243 lines
6.3 KiB
C
243 lines
6.3 KiB
C
/*
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* Copyright 2004 James Bursa <james@netsurf-browser.org>
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* Copyright 2009 John-Mark Bell <jmb@netsurf-browser.org>
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*
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* This file is part of NetSurf, http://www.netsurf-browser.org/
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*
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* NetSurf is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* NetSurf is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <assert.h>
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#include "utils/nsoption.h"
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#include "utils/log.h"
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#include "css/utils.h"
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/** Screen DPI in fixed point units: defaults to 90, which RISC OS uses */
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css_fixed nscss_screen_dpi = F_90;
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/** Medium screen density for device viewing distance. */
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css_fixed nscss_baseline_pixel_density = F_96;
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/**
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* Map viewport-relative length units to either vh or vw.
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*
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* Non-viewport-relative units are unchanged.
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*
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* \param[in] ctx Length conversion context.
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* \param[in] unit Unit to map.
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* \return the mapped unit.
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*/
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static inline css_unit css_utils__fudge_viewport_units(
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const nscss_len_ctx *ctx,
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css_unit unit)
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{
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switch (unit) {
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case CSS_UNIT_VI:
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assert(ctx->root_style != NULL);
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if (css_computed_writing_mode(ctx->root_style) ==
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CSS_WRITING_MODE_HORIZONTAL_TB) {
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unit = CSS_UNIT_VW;
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} else {
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unit = CSS_UNIT_VH;
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}
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break;
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case CSS_UNIT_VB:
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assert(ctx->root_style != NULL);
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if (css_computed_writing_mode(ctx->root_style) ==
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CSS_WRITING_MODE_HORIZONTAL_TB) {
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unit = CSS_UNIT_VH;
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} else {
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unit = CSS_UNIT_VW;
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}
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break;
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case CSS_UNIT_VMIN:
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if (ctx->vh < ctx->vw) {
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unit = CSS_UNIT_VH;
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} else {
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unit = CSS_UNIT_VW;
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}
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break;
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case CSS_UNIT_VMAX:
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if (ctx->vh > ctx->vw) {
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unit = CSS_UNIT_VH;
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} else {
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unit = CSS_UNIT_VW;
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}
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break;
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default: break;
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}
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return unit;
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}
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/* exported interface documented in content/handlers/css/utils.h */
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css_fixed nscss_len2pt(
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const nscss_len_ctx *ctx,
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css_fixed length,
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css_unit unit)
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{
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/* Length must not be relative */
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assert(unit != CSS_UNIT_EM &&
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unit != CSS_UNIT_EX &&
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unit != CSS_UNIT_CH &&
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unit != CSS_UNIT_REM);
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unit = css_utils__fudge_viewport_units(ctx, unit);
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switch (unit) {
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/* We assume the screen and any other output has the same dpi */
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/* 1in = DPIpx => 1px = (72/DPI)pt */
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case CSS_UNIT_PX: return FDIV(FMUL(length, F_72), F_96);
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/* 1in = 72pt */
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case CSS_UNIT_IN: return FMUL(length, F_72);
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/* 1in = 2.54cm => 1cm = (72/2.54)pt */
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case CSS_UNIT_CM: return FMUL(length,
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FDIV(F_72, FLTTOFIX(2.54)));
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/* 1in = 25.4mm => 1mm = (72/25.4)pt */
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case CSS_UNIT_MM: return FMUL(length,
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FDIV(F_72, FLTTOFIX(25.4)));
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/* 1in = 101.6q => 1mm = (72/101.6)pt */
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case CSS_UNIT_Q: return FMUL(length,
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FDIV(F_72, FLTTOFIX(101.6)));
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case CSS_UNIT_PT: return length;
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/* 1pc = 12pt */
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case CSS_UNIT_PC: return FMUL(length, INTTOFIX(12));
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case CSS_UNIT_VH: return FDIV(FMUL(FDIV(FMUL(length, ctx->vh), F_100), F_72), F_96);
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case CSS_UNIT_VW: return FDIV(FMUL(FDIV(FMUL(length,ctx->vw), F_100), F_72), F_96);
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default: break;
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}
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return 0;
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}
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/* exported interface documented in content/handlers/css/utils.h */
