From ddeadd1c02880367ad786b113d352a519f45ec73 Mon Sep 17 00:00:00 2001
From: John Mark Bell <jmb@netsurf-browser.org>
Date: Thu, 23 Jul 2009 23:05:34 +0000
Subject: Merge LibCSS port to trunk.

svn path=/trunk/netsurf/; revision=8752
---
 css/utils.c | 124 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)
 create mode 100644 css/utils.c

(limited to 'css/utils.c')

diff --git a/css/utils.c b/css/utils.c
new file mode 100644
index 000000000..5ed569474
--- /dev/null
+++ b/css/utils.c
@@ -0,0 +1,124 @@
+/*
+ * 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;
+}
+
-- 
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