Refactor text plotter and other font functions to remove dependency on CSS.

svn path=/trunk/netsurf/; revision=8641

7 files changed, 266 insertions, 70 deletions

diff --git a/render/font.c b/render/font.c
new file mode 100644
index 000000000..089fcff5a
--- /dev/null
+++ b/render/font.c
@@ -0,0 +1,150 @@
+/*
+ * 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 "css/css.h"
+#include "render/font.h"
+
+static plot_font_generic_family_t plot_font_generic_family(
+		css_font_family css);
+static int plot_font_weight(css_font_weight css);
+static plot_font_flags_t plot_font_flags(css_font_style style,
+		css_font_variant variant);
+
+/**
+ * Populate a font style using data from a computed CSS style
+ *
+ * \param css     Computed style to consider
+ * \param fstyle  Font style to populate
+ */
+void font_plot_style_from_css(const struct css_style *css,
+		plot_font_style_t *fstyle)
+{
+	fstyle->family = plot_font_generic_family(css->font_family);
+	fstyle->size = css_len2pt(&css->font_size.value.length, css);
+	fstyle->weight = plot_font_weight(css->font_weight);
+	fstyle->flags = plot_font_flags(css->font_style, css->font_variant);
+	fstyle->foreground = css->color;
+	fstyle->background = 0;
+}
+
+/******************************************************************************
+ * Helper functions                                                           *
+ ******************************************************************************/
+
+/**
+ * Map a generic CSS font family to a generic plot font family
+ *
+ * \param css  Generic CSS font family
+ * \return Plot font family
+ */
+plot_font_generic_family_t plot_font_generic_family(
+		css_font_family css)
+{
+	plot_font_generic_family_t plot;
+
+	switch (css) {
+	case CSS_FONT_FAMILY_SERIF:
+		plot = PLOT_FONT_FAMILY_SERIF;
+		break;
+	case CSS_FONT_FAMILY_MONOSPACE:
+		plot = PLOT_FONT_FAMILY_MONOSPACE;
+		break;
+	case CSS_FONT_FAMILY_CURSIVE:
+		plot = PLOT_FONT_FAMILY_CURSIVE;
+		break;
+	case CSS_FONT_FAMILY_FANTASY:
+		plot = PLOT_FONT_FAMILY_FANTASY;
+		break;
+	case CSS_FONT_FAMILY_SANS_SERIF:
+	default:
+		plot = PLOT_FONT_FAMILY_SANS_SERIF;
+		break;
+	}
+
+	return plot;
+}
+
+/**
+ * Map a CSS font weight to a plot weight value
+ *
+ * \param css  CSS font weight
+ * \return Plot weight
+ */
+int plot_font_weight(css_font_weight css)
+{
+	int weight;
+
+	switch (css) {
+	case CSS_FONT_WEIGHT_100:
+		weight = 100;
+		break;
+	case CSS_FONT_WEIGHT_200:
+		weight = 200;
+		break;
+	case CSS_FONT_WEIGHT_300:
+		weight = 300;
+		break;
+	case CSS_FONT_WEIGHT_400:
+	case CSS_FONT_WEIGHT_NORMAL:
+	default:
+		weight = 400;
+		break;
+	case CSS_FONT_WEIGHT_500:
+		weight = 500;
+		break;
+	case CSS_FONT_WEIGHT_600:
+		weight = 600;
+		break;
+	case CSS_FONT_WEIGHT_700:
+	case CSS_FONT_WEIGHT_BOLD:
+		weight = 700;
+		break;
+	case CSS_FONT_WEIGHT_800:
+		weight = 800;
+		break;
+	case CSS_FONT_WEIGHT_900:
+		weight = 900;
+		break;
+	}
+
+	return weight;
+}
+
+/**
+ * Map a CSS font style and font variant to plot font flags
+ * 
+ * \param style    CSS font style
+ * \param variant  CSS font variant
+ * \return Computed plot flags
+ */
+plot_font_flags_t plot_font_flags(css_font_style style,
+		css_font_variant variant)
+{
+	plot_font_flags_t flags = FONTF_NONE;
+
+	if (style == CSS_FONT_STYLE_ITALIC)
+		flags |= FONTF_ITALIC;
+	else if (style == CSS_FONT_STYLE_OBLIQUE)
+		flags |= FONTF_OBLIQUE;
+
+	if (variant == CSS_FONT_VARIANT_SMALL_CAPS)
+		flags |= FONTF_SMALLCAPS;
+
+	return flags;
+}
+
diff --git a/render/font.h b/render/font.h
index acfd7c727..9a80af329 100644
--- a/render/font.h
+++ b/render/font.h
@@ -35,23 +35,25 @@
 #include <stdbool.h>
 #include <stddef.h>
 
