Cleanup GtkIMContext related code by splitting it into separated source file.

chrome/browser/renderer_host/render_widget_host_view_gtk.cc

Index: chrome/browser/renderer_host/render_widget_host_view_gtk.cc
===================================================================
--- chrome/browser/renderer_host/render_widget_host_view_gtk.cc	(revision 22567)
+++ chrome/browser/renderer_host/render_widget_host_view_gtk.cc	(working copy)
@@ -10,6 +10,9 @@
 #include <gdk/gdkx.h>
 #include <cairo/cairo.h>
 
+#include <algorithm>
+#include <string>
+
 #include "base/gfx/gtk_util.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
@@ -21,6 +24,7 @@
 #include "chrome/common/render_messages.h"
 #include "chrome/common/x11_util.h"
 #include "chrome/browser/renderer_host/backing_store.h"
+#include "chrome/browser/renderer_host/gtk_im_context_wrapper.h"
 #include "chrome/browser/renderer_host/render_widget_host.h"
 #include "webkit/api/public/gtk/WebInputEventFactory.h"
 #include "webkit/glue/webcursor_gtk_data.h"
@@ -30,569 +34,6 @@
 
 using WebKit::WebInputEventFactory;
 
-// This class is a conveience wrapper for GtkIMContext.
-class RenderWidgetHostViewGtkIMContext {
- public:
-  explicit RenderWidgetHostViewGtkIMContext(RenderWidgetHostViewGtk* host_view)
-      : host_view_(host_view),
-        context_(gtk_im_multicontext_new()),
-        context_simple_(gtk_im_context_simple_new()),
-        is_focused_(false),
-        is_composing_text_(false),
-        is_enabled_(false),
-        is_in_key_event_handler_(false),
-        preedit_cursor_position_(0),
-        is_preedit_changed_(false) {
-    DCHECK(context_);
-    DCHECK(context_simple_);
-
-    // context_ and context_simple_ share the same callback handlers.
-    // All data come from them are treated equally.
-    // context_ is for full input method support.
-    // context_simple_ is for supporting dead/compose keys when input method is
-    // disabled by webkit, eg. in password input box.
-    g_signal_connect(context_, "preedit_start",
-                     G_CALLBACK(HandlePreeditStartThunk), this);
-    g_signal_connect(context_, "preedit_end",
-                     G_CALLBACK(HandlePreeditEndThunk), this);
-    g_signal_connect(context_, "preedit_changed",
-                     G_CALLBACK(HandlePreeditChangedThunk), this);
-    g_signal_connect(context_, "commit",
-                     G_CALLBACK(HandleCommitThunk), this);
-
-    g_signal_connect(context_simple_, "preedit_start",
-                     G_CALLBACK(HandlePreeditStartThunk), this);
-    g_signal_connect(context_simple_, "preedit_end",
-                     G_CALLBACK(HandlePreeditEndThunk), this);
-    g_signal_connect(context_simple_, "preedit_changed",
-                     G_CALLBACK(HandlePreeditChangedThunk), this);
-    g_signal_connect(context_simple_, "commit",
-                     G_CALLBACK(HandleCommitThunk), this);
-  }
-
-  ~RenderWidgetHostViewGtkIMContext() {
-    if (context_)
-      g_object_unref(context_);
-    if (context_simple_)
-      g_object_unref(context_simple_);
-  }
-
-  void ProcessKeyEvent(GdkEventKey* event) {
-    // Indicates preedit-changed and commit signal handlers that we are
-    // processing a key event.
-    is_in_key_event_handler_ = true;
-    // Reset this flag so that we can know if preedit is changed after
-    // processing this key event.
-    is_preedit_changed_ = false;
-    // Clear it so that we can know if something needs committing after
-    // processing this key event.
-    commit_text_.clear();
-
-    // According to Document Object Model (DOM) Level 3 Events Specification
-    // Appendix A: Keyboard events and key identifiers
-    // http://www.w3.org/TR/DOM-Level-3-Events/keyset.html:
-    // The event sequence would be:
-    // 1. keydown
-    // 2. textInput
-    // 3. keyup
-    //
-    // So keydown must be sent to webkit before sending input method result,
-    // while keyup must be sent afterwards.
