     //These describe the parameters to create (uniquely identify) the pre-blend.

     uint32_t    fLumBits;

     uint8_t     fDeviceGamma; //2.6, (0.0, 4.0) gamma, 0.0 for sRGB

     uint8_t     fPaintGamma;  //2.6, (0.0, 4.0) gamma, 0.0 for sRGB

     uint8_t     fContrast;    //0.8+1, [0.0, 1.0] artificial contrast

     uint8_t     fReservedAlign;

     SkScalar getDeviceGamma() const {

         return SkIntToScalar(fDeviceGamma) / (1 << 6);

     }

     void setDeviceGamma(SkScalar dg) {

         SkASSERT(0 <= dg && dg < SkIntToScalar(4));

         fDeviceGamma = SkScalarFloorToInt(dg * (1 << 6));

     }

     SkScalar getPaintGamma() const {

         return SkIntToScalar(fPaintGamma) / (1 << 6);

     }

     void setPaintGamma(SkScalar pg) {

         SkASSERT(0 <= pg && pg < SkIntToScalar(4));

         fPaintGamma = SkScalarFloorToInt(pg * (1 << 6));

     }

     SkScalar getContrast() const {

         return SkIntToScalar(fContrast) / ((1 << 8) - 1);

     }

     void setContrast(SkScalar c) {

         SkASSERT(0 <= c && c <= SK_Scalar1);

         fContrast = SkScalarRoundToInt(c * ((1 << 8) - 1));

     }

     /**

      *  Causes the luminance color and contrast to be ignored, and the

      *  paint and device gamma to be effectively 1.0.

      */

     void ignorePreBlend() {

         setLuminanceColor(SK_ColorTRANSPARENT);

         setPaintGamma(SK_Scalar1);

         setDeviceGamma(SK_Scalar1);

         setContrast(0);

     }

     uint8_t     fMaskFormat;

     uint8_t     fStrokeJoin;

     uint16_t    fFlags;

     // Warning: when adding members note that the size of this structure

     // must be a multiple of 4. SkDescriptor requires that its arguments be

     // multiples of four and this structure is put in an SkDescriptor in

     // SkPaint::MakeRec.

     void    getMatrixFrom2x2(SkMatrix*) const;

     void    getLocalMatrix(SkMatrix*) const;

     void    getSingleMatrix(SkMatrix*) const;

     inline SkPaint::Hinting getHinting() const;

     inline void setHinting(SkPaint::Hinting);

     SkMask::Format getFormat() const {

         return static_cast<SkMask::Format>(fMaskFormat);

     }

     SkColor getLuminanceColor() const {

         return fLumBits;

     }

     void setLuminanceColor(SkColor c) {

         fLumBits = c;

     }

 };

 //The following typedef hides from the rest of the implementation the number of

 //most significant bits to consider when creating mask gamma tables. Two bits

 //per channel was chosen as a balance between fidelity (more bits) and cache

 //sizes (fewer bits). Three bits per channel was chosen when #303942; (used by

 //the Chrome UI) turned out too green.

 typedef SkTMaskGamma<3, 3, 3> SkMaskGamma;

 class SkScalerContext {

 public:

     typedef SkScalerContextRec Rec;

     enum Flags {

         kFrameAndFill_Flag        = 0x0001,

         kDevKernText_Flag         = 0x0002,

         kEmbeddedBitmapText_Flag  = 0x0004,

         kEmbolden_Flag            = 0x0008,

         kSubpixelPositioning_Flag = 0x0010,

         kForceAutohinting_Flag    = 0x0020,  // Use auto instead of bytcode hinting if hinting.

         kVertical_Flag            = 0x0040,

         // together, these two flags resulting in a two bit value which matches

         // up with the SkPaint::Hinting enum.

         kHinting_Shift            = 7, // to shift into the other flags above

         kHintingBit1_Flag         = 0x0080,

         kHintingBit2_Flag         = 0x0100,

         // Pixel geometry information.

         // only meaningful if fMaskFormat is LCD16 or LCD32

         kLCD_Vertical_Flag        = 0x0200,    // else Horizontal

         kLCD_BGROrder_Flag        = 0x0400,    // else RGB order

         // Generate A8 from LCD source (for GDI and CoreGraphics).