-
-struct css_style;
-
+#include "css/css.h"
+#include "desktop/plot_style.h"
 
 struct font_functions
 {
-	bool (*font_width)(const struct css_style *style,
+	bool (*font_width)(const plot_font_style_t *fstyle,
 			const char *string, size_t length,
 			int *width);
-	bool (*font_position_in_string)(const struct css_style *style,
+	bool (*font_position_in_string)(const plot_font_style_t *fstyle,
 			const char *string, size_t length,
 			int x, size_t *char_offset, int *actual_x);
-	bool (*font_split)(const struct css_style *style,
+	bool (*font_split)(const plot_font_style_t *fstyle,
 			const char *string, size_t length,
 			int x, size_t *char_offset, int *actual_x);
 };
 
 extern const struct font_functions nsfont;
 
+void font_plot_style_from_css(const struct css_style *css, 
+		plot_font_style_t *fstyle);
+
 #endif
diff --git a/render/html.h b/render/html.h
index f1ab9d86d..e6c322e14 100644
--- a/render/html.h
+++ b/render/html.h
@@ -28,6 +28,7 @@
 #include <stdbool.h>
 #include "content/content_type.h"
 #include "css/css.h"
+#include "desktop/plot_style.h"
 #include "render/parser_binding.h"
 
 struct box;
@@ -197,11 +198,11 @@ bool html_redraw(struct content *c, int x, int y,
 
 bool text_redraw(const char *utf8_text, size_t utf8_len,
 		size_t offset, bool space,
-		struct css_style *style,
+		const plot_font_style_t *fstyle,
 		int x, int y,
 		struct rect *clip,
 		int height,
-		float scale, colour current_background_color,
+		float scale,
 		bool excluded);
 
 #endif
diff --git a/render/html_redraw.c b/render/html_redraw.c
index 0fc10cb6c..64fc6066b 100644
--- a/render/html_redraw.c
+++ b/render/html_redraw.c
@@ -747,6 +747,10 @@ bool html_redraw_text_box(struct box *box, int x, int y,
 {
 	bool excluded = (box->object != NULL);
 	struct rect clip;
+	plot_font_style_t fstyle;
+
+	font_plot_style_from_css(box->style, &fstyle);
+	fstyle.background = current_background_color;
 
 	clip.x0 = x0;
 	clip.y0 = y0;
@@ -754,9 +758,8 @@ bool html_redraw_text_box(struct box *box, int x, int y,
 	clip.y1 = y1;
 
 	if (!text_redraw(box->text, box->length, box->byte_offset,
-			box->space, box->style, x, y,
-			&clip, box->height, scale,
-			current_background_color, excluded))
+			box->space, &fstyle, x, y,
+			&clip, box->height, scale, excluded))
 		return false;
 
 	/* does this textbox contain the ghost caret? */
@@ -769,7 +772,6 @@ bool html_redraw_text_box(struct box *box, int x, int y,
 	return true;
 }
 
-
 /**
  * Redraw a short text string, complete with highlighting
  * (for selection/search) and ghost caret
@@ -778,22 +780,21 @@ bool html_redraw_text_box(struct box *box, int x, int y,
  * \param  utf8_len   length of string, in bytes
  * \param  offset     byte offset within textual representation
  * \param  space      indicates whether string is followed by a space
- * \param  style      text style to use
+ * \param  fstyle     text style to use
  * \param  x          x ordinate at which to plot text
  * \param  y          y ordinate at which to plot text
  * \param  clip       pointer to current clip rectangle
  * \param  height     height of text string
  * \param  scale      current display scale (1.0 = 100%)
- * \param  current_background_color
  * \param  excluded   exclude this text string from the selection
  * \return true iff successful and redraw should proceed
  */
 
 bool text_redraw(const char *utf8_text, size_t utf8_len,
-		size_t offset, bool space, struct css_style *style,
+		size_t offset, bool space, const plot_font_style_t *fstyle,
 		int x, int y, struct rect *clip,
 		int height,
-		float scale, colour current_background_color,
+		float scale,
 		bool excluded)
 {
 	bool highlighted = false;
@@ -828,6 +829,7 @@ bool text_redraw(const char *utf8_text, size_t utf8_len,
 			bool text_visible = true;
 			int startx, endx;
 			plot_style_t *pstyle_fill_hback = plot_style_fill_white;
+			plot_font_style_t fstyle_hback = *fstyle;
 
 			if (end_idx > utf8_len) {
 				/* adjust for trailing space, not present in
@@ -836,11 +838,11 @@ bool text_redraw(const char *utf8_text, size_t utf8_len,
 				endtxt_idx = utf8_len;
 			}
 
