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-rw-r--r--trunk/pango/mapping.c328
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+/* Pango
+ * mapping.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.
+ */
+
+#include <config.h>
+
+/* 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-glyph.h"
+
+/**
+ * pango_glyph_string_index_to_x:
+ * @glyphs: the glyphs return from pango_shape()
+ * @text: the text for the run
+ * @length: the number of bytes (not characters) in @text.
+ * @analysis: the analysis information return from pango_itemize()
+ * @index_: the byte index within @text
+ * @trailing: whether we should compute the result for the beginning
+ * or end of the character.
+ * @x_pos: location to store result
+ *
+ * Converts from character position to x position. (X position
+ * is measured from the left edge of the run). Character positions
+ * are computed by dividing up each cluster into equal portions.
+ */
+
+void
+pango_glyph_string_index_to_x (PangoGlyphString *glyphs,
+ char *text,
+ int length,
+ PangoAnalysis *analysis,
+ int index,
+ gboolean trailing,
+ int *x_pos)
+{
+ int i;
+ int start_xpos = 0;
+ int end_xpos = 0;
+ int width = 0;
+
+ int start_index = -1;
+ int end_index = -1;
+
+ int cluster_chars = 0;
+ int cluster_offset = 0;
+
+ char *p;
+
+ 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] > index)
+ {
+ end_index = glyphs->log_clusters[i];
+ end_xpos = width;
+ break;
+ }
+
+ if (glyphs->log_clusters[i] != start_index)
+ {
+ start_index = 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] > index)
+ {
+ end_index = glyphs->log_clusters[i];
+ end_xpos = width;
+ break;
+ }
+
+ if (glyphs->log_clusters[i] != start_index)
+ {
+ start_index = glyphs->log_clusters[i];
+ start_xpos = width;
+ }
+
+ width += glyphs->glyphs[i].geometry.width;
+ }
+ }
+
+ if (end_index == -1)
+ {
+ end_index = length;
+ end_xpos = (analysis->level % 2) ? 0 : width;
+ }
+
+ /* Calculate offset of character within cluster */
+
+ p = text + start_index;
+ while (p < text + end_index)
+ {
+ if (p < text + index)
+ cluster_offset++;
+ cluster_chars++;
+ p = g_utf8_next_char (p);
+ }
+
+ if (trailing)
+ cluster_offset += 1;
+
+ *x_pos = ((cluster_chars - cluster_offset) * start_xpos +
+ cluster_offset * end_xpos) / cluster_chars;
+}
+
+/**
+ * pango_glyph_string_x_to_index:
+ * @glyphs: the glyphs return from pango_shape()
+ * @text: the text for the run
+ * @length: the number of bytes (not characters) in text.
+ * @analysis: the analysis information return from pango_itemize()
+ * @x_pos: the x offset (in #PangoGlyphUnit)
+ * @index_: location to store calculated byte index within @text
+ * @trailing: location to store a integer indicating where
+ * whether the user clicked on the leading or trailing
+ * edge of the character.
+ *
+ * Convert from x offset to character position. Character positions
+ * are computed by dividing up each cluster into equal portions.
+ * In scripts where positioning within a cluster is not allowed
+ * (such as Thai), the returned value may not be a valid cursor
+ * position; the caller must combine the result with the logical
+ * attributes for the text to compute the valid cursor position.
+ */
+void
+pango_glyph_string_x_to_index (PangoGlyphString *glyphs,
+ char *text,
+ int length,
+ PangoAnalysis *analysis,
+ int x_pos,
+ int *index,
+ gboolean *trailing)
+{
+ int i;
+ int start_xpos = 0;
+ int end_xpos = 0;
+ int width = 0;
+
+ int start_index = -1;
+ int end_index = -1;
+
+ int cluster_chars = 0;
+ char *p;
+
+ 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 (glyphs->log_clusters[i] != start_index)
+ {
+ if (found)
+ {
+ end_index = glyphs->log_clusters[i];
+ end_xpos = width;
+ break;
+ }
+ else
+ {
+ start_index = 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 (glyphs->log_clusters[i] != start_index)
+ {
+ if (found)
+ {
+ end_index = glyphs->log_clusters[i];
+ end_xpos = width;
+ break;
+ }
+ else
+ {
+ start_index = 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;
+ }
+ }
+
+ if (end_index == -1)
+ {
+ end_index = length;
+ end_xpos = (analysis->level % 2) ? 0 : width;
+ }
+
+ /* Calculate number of chars within cluster */
+ p = text + start_index;
+ while (p < text + end_index)
+ {
+ p = g_utf8_next_char (p);
+ cluster_chars++;
+ }
+
+ if (start_xpos == end_xpos)
+ {
+ if (index)
+ *index = start_index;
+ if (trailing)
+ *trailing = 0;
+ }
+ else
+ {
+ double cp = ((double)(x_pos - start_xpos) * cluster_chars) / (end_xpos - start_xpos);
+
+ /* LTR and right-to-left have to be handled separately
+ * here because of the edge condition when we are exactly
+ * at a pixel boundary; end_xpos goes with the next
+ * character for LTR, with the previous character for RTL.
+ */
+ if (start_xpos < end_xpos) /* Left-to-right */
+ {
+ if (index)
+ {
+ char *p = text + start_index;
+ int i = 0;
+
+ while (i + 1 <= cp)
+ {
+ p = g_utf8_next_char (p);
+ i++;
+ }
+
+ *index = (p - text);
+ }
+
+ if (trailing)
+ *trailing = (cp - (int)cp >= 0.5) ? 1 : 0;
+ }
+ else /* Right-to-left */
+ {
+ if (index)
+ {
+ char *p = text + start_index;
+ int i = 0;
+
+ while (i + 1 < cp)
+ {
+ p = g_utf8_next_char (p);
+ i++;
+ }
+
+ *index = (p - text);
+ }
+
+ if (trailing)
+ {
+ double cp_flip = cluster_chars - cp;
+ *trailing = (cp_flip - (int)cp_flip >= 0.5) ? 0 : 1;
+ }
+ }
+ }
+}
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