aboutsummaryrefslogtreecommitdiffhomepage
path: root/include/core/SkFont.h
blob: 6aba23085440ed8c1197b893e2d078d486b0612b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
/*
 * Copyright 2014 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkFont_DEFINED
#define SkFont_DEFINED

#include "SkRefCnt.h"
#include "SkScalar.h"

class SkPaint;
class SkTypeface;

enum SkTextEncoding {
    kUTF8_SkTextEncoding,
    kUTF16_SkTextEncoding,
    kUTF32_SkTextEncoding,
    kGlyphID_SkTextEncoding,
};

/*
 1. The Hinting enum in SkPaint is gone entirely, absorbed into SkFont's flags.

 2. SkPaint Flags look like this today

 enum Flags {
     kAntiAlias_Flag       = 0x01,   //!< mask to enable antialiasing
     kDither_Flag          = 0x04,   //!< mask to enable dithering
     kFakeBoldText_Flag    = 0x20,   //!< mask to enable fake-bold text
     kLinearText_Flag      = 0x40,   //!< mask to enable linear-text
     kSubpixelText_Flag    = 0x80,   //!< mask to enable subpixel text positioning
     kLCDRenderText_Flag   = 0x200,  //!< mask to enable subpixel glyph renderering
     kEmbeddedBitmapText_Flag = 0x400, //!< mask to enable embedded bitmap strikes
     kAutoHinting_Flag     = 0x800,  //!< mask to force Freetype's autohinter
     kVerticalText_Flag    = 0x1000,
 };

 SkFont would absorb these:

     kFakeBoldText_Flag    = 0x20,   //!< mask to enable fake-bold text
     kLinearText_Flag      = 0x40,   //!< mask to enable linear-text
     kSubpixelText_Flag    = 0x80,   //!< mask to enable subpixel text positioning
     kLCDRenderText_Flag   = 0x200,  //!< mask to enable subpixel glyph renderering
     kEmbeddedBitmapText_Flag = 0x400, //!< mask to enable embedded bitmap strikes
     kAutoHinting_Flag     = 0x800,  //!< mask to force Freetype's autohinter
     kVerticalText_Flag    = 0x1000,

 leaving these still in paint

     kAntiAlias_Flag       = 0x01,   //!< mask to enable antialiasing
     kDither_Flag          = 0x04,   //!< mask to enable dithering

 3. Antialiasing

    SkFont has a mask-type: BW, AA, LCD
    SkPaint has antialias boolean

    What to do if the font's mask-type disagrees with the paint?

 */

class SkFont : public SkRefCnt {
public:
    enum Flags {
        /**
         *  Use the system's automatic hinting mechanism to hint the typeface.
         *  This is a last resort hinting method applied only if other hinting methods do not apply.
         *  TODO: where to put auto-normal vs auto-light?
         */
        kEnableAutoHints_Flag       = 1 << 0,

        /**
         *  If the typeface contains explicit bytecodes for hinting, use them.
         *  If both bytecode and auto hints are specified, attempt to use the bytecodes first;
         *  if that fails (e.g. there are no codes), then attempt to autohint.
         */
        kEnableByteCodeHints_Flag   = 1 << 1,

        /**
         *  If the typeface contains explicit bitmaps for hinting, use them.
         *  If both bytecode and auto hints are also specified, attempt to use the bitmaps first;
         *  if that fails (e.g. there are no bitmaps), then attempt to bytecode or autohint.
         */
        kEmbeddedBitmaps_Flag       = 1 << 2,

        /**
         *  Use rounded metric values (e.g. advance).
         *  If either auto or bytecode hinting was used, apply those results to the metrics of the
         *  glyphs as well. If no hinting was applied, the metrics will just be rounded to the
         *  nearest integer.
         *
         *  This applies to calls that return metrics (e.g. measureText) and to drawing the glyphs
         *  (see SkCanvas drawText and drawPosText).
         */
        kUseNonlinearMetrics_Flag   = 1 << 3,

        kVertical_Flag              = 1 << 4,

        kEmbolden_Flag              = 1 << 6,
    };

    enum MaskType {
        kBW_MaskType,
        kA8_MaskType,
        kLCD_MaskType,
    };

    static sk_sp<SkFont> Make(sk_sp<SkTypeface>, SkScalar size, MaskType, uint32_t flags);
    static sk_sp<SkFont> Make(sk_sp<SkTypeface>, SkScalar size, SkScalar scaleX, SkScalar skewX,
                              MaskType, uint32_t flags);

    /**
     *  Return a font with the same attributes of this font, but with the specified size.
     *  If size is not supported (e.g. <= 0 or non-finite) NULL will be returned.
     */
    sk_sp<SkFont> makeWithSize(SkScalar size) const;
    /**
     *  Return a font with the same attributes of this font, but with the flags.
     */
    sk_sp<SkFont> makeWithFlags(uint32_t newFlags) const;

    SkTypeface* getTypeface() const { return fTypeface.get(); }
    SkScalar    getSize() const { return fSize; }
    SkScalar    getScaleX() const { return fScaleX; }
    SkScalar    getSkewX() const { return fSkewX; }
    uint32_t    getFlags() const { return fFlags; }
    MaskType    getMaskType() const { return (MaskType)fMaskType; }

    bool isVertical() const { return SkToBool(fFlags & kVertical_Flag); }
    bool isEmbolden() const { return SkToBool(fFlags & kEmbolden_Flag); }
    bool isEnableAutoHints() const { return SkToBool(fFlags & kEnableAutoHints_Flag); }
    bool isEnableByteCodeHints() const { return SkToBool(fFlags & kEnableByteCodeHints_Flag); }
    bool isUseNonLinearMetrics() const { return SkToBool(fFlags & kUseNonlinearMetrics_Flag); }

    int textToGlyphs(const void* text, size_t byteLength, SkTextEncoding,
                     SkGlyphID glyphs[], int maxGlyphCount) const;

    int countText(const void* text, size_t byteLength, SkTextEncoding encoding) {
        return this->textToGlyphs(text, byteLength, encoding, nullptr, 0);
    }

    SkScalar measureText(const void* text, size_t byteLength, SkTextEncoding) const;

    static sk_sp<SkFont> Testing_CreateFromPaint(const SkPaint&);

private:
    static constexpr int kAllFlags = 0xFF;

    SkFont(sk_sp<SkTypeface>, SkScalar size, SkScalar scaleX, SkScalar skewX, MaskType,
           uint32_t flags);

    sk_sp<SkTypeface> fTypeface;
    SkScalar    fSize;
    SkScalar    fScaleX;
    SkScalar    fSkewX;
    uint16_t    fFlags;
    uint8_t     fMaskType;
//  uint8_t     fPad;
};

#endif