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4349 | Serge | 1 | FreeType font driver for BDF fonts |
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3 | Francesco Zappa Nardelli |
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7 | Introduction |
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8 | ************ |
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9 | |||
10 | BDF (Bitmap Distribution Format) is a bitmap font format defined by Adobe, |
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11 | which is intended to be easily understood by both humans and computers. |
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12 | This code implements a BDF driver for the FreeType library, following the |
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13 | Adobe Specification V 2.2. The specification of the BDF font format is |
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14 | available from Adobe's web site: |
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16 | http://partners.adobe.com/public/developer/en/font/5005.BDF_Spec.pdf |
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18 | Many good bitmap fonts in bdf format come with XFree86 (www.XFree86.org). |
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19 | They do not define vertical metrics, because the X Consortium BDF |
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20 | specification has removed them. |
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23 | Encodings |
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24 | ********* |
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26 | The variety of encodings that accompanies bdf fonts appears to encompass the |
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27 | small set defined in freetype.h. On the other hand, two properties that |
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28 | specify encoding and registry are usually defined in bdf fonts. |
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30 | I decided to make these two properties directly accessible, leaving to the |
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31 | client application the work of interpreting them. For instance: |
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34 | #include FT_INTERNAL_BDF_TYPES_H |
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35 | |||
36 | FT_Face face; |
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37 | BDF_Public_Face bdfface; |
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38 | |||
39 | |||
40 | FT_New_Face( library, ..., &face ); |
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41 | |||
42 | bdfface = (BDF_Public_Face)face; |
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43 | |||
44 | if ( ( bdfface->charset_registry == "ISO10646" ) && |
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45 | ( bdfface->charset_encoding == "1" ) ) |
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46 | [..] |
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49 | Thus the driver always exports `ft_encoding_none' as face->charmap.encoding. |
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50 | FT_Get_Char_Index's behavior is unmodified, that is, it converts the ULong |
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51 | value given as argument into the corresponding glyph number. |
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53 | If the two properties are not available, Adobe Standard Encoding should be |
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54 | assumed. |
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55 | |||
56 | |||
57 | Anti-Aliased Bitmaps |
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58 | ******************** |
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59 | |||
60 | The driver supports an extension to the BDF format as used in Mark Leisher's |
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61 | xmbdfed bitmap font editor. Microsoft's SBIT tool expects bitmap fonts in |
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62 | that format for adding anti-aliased them to TrueType fonts. It introduces a |
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63 | fourth field to the `SIZE' keyword which gives the bpp value (bits per |
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64 | pixel) of the glyph data in the font. Possible values are 1 (the default), |
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65 | 2 (four gray levels), 4 (16 gray levels), and 8 (256 gray levels). The |
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66 | driver returns either a bitmap with 1 bit per pixel or a pixmap with 8bits |
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67 | per pixel (using 4, 16, and 256 gray levels, respectively). |
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68 | |||
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70 | Known problems |
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71 | ************** |
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72 | |||
73 | - A font is entirely loaded into memory. Obviously, this is not the Right |
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74 | Thing(TM). If you have big fonts I suggest you convert them into PCF |
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75 | format (using the bdftopcf utility): the PCF font drive of FreeType can |
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76 | perform incremental glyph loading. |
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77 | |||
78 | When I have some time, I will implement on-demand glyph parsing. |
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79 | |||
80 | - Except for encodings properties, client applications have no visibility of |
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81 | the PCF_Face object. This means that applications cannot directly access |
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82 | font tables and must trust FreeType. |
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83 | |||
84 | - Currently, glyph names are ignored. |
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85 | |||
86 | I plan to give full visibility of the BDF_Face object in an upcoming |
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87 | revision of the driver, thus implementing also glyph names. |
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88 | |||
89 | - As I have never seen a BDF font that defines vertical metrics, vertical |
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90 | metrics are (parsed and) discarded. If you own a BDF font that defines |
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91 | vertical metrics, please let me know (I will implement them in 5-10 |
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92 | minutes). |
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93 | |||
94 | |||
95 | License |
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96 | ******* |
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97 | |||
98 | Copyright (C) 2001-2002 by Francesco Zappa Nardelli |
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99 | |||
100 | Permission is hereby granted, free of charge, to any person obtaining |
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101 | a copy of this software and associated documentation files (the |
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102 | "Software"), to deal in the Software without restriction, including |
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103 | without limitation the rights to use, copy, modify, merge, publish, |
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104 | distribute, sublicense, and/or sell copies of the Software, and to |
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105 | permit persons to whom the Software is furnished to do so, subject to |
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106 | the following conditions: |
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107 | |||
108 | The above copyright notice and this permission notice shall be |
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109 | included in all copies or substantial portions of the Software. |
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110 | |||
111 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
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112 | EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
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113 | MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
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114 | IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY |
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115 | CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, |
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116 | TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE |
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117 | SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
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118 | |||
119 | *** Portions of the driver (that is, bdflib.c and bdf.h): |
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120 | |||
121 | Copyright 2000 Computing Research Labs, New Mexico State University |
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122 | Copyright 2001-2002, 2011 Francesco Zappa Nardelli |
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123 | |||
124 | Permission is hereby granted, free of charge, to any person obtaining a |
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125 | copy of this software and associated documentation files (the "Software"), |
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126 | to deal in the Software without restriction, including without limitation |
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127 | the rights to use, copy, modify, merge, publish, distribute, sublicense, |
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128 | and/or sell copies of the Software, and to permit persons to whom the |
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129 | Software is furnished to do so, subject to the following conditions: |
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130 | |||
131 | The above copyright notice and this permission notice shall be included in |
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132 | all copies or substantial portions of the Software. |
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133 | |||
134 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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135 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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136 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
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137 | THE COMPUTING RESEARCH LAB OR NEW MEXICO STATE UNIVERSITY BE LIABLE FOR ANY |
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138 | CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT |
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139 | OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR |
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140 | THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
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141 | |||
142 | |||
143 | Credits |
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144 | ******* |
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145 | |||
146 | This driver is based on excellent Mark Leisher's bdf library. If you |
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147 | find something good in this driver you should probably thank him, not |
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148 | me. |