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/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef GFX_FT2UTILS_H
#define GFX_FT2UTILS_H
#include "cairo-ft.h"
#include "gfxFT2FontBase.h"
#include "mozilla/Likely.h"
// Rounding and truncation functions for a FreeType fixed point number
// (FT26Dot6) stored in a 32bit integer with high 26 bits for the integer
// part and low 6 bits for the fractional part.
#define FLOAT_FROM_26_6(x) ((x) / 64.0)
#define FLOAT_FROM_16_16(x) ((x) / 65536.0)
#define ROUND_26_6_TO_INT(x) ((x) >= 0 ? ((32 + (x)) >> 6) \
: -((32 - (x)) >> 6))
typedef struct FT_FaceRec_* FT_Face;
class gfxFT2LockedFace {
public:
explicit gfxFT2LockedFace(gfxFT2FontBase *aFont) :
mGfxFont(aFont),
mFace(cairo_ft_scaled_font_lock_face(aFont->CairoScaledFont()))
{ }
~gfxFT2LockedFace()
{
if (mFace) {
cairo_ft_scaled_font_unlock_face(mGfxFont->CairoScaledFont());
}
}
FT_Face get() { return mFace; };
/**
* Get the glyph id for a Unicode character representable by a single
* glyph, or return zero if there is no such glyph. This does no caching,
* so you probably want gfxFcFont::GetGlyph.
*/
uint32_t GetGlyph(uint32_t aCharCode);
/**
* Returns 0 if there is no variation selector cmap subtable.
*/
uint32_t GetUVSGlyph(uint32_t aCharCode, uint32_t aVariantSelector);
void GetMetrics(gfxFont::Metrics* aMetrics, uint32_t* aSpaceGlyph);
// A scale factor for use in converting horizontal metrics from font units
// to pixels.
gfxFloat XScale()
{
if (MOZ_UNLIKELY(!mFace))
return 0.0;
const FT_Size_Metrics& ftMetrics = mFace->size->metrics;
if (FT_IS_SCALABLE(mFace)) {
// Prefer FT_Size_Metrics::x_scale to x_ppem as x_ppem does not
// have subpixel accuracy.
//
// FT_Size_Metrics::x_scale is in 16.16 fixed point format. Its
// (fractional) value is a factor that converts vertical metrics
// from design units to units of 1/64 pixels, so that the result
// may be interpreted as pixels in 26.6 fixed point format.
return FLOAT_FROM_26_6(FLOAT_FROM_16_16(ftMetrics.x_scale));
}
// Not scalable.
// FT_Size_Metrics doc says x_scale is "only relevant for scalable
// font formats".
return gfxFloat(ftMetrics.x_ppem) / gfxFloat(mFace->units_per_EM);
}
protected:
/**
* Get extents for a simple character representable by a single glyph.
* The return value is the glyph id of that glyph or zero if no such glyph
* exists. aExtents is only set when this returns a non-zero glyph id.
*/
uint32_t GetCharExtents(char aChar, cairo_text_extents_t* aExtents);
typedef FT_UInt (*CharVariantFunction)(FT_Face face,
FT_ULong charcode,
FT_ULong variantSelector);
CharVariantFunction FindCharVariantFunction();
RefPtr<gfxFT2FontBase> mGfxFont;
FT_Face mFace;
};
#endif /* GFX_FT2UTILS_H */
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