         // only meaningful if fMaskFormat is kA8

         kGenA8FromLCD_Flag        = 0x0800, // could be 0x200 (bit meaning dependent on fMaskFormat)

     };

     // computed values

     enum {

         kHinting_Mask   = kHintingBit1_Flag | kHintingBit2_Flag,

     };

     SkScalerContext(SkTypeface*, const SkDescriptor*);

     virtual ~SkScalerContext();

     SkTypeface* getTypeface() const { return fTypeface.get(); }

     SkMask::Format getMaskFormat() const {

         return (SkMask::Format)fRec.fMaskFormat;

     }

     bool isSubpixel() const {

         return SkToBool(fRec.fFlags & kSubpixelPositioning_Flag);

     }

     // remember our glyph offset/base

     void setBaseGlyphCount(unsigned baseGlyphCount) {

         fBaseGlyphCount = baseGlyphCount;

     }

     /** Return the corresponding glyph for the specified unichar. Since contexts

         may be chained (under the hood), the glyphID that is returned may in

         fact correspond to a different font/context. In that case, we use the

         base-glyph-count to know how to translate back into local glyph space.

      */

     uint16_t charToGlyphID(SkUnichar uni);

     /** Map the glyphID to its glyph index, and then to its char code. Unmapped

         glyphs return zero.

     */

     SkUnichar glyphIDToChar(uint16_t glyphID);

     unsigned    getGlyphCount() { return this->generateGlyphCount(); }

     void        getAdvance(SkGlyph*);

     void        getMetrics(SkGlyph*);

     void        getImage(const SkGlyph&);

     void        getPath(const SkGlyph&, SkPath*);

     void        getFontMetrics(SkPaint::FontMetrics*);

 #ifdef SK_BUILD_FOR_ANDROID

     unsigned getBaseGlyphCount(SkUnichar charCode);

     // This function must be public for SkTypeface_android.h, but should not be

     // called by other callers

     SkFontID findTypefaceIdForChar(SkUnichar uni);

 #endif

     static inline void MakeRec(const SkPaint&, const SkDeviceProperties* deviceProperties,

                                const SkMatrix*, Rec* rec);

     static inline void PostMakeRec(const SkPaint&, Rec*);

     static SkMaskGamma::PreBlend GetMaskPreBlend(const Rec& rec);

 protected:

     Rec         fRec;

     unsigned    fBaseGlyphCount;

     /** Generates the contents of glyph.fAdvanceX and glyph.fAdvanceY.

      *  May call getMetrics if that would be just as fast.

      */

     virtual void generateAdvance(SkGlyph* glyph) = 0;

     /** Generates the contents of glyph.fWidth, fHeight, fTop, fLeft,

      *  as well as fAdvanceX and fAdvanceY if not already set.

      *

      *  TODO: fMaskFormat is set by getMetrics later; cannot be set here.

      */

     virtual void generateMetrics(SkGlyph* glyph) = 0;

     /** Generates the contents of glyph.fImage.

      *  When called, glyph.fImage will be pointing to a pre-allocated,

      *  uninitialized region of memory of size glyph.computeImageSize().

      *  This method may change glyph.fMaskFormat if the new image size is

      *  less than or equal to the old image size.

      *

      *  Because glyph.computeImageSize() will determine the size of fImage,

      *  generateMetrics will be called before generateImage.

      */

     virtual void generateImage(const SkGlyph& glyph) = 0;

     /** Sets the passed path to the glyph outline.

      *  If this cannot be done the path is set to empty;

      *  this is indistinguishable from a glyph with an empty path.

      *  This does not set glyph.fPath.

      *

      *  TODO: path is always glyph.fPath, no reason to pass separately.

      */

     virtual void generatePath(const SkGlyph& glyph, SkPath* path) = 0;

     /** Retrieves font metrics.

      *  TODO: there is now a vertical bit, no need for two parameters.

      */

     virtual void generateFontMetrics(SkPaint::FontMetrics* mX,

                                      SkPaint::FontMetrics* mY) = 0;

     /** Returns the number of glyphs in the font. */

     virtual unsigned generateGlyphCount() = 0;

     /** Returns the glyph id for the given unichar.

