Hijack mouse-related events for TOUCH_UI builds

views/touchui/touch_event_dispatcher_gtk.cc

+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// This file contains a function that receives a message from the message pump
+// and dispatches that message to the appropriate root view.  That function is
+// 'DispatchEventForTouchUIGtk'.  (Last function in this file.)
+//
+// The appropriate RootView is determined for each incoming event.  The platform
+// specific event is converted to a views event and dispatched directly to the
+// appropriate RootView.
+//
+// This implementation is Gdk specific at the moment, but a future CL will
+// provide a dispatcher that handles events from an X Windows message pump.
+
+// TODO(wyck): Make X Windows versions of all GdkEvent functions.
+// (See individual TODO's below)
+//
+// When we switch the message pump from one that gives us GdkEvents to one that
+// gives us X Windows events, we will need another version of each function.
+// These ones are obviously specific to GdkEvent.
+//
+// Potential names:
+//   Maybe DispatchEventForTouchUIGtk will become DispatchEventForTouchUIX11.
+//
+// It may not be necessary to filter events with IsTouchEvent in the X version,
+// because the message pump may pre-filter the message so that we get only
+// touch events and there is nothing to filter out.
+
+#include <gdk/gdk.h>
+#include <gdk/gdkx.h>
+
+#include "views/widget/root_view.h"
+#include "views/widget/widget_gtk.h"
+
+namespace views {
+
+// gets the RootView associated with the GdkEvent.
+//
+// TODO(wyck): Make X Windows version of this function. (see earlier comment)
+static RootView* FindRootViewForGdkEvent(GdkEvent* event) {
+  GdkEventAny* event_any = reinterpret_cast<GdkEventAny*>(event);
+  if (!event_any) {
+    DLOG(WARNING) << "FindRootViewForGdkEvent was passed a null GdkEvent";
+    return NULL;
+  }
+  GdkWindow* gdk_window = event_any->window;
+
+  // and get the parent
+  gpointer data = NULL;
+  gdk_window_get_user_data(gdk_window, &data);
+  GtkWidget* gtk_widget = reinterpret_cast<GtkWidget*>(data);
+  if (!gtk_widget) {
+    DLOG(WARNING) << "no GtkWidget found for that GdkWindow";
+    return NULL;
+  }
+  WidgetGtk* widget_gtk = WidgetGtk::GetViewForNative(gtk_widget);
+
+  if (!widget_gtk) {
+    DLOG(WARNING) << "no WidgetGtk found for that GtkWidget";
+    return NULL;
+  }
+  return widget_gtk->GetRootView();
+}
+
+// Specialized dispatch for GDK_BUTTON_PRESS events
+static void DispatchButtonPressGtk(const GdkEventButton& event,
+                                   RootView* root_view) {
+  // TODO(wyck): may need to remap coordinates:
+  // If so, it's like this:
+  // gdk_window_get_root_origin(dest, &dest_x, &dest_y);
+  // *x = event->x_root - dest_x;
+  // *y = event->y_root - dest_y;
+
+  if (event.type == GDK_2BUTTON_PRESS || event.type == GDK_3BUTTON_PRESS) {
+    // TODO(wyck): decide what to do about 2 button and 3 button press msgs.
+    // You get both a GDK_BUTTON_PRESS and a GDK_2BUTTON_PRESS, so that's
+    // a bit weird.
+    // I'll ignore these events for now.
+    return;
+  }
+
+  MouseEvent mouse_pressed(Event::ET_MOUSE_PRESSED, event.x, event.y,
+      WidgetGtk::GetFlagsForEventButton(event));
+  root_view->OnMousePressed(mouse_pressed);
+}
+
+// Specialized dispatch for GDK_BUTTON_RELEASE events
+static void DispatchButtonReleaseGtk(const GdkEventButton& event,
+                                     RootView* root_view) {
+  // TODO(wyck): may need to remap coordinates.
+  // If so, it's like this:
+  // gdk_window_get_root_origin(dest, &dest_x, &dest_y);
+  // *x = event->x_root - dest_x;
+  // *y = event->y_root - dest_y;
+
+  MouseEvent mouse_up(Event::ET_MOUSE_RELEASED, event.x, event.y,
+      WidgetGtk::GetFlagsForEventButton(event));
+
+  root_view->OnMouseReleased(mouse_up, false);
+}
+
+// Specialized dispatch for GDK_MOTION_NOTIFY events
+static void DispatchMotionNotifyGtk(const GdkEventMotion& event,
+                                    RootView* root_view) {
+  // Regarding GDK_POINTER_MOTION_HINT_MASK:
+  // GDK_POINTER_MOTION_HINT_MASK may have been used to reduce the number of
+  // GDK_MOTION_NOTIFY events received. Normally a GDK_MOTION_NOTIFY event is
+  // received each time the mouse moves.  But in the hint case, some events are
+  // marked with is_hint TRUE.  Without further action after a hint, no more
+  // motion events will be received.
+  // To receive more motion events after a motion hint event, the application
+  // needs to ask for more by calling gdk_event_request_motions().
+  if (event.is_hint) {
+    gdk_event_request_motions(&event);
+  }
+
+  // TODO(wyck): handle dragging
+  // Apparently it's our job to determine the difference between a move and a
+  // drag.  We should dispatch OnMouseDragged with ET_MOUSE_DRAGGED instead.