-    // However on Windows, if a keydown event has been processed by IME, its
-    // virtual keycode will be changed to VK_PROCESSKEY(0xE5) before being sent
-    // to application.
-    // To emulate the windows behavior as much as possible, we need to send the
-    // key event to the GtkIMContext object first, and decide whether or not to
-    // send the original key event to webkit according to the result from IME.
-    //
-    // If IME is enabled by WebKit, this event will be dispatched to context_
-    // to get full IME support. Otherwise it'll be dispatched to
-    // context_simple_, so that dead/compose keys can still work.
-    //
-    // It sends a "commit" signal when it has a character to be inserted
-    // even when we use a US keyboard so that we can send a Char event
-    // (or an IME event) to the renderer in our "commit"-signal handler.
-    // We should send a KeyDown (or a KeyUp) event before dispatching this
-    // event to the GtkIMContext object (and send a Char event) so that WebKit
-    // can dispatch the JavaScript events in the following order: onkeydown(),
-    // onkeypress(), and onkeyup(). (Many JavaScript pages assume this.)
-    gboolean filtered = false;
-    if (is_enabled_) {
-      filtered = gtk_im_context_filter_keypress(context_, event);
-    } else {
-      filtered = gtk_im_context_filter_keypress(context_simple_, event);
-    }
-
-    NativeWebKeyboardEvent wke(event);
-
-    // Send filtered keydown event before sending IME result.
-    if (event->type == GDK_KEY_PRESS && filtered)
-      ProcessFilteredKeyPressEvent(&wke);
-
-    // Send IME results. In most cases, it's only available if the key event
-    // is filtered by IME. But in rare cases, an unfiltered key event may also
-    // generate IME results.
-    // Any IME results generated by a unfiltered key down event must be sent
-    // before the key down event, to avoid some tricky issues. For example,
-    // when using latin-post input method, pressing 'a' then Backspace, may
-    // generate following events in sequence:
-    //  1. keydown 'a' (filtered)
-    //  2. preedit changed to "a"
-    //  3. keyup 'a' (unfiltered)
-    //  4. keydown Backspace (unfiltered)
-    //  5. commit "a"
-    //  6. preedit end
-    //  7. keyup Backspace (unfiltered)
-    //
-    // In this case, the input box will be in a strange state if keydown
-    // Backspace is sent to webkit before commit "a" and preedit end.
-    ProcessInputMethodResult(event, filtered);
-
-    // Send unfiltered keydown and keyup events after sending IME result.
-    if (event->type == GDK_KEY_PRESS && !filtered)
-      ProcessUnfilteredKeyPressEvent(&wke);
-    else if (event->type == GDK_KEY_RELEASE)
-      host_view_->GetRenderWidgetHost()->ForwardKeyboardEvent(wke);
-
-    // End of key event processing.
-    is_in_key_event_handler_ = false;
-  }
-
-  void UpdateStatus(int control, const gfx::Rect& caret_rect) {
-    // The renderer has updated its IME status.
-    // Control the GtkIMContext object according to this status.
-    if (!context_ || !is_focused_)
-      return;
-
-    DCHECK(!is_in_key_event_handler_);
-
-    // TODO(james.su@gmail.com): Following code causes a side effect:
-    // When trying to move cursor from one text input box to another while
-    // composition text is still not confirmed, following CompleteComposition()
-    // calls will prevent the cursor from moving outside the first input box.
-    if (control == IME_DISABLE) {
-      if (is_enabled_) {
-        CompleteComposition();
-        gtk_im_context_reset(context_simple_);
-        gtk_im_context_focus_out(context_);
-        is_enabled_ = false;
-      }
-    } else {
-      // Enable the GtkIMContext object if it's not enabled yet.
-      if (!is_enabled_) {
-        // Reset context_simple_ to its initial state, in case it's currently
-        // in middle of a composition session inside a password box.
-        gtk_im_context_reset(context_simple_);
-        gtk_im_context_focus_in(context_);
-        // It might be true when switching from a password box in middle of a
-        // composition session.
-        is_composing_text_ = false;
-        is_enabled_ = true;
-      } else if (control == IME_COMPLETE_COMPOSITION) {
-        CompleteComposition();
-      }
-
-      // Updates the position of the IME candidate window.
-      // The position sent from the renderer is a relative one, so we need to
-      // attach the GtkIMContext object to this window before changing the
-      // position.
-      GdkRectangle cursor_rect(caret_rect.ToGdkRectangle());
-      gtk_im_context_set_cursor_location(context_, &cursor_rect);
-    }
-  }
-
-  void OnFocusIn() {
-    if (is_focused_)
-      return;
-
-    // Tracks the focused state so that we can give focus to the
-    // GtkIMContext object correctly later when IME is enabled by WebKit.
-    is_focused_ = true;
-
-    // We should call gtk_im_context_set_client_window() only when this window
-    // gain (or release) the window focus because an immodule may reset its
-    // internal status when processing this function.
-    gtk_im_context_set_client_window(context_,
-                                     host_view_->native_view()->window);
-
-    // Notify the GtkIMContext object of this focus-in event only if IME is
-    // enabled by WebKit.
-    if (is_enabled_)
-      gtk_im_context_focus_in(context_);
-
-    // Actually current GtkIMContextSimple implementation doesn't care about
-    // client window. This line is just for safe.
-    gtk_im_context_set_client_window(context_simple_,
-                                     host_view_->native_view()->window);
-
-    // context_simple_ is always enabled.
-    // Actually it doesn't care focus state at all.
-    gtk_im_context_focus_in(context_simple_);
-
-    // Enables RenderWidget's IME related events, so that we can be notified
-    // when WebKit wants to enable or disable IME.
-    host_view_->GetRenderWidgetHost()->ImeSetInputMode(true);
-  }
-
-  void OnFocusOut() {
-    if (!is_focused_)
-      return;
-
-    // Tracks the focused state so that we won't give focus to the
-    // GtkIMContext object unexpectly.
-    is_focused_ = false;
-
-    // Notify the GtkIMContext object of this focus-out event only if IME is
-    // enabled by WebKit.
-    if (is_enabled_) {
-      // To reset the GtkIMContext object and prevent data loss.
-      CompleteComposition();
-      gtk_im_context_focus_out(context_);
-    }
-
-    // Detach this GtkIMContext object from this window.
-    gtk_im_context_set_client_window(context_, NULL);
-
-    // To make sure it'll be in correct state when focused in again.
-    gtk_im_context_reset(context_simple_);
-    gtk_im_context_focus_out(context_simple_);
-    gtk_im_context_set_client_window(context_simple_, NULL);
-
-    // Reset stored IME status.
-    is_composing_text_ = false;
-    preedit_text_.clear();
-    preedit_cursor_position_ = 0;
-
-    // Disable RenderWidget's IME related events to save bandwidth.
-    host_view_->GetRenderWidgetHost()->ImeSetInputMode(false);
-  }
-
- private:
-  // Check if a text needs commit by forwarding a char event instead of
-  // by confirming as a composition text.
-  bool NeedCommitByForwardingCharEvent() {
-    // If there is no composition text and has only one character to be
-    // committed, then the character will be send to webkit as a Char event
-    // instead of a confirmed composition text.
-    // It should be fine to handle BMP character only, as non-BMP characters
-    // can always be committed as confirmed composition text.
-    return !is_composing_text_ && commit_text_.length() == 1;
-  }
-
-  void ProcessFilteredKeyPressEvent(NativeWebKeyboardEvent* wke) {
-    // Copied from third_party/WebKit/WebCore/page/EventHandler.cpp
-    //
-    // Match key code of composition keydown event on windows.
-    // IE sends VK_PROCESSKEY which has value 229;
-    //
-    // Please refer to following documents for detals:
-    // - Virtual-Key Codes
-    //   http://msdn.microsoft.com/en-us/library/ms645540(VS.85).aspx
-    // - How the IME System Works
-    //   http://msdn.microsoft.com/en-us/library/cc194848.aspx
-    // - ImmGetVirtualKey Function
-    //   http://msdn.microsoft.com/en-us/library/dd318570(VS.85).aspx
-    const int kCompositionEventKeyCode = 229;
-
-    // If IME has filtered this event, then replace virtual key code with
-    // VK_PROCESSKEY. See comment in ProcessKeyEvent() for details.
-    // It's only required for keydown events.
-    // To emulate windows behavior, when input method is enabled, if the commit
-    // text can be emulated by a Char event, then don't do this replacement.
