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