[Linux] Handle preedit string in omnibox correctly (part1).

This CL hooks GtkTextView's "preedit-changed" signal (added since 2.20.0) to clear existing selection range when a preedit string is set.

BUG=18808 IME canidate and previous URL will show together in Omnibox when typing Chinese using SCIM
TEST=See bug reports.

Review URL: http://codereview.chromium.org/4190006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@64170 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 34 insertions, 0 deletions

diff --git a/chrome/browser/autocomplete/autocomplete_edit_view_gtk.cc b/chrome/browser/autocomplete/autocomplete_edit_view_gtk.cc
index 0249c6b..e2d085e 100644
--- a/chrome/browser/autocomplete/autocomplete_edit_view_gtk.cc
+++ b/chrome/browser/autocomplete/autocomplete_edit_view_gtk.cc
@@ -304,6 +304,10 @@ void AutocompleteEditViewGtk::Init() {
                    G_CALLBACK(&HandleWidgetDirectionChangedThunk), this);
   g_signal_connect(text_view_, "delete-from-cursor",
                    G_CALLBACK(&HandleDeleteFromCursorThunk), this);
+#if GTK_CHECK_VERSION(2,20,0)
+  g_signal_connect(text_view_, "preedit-changed",
+                   G_CALLBACK(&HandlePreeditChangedThunk), this);
+#endif
 
   // Setup for the Instant suggestion text view.
   instant_view_ = gtk_text_view_new();
@@ -1705,3 +1709,24 @@ void AutocompleteEditViewGtk::UpdatePrimarySelectionIfValidURL() {
     OwnPrimarySelection(selected_text_);
   }
 }
+
+#if GTK_CHECK_VERSION(2,20,0)
+void AutocompleteEditViewGtk::HandlePreeditChanged(GtkWidget* sender,
+                                                   const gchar* preedit) {
+  // GtkTextView won't fire "begin-user-action" and "end-user-action" signals
+  // when changing the preedit string, so we need to call
+  // OnBeforePossibleChange() and OnAfterPossibleChange() by ourselves.
+  OnBeforePossibleChange();
+  if (preedit && *preedit) {
+    // GtkTextView will only delete the selection range when committing the
+    // preedit string, which will cause very strange behavior, so we need to
+    // delete the selection range here explicitly. See http://crbug.com/18808.
+    if (preedit_.empty())
+      gtk_text_buffer_delete_selection(text_buffer_, false, true);
+    preedit_ = UTF8ToWide(preedit);
+  } else {
+    preedit_.clear();
+  }
+  OnAfterPossibleChange();
+}
+#endif
diff --git a/chrome/browser/autocomplete/autocomplete_edit_view_gtk.h b/chrome/browser/autocomplete/autocomplete_edit_view_gtk.h
index 2cbbc2a..9feec20 100644
--- a/chrome/browser/autocomplete/autocomplete_edit_view_gtk.h
+++ b/chrome/browser/autocomplete/autocomplete_edit_view_gtk.h
@@ -211,6 +211,10 @@ class AutocompleteEditViewGtk : public AutocompleteEditView,
                        HandleDeleteFromCursor, GtkDeleteType, gint);
   CHROMEGTK_CALLBACK_1(AutocompleteEditViewGtk, gboolean,
                        HandleInstantViewButtonPress, GdkEventButton*);
+#if GTK_CHECK_VERSION(2,20,0)
+  CHROMEGTK_CALLBACK_1(AutocompleteEditViewGtk, void, HandlePreeditChanged,
+                       const gchar*);
+#endif
 
   // Callback for the PRIMARY selection clipboard.
   static void ClipboardGetSelectionThunk(GtkClipboard* clipboard,
@@ -422,6 +426,11 @@ class AutocompleteEditViewGtk : public AutocompleteEditView,
   // is not suggested text, that means the user manually made the selection.
   bool selection_suggested_;
 
+#if GTK_CHECK_VERSION(2,20,0)
+  // Stores the text being composed by the input method.
+  std::wstring preedit_;
+#endif
+
   DISALLOW_COPY_AND_ASSIGN(AutocompleteEditViewGtk);
 };