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css_fixed nscss_len2px(
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const nscss_len_ctx *ctx,
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css_fixed length,
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css_unit unit,
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const css_computed_style *style)
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{
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/* We assume the screen and any other output has the same dpi */
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css_fixed px_per_unit;
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unit = css_utils__fudge_viewport_units(ctx, unit);
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switch (unit) {
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case CSS_UNIT_EM:
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case CSS_UNIT_EX:
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case CSS_UNIT_CH:
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{
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css_fixed font_size = 0;
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css_unit font_unit = CSS_UNIT_PT;
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assert(style != NULL);
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css_computed_font_size(style, &font_size, &font_unit);
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/* Convert to points */
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font_size = nscss_len2pt(ctx, font_size, font_unit);
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/* Clamp to configured minimum */
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if (font_size < FDIV(INTTOFIX(nsoption_int(font_min_size)), F_10)) {
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font_size = FDIV(INTTOFIX(nsoption_int(font_min_size)), F_10);
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}
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/* Convert to pixels (manually, to maximise precision)
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* 1in = 72pt => 1pt = (DPI/72)px */
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px_per_unit = FDIV(FMUL(font_size, F_96), F_72);
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/* Scale non-em units to em. We have fixed ratios. */
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switch (unit) {
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case CSS_UNIT_EX:
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px_per_unit = FMUL(px_per_unit, FLTTOFIX(0.6));
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break;
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case CSS_UNIT_CH:
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px_per_unit = FMUL(px_per_unit, FLTTOFIX(0.4));
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break;
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default: break;
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}
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}
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break;
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case CSS_UNIT_PX:
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px_per_unit = F_1;
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break;
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/* 1in = 96 CSS pixels */
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case CSS_UNIT_IN:
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px_per_unit = F_96;
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break;
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/* 1in = 2.54cm => 1cm = (DPI/2.54)px */
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case CSS_UNIT_CM:
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px_per_unit = FDIV(F_96, FLTTOFIX(2.54));
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break;
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/* 1in = 25.4mm => 1mm = (DPI/25.4)px */
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case CSS_UNIT_MM:
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px_per_unit = FDIV(F_96, FLTTOFIX(25.4));
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break;
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/* 1in = 101.6q => 1q = (DPI/101.6)px */
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case CSS_UNIT_Q:
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px_per_unit = FDIV(F_96, FLTTOFIX(101.6));
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break;
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/* 1in = 72pt => 1pt = (DPI/72)px */
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case CSS_UNIT_PT:
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px_per_unit = FDIV(F_96, F_72);
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break;
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/* 1pc = 12pt => 1in = 6pc => 1pc = (DPI/6)px */
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case CSS_UNIT_PC:
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px_per_unit = FDIV(F_96, INTTOFIX(6));
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break;
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case CSS_UNIT_REM:
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{
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css_fixed font_size = 0;
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css_unit font_unit = CSS_UNIT_PT;
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assert(ctx->root_style != NULL);
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css_computed_font_size(ctx->root_style,
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&font_size, &font_unit);
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/* Convert to points */
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font_size = nscss_len2pt(ctx, font_size, font_unit);
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/* Clamp to configured minimum */
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if (font_size < FDIV(INTTOFIX(nsoption_int(font_min_size)), F_10)) {
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font_size = FDIV(INTTOFIX(nsoption_int(font_min_size)), F_10);
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}
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/* Convert to pixels (manually, to maximise precision)
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* 1in = 72pt => 1pt = (DPI/72)px */
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px_per_unit = FDIV(FMUL(font_size, F_96), F_72);
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break;
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}
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case CSS_UNIT_VH:
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px_per_unit = FDIV(ctx->vh, F_100);
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break;
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case CSS_UNIT_VW:
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px_per_unit = FDIV(ctx->vw, F_100);
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break;
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default:
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px_per_unit = 0;
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break;
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}
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px_per_unit = nscss_pixels_css_to_physical(px_per_unit);
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/* Ensure we round px_per_unit to the nearest whole number of pixels:
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* the use of FIXTOINT() below will truncate. */
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px_per_unit += F_0_5;
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/* Calculate total number of pixels */
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return FMUL(length, TRUNCATEFIX(px_per_unit));
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}
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