Fleshes out the tooltip implementation for views on Gtk. It doesn't...

views/widget/tooltip_manager_gtk.cc

 // Copyright (c) 2009 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.
 
 #include "views/widget/tooltip_manager_gtk.h"
 
 #include "app/gfx/font.h"
 #include "base/logging.h"
+#include "base/string_util.h"
+#include "views/focus/focus_manager.h"
+#include "views/widget/root_view.h"
+#include "views/widget/widget_gtk.h"
+
+// WARNING: this implementation is good for a start, but it doesn't give us
+// control of tooltip positioning both on mouse events and when showing from
+// keyboard. We may need to write our own to give us the control we need.
 
 namespace views {
 
+static gfx::Font* LoadDefaultFont() {
+  // Create a tooltip widget and extract the font from it (we have to realize
+  // it to make sure the correct font gets set).
+  GtkWidget* window = gtk_window_new(GTK_WINDOW_POPUP);
+  gtk_widget_set_name(window, "gtk-tooltip");
+  GtkWidget* label = gtk_label_new("");
+  gtk_widget_show(label);
+
+  gtk_container_add(GTK_CONTAINER(window), label);
+  gtk_widget_realize(window);
+
+  GtkStyle* style = gtk_widget_get_style(label);
+  PangoFontDescription* pfd = style->font_desc;
+  gfx::Font* font = new gfx::Font(gfx::Font::CreateFont(pfd));
+  pango_font_description_free(pfd);
+
+  gtk_widget_destroy(window);
+
+  return font;
+}
+
 // static
 int TooltipManager::GetTooltipHeight() {
-  NOTIMPLEMENTED();
+  // This is only used to position the tooltip, and we don't yet support
+  // positioning the tooltip, it isn't worth trying to implement this.
   return 0;
 }
 
 // static
 gfx::Font TooltipManager::GetDefaultFont() {
-  NOTIMPLEMENTED();
-  return gfx::Font();
+  static gfx::Font* font = NULL;
+  if (!font)
+    font = LoadDefaultFont();
+
+  return *font;
 }
 
 // static
 const std::wstring& TooltipManager::GetLineSeparator() {
   static std::wstring* line_separator = NULL;
   if (!line_separator)
     line_separator = new std::wstring(L"\n");
   return *line_separator;
 }
 
-TooltipManagerGtk::TooltipManagerGtk(Widget* widget) : widget_(widget) {
+// Callback from gtk_container_foreach. If |*label_p| is NULL and |widget| is
+// a GtkLabel, |*label_p| is set to |widget|. Used to find the first GtkLabel
+// in a container.
+static void LabelLocatorCallback(GtkWidget* widget,
+                                 gpointer label_p) {
+  GtkWidget** label = static_cast<GtkWidget**>(label_p);
+  if (!*label && GTK_IS_LABEL(widget))
+    *label = widget;
+}
+
+// By default GtkTooltip wraps at a longish string. We want more control over
+// that wrapping. The only way to do that is dig out the label and set
+// gtk_label_set_max_width_chars, which is what this code does. I also tried
+// setting a custom widget on the tooltip, but there is a bug in Gtk that
+// triggers continually hiding/showing the widget in that case.
+static void AdjustLabel(GtkTooltip* tooltip) {
+  static const char kAdjustedLabelPropertyValue[] = "_adjusted_label_";
+  gpointer adjusted_value = g_object_get_data(G_OBJECT(tooltip),
+                                              kAdjustedLabelPropertyValue);
+  if (adjusted_value)
+    return;
+
+  adjusted_value = reinterpret_cast<gpointer>(1);
+  g_object_set_data(G_OBJECT(tooltip), kAdjustedLabelPropertyValue,
+                    adjusted_value);
+
+  GtkWidget* parent;
+  {
+    // Create a label so that we can get the parent. The Tooltip ends up taking
+    // ownership of the label and deleting it.
+    GtkWidget* label = gtk_label_new("");
+    gtk_tooltip_set_custom(tooltip, label);
+    parent = gtk_widget_get_parent(label);
+    gtk_tooltip_set_custom(tooltip, NULL);
+  }
+  if (parent) {
+    // We found the parent, find the first label, which is where the tooltip
+    // text ends up going.
+    GtkLabel* real_label = NULL;
+    gtk_container_foreach(GTK_CONTAINER(parent), LabelLocatorCallback,
+                          static_cast<gpointer>(&real_label));
+    if (real_label)
+      gtk_label_set_max_width_chars(GTK_LABEL(real_label), 3000);
+  }
+}
+
+TooltipManagerGtk::TooltipManagerGtk(WidgetGtk* widget)
+    : widget_(widget),
+      keyboard_view_(NULL) {
+}
+
+bool TooltipManagerGtk::ShowTooltip(int x, int y, bool for_keyboard,
+                                    GtkTooltip* tooltip) {
+  View* view = NULL;
+  gfx::Point view_loc;
+  if (keyboard_view_) {
+    view = keyboard_view_;
+    view_loc.SetPoint(view->width() / 2, view->height() / 2);
+  } else if (!for_keyboard) {
+    RootView* root_view = widget_->GetRootView();
+    view = root_view->GetViewForPoint(gfx::Point(x, y));
+    view_loc.SetPoint(x, y);
+    View::ConvertPointFromWidget(view, &view_loc);
+  } else {
+    FocusManager* focus_manager = widget_->GetFocusManager();
+    if (focus_manager) {
+      view = focus_manager->GetFocusedView();
+      if (view)
+        view_loc.SetPoint(view->width() / 2, view->height() / 2);
+    }
+  }
+
+  if (!view)
+    return false;
+
+  std::wstring text;
+  if (!view->GetTooltipText(view_loc.x(), view_loc.y(), &text))
+    return false;
+
+  AdjustLabel(tooltip);
+
+  // Sets the area of the tooltip. This way if different views in the same
+  // widget have tooltips the tooltip doesn't get stuck at the same location.
+  gfx::Rect vis_bounds = view->GetVisibleBounds();
+  gfx::Point widget_loc(vis_bounds.x(), vis_bounds.y());
+  View::ConvertPointToWidget(view, &widget_loc);
+  GdkRectangle tip_area = { widget_loc.x(), widget_loc.y(),
+                            vis_bounds.width(), vis_bounds.height() };
+  gtk_tooltip_set_tip_area(tooltip, &tip_area);
+
+  int max_width, line_count;
+  gfx::Point screen_loc(x, y);
+  View::ConvertPointToScreen(widget_->GetRootView(), &screen_loc);
+  TrimTooltipToFit(&text, &max_width, &line_count, screen_loc.x(),
+                   screen_loc.y());
+  gtk_tooltip_set_text(tooltip, WideToUTF8(text).c_str());
+
+  return true;
 }
 
 void TooltipManagerGtk::UpdateTooltip() {
-  NOTIMPLEMENTED();
+  // UpdateTooltip may be invoked after the widget has been destroyed.
+  GtkWidget* widget = widget_->GetNativeView();
+  if (!widget)
+    return;
+
+  GdkDisplay* display = gtk_widget_get_display(widget);
+  if (display)
+    gtk_tooltip_trigger_tooltip_query(display);
 }
 
 void TooltipManagerGtk::TooltipTextChanged(View* view) {
-  NOTIMPLEMENTED();
+  UpdateTooