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