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
|
/*
* Copyright 2004 James Bursa <james@netsurf-browser.org>
* Copyright 2009 John-Mark Bell <jmb@netsurf-browser.org>
*
* This file is part of NetSurf, http://www.netsurf-browser.org/
*
* NetSurf is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* NetSurf is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <assert.h>
#include "css/utils.h"
#include "desktop/options.h"
#include "utils/log.h"
/** Screen DPI in fixed point units: defaults to 90, which RISC OS uses */
css_fixed nscss_screen_dpi = INTTOFIX(90);
/**
* Convert an absolute CSS length to points.
*
* \param length Length to convert
* \param unit Corresponding unit
* \return length in points
*/
css_fixed nscss_len2pt(css_fixed length, css_unit unit)
{
/* Length must not be relative */
assert(unit != CSS_UNIT_EM && unit != CSS_UNIT_EX);
switch (unit) {
/* We assume the screen and any other output has the same dpi */
/* 1in = DPIpx => 1px = (72/DPI)pt */
case CSS_UNIT_PX: return FDIV(FMULI(length, 72), nscss_screen_dpi);
/* 1in = 72pt */
case CSS_UNIT_IN: return FMULI(length, 72);
/* 1in = 2.54cm => 1cm = (72/2.54)pt */
case CSS_UNIT_CM: return FMUL(length,
FDIV(INTTOFIX(72), FLTTOFIX(2.54)));
/* 1in = 25.4mm => 1mm = (72/25.4)pt */
case CSS_UNIT_MM: return FMUL(length,
FDIV(INTTOFIX(72), FLTTOFIX(25.4)));
case CSS_UNIT_PT: return length;
/* 1pc = 12pt */
case CSS_UNIT_PC: return FMULI(length, 12);
default: break;
}
return 0;
}
/**
* Convert a CSS length to pixels.
*
* \param length Length to convert
* \param unit Corresponding unit
* \param style Computed style applying to length. May be NULL if unit is
* neither em nor ex
* \return length in pixels
*/
css_fixed nscss_len2px(css_fixed length, css_unit unit,
const css_computed_style *style)
{
/* We assume the screen and any other output has the same dpi */
const css_fixed lendpi = FMUL(length, nscss_screen_dpi);
assert(style != NULL || (unit != CSS_UNIT_EM && unit != CSS_UNIT_EX));
switch (unit) {
case CSS_UNIT_EM:
case CSS_UNIT_EX:
{
css_fixed font_size = 0;
css_unit font_unit = CSS_UNIT_PT;
css_computed_font_size(style, &font_size, &font_unit);
/* Convert to points */
font_size = nscss_len2pt(font_size, font_unit);
/* Clamp to configured minimum */
if (font_size < FDIVI(INTTOFIX(option_font_min_size), 10)) {
font_size = FDIVI(INTTOFIX(option_font_min_size), 10);
}
/* Expand relative length */
length = FMUL(length,
nscss_len2px(font_size, CSS_UNIT_PT, style));
/* Scale ex units: we use a fixed ratio of 1ex = 0.6em */
if (unit == CSS_UNIT_EX)
length = FMUL(length, FLTTOFIX(0.6));
return length;
}
case CSS_UNIT_PX: return length;
/* 1in = DPIpx */
case CSS_UNIT_IN: return lendpi;
/* 1in = 2.54cm => 1cm = (DPI/2.54)px */
case CSS_UNIT_CM: return FDIV(lendpi, FLTTOFIX(2.54));
/* 1in = 25.4mm => 1mm = (DPI/25.4)px */
case CSS_UNIT_MM: return FDIV(lendpi, FLTTOFIX(25.4));
/* 1in = 72pt => 1pt = (DPI/72)px */
case CSS_UNIT_PT: return FDIV(lendpi, INTTOFIX(72));
/* 1pc = 12pt => 1in = 6pc => 1pc = (DPI/6)px */
case CSS_UNIT_PC: return FDIV(lendpi, INTTOFIX(6));
default: break;
}
return 0;
}
|
