/*
* 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*);
/** Return the size in bytes of the associated gamma lookup table
*/
static size_t GetGammaLUTSize(SkScalar contrast, SkScalar paintGamma, SkScalar deviceGamma,
int* width, int* height);
/** Get the associated gamma lookup table. The 'data' pointer must point to pre-allocated
memory, with size in bytes greater than or equal to the return value of getGammaLUTSize().
*/
static void GetGammaLUTData(SkScalar contrast, SkScalar paintGamma, SkScalar deviceGamma,
void* data);
#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 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