netsurf/gtk/font_pango.c

322 lines
8.6 KiB
C

/*
* Copyright 2005 James Bursa <bursa@users.sourceforge.net>
*
* 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/>.
*/
/** \file
* Font handling (GTK implementation).
*
* Pango is used handle and render fonts.
*/
#include <assert.h>
#include <stdio.h>
#include <gtk/gtk.h>
#include "css/css.h"
#include "css/utils.h"
#include "gtk/font_pango.h"
#include "gtk/plotters.h"
#include "render/font.h"
#include "utils/utils.h"
#include "utils/log.h"
#include "desktop/options.h"
static bool nsfont_width(const plot_font_style_t *fstyle,
const char *string, size_t length,
int *width);
static bool nsfont_position_in_string(const plot_font_style_t *fstyle,
const char *string, size_t length,
int x, size_t *char_offset, int *actual_x);
static bool nsfont_split(const plot_font_style_t *style,
const char *string, size_t length,
int x, size_t *char_offset, int *actual_x);
const struct font_functions nsfont = {
nsfont_width,
nsfont_position_in_string,
nsfont_split
};
static PangoContext *nsfont_pango_context = NULL;
static PangoLayout *nsfont_pango_layout = NULL;
static inline void nsfont_pango_check(void)
{
if (nsfont_pango_context == NULL) {
LOG(("Creating nsfont_pango_context."));
nsfont_pango_context = gdk_pango_context_get();
}
if (nsfont_pango_layout == NULL) {
LOG(("Creating nsfont_pango_layout."));
nsfont_pango_layout = pango_layout_new(nsfont_pango_context);
}
}
/**
* Measure the width of a string.
*
* \param fstyle plot style for this text
* \param string UTF-8 string to measure
* \param length length of string
* \param width updated to width of string[0..length)
* \return true on success, false on error and error reported
*/
bool nsfont_width(const plot_font_style_t *fstyle,
const char *string, size_t length,
int *width)
{
PangoFontDescription *desc;
if (length == 0) {
*width = 0;
return true;
}
nsfont_pango_check();
desc = nsfont_style_to_description(fstyle);
pango_layout_set_font_description(nsfont_pango_layout, desc);
pango_layout_set_text(nsfont_pango_layout, string, length);
pango_layout_get_pixel_size(nsfont_pango_layout, width, 0);
pango_font_description_free(desc);
/* LOG(("fstyle: %p string:\"%.*s\", length: %u, width: %dpx",
fstyle, length, string, length, *width));
*/
return true;
}
/**
* Find the position in a string where an x coordinate falls.
*
* \param fstyle plot style for this text
* \param string UTF-8 string to measure
* \param length length of string
* \param x x coordinate to search for
* \param char_offset updated to offset in string of actual_x, [0..length]
* \param actual_x updated to x coordinate of character closest to x
* \return true on success, false on error and error reported
*/
bool nsfont_position_in_string(const plot_font_style_t *fstyle,
const char *string, size_t length,
int x, size_t *char_offset, int *actual_x)
{
int index;
PangoFontDescription *desc;
PangoRectangle pos;
nsfont_pango_check();
desc = nsfont_style_to_description(fstyle);
pango_layout_set_font_description(nsfont_pango_layout, desc);
pango_layout_set_text(nsfont_pango_layout, string, length);
if (pango_layout_xy_to_index(nsfont_pango_layout, x * PANGO_SCALE,
0, &index, 0) == FALSE)
index = length;
pango_layout_index_to_pos(nsfont_pango_layout, index, &pos);
pango_font_description_free(desc);
*char_offset = index;
*actual_x = PANGO_PIXELS(pos.x);
return true;
}
/**
* Find where to split a string to make it fit a width.
*
* \param fstyle style for this text
* \param string UTF-8 string to measure
* \param length length of string, in bytes
* \param x width available
* \param char_offset updated to offset in string of actual_x, [1..length]
* \param actual_x updated to x coordinate of character closest to x
* \return true on success, false on error and error reported
*
* On exit, char_offset indicates first character after split point.
*
* Note: char_offset of 0 should never be returned.