-    if (!NeedCommitByForwardingCharEvent()) {
-      wke->windowsKeyCode = kCompositionEventKeyCode;
-      // Prevent RenderView::UnhandledKeyboardEvent() from processing it.
-      // Otherwise unexpected result may occur. For example if it's a
-      // Backspace key event, the browser may go back to previous page.
-      if (wke->os_event) {
-        wke->os_event->keyval = GDK_VoidSymbol;
-        wke->os_event->state = 0;
-      }
-    }
-    host_view_->GetRenderWidgetHost()->ForwardKeyboardEvent(*wke);
-  }
-
-  void ProcessUnfilteredKeyPressEvent(NativeWebKeyboardEvent* wke) {
-    RenderWidgetHost* host = host_view_->GetRenderWidgetHost();
-
-    // Send keydown event as it, because it's not filtered by IME.
-    host->ForwardKeyboardEvent(*wke);
-
-    // IME is disabled by WebKit or the GtkIMContext object cannot handle
-    // this key event.
-    // This case is caused by two reasons:
-    // 1. The given key event is a control-key event, (e.g. return, page up,
-    //    page down, tab, arrows, etc.) or;
-    // 2. The given key event is not a control-key event but printable
-    //    characters aren't assigned to the event, (e.g. alt+d, etc.)
-    // Create a Char event manually from this key event and send it to the
-    // renderer when this Char event contains a printable character which
-    // should be processed by WebKit.
-    // isSystemKey will be set to true if this key event has Alt modifier,
-    // see WebInputEventFactory::keyboardEvent() for details.
-    if (wke->text[0]) {
-      wke->type = WebKit::WebInputEvent::Char;
-      host->ForwardKeyboardEvent(*wke);
-    }
-  }
-
-  // Processes result returned from input method after filtering a key event.
-  // |filtered| indicates if the key event was filtered by the input method.
-  void ProcessInputMethodResult(const GdkEventKey* event, bool filtered) {
-    RenderWidgetHost* host = host_view_->GetRenderWidgetHost();
-    bool committed = false;
-    // We do commit before preedit change, so that we can optimize some
-    // unnecessary preedit changes.
-    if (commit_text_.length()) {
-      if (filtered && NeedCommitByForwardingCharEvent()) {
-        // Send a Char event when we input a composed character without IMEs
-        // so that this event is to be dispatched to onkeypress() handlers,
-        // autofill, etc.
-        // Only commit text generated by a filtered key down event can be sent
-        // as a Char event, because a unfiltered key down event will probably
-        // generate another Char event.
-        // TODO(james.su@gmail.com): Is it necessary to support non BMP chars
-        // here?
-        NativeWebKeyboardEvent char_event(commit_text_[0],
-                                          event->state,
-                                          base::Time::Now().ToDoubleT());
-        host->ForwardKeyboardEvent(char_event);
-      } else {
-        committed = true;
-        // Send an IME event.
-        // Unlike a Char event, an IME event is NOT dispatched to onkeypress()
-        // handlers or autofill.
-        host->ImeConfirmComposition(commit_text_);
-        // Set this flag to false, as this composition session has been
-        // finished.
-        is_composing_text_ = false;
-      }
-    }
-
-    // Send preedit text only if it's changed.
-    // If a text has been committed, then we don't need to send the empty
-    // preedit text again.
-    if (is_preedit_changed_) {
-      if (preedit_text_.length()) {
-        host->ImeSetComposition(preedit_text_, preedit_cursor_position_,
-                                -1, -1);
-      } else if (!committed) {
-        host->ImeCancelComposition();
-      }
-    }
-  }
-
-  void CompleteComposition() {
-    if (!is_enabled_)
-      return;
-
-    // If WebKit requires to complete current composition, then we need commit
-    // existing preedit text and reset the GtkIMContext object.
-
-    // Backup existing preedit text to avoid it's being cleared when resetting
-    // the GtkIMContext object.
-    string16 old_preedit_text = preedit_text_;
-
-    // Clear it so that we can know if anything is committed by following
-    // line.
-    commit_text_.clear();
-
-    // Resetting the GtkIMContext. Input method may commit something at this
-    // point. In this case, we shall not commit the preedit text again.