-			if (!nsfont.font_width(style, utf8_text, start_idx,
+			if (!nsfont.font_width(fstyle, utf8_text, start_idx,
 					&startx))
 				startx = 0;
 
-			if (!nsfont.font_width(style, utf8_text, endtxt_idx,
+			if (!nsfont.font_width(fstyle, utf8_text, endtxt_idx,
 					&endx))
 				endx = 0;
 
@@ -850,7 +852,7 @@ bool text_redraw(const char *utf8_text, size_t utf8_len,
 				int spc_width;
 				/* \todo is there a more elegant/efficient
 				 * solution? */
-				if (nsfont.font_width(style, " ", 1,
+				if (nsfont.font_width(fstyle, " ", 1,
 						&spc_width))
 					endx += spc_width;
 			}
@@ -863,15 +865,13 @@ bool text_redraw(const char *utf8_text, size_t utf8_len,
 			/* draw any text preceding highlighted portion */
 			if (start_idx > 0 &&
 				!plot.text(x, y + (int) (height * 0.75 * scale),
-						style, utf8_text, start_idx,
-						current_background_color,
-						/*print_text_black ? 0 :*/
-						style->color))
+						utf8_text, start_idx,
+						fstyle))
 				return false;
 
 			/* decide whether highlighted portion is to be
 			 * white-on-black or black-on-white */
-			if ((current_background_color & 0x808080) == 0x808080)
+			if ((fstyle->background & 0x808080) == 0x808080)
 				pstyle_fill_hback = plot_style_fill_black;
 
 			/* highlighted portion */
@@ -894,11 +894,15 @@ bool text_redraw(const char *utf8_text, size_t utf8_len,
 				}
 			}
 
+			fstyle_hback.background = 
+				pstyle_fill_hback->fill_colour ^ 0xffffff;
+			fstyle_hback.foreground = 
+				pstyle_fill_hback->fill_colour;
+
 			if (text_visible &&
 				!plot.text(x, y + (int) (height * 0.75 * scale),
-						style, utf8_text, endtxt_idx,
-						pstyle_fill_hback->fill_colour,
-						pstyle_fill_hback->fill_colour ^						0xffffff))
+						utf8_text, endtxt_idx,
+						&fstyle_hback))
 				return false;
 
 			/* draw any text succeeding highlighted portion */
@@ -914,10 +918,8 @@ bool text_redraw(const char *utf8_text, size_t utf8_len,
 
 					if (!plot.text(x, y + (int)
 						(height * 0.75 * scale),
-						style, utf8_text, utf8_len,
-						current_background_color,
-						/*print_text_black ? 0 :*/
-						style->color))
+						utf8_text, utf8_len,
+						fstyle))
 						return false;
 				}
 			}
@@ -931,9 +933,8 @@ bool text_redraw(const char *utf8_text, size_t utf8_len,
 
 	if (!highlighted) {
 		if (!plot.text(x, y + (int) (height * 0.75 * scale),
-				style, utf8_text, utf8_len,
-				current_background_color,
-				/*print_text_black ? 0 :*/ style->color))
+				utf8_text, utf8_len,
+				fstyle))
 			return false;
 	}
 	return true;
@@ -1396,6 +1397,10 @@ bool html_redraw_file(int x, int y, int width, int height,
 	int text_width;
 	const char *text;
 	size_t length;
+	plot_font_style_t fstyle;
+
+	font_plot_style_from_css(box->style, &fstyle);
+	fstyle.background = background_colour;
 
 	if (box->gadget->value)
 		text = box->gadget->value;
@@ -1403,7 +1408,7 @@ bool html_redraw_file(int x, int y, int width, int height,
 		text = messages_get("Form_Drop");
 	length = strlen(text);
 
