1 /* This header file gives the metrics for the vector fonts. */ 2 3 /* Our choice for stroke width, in terms of virtual pixels. This number is 4 magic: just slightly greater than sqrt(2), so that adjacent strokes that 5 are inclined at a 45 degree angle will overlap as they should. 6 7 (According to ``Calligraphy for Computers'', the Hershey fonts were 8 designed to be drawn by an electron beam the intensity of which fell to 9 50% at a transverse displacement of one unit.) */ 10 11 #define HERSHEY_STROKE_WIDTH 1.42 12 13 /* This value gives good results for the Japanese characters (Kana and 14 Kanji). */ 15 #define HERSHEY_ORIENTAL_STROKE_WIDTH 1.175 16 17 /* According to Allen Hershey, 1 em = 32 virtual pixels for his alphabets 18 of principal size. But taking into account the width of the strokes 19 (nominally 1 virtual pixel), if the characters are thought of as resting 20 on a baseline, the baseline (and the capline, etc.) should be located at 21 half-integer values of the vertical coordinate. That changes things 22 slightly (an em should be 33 virtual pixels, not 32). 23 24 Incidentally his recommended spacing between lines is 40 pixels (24 for 25 indexical size), i.e., 1.2 em or so (1 em is the minimum possible 26 spacing). 27 */ 28 29 /* Dimensions for characters in principal [large] size. The `centerline' 30 is located at y=0, in the original coordinate system. The `topline' and 31 `bottomline' are determined by the tallest characters, which are 32 parentheses, brackets, and braces. */ 33 34 #define HERSHEY_LARGE_BASELINE (-9.5) /* relative to centerline */ 35 #define HERSHEY_LARGE_CAPLINE 12.5 /* relative to centerline */ 36 #define HERSHEY_LARGE_TOPLINE 16.5 /* relative to centerline */ 37 #define HERSHEY_LARGE_BOTTOMLINE -16.5 /* relative to centerline */ 38 39 #define HERSHEY_LARGE_CAPHEIGHT 22 /* i.e. capline - baseline */ 40 #define HERSHEY_LARGE_ASCENT 26 /* i.e. topline - baseline */ 41 #define HERSHEY_LARGE_DESCENT 7 /* i.e. baseline - bottomline */ 42 #define HERSHEY_LARGE_HEIGHT (HERSHEY_LARGE_ASCENT + HERSHEY_LARGE_DESCENT) 43 #define HERSHEY_LARGE_EM 33 44 45 /* Dimensions for characters in indexical [medium] size. The `centerline' 46 is located at y=0, in the original coordinate system. The `topline' and 47 `bottomline' are determined by the tallest characters, which are 48 parentheses, brackets, and braces. */ 49 50 #define HERSHEY_MEDIUM_BASELINE (-6.5) /* relative to centerline */ 51 #define HERSHEY_MEDIUM_CAPLINE 7.5 /* relative to centerline */ 52 #define HERSHEY_MEDIUM_TOPLINE 10.5 /* relative to centerline */ 53 #define HERSHEY_MEDIUM_BOTTOMLINE -10.5 /* relative to centerline */ 54 55 #define HERSHEY_MEDIUM_CAPHEIGHT 14 /* i.e. capline - baseline */ 56 #define HERSHEY_MEDIUM_ASCENT 17 /* i.e. topline - baseline */ 57 #define HERSHEY_MEDIUM_DESCENT 4 /* i.e. baseline - bottomline */ 58 #define HERSHEY_MEDIUM_HEIGHT (HERSHEY_MEDIUM_ASCENT + HERSHEY_MEDIUM_DESCENT) 59 #define HERSHEY_MEDIUM_EM 21 60 61 /* Dimensions for characters in cartographic [small] size. The 62 `centerline' is located at y=0, in the original coordinate system. The 63 `topline' and `bottomline' are determined by the tallest characters, 64 which are parentheses, brackets, and braces. In the cartographic size 65 there are only parentheses, and unlike the other two sizes they are not 66 symmetric about y=0 (since they will surround only upper-case letters; 67 there are no lower-case letters in cartographic). */ 68 69 #define HERSHEY_SMALL_BASELINE (-4.5) /* relative to centerline */ 70 #define HERSHEY_SMALL_CAPLINE 5.5 /* relative to centerline */ 71 #define HERSHEY_SMALL_TOPLINE 6.5 /* relative to centerline */ 72 #define HERSHEY_SMALL_BOTTOMLINE -5.5 /* relative to centerline */ 73 74 #define HERSHEY_SMALL_CAPHEIGHT 10 /* i.e. capline - baseline */ 75 #define HERSHEY_SMALL_ASCENT 11 /* i.e. topline - baseline */ 76 #define HERSHEY_SMALL_DESCENT 1 /* i.e. baseline - bottomline */ 77 #define HERSHEY_SMALL_HEIGHT (HERSHEY_SMALL_ASCENT + HERSHEY_SMALL_DESCENT) 78 #define HERSHEY_SMALL_EM 12 79 80 /* Vertical positionings (in alabel_str.c) are now based on the assumption 81 that all characters we are dealing with are of principal [large] size. 82 I see no graceful way to handle positionings relative to the baseline 83 for the other two sizes. Of course, centered positioning will work 84 perfectly, since the Hershey glyphs were designed for that. */ 85 86 #define HERSHEY_BASELINE HERSHEY_LARGE_BASELINE 87 #define HERSHEY_ASCENT HERSHEY_LARGE_ASCENT 88 #define HERSHEY_DESCENT HERSHEY_LARGE_DESCENT 89 #define HERSHEY_HEIGHT HERSHEY_LARGE_HEIGHT 90 #define HERSHEY_EM HERSHEY_LARGE_EM 91 92 /* PAUL MURRELL 93 I have converted HERSHEY_UNITS_TO_USER_UNITS into 94 HERSHEY_X_UNITS_TO_USER_UNITS and HERSHEY_Y_UNITS_TO_USER_UNITS 95 (Not sure how the original authors got away with ignoring 96 the distinction ?) 97 ... and added HERSHEY_UNITS_TO_DEVICE_UNITS 98 ... and replaced HERSHEY_EM with HERSHEY_LARGE_CAPHEIGHT 99 */ 100 101 /* The scaling between distances in Hershey units and distances in user 102 coordinates. Idea is that the font size (i.e. the nominal minimum 103 inter-line spacing) corresponds to HERSHEY_LARGE_CAPHEIGHT Hershey units. */ 104 105 #define HERSHEY_X_UNITS_TO_USER_UNITS(size) \ 106 ((size)*((gc->ps * gc->cex / 72.27) / (dd->dev)->ipr[0])/(HERSHEY_LARGE_HEIGHT)) 107 108 #define HERSHEY_Y_UNITS_TO_USER_UNITS(size) \ 109 ((size)*((gc->ps * gc->cex / 72.27) / (dd->dev)->ipr[1])/(HERSHEY_LARGE_HEIGHT)) 110 111 /* 112 * R Graphics Engine line width of 1 is approx 1/96 inches (0.75 points) 113 * We calculate Hershey line width in points and then multiply by 4/3 to 114 * convert to R Graphics Engine line width units 115 */ 116 #define HERSHEY_LINE_WIDTH_TO_LWD(width) \ 117 ((width)*((4/3)*(gc->ps * gc->cex))/(HERSHEY_LARGE_HEIGHT)) 118 119 /************************************************************************/ 120 121 /* Some miscellaneous information on typesetting mathematics, taken from 122 Allen Hershey's 1969 TR (see g_her_glyph.c): 123 124 Subscripts and superscripts, in math text, should be in indexical size. 125 The centerline of subscripts/superscripts would be lowered/raised by 10 126 vertical units. 127 128 [In principal size the centerline is 9.5 units above the baseline; in 129 indexical size the centerline is 6.5 units above the baseline. So when 130 going to subscripts, the baseline should be lowered by 7 units; when 131 going to superscripts, the baseline should be raised by 13 units. This 132 is not actually the scheme we use; see alabel_str.c. -- rsm] 133 134 In math text the quantity being supplied with a sub/superscript is 135 typically an italic character. The transitions principal->superscript 136 and subscript->principal are accordingly accompanied by 2 add'l units of 137 horizontal space. 138 139 In math text, conjuctive/predicative signs should be given a extra 140 spacing of 1/2 en (i.e. 1/4 em), i.e. 8 units in principal size, to 141 either side. This is accomplished by glyph 2198 (or 1198, in indexical 142 size). 143 144 Case fractions (e.g. \frac34) are formed by raising/lowering 145 indexical-size characters by 12 vertical units; in mathematical text, 146 they should be given a small (4-unit) spacing to either side. 147 148 Simple limits, for sum and integral signs, are in indexical size, and 149 are raised/lowered by 24 units. */ 150 151 /************************************************************************/ 152