*
* Returns:
* char_offset giving split point closest to x, where actual_x <= x
* else
* char_offset giving split point closest to x, where actual_x > x
*
* Returning char_offset == length means no split possible
*/
bool nsfont_split(const plot_font_style_t *fstyle,
const char *string, size_t length,
int x, size_t *char_offset, int *actual_x)
{
int index = length;
PangoFontDescription *desc;
PangoContext *context;
PangoLayout *layout;
PangoLayoutLine *line;
desc = nsfont_style_to_description(fstyle);
context = gdk_pango_context_get();
layout = pango_layout_new(context);
pango_layout_set_font_description(layout, desc);
pango_layout_set_text(layout, string, length);
/* Limit width of layout to the available width */
pango_layout_set_width(layout, x * PANGO_SCALE);
/* Request word wrapping */
pango_layout_set_wrap(layout, PANGO_WRAP_WORD);
/* Prevent pango treating linebreak characters as line breaks */
pango_layout_set_single_paragraph_mode(layout, TRUE);
/* Obtain the second line of the layout (if there is one) */
line = pango_layout_get_line(layout, 1);
if (line != NULL) {
/* Pango split the text. The line's start_index indicates the
* start of the character after the line break. */
index = line->start_index;
}
g_object_unref(layout);
g_object_unref(context);
pango_font_description_free(desc);
*char_offset = index;
/* Obtain the pixel offset of the split character */
nsfont_width(fstyle, string, index, actual_x);
return true;
}
/**
* Render a string.
*
* \param x x coordinate
* \param y y coordinate
* \param string UTF-8 string to measure
* \param length length of string
* \param style plot style for this text
* \return true on success, false on error and error reported
*/
bool nsfont_paint(int x, int y, const char *string, size_t length,
const plot_font_style_t *fstyle)
{
PangoFontDescription *desc;
PangoLayout *layout;
PangoLayoutLine *line;
gint size;
if (length == 0)
return true;
desc = nsfont_style_to_description(fstyle);
size = (gint)(pango_font_description_get_size(desc));
if (pango_font_description_get_size_is_absolute(desc))
pango_font_description_set_absolute_size(desc, size);
else
pango_font_description_set_size(desc, size);
layout = pango_cairo_create_layout(current_cr);
pango_layout_set_font_description(layout, desc);
pango_layout_set_text(layout, string, length);
line = pango_layout_get_line(layout, 0);
cairo_move_to(current_cr, x, y + 0.5);
nsgtk_set_colour(fstyle->foreground);
pango_cairo_show_layout_line(current_cr, line);
pango_font_description_free(desc);
return true;
}
/**
* Convert a plot style to a PangoFontDescription.
*
* \param style plot style for this text
* \return a new Pango font description
*/
PangoFontDescription *nsfont_style_to_description(
const plot_font_style_t *fstyle)
{
unsigned int size;
PangoFontDescription *desc;
PangoStyle style = PANGO_STYLE_NORMAL;
switch (fstyle->family) {
case PLOT_FONT_FAMILY_SERIF:
desc = pango_font_description_from_string(nsoption_charp(font_serif));
break;
case PLOT_FONT_FAMILY_MONOSPACE:
desc = pango_font_description_from_string(nsoption_charp(font_mono));
break;
case PLOT_FONT_FAMILY_CURSIVE:
desc = pango_font_description_from_string(nsoption_charp(font_cursive));
break;
case PLOT_FONT_FAMILY_FANTASY:
desc = pango_font_description_from_string(nsoption_charp(font_fantasy));
break;
case PLOT_FONT_FAMILY_SANS_SERIF:
default:
desc = pango_font_description_from_string(nsoption_charp(font_sans));
break;
}
size = (fstyle->size * PANGO_SCALE) / FONT_SIZE_SCALE;
if (fstyle->flags & FONTF_ITALIC)
style = PANGO_STYLE_ITALIC;
else if (fstyle->flags & FONTF_OBLIQUE)
style = PANGO_STYLE_OBLIQUE;
pango_font_description_set_style(desc, style);
pango_font_description_set_weight(desc, (PangoWeight) fstyle->weight);
pango_font_description_set_size(desc, size);
if (fstyle->flags & FONTF_SMALLCAPS) {
pango_font_description_set_variant(desc,
PANGO_VARIANT_SMALL_CAPS);
} else {
pango_font_description_set_variant(desc, PANGO_VARIANT_NORMAL);
}
return desc;
}