-	if (!nsfont.font_width(box->style, text, length, &text_width))
+	if (!nsfont.font_width(&fstyle, text, length, &text_width))
 		return false;
 	text_width *= scale;
 	if (width < text_width + 8)
@@ -1411,9 +1416,7 @@ bool html_redraw_file(int x, int y, int width, int height,
 	else
 		x = x + 4;
 
-	return plot.text(x, y + height * 0.75, box->style, text, length,
-			background_colour,
-			/*print_text_black ? 0 :*/ box->style->color);
+	return plot.text(x, y + height * 0.75, text, length, &fstyle);
 }
 
 
diff --git a/render/layout.c b/render/layout.c
index 96a9b6168..5bf03a157 100644
--- a/render/layout.c
+++ b/render/layout.c
@@ -1668,6 +1668,7 @@ bool layout_line(struct box *first, int *width, int *y,
 	unsigned int i;
 	struct css_length gadget_size; /* Checkbox / radio buttons */
 	const struct font_functions *font_func = content->data.html.font_func;
+	plot_font_style_t fstyle;
 
 	gadget_size.unit = CSS_UNIT_EM;
 	gadget_size.value = 1;
@@ -1722,6 +1723,9 @@ bool layout_line(struct box *first, int *width, int *y,
 				 b->style->position == CSS_POSITION_FIXED))
 			continue;
 
+		assert(b->style != NULL);
+		font_plot_style_from_css(b->style, &fstyle);
+
 		x += space_after;
 
 		if (b->type == BOX_INLINE_BLOCK) {
@@ -1763,7 +1767,7 @@ bool layout_line(struct box *first, int *width, int *y,
 			b->width = 0;
 			if (b->space) {
 				/** \todo optimize out */
-				font_func->font_width(b->style, " ", 1,
+				font_func->font_width(&fstyle, " ", 1,
 						&space_after);
 			} else {
 				space_after = 0;
@@ -1801,7 +1805,7 @@ bool layout_line(struct box *first, int *width, int *y,
 							data.select.items; o;
 							o = o->next) {
 						int opt_width;
-						font_func->font_width(b->style,
+						font_func->font_width(&fstyle,
 								o->text,
 								strlen(o->text),
 								&opt_width);
@@ -1812,7 +1816,7 @@ bool layout_line(struct box *first, int *width, int *y,
 
 					b->width = opt_maxwidth;
 				} else {
-					font_func->font_width(b->style, b->text,
+					font_func->font_width(&fstyle, b->text,
 						b->length, &b->width);
 				}
 			}
@@ -1820,7 +1824,7 @@ bool layout_line(struct box *first, int *width, int *y,
 			x += b->width;
 			if (b->space)
 				/** \todo optimize out */
-				font_func->font_width(b->style, " ", 1,
+				font_func->font_width(&fstyle, " ", 1,
 						&space_after);
 			else
 				space_after = 0;
@@ -1957,10 +1961,13 @@ bool layout_line(struct box *first, int *width, int *y,
 				space_after = 0;
 			else if (b->text || b->type == BOX_INLINE_END) {
 				space_after = 0;
-				if (b->space)
+				if (b->space) {
+					font_plot_style_from_css(b->style, 
+							&fstyle);
 					/** \todo handle errors, optimize */
-					font_func->font_width(b->style, " ", 1,
+					font_func->font_width(&fstyle, " ", 1,
 							&space_after);
+				}
 			} else
 				space_after = 0;
 			split_box = b;
@@ -2099,10 +2106,12 @@ bool layout_line(struct box *first, int *width, int *y,
 
 		if (space == 0)
 			w = split_box->width;
-		else
+		else {
+			font_plot_style_from_css(split_box->style, &fstyle);
 			/** \todo handle errors */
-			font_func->font_width(split_box->style, split_box->text,
+			font_func->font_width(&fstyle, split_box->text,
 					space, &w);
+		}
 
 		LOG(("splitting: split_box %p \"%.*s\", space %zu, w %i, "
 				"left %p, right %p, inline_count %u",
@@ -2171,8 +2180,9 @@ bool layout_line(struct box *first, int *width, int *y,
 		} else {
 			/* fit as many words as possible */
 			assert(space != 0);
+			font_plot_style_from_css(split_box->style, &fstyle);
 			/** \todo handle errors */
-			font_func->font_split(split_box->style,
+			font_func->font_split(&fstyle,
 					split_box->text, split_box->length,
 					x1 - x0 - x - space_before, &space, &w);
 			LOG(("'%.*s' %i %zu %i", (int) split_box->length,
@@ -2294,6 +2304,8 @@ struct box *layout_minmax_line(struct box *first,
 	size_t i, j;
 	struct box *b;
 	struct css_length gadget_size; /* Checkbox / radio buttons */
+	plot_font_style_t fstyle;
+
 	gadget_size.unit = CSS_UNIT_EM;
 	gadget_size.value = 1;
 