-    gtk_im_context_reset(context_);
-
-    // If nothing was committed by above line, then commit stored preedit text
-    // to prevent data loss.
-    if (old_preedit_text.length() && commit_text_.length() == 0) {
-      host_view_->GetRenderWidgetHost()->ImeConfirmComposition(
-          old_preedit_text);
-    }
-
-    is_composing_text_ = false;
-    preedit_text_.clear();
-    preedit_cursor_position_ = 0;
-  }
-
-  // Real code of "commit" signal handler.
-  void HandleCommit(const string16& text) {
-    // Append the text to the buffer, because commit signal might be fired
-    // multiple times when processing a key event.
-    commit_text_.append(text);
-    // Nothing needs to do, if it's currently in ProcessKeyEvent()
-    // handler, which will send commit text to webkit later. Otherwise,
-    // we need send it here.
-    // It's possible that commit signal is fired without a key event, for
-    // example when user input via a voice or handwriting recognition software.
-    // In this case, the text must be committed directly.
-    if (!is_in_key_event_handler_) {
-      host_view_->GetRenderWidgetHost()->ImeConfirmComposition(text);
-    }
-  }
-
-  // Real code of "preedit-start" signal handler.
-  void HandlePreeditStart() {
-    is_composing_text_ = true;
-  }
-
-  // Real code of "preedit-changed" signal handler.
-  void HandlePreeditChanged(const string16& text, int cursor_position) {
-    bool changed = false;
-    // If preedit text or cursor position is not changed since last time,
-    // then it's not necessary to update it again.
-    // Preedit text is always stored, so that we can commit it when webkit
-    // requires.
-    // Don't set is_preedit_changed_ to false if there is no change, because
-    // this handler might be called multiple times with the same data.
-    if (cursor_position != preedit_cursor_position_ || text != preedit_text_) {
-      preedit_text_ = text;
-      preedit_cursor_position_ = cursor_position;
-      is_preedit_changed_ = true;
-      changed = true;
-    }
-
-    // In case we are using a buggy input method which doesn't fire
-    // "preedit_start" signal.
-    if (text.length())
-      is_composing_text_ = true;
-
-    // Nothing needs to do, if it's currently in ProcessKeyEvent()
-    // handler, which will send preedit text to webkit later.
-    // Otherwise, we need send it here if it's been changed.
-    if (!is_in_key_event_handler_ && changed) {
-      if (text.length()) {
-        host_view_->GetRenderWidgetHost()->ImeSetComposition(
-            text, cursor_position, -1, -1);
-      } else {
-        host_view_->GetRenderWidgetHost()->ImeCancelComposition();
-      }
-    }
-  }
-
-  // Real code of "preedit-end" signal handler.
-  void HandlePreeditEnd() {
-    bool changed = false;
-    if (preedit_text_.length()) {
-      // The composition session has been finished.
-      preedit_text_.clear();
-      preedit_cursor_position_ = 0;
-      is_preedit_changed_ = true;
-      changed = true;
-    }
-
-    // If there is still a preedit text when firing "preedit-end" signal,
-    // we need inform webkit to clear it.
-    // It's only necessary when it's not in ProcessKeyEvent ().
-    if (!is_in_key_event_handler_ && changed) {
-      host_view_->GetRenderWidgetHost()->ImeCancelComposition();
-    }
-
-    // Don't set is_composing_text_ to false here, because "preedit_end"
-    // signal may be fired before "commit" signal.
-  }
-
- private:
-  // Signal handlers of GtkIMContext object.
-  static void HandleCommitThunk(GtkIMContext* context, gchar* text,
-                                RenderWidgetHostViewGtkIMContext* self) {
-    self->HandleCommit(UTF8ToUTF16(text));
-  }
-
-  static void HandlePreeditStartThunk(GtkIMContext* context,
-                                      RenderWidgetHostViewGtkIMContext* self) {
-    self->HandlePreeditStart();
-  }
-
-  static void HandlePreeditChangedThunk(
-      GtkIMContext* context, RenderWidgetHostViewGtkIMContext* self) {
-    gchar* text = NULL;
-    gint cursor_position = 0;
-    gtk_im_context_get_preedit_string(context, &text, NULL, &cursor_position);
-    self->HandlePreeditChanged(UTF8ToUTF16(text), cursor_position);
-    g_free(text);
-  }
-
-  static void HandlePreeditEndThunk(GtkIMContext* context,
-                                    RenderWidgetHostViewGtkIMContext* self) {
-    self->HandlePreeditEnd();
-  }
-
- private:
-  // The parent object.
