[gimp] app: IM preedit displayed as expected.

[Jehan Pagès <jehanp src gnome org>]

commit 2cfed0cb527422c966e0bae7d8a7727ef945e764
Author: Jehan <jehan girinstud io>
Date:   Mon May 9 00:35:19 2016 +0200

    app: IM preedit displayed as expected.
    
    When gtk_im_context_get_preedit_string(), we have to inspect the
    returned Pango attributes, so that the preedit string can be displayed
    in the expected fashion (i.e. as in other programs).
    Some input methods in particular would even break the preedit strings
    in several chunks of text displayed differently (for instance Japanese),
    depending on the cursor position within the preedit string.

 app/tools/gimptexttool-editor.c |  189 ++++++++++++++++++++++++++++++++++----
 app/tools/gimptexttool.h        |    2 +
 2 files changed, 171 insertions(+), 20 deletions(-)
---
diff --git a/app/tools/gimptexttool-editor.c b/app/tools/gimptexttool-editor.c
index 44e1564..c930194 100644
--- a/app/tools/gimptexttool-editor.c
+++ b/app/tools/gimptexttool-editor.c
@@ -533,6 +533,27 @@ gimp_text_tool_editor_key_release (GimpTextTool *text_tool,
 void
 gimp_text_tool_reset_im_context (GimpTextTool *text_tool)
 {
+  /* Cancel any ungoing preedit on reset. */
+  if (text_tool->preedit_string && *text_tool->preedit_string)
+    {
+      GtkTextBuffer *buffer = GTK_TEXT_BUFFER (text_tool->buffer);
+      GtkTextIter    start;
+      GtkTextIter    end;
+
+      gtk_text_buffer_get_iter_at_mark (buffer, &start,
+                                        text_tool->preedit_start);
+      gtk_text_buffer_get_iter_at_mark (buffer, &end,
+                                        text_tool->preedit_end);
+      gtk_text_buffer_delete_interactive (buffer, &start, &end, TRUE);
+
+      g_free (text_tool->preedit_string);
+      text_tool->preedit_string = NULL;
+      gtk_text_buffer_delete_mark (buffer, text_tool->preedit_start);
+      gtk_text_buffer_delete_mark (buffer, text_tool->preedit_end);
+      text_tool->preedit_start = NULL;
+      text_tool->preedit_end = NULL;
+    }
+
   if (text_tool->needs_im_reset)
     {
       text_tool->needs_im_reset = FALSE;
@@ -1342,40 +1363,148 @@ gimp_text_tool_im_preedit_changed (GtkIMContext *context,
                                    GimpTextTool *text_tool)
 {
   GtkTextBuffer *buffer = GTK_TEXT_BUFFER (text_tool->buffer);
+  PangoAttrList *attrs;
 
   if (text_tool->preedit_string)
-    g_free (text_tool->preedit_string);
-
-  gtk_im_context_get_preedit_string (context,
-                                     &text_tool->preedit_string, NULL,
-                                     &text_tool->preedit_cursor);
+    {
+      if (*text_tool->preedit_string)
+        {
+          GtkTextIter start;
+          GtkTextIter end;
+
+          gtk_text_buffer_get_iter_at_mark (buffer, &start,
+                                            text_tool->preedit_start);
+          gtk_text_buffer_get_iter_at_mark (buffer, &end,
+                                            text_tool->preedit_end);
+          gtk_text_buffer_delete_interactive (buffer, &start, &end, TRUE);
+
+          gtk_text_buffer_delete_mark (buffer, text_tool->preedit_start);
+          gtk_text_buffer_delete_mark (buffer, text_tool->preedit_end);
+          text_tool->preedit_start = NULL;
+          text_tool->preedit_end = NULL;
+        }
+      g_free (text_tool->preedit_string);
+      text_tool->preedit_string = NULL;
+    }
 
   gimp_text_tool_delete_selection (text_tool);
 
+  gtk_im_context_get_preedit_string (context,
+                                     &text_tool->preedit_string, &attrs,
+                                     &text_tool->preedit_cursor);
   if (text_tool->preedit_string && *text_tool->preedit_string)
     {
-      GtkTextIter start;
-      GtkTextIter end;
-      gint        line;
-      gint        pos;
+      PangoAttrIterator *attr_iter;
+      GtkTextIter        iter;
+      gint               i;
 
-      /* Get current position. */
-      gtk_text_buffer_get_iter_at_mark (buffer, &start,
+      /* Save the preedit start position. */
+      gtk_text_buffer_get_iter_at_mark (buffer, &iter,
                                         gtk_text_buffer_get_insert (buffer));
-      pos  = gtk_text_iter_get_line_index (&start);
-      line = gtk_text_iter_get_line (&start);
+      text_tool->preedit_start = gtk_text_buffer_create_mark (buffer,
+                                                              "preedit-start",
+                                                              &iter, TRUE);
 
-      /* Insert the preedit text at current cursor position. */
-      gimp_text_tool_enter_text (text_tool, text_tool->preedit_string);
+      /* Loop through chunks of preedit text with different attributes. */
+      attr_iter = pango_attr_list_get_iterator (attrs);
+      do
+        {
+          gint attr_start;
+          gint attr_end;
 