      *  If there is no 1:1 mapping from the unichar to a glyph id, returns 0.

      */

     virtual uint16_t generateCharToGlyph(SkUnichar unichar) = 0;

     /** Returns the unichar for the given glyph id.

      *  If there is no 1:1 mapping from the glyph id to a unichar, returns 0.

      *  The default implementation always returns 0, indicating failure.

      */

     virtual SkUnichar generateGlyphToChar(uint16_t glyphId);

     void forceGenerateImageFromPath() { fGenerateImageFromPath = true; }

 private:

     // never null

     SkAutoTUnref<SkTypeface> fTypeface;

 #ifdef SK_BUILD_FOR_ANDROID

     SkPaintOptionsAndroid fPaintOptionsAndroid;

 #endif

     // optional object, which may be null

     SkPathEffect*   fPathEffect;

     SkMaskFilter*   fMaskFilter;

     SkRasterizer*   fRasterizer;

     // if this is set, we draw the image from a path, rather than

     // calling generateImage.

     bool fGenerateImageFromPath;

     void internalGetPath(const SkGlyph& glyph, SkPath* fillPath,

                          SkPath* devPath, SkMatrix* fillToDevMatrix);

     // Return the context associated with the next logical typeface, or NULL if

     // there are no more entries in the fallback chain.

     SkScalerContext* allocNextContext() const;

     // return the next context, treating fNextContext as a cache of the answer

     SkScalerContext* getNextContext();

     // returns the right context from our link-list for this glyph. If no match

     // is found, just returns the original context (this)

     SkScalerContext* getGlyphContext(const SkGlyph& glyph);

     // returns the right context from our link-list for this char. If no match

     // is found it returns NULL. If a match is found then the glyphID param is

     // set to the glyphID that maps to the provided char.

     SkScalerContext* getContextFromChar(SkUnichar uni, uint16_t* glyphID);

     // link-list of context, to handle missing chars. null-terminated.

     SkScalerContext* fNextContext;

     // SkMaskGamma::PreBlend converts linear masks to gamma correcting masks.

 protected:

     // Visible to subclasses so that generateImage can apply the pre-blend directly.

     const SkMaskGamma::PreBlend fPreBlend;

 private:

     // When there is a filter, previous steps must create a linear mask

     // and the pre-blend applied as a final step.

     const SkMaskGamma::PreBlend fPreBlendForFilter;

 };

 #define kRec_SkDescriptorTag            SkSetFourByteTag('s', 'r', 'e', 'c')

 #define kPathEffect_SkDescriptorTag     SkSetFourByteTag('p', 't', 'h', 'e')

 #define kMaskFilter_SkDescriptorTag     SkSetFourByteTag('m', 's', 'k', 'f')

 #define kRasterizer_SkDescriptorTag     SkSetFourByteTag('r', 'a', 's', 't')

 #ifdef SK_BUILD_FOR_ANDROID

 #define kAndroidOpts_SkDescriptorTag    SkSetFourByteTag('a', 'n', 'd', 'r')

 #endif

 ///////////////////////////////////////////////////////////////////////////////

 enum SkAxisAlignment {

     kNone_SkAxisAlignment,

     kX_SkAxisAlignment,

     kY_SkAxisAlignment

 };

 /**

  *  Return the axis (if any) that the baseline for horizontal text will land on

  *  after running through the specified matrix.

  *

  *  As an example, the identity matrix will return kX_SkAxisAlignment

  */

 SkAxisAlignment SkComputeAxisAlignmentForHText(const SkMatrix& matrix);

 ///////////////////////////////////////////////////////////////////////////////

 SkPaint::Hinting SkScalerContextRec::getHinting() const {

     unsigned hint = (fFlags & SkScalerContext::kHinting_Mask) >>

                                             SkScalerContext::kHinting_Shift;

     return static_cast<SkPaint::Hinting>(hint);

 }

 void SkScalerContextRec::setHinting(SkPaint::Hinting hinting) {

     fFlags = (fFlags & ~SkScalerContext::kHinting_Mask) |

                                 (hinting << SkScalerContext::kHinting_Shift);

 }

 #endif