@@ -2334,6 +2346,9 @@ struct box *layout_minmax_line(struct box *first,
 			continue;
 		}
 
+		assert(b->style);
+		font_plot_style_from_css(b->style, &fstyle);
+
 		if (b->type == BOX_INLINE && !b->object) {
 			fixed = frac = 0;
 			calculate_mbp_width(b->style, LEFT, true, true, true,
@@ -2353,7 +2368,7 @@ struct box *layout_minmax_line(struct box *first,
 			if (0 < fixed)
 				max += fixed;
 			if (b->next && b->space) {
-				font_func->font_width(b->style, " ", 1, &width);
+				font_func->font_width(&fstyle, " ", 1, &width);
 				max += width;
 			}
 			continue;
@@ -2379,7 +2394,7 @@ struct box *layout_minmax_line(struct box *first,
 							data.select.items; o;
 							o = o->next) {
 						int opt_width;
-						font_func->font_width(b->style,
+						font_func->font_width(&fstyle,
 								o->text,
 								strlen(o->text),
 								&opt_width);
@@ -2390,13 +2405,13 @@ struct box *layout_minmax_line(struct box *first,
 
 					b->width = opt_maxwidth;
 				} else {
-					font_func->font_width(b->style, b->text,
+					font_func->font_width(&fstyle, b->text,
 						b->length, &b->width);
 				}
 			}
 			max += b->width;
 			if (b->next && b->space) {
-				font_func->font_width(b->style, " ", 1, &width);
+				font_func->font_width(&fstyle, " ", 1, &width);
 				max += width;
 			}
 
@@ -2406,7 +2421,7 @@ struct box *layout_minmax_line(struct box *first,
 				for (j = i; j != b->length &&
 						b->text[j] != ' '; j++)
 					;
-				font_func->font_width(b->style, b->text + i,
+				font_func->font_width(&fstyle, b->text + i,
 						j - i, &width);
 				if (min < width)
 					min = width;
@@ -3327,6 +3342,7 @@ void layout_lists(struct box *box,
 {
 	struct box *child;
 	struct box *marker;
+	plot_font_style_t fstyle;
 
 	for (child = box->children; child; child = child->next) {
 		if (child->list_marker) {
@@ -3338,11 +3354,14 @@ void layout_lists(struct box *box,
 				marker->y = (line_height(marker->style) -
 						marker->height) / 2;
 			} else if (marker->text) {
-				if (marker->width == UNKNOWN_WIDTH)
-					font_func->font_width(marker->style,
+				if (marker->width == UNKNOWN_WIDTH) {
+					font_plot_style_from_css(marker->style, 
+							&fstyle);
+					font_func->font_width(&fstyle,
 							marker->text,
 							marker->length,
 							&marker->width);
+				}
 				marker->x = -marker->width;
 				marker->y = 0;
 				marker->height = line_height(marker->style);
diff --git a/render/loosen.c b/render/loosen.c
index 80f64bdcb..85136d89b 100644
--- a/render/loosen.c
+++ b/render/loosen.c
@@ -115,6 +115,10 @@ bool loosen_text(struct box *text, int width, struct content *content)
 	unsigned int position;
 	const struct font_functions *font_func;
 
+	plot_font_style_t fstyle;
+
+	font_plot_style_from_css(text->style, &fstyle);
+
 	if (content->type == CONTENT_HTML)
 		font_func = content->data.html.font_func;
 	else
@@ -134,7 +138,7 @@ bool loosen_text(struct box *text, int width, struct content *content)
 	position = 0;
 
 	while (position < text->length) {
-		font_func->font_position_in_string(text->style,
+		font_func->font_position_in_string(&fstyle,
 				text->text + position,
 				text->length - position,
 				width, &offset, &actual_x);
diff --git a/render/textplain.c b/render/textplain.c
index c1ee1cf43..dd3d168f9 100644
--- a/render/textplain.c
+++ b/render/textplain.c
@@ -49,11 +49,20 @@
 
