gfx/thebes/gfxFT2Utils.h@97036ab72558
gfx/thebes/gfxFT2Utils.h
Tue, 06 Jan 2015 21:39:09 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Tue, 06 Jan 2015 21:39:09 +0100
- branch
- TOR_BUG_9701
- changeset 8
- 97036ab72558
- permissions
- -rw-r--r--
Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.
1 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
2 * This Source Code Form is subject to the terms of the Mozilla Public
3 * License, v. 2.0. If a copy of the MPL was not distributed with this
4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6 #ifndef GFX_FT2UTILS_H
7 #define GFX_FT2UTILS_H
9 #include "cairo-ft.h"
10 #include "gfxFT2FontBase.h"
11 #include "mozilla/Likely.h"
13 // Rounding and truncation functions for a FreeType fixed point number
14 // (FT26Dot6) stored in a 32bit integer with high 26 bits for the integer
15 // part and low 6 bits for the fractional part.
16 #define FLOAT_FROM_26_6(x) ((x) / 64.0)
17 #define FLOAT_FROM_16_16(x) ((x) / 65536.0)
18 #define ROUND_26_6_TO_INT(x) ((x) >= 0 ? ((32 + (x)) >> 6) \
19 : -((32 - (x)) >> 6))
21 typedef struct FT_FaceRec_* FT_Face;
23 class gfxFT2LockedFace {
24 public:
25 gfxFT2LockedFace(gfxFT2FontBase *aFont) :
26 mGfxFont(aFont),
27 mFace(cairo_ft_scaled_font_lock_face(aFont->CairoScaledFont()))
28 { }
29 ~gfxFT2LockedFace()
30 {
31 if (mFace) {
32 cairo_ft_scaled_font_unlock_face(mGfxFont->CairoScaledFont());
33 }
34 }
36 FT_Face get() { return mFace; };
38 /**
39 * Get the glyph id for a Unicode character representable by a single
40 * glyph, or return zero if there is no such glyph. This does no caching,
41 * so you probably want gfxFcFont::GetGlyph.
42 */
43 uint32_t GetGlyph(uint32_t aCharCode);
44 /**
45 * Returns 0 if there is no variation selector cmap subtable.
46 */
47 uint32_t GetUVSGlyph(uint32_t aCharCode, uint32_t aVariantSelector);
49 void GetMetrics(gfxFont::Metrics* aMetrics, uint32_t* aSpaceGlyph);
51 // A scale factor for use in converting horizontal metrics from font units
52 // to pixels.
53 gfxFloat XScale()
54 {
55 if (MOZ_UNLIKELY(!mFace))
56 return 0.0;
58 const FT_Size_Metrics& ftMetrics = mFace->size->metrics;
60 if (FT_IS_SCALABLE(mFace)) {
61 // Prefer FT_Size_Metrics::x_scale to x_ppem as x_ppem does not
62 // have subpixel accuracy.
63 //
64 // FT_Size_Metrics::x_scale is in 16.16 fixed point format. Its
65 // (fractional) value is a factor that converts vertical metrics
66 // from design units to units of 1/64 pixels, so that the result
67 // may be interpreted as pixels in 26.6 fixed point format.
68 return FLOAT_FROM_26_6(FLOAT_FROM_16_16(ftMetrics.x_scale));
69 }
71 // Not scalable.
72 // FT_Size_Metrics doc says x_scale is "only relevant for scalable
73 // font formats".
74 return gfxFloat(ftMetrics.x_ppem) / gfxFloat(mFace->units_per_EM);
75 }
77 protected:
78 /**
79 * Get extents for a simple character representable by a single glyph.
80 * The return value is the glyph id of that glyph or zero if no such glyph
81 * exists. aExtents is only set when this returns a non-zero glyph id.
82 */
83 uint32_t GetCharExtents(char aChar, cairo_text_extents_t* aExtents);
85 typedef FT_UInt (*CharVariantFunction)(FT_Face face,
86 FT_ULong charcode,
87 FT_ULong variantSelector);
88 CharVariantFunction FindCharVariantFunction();
90 nsRefPtr<gfxFT2FontBase> mGfxFont;
91 FT_Face mFace;
92 };
94 #endif /* GFX_FT2UTILS_H */
