[gspell/wip/entry-context-menu: 3/3] EntryUtils: add function to get char position at GdkEventButton

[Sébastien Wilmet <swilmet src gnome org>]

commit d703d6fc2526d4e698086b5e3ad2e73a8169a2d7
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Fri Nov 25 18:45:05 2016 +0100

    EntryUtils: add function to get char position at GdkEventButton

 gspell/gspell-entry-utils.c |   61 +++++++++++++++++++++++++++++++++++++++++++
 gspell/gspell-entry-utils.h |   11 +++++--
 2 files changed, 69 insertions(+), 3 deletions(-)
---
diff --git a/gspell/gspell-entry-utils.c b/gspell/gspell-entry-utils.c
index 3a081b4..718198c 100644
--- a/gspell/gspell-entry-utils.c
+++ b/gspell/gspell-entry-utils.c
@@ -148,4 +148,65 @@ _gspell_entry_utils_get_words (GtkEntry *entry)
        return g_slist_reverse (list);
 }
 
+static gint
+get_cursor_byte_position (GtkEntry *entry)
+{
+       return 0;
+}
+
+/* The return value is in characters, not bytes. And a position suitable for the
+ * text in the GtkEntryBuffer, i.e. without the preedit text.
+ */
+gint
+_gspell_entry_utils_get_char_position_at_event (GtkEntry       *entry,
+                                               GdkEventButton *event,
+                                               gint            preedit_byte_length)
+{
+       gint scroll_offset; /* in pixels */
+       gint x; /* in pixels */
+       PangoLayout *layout;
+       PangoLayoutLine *line;
+       gint byte_index;
+       gint trailing_chars;
+       gint cursor_byte_pos;
+       const gchar *text;
+       gint char_pos;
+
+       g_object_get (entry,
+                     "scroll-offset", &scroll_offset,
+                     NULL);
+
+       x = event->x + scroll_offset;
+
+       layout = gtk_entry_get_layout (entry);
+       line = pango_layout_get_line_readonly (layout, 0);
+
+       pango_layout_line_x_to_index (line,
+                                     x * PANGO_SCALE,
+                                     &byte_index,
+                                     &trailing_chars);
+
+       cursor_byte_pos = get_cursor_byte_position (entry);
+
+       if (preedit_byte_length > 0 &&
+           cursor_byte_pos <= byte_index)
+       {
+               if (cursor_byte_pos + preedit_byte_length <= byte_index)
+               {
+                       byte_index -= preedit_byte_length;
+               }
+               else
+               {
+                       byte_index = cursor_byte_pos;
+                       trailing_chars = 0;
+               }
+       }
+
+       text = gtk_entry_get_text (entry);
+       char_pos = g_utf8_pointer_to_offset (text, text + byte_index);
+       char_pos += trailing;
+
+       return char_pos;
+}
+
 /* ex:set ts=8 noet: */
diff --git a/gspell/gspell-entry-utils.h b/gspell/gspell-entry-utils.h
index 813b5b2..8a9d483 100644
--- a/gspell/gspell-entry-utils.h
+++ b/gspell/gspell-entry-utils.h
@@ -43,13 +43,18 @@ struct _GspellEntryWord
 };
 
 G_GNUC_INTERNAL
-GspellEntryWord *_gspell_entry_word_new                        (void);
+GspellEntryWord *_gspell_entry_word_new                                (void);
 
 G_GNUC_INTERNAL
-void            _gspell_entry_word_free                (gpointer data);
+void            _gspell_entry_word_free                        (gpointer data);
 
 G_GNUC_INTERNAL
-GSList *        _gspell_entry_utils_get_words          (GtkEntry *entry);
+GSList *        _gspell_entry_utils_get_words                  (GtkEntry *entry);
+
+G_GNUC_INTERNAL
+gint            _gspell_entry_utils_get_char_position_at_event (GtkEntry       *entry,
+                                                                GdkEventButton *event,
+                                                                gint            preedit_byte_length);
 
 G_END_DECLS