 #define TAB_WIDTH 8  /* must be power of 2 currently */
 
-static struct css_style textplain_style;
+static plot_font_style_t textplain_style = {
+	.family = PLOT_FONT_FAMILY_MONOSPACE,
+	.size = 10,
+	.weight = 400,
+	.flags = FONTF_NONE,
+	.background = 0xffffff,
+	.foreground = 0x000000,
+};
+
 static int textplain_tab_width = 256;  /* try for a sensible default */
 
 static int textplain_coord_from_offset(const char *text, size_t offset,
 	size_t length);
+static float textplain_line_height(void);
 
 
 /**
@@ -68,9 +77,6 @@ bool textplain_create(struct content *c, const char *params[])
 	iconv_t iconv_cd;
 	union content_msg_data msg_data;
 
-	textplain_style = css_base_style;
-	textplain_style.font_family = CSS_FONT_FAMILY_MONOSPACE;
-
 	utf8_data = talloc_array(c, char, CHUNK);
 	if (!utf8_data)
 		goto no_memory;
@@ -281,9 +287,7 @@ void textplain_reformat(struct content *c, int width, int height)
 
 	c->data.textplain.physical_line_count = line_count;
 	c->width = width;
-	c->height = line_count *
-			css_len2px(&textplain_style.font_size.value.length,
-			&textplain_style) * 1.2 + MARGIN + MARGIN;
+	c->height = line_count * textplain_line_height() + MARGIN + MARGIN;
 
 	return;
 
@@ -332,8 +336,7 @@ bool textplain_redraw(struct content *c, int x, int y,
 	char *utf8_data = c->data.textplain.utf8_data;
 	long lineno;
 	unsigned long line_count = c->data.textplain.physical_line_count;
-	float line_height = css_len2px(&textplain_style.font_size.value.length,
-			&textplain_style) * 1.2;
+	float line_height = textplain_line_height();
 	float scaled_line_height = line_height * scale;
 	long line0 = clip_y0 / scaled_line_height - 1;
 	long line1 = clip_y1 / scaled_line_height + 1;
@@ -370,6 +373,9 @@ bool textplain_redraw(struct content *c, int x, int y,
 	else
 		plot_style_highlight = plot_style_fill_white;
 
+	/* Set background colour to plot with */
+	textplain_style.background = background_colour;
+
 	x += MARGIN * scale;
 	y += MARGIN * scale;
 	for (lineno = line0; lineno != line1; lineno++) {
@@ -396,8 +402,7 @@ bool textplain_redraw(struct content *c, int x, int y,
 					line[lineno].start + offset, false,
 					&textplain_style,
 					tx, y + (lineno * scaled_line_height),
-					&clip, line_height, scale,
-					background_colour, false))
+					&clip, line_height, scale, false))
 				return false;
 
 			if (next_offset >= length)
@@ -468,8 +473,7 @@ bool textplain_redraw(struct content *c, int x, int y,
 
 size_t textplain_offset_from_coords(struct content *c, int x, int y, int dir)
 {
-	float line_height = css_len2px(&textplain_style.font_size.value.length,
-			&textplain_style) * 1.2;
+	float line_height = textplain_line_height();
 	struct textplain_line *line;
 	const char *text;
 	unsigned nlines;
@@ -618,8 +622,7 @@ int textplain_coord_from_offset(const char *text, size_t offset, size_t length)
 void textplain_coords_from_range(struct content *c, unsigned start, unsigned end,
 		struct rect *r)
 {
-	float line_height = css_len2px(&textplain_style.font_size.value.length,
-			&textplain_style) * 1.2;
+	float line_height = textplain_line_height();
 	char *utf8_data = c->data.textplain.utf8_data;
 	struct textplain_line *line;
 	unsigned lineno = 0;
@@ -719,3 +722,17 @@ char *textplain_get_raw_data(struct content *c, unsigned start, unsigned end,
 
 	return c->data.textplain.utf8_data + start;
 }
+
+/**
+ * Calculate the line height, in pixels
+ * 
+ * \return Line height, in pixels
+ */
+float textplain_line_height(void)
+{
+	/* Size is in points, so convert to pixels. 
+	 * Then use a constant line height of 1.2 x font size.
+	 */
+	return (textplain_style.size * css_screen_dpi / 72) * 1.2;
+}
+