+  // It's unclear what constitutes the dragging state.  Which button(s)?
+  int flags = Event::GetFlagsFromGdkState(event.state);
+  MouseEvent mouse_move(Event::ET_MOUSE_MOVED, event.x, event.y, flags);
+  root_view->OnMouseMoved(mouse_move);
+}
+
+// Specialized dispatch for GDK_ENTER_NOTIFY events
+static void DispatchEnterNotifyGtk(const GdkEventCrossing& event,
+                                   RootView* root_view) {
+  // TODO(wyck): I'm not sure if this is necessary yet
+  int flags = (Event::GetFlagsFromGdkState(event.state) &
+               ~(Event::EF_LEFT_BUTTON_DOWN |
+                 Event::EF_MIDDLE_BUTTON_DOWN |
+                 Event::EF_RIGHT_BUTTON_DOWN));
+  MouseEvent mouse_move(Event::ET_MOUSE_MOVED, event.x, event.y, flags);
+  root_view->OnMouseMoved(mouse_move);
+}
+
+// Specialized dispatch for GDK_LEAVE_NOTIFY events
+static void DispatchLeaveNotifyGtk(const GdkEventCrossing& event,
+                                   RootView* root_view) {
+  // TODO(wyck): I'm not sure if this is necessary yet
+  root_view->ProcessOnMouseExited();
+}
+
+// Dispatch an input-related GdkEvent to a RootView
+static void DispatchEventToRootViewGtk(GdkEvent* event, RootView* root_view) {
+  if (!event) {
+    DLOG(WARNING) << "DispatchEventToRootView was passed a null GdkEvent";
+    return;
+  }
+  if (!root_view) {
+    DLOG(WARNING) << "DispatchEventToRootView was passed a null RootView";
+    return;
+  }
+  switch (event->type) {
+    case GDK_BUTTON_PRESS:
+      DispatchButtonPressGtk(*reinterpret_cast<GdkEventButton*>(event),
+                             root_view);
+      break;
+    case GDK_BUTTON_RELEASE:
+      DispatchButtonReleaseGtk(*reinterpret_cast<GdkEventButton*>(event),
+                               root_view);
+      break;
+    case GDK_MOTION_NOTIFY:
+      DispatchMotionNotifyGtk(*reinterpret_cast<GdkEventMotion*>(event),
+                              root_view);
+      break;
+    case GDK_ENTER_NOTIFY:
+      DispatchEnterNotifyGtk(*reinterpret_cast<GdkEventCrossing*>(event),
+                             root_view);
+      break;
+    case GDK_LEAVE_NOTIFY:
+      DispatchLeaveNotifyGtk(*reinterpret_cast<GdkEventCrossing*>(event),
+                             root_view);
+      break;
+    case GDK_2BUTTON_PRESS:
+      DispatchButtonPressGtk(*reinterpret_cast<GdkEventButton*>(event),
+                             root_view);
+      break;
+    case GDK_3BUTTON_PRESS:
+      DispatchButtonPressGtk(*reinterpret_cast<GdkEventButton*>(event),
+                             root_view);
+      break;
+    default:
+      NOTREACHED();
+      break;
+  }
+}
+
+// Called for input-related events only.  Dispatches them directly to the
+// associated RootView.
+//
+// TODO(wyck): Make X Windows version of this function. (see earlier comment)
+static void HijackEventForTouchUIGtk(GdkEvent* event) {
+  // TODO(wyck): something like this...
+  RootView* root_view = FindRootViewForGdkEvent(event);
+  if (!root_view) {
+    DLOG(WARNING) << "no RootView found for that GdkEvent";
+    return;
+  }
+  DispatchEventToRootViewGtk(event, root_view);
+}
+
+// returns true if the GdkEvent is a touch-related input event.
+//
+// TODO(wyck): Make X Windows version of this function. (see earlier comment)
+//
+// If the X Windows events are not-prefiltered, then we can provide a filtering
+// function similar to this GdkEvent-specific function.  Otherwise this function
+// is not needed at all for the X Windows version.
+static bool IsTouchEventGtk(GdkEvent* event) {
+  switch (event->type) {
+    case GDK_BUTTON_PRESS:
+    case GDK_BUTTON_RELEASE:
+    case GDK_MOTION_NOTIFY:
+    case GDK_ENTER_NOTIFY:
+    case GDK_LEAVE_NOTIFY:
+    case GDK_2BUTTON_PRESS:
+    case GDK_3BUTTON_PRESS:
+      return true;
+    default:
+      return false;
+  }
+}
+
+// This is the public entry point for the touch event dispatcher.
+//
+// Hijacks input-related events and routes them directly to a widget_gtk.
+// Returns false for non-input-related events, in which case the caller is still
+// responsible for dispatching the event.
+//
+// TODO(wyck): Make X Windows version of this function. (see earlier comment)
+bool DispatchEventForTouchUIGtk(GdkEvent* event) {
+  // is this is an input-related event...
+  if (IsTouchEventGtk(event)) {
+    HijackEventForTouchUIGtk(event);
+    return true;
+  } else {
+    return false;
+  }
+}
+}  // namespace views