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/* Pango
* itemize.c:
*
* Copyright (C) 1999 Red Hat Software
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/* The initial implementation here is script independent,
* but it might actually need to be virtualized into the
* rendering modules. Otherwise, we probably will end up
* enforcing unnatural cursor behavior for some languages.
*
* The only distinction that Uniscript makes is whether
* cursor positioning is allowed within clusters or not.
*/
#include <pango.h>
#include <unicode.h>
/**
* pango_cp_to_x:
* @text: the text for the run
* @length: the number of bytes (not characters) in @text.
* @analysis: the analysis information return from pango_itemize()
* @glyphs: the glyphs return from pango_shape()
* @char_pos: the character position
* @trailing: whether we should compute the result for the beginning
* or end of the character (or cluster - the decision
* for which may be script dependent).
* @x_pos: location to store result
*
* Converts from character position to x position. (X position
* is measured from the left edge of the run)
*/
void
pango_cp_to_x (gchar *text,
gint length,
PangoAnalysis *analysis,
PangoGlyphString *glyphs,
gint char_pos,
gboolean trailing,
gint *x_pos)
{
gint i;
gint start_xpos = 0;
gint end_xpos = 0;
gint width = 0;
gint start_char = -1;
gint end_char = -1;
g_return_if_fail (glyphs != NULL);
g_return_if_fail (length >= 0);
g_return_if_fail (length == 0 || text != NULL);
if (!x_pos) /* Allow the user to do the useless */
return;
if (glyphs->num_glyphs == 0)
{
*x_pos = 0;
return;
}
/* Calculate the starting and ending character positions
* and x positions for the cluster
*/
if (analysis->level % 2) /* Right to left */
{
for (i = glyphs->num_glyphs - 1; i >= 0; i--)
width += glyphs->glyphs[i].geometry.width;
for (i = glyphs->num_glyphs - 1; i >= 0; i--)
{
if (glyphs->log_clusters[i] > char_pos)
{
end_char = glyphs->log_clusters[i];
end_xpos = width;
break;
}
if (start_char == -1 || glyphs->log_clusters[i] != start_char)
{
start_char = glyphs->log_clusters[i];
start_xpos = width;
}
width -= glyphs->glyphs[i].geometry.width;
}
}
else /* Left to right */
{
for (i = 0; i < glyphs->num_glyphs; i++)
{
if (glyphs->log_clusters[i] > char_pos)
{
end_char = glyphs->log_clusters[i];
end_xpos = width;
break;
}
if (start_char == -1 || glyphs->log_clusters[i] != start_char)
{
start_char = glyphs->log_clusters[i];
start_xpos = width;
}
width += glyphs->glyphs[i].geometry.width;
}
}
/* We need the character index of one past the end of the
* string, and so we have to recalculate the entire length
* of the string...
*/
if (end_char == -1)
{
end_char = unicode_strlen (text, length);
end_xpos = (analysis->level % 2) ? 0 : width;
}
/* Now interpolate the result. For South Asian languages
* we actually shouldn't iterpolate
*/
if (trailing)
char_pos += 1;
*x_pos = (((double)(end_char - char_pos)) * start_xpos +
((double)(char_pos - start_char)) * end_xpos) /
(end_char - start_char);
}
/**
* pango_x_to_cp:
* @text: the text for the run
* @length: the number of bytes (not characters) in text.
* @analysis: the analysis information return from pango_itemize()
* @glyphs: the glyphs return from pango_shape()
* @x_pos: location to store the returned x character position
* @char_pos: location to store calculated character position.
* @trailing: location to store a integer indicating where
* in the cluster the user clicked. If the script
* allows positioning within the cluster, it is either
* 0 or 1; otherwise it is either 0 or the number
* of characters in the cluster. In either case
* 0 represents the trailing edge of the cluster.
*
* Converts from x position to x character. (X position
* is measured from the left edge of the run)
*/
void
pango_x_to_cp (gchar *text,
gint length,
PangoAnalysis *analysis,
PangoGlyphString *glyphs,
gint x_pos,
gint *char_pos,
gint *trailing)
{
gint i;
gint start_xpos = 0;
gint end_xpos = 0;
gint width = 0;
gint start_char = -1;
gint end_char = -1;
gboolean found = FALSE;
/* Find the cluster containing the position */
width = 0;
if (analysis->level % 2) /* Right to left */
{
for (i = glyphs->num_glyphs - 1; i >= 0; i--)
width += glyphs->glyphs[i].geometry.width;
for (i = glyphs->num_glyphs - 1; i >= 0; i--)
{
if (start_char == -1 || glyphs->log_clusters[i] != start_char)
{
if (found)
{
end_char = glyphs->log_clusters[i];
end_xpos = width;
break;
}
else
{
start_char = glyphs->log_clusters[i];
start_xpos = width;
}
}
width -= glyphs->glyphs[i].geometry.width;
if (width <= x_pos && x_pos < width + glyphs->glyphs[i].geometry.width)
found = TRUE;
}
}
else /* Left to right */
{
for (i = 0; i < glyphs->num_glyphs; i++)
{
if (start_char == -1 || glyphs->log_clusters[i] != start_char)
{
if (found)
{
end_char = glyphs->log_clusters[i];
end_xpos = width;
break;
}
else
{
start_char = glyphs->log_clusters[i];
start_xpos = width;
}
}
if (width <= x_pos && x_pos < width + glyphs->glyphs[i].geometry.width)
found = TRUE;
width += glyphs->glyphs[i].geometry.width;
}
}
/* We need the character index of one past the end of the
* string, and so we have to recalculate the entire length
* of the string...
*/
if (end_char == -1)
{
end_char = unicode_strlen (text, length);
end_xpos = (analysis->level % 2) ? 0 : width;
}
if (start_xpos == end_xpos)
{
if (char_pos)
*char_pos = start_char;
if (trailing)
trailing = 0;
}
else
{
double cp = (((double)(end_xpos - x_pos)) * start_char +
((double)(x_pos - start_xpos)) * end_char) /
(end_xpos - start_xpos);
if (char_pos)
*char_pos = (int)cp;
if (trailing)
*trailing = (cp - (int)cp) > 0.5 ? 1 : 0;
}
}
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