-  RenderWidgetHostViewGtk* host_view_;
-
-  // The GtkIMContext object.
-  // In terms of the DOM event specification Appendix A
-  //   <http://www.w3.org/TR/DOM-Level-3-Events/keyset.html>,
-  // GTK uses a GtkIMContext object for the following two purposes:
-  //  1. Composing Latin characters (A.1.2), and;
-  //  2. Composing CJK characters with an IME (A.1.3).
-  // Many JavaScript pages assume composed Latin characters are dispatched to
-  // their onkeypress() handlers but not dispatched CJK characters composed
-  // with an IME. To emulate this behavior, we should monitor the status of
-  // this GtkIMContext object and prevent sending Char events when a
-  // GtkIMContext object sends a "commit" signal with the CJK characters
-  // composed by an IME.
-  GtkIMContext* context_;
-
-  // A GtkIMContextSimple object, for supporting dead/compose keys when input
-  // method is disabled, eg. in password input box.
-  GtkIMContext* context_simple_;
-
-  // Whether or not this widget is focused.
-  bool is_focused_;
-
-  // Whether or not the above GtkIMContext is composing a text with an IME.
-  // This flag is used in "commit" signal handler of the GtkIMContext object,
-  // which determines how to submit the result text to WebKit according to this
-  // flag.
-  // If this flag is true or there are more than one characters in the result,
-  // then the result text will be committed to WebKit as a confirmed
-  // composition. Otherwise, it'll be forwarded as a key event.
-  //
-  // The GtkIMContext object sends a "preedit_start" before it starts composing
-  // a text and a "preedit_end" signal after it finishes composing it.
-  // "preedit_start" signal is monitored to turn it on.
-  // We don't monitor "preedit_end" signal to turn it off, because an input
-  // method may fire "preedit_end" signal before "commit" signal.
-  // A buggy input method may not fire "preedit_start" and/or "preedit_end"
-  // at all, so this flag will also be set to true when "preedit_changed" signal
-  // is fired with non-empty preedit text.
-  bool is_composing_text_;
-
-  // Whether or not the IME is enabled.
-  // This flag is actually controlled by RenderWidget.
-  // It shall be set to false when an ImeUpdateStatus message with control ==
-  // IME_DISABLE is received, and shall be set to true if control ==
-  // IME_COMPLETE_COMPOSITION or IME_MOVE_WINDOWS.
-  // When this flag is false, keyboard events shall be dispatched directly
-  // instead of sending to context_.
-  bool is_enabled_;
-
-  // Whether or not it's currently running inside key event handler.
-  // If it's true, then preedit-changed and commit handler will backup the
-  // preedit or commit text instead of sending them down to webkit.
-  // key event handler will send them later.
-  bool is_in_key_event_handler_;
-
-  // Stores a copy of the most recent preedit text retrieved from context_.
-  // When an ImeUpdateStatus message with control == IME_COMPLETE_COMPOSITION
-  // is received, this stored preedit text (if not empty) shall be committed,
-  // and context_ shall be reset.
-  string16 preedit_text_;
-
-  // Stores the cursor position in the stored preedit text.
-  int preedit_cursor_position_;
-
-  // Whether or not the preedit has been changed since last key event.
-  bool is_preedit_changed_;
-
-  // Stores a copy of the most recent commit text received by commit signal
-  // handler.
-  string16 commit_text_;
-
-  DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewGtkIMContext);
-};
-
 // This class is a simple convenience wrapper for Gtk functions. It has only
 // static methods.
 class RenderWidgetHostViewGtkWidget {
@@ -642,8 +83,7 @@
                            G_CALLBACK(MouseScrollEvent), host_view);
 
     // Create GtkIMContext wrapper object.
-    host_view->im_context_.reset(
-        new RenderWidgetHostViewGtkIMContext(host_view));
+    host_view->im_context_.reset(new GtkIMContextWrapper(host_view));
 
     return widget;
   }