-      /* Get the new position. */
-      gtk_text_buffer_get_iter_at_mark (buffer, &end,
+          pango_attr_iterator_range (attr_iter, &attr_start, &attr_end);
+          if (attr_start < strlen (text_tool->preedit_string))
+            {
+              GSList      *attrs_pos;
+              GtkTextMark *start_mark;
+              GtkTextIter  start;
+              GtkTextIter  end;
+
+              gtk_text_buffer_get_iter_at_mark (buffer, &start,
+                                                gtk_text_buffer_get_insert (buffer));
+              start_mark = gtk_text_buffer_create_mark (buffer,
+                                                        NULL,
+                                                        &start, TRUE);
+
+              gtk_text_buffer_begin_user_action (buffer);
+
+              /* Insert the preedit chunk at current cursor position. */
+              gtk_text_buffer_insert_at_cursor (GTK_TEXT_BUFFER (text_tool->buffer),
+                                                text_tool->preedit_string + attr_start,
+                                                attr_end - attr_start);
+              gtk_text_buffer_get_iter_at_mark (buffer, &start,
+                                                start_mark);
+              gtk_text_buffer_delete_mark (buffer, start_mark);
+              gtk_text_buffer_get_iter_at_mark (buffer, &end,
+                                                gtk_text_buffer_get_insert (buffer));
+
+              /* Apply text attributes to preedit text. */
+              attrs_pos = pango_attr_iterator_get_attrs (attr_iter);
+              while (attrs_pos)
+                {
+                  PangoAttribute *attr = attrs_pos->data;
+
+                  if (attr)
+                    {
+                      switch (attr->klass->type)
+                        {
+                        case PANGO_ATTR_UNDERLINE:
+                          gtk_text_buffer_apply_tag (buffer,
+                                                     text_tool->buffer->underline_tag,
+                                                     &start, &end);
+                          break;
+                        case PANGO_ATTR_BACKGROUND:
+                        case PANGO_ATTR_FOREGROUND:
+                            {
+                              PangoAttrColor *color_attr = (PangoAttrColor *) attr;
+                              GimpRGB         color;
+
+                              color.r = (gdouble) color_attr->color.red / 65535.0;
+                              color.g = (gdouble) color_attr->color.green / 65535.0;
+                              color.b = (gdouble) color_attr->color.blue / 65535.0;
+
+                              if (attr->klass->type == PANGO_ATTR_BACKGROUND)
+                                {
+                                  gimp_text_buffer_set_bg_color (text_tool->buffer,
+                                                                 &start, &end,
+                                                                 &color);
+                                }
+                              else
+                                {
+                                  gimp_text_buffer_set_color (text_tool->buffer,
+                                                              &start, &end,
+                                                              &color);
+                                }
+                            }
+                          break;
+                        default:
+                          /* Unsupported tags. */
+                          break;
+                        }
+                    }
+                  attrs_pos = attrs_pos->next;
+                }
+              gtk_text_buffer_end_user_action (buffer);
+            }
+        }
+      while (pango_attr_iterator_next (attr_iter));
+
+      /* Save the preedit end position. */
+      gtk_text_buffer_get_iter_at_mark (buffer, &iter,
                                         gtk_text_buffer_get_insert (buffer));
+      text_tool->preedit_end = gtk_text_buffer_create_mark (buffer,
+                                                            "preedit-end",
+                                                            &iter, TRUE);
 
-      /* Select the preedit text. */
-      gtk_text_buffer_get_iter_at_line_index (buffer, &start, line, pos);
-      gtk_text_buffer_select_range (buffer, &start, &end);
+      /* Move the cursor to the expected location. */
+      gtk_text_buffer_get_iter_at_mark (buffer, &iter, text_tool->preedit_start);
+      for (i = 0; i < text_tool->preedit_cursor; i++)
+        gtk_text_iter_forward_char (&iter);
+      gtk_text_buffer_place_cursor (buffer, &iter);
+
+      pango_attr_iterator_destroy (attr_iter);
     }
+  pango_attr_list_unref (attrs);
 }
 
 static void
@@ -1383,7 +1512,27 @@ gimp_text_tool_im_commit (GtkIMContext *context,
                           const gchar  *str,
                           GimpTextTool *text_tool)
 {
+  if (text_tool->preedit_string && *text_tool->preedit_string)
+    {
+      GtkTextBuffer *buffer = GTK_TEXT_BUFFER (text_tool->buffer);
+      GtkTextIter    start;
+      GtkTextIter    end;
+
+      gtk_text_buffer_get_iter_at_mark (buffer, &start,
+                                        text_tool->preedit_start);
+      gtk_text_buffer_get_iter_at_mark (buffer, &end,
+                                        text_tool->preedit_end);
+      gtk_text_buffer_delete_interactive (buffer, &start, &end, TRUE);
+
+      gtk_text_buffer_delete_mark (buffer, text_tool->preedit_start);
+      gtk_text_buffer_delete_mark (buffer, text_tool->preedit_end);
+      text_tool->preedit_start = NULL;
+      text_tool->preedit_end = NULL;
+    }
   gimp_text_tool_enter_text (text_tool, str);
+
+  g_free (text_tool->preedit_string);
+  text_tool->preedit_string = NULL;
 }
 
 static gboolean
diff --git a/app/tools/gimptexttool.h b/app/tools/gimptexttool.h
index a99e5bb..0c8a8a1 100644
--- a/app/tools/gimptexttool.h
+++ b/app/tools/gimptexttool.h
@@ -79,6 +79,8 @@ struct _GimpTextTool
 
   gchar          *preedit_string;
   gint            preedit_cursor;
+  GtkTextMark    *preedit_start;
+  GtkTextMark    *preedit_end;
 
   gboolean        overwrite_mode;
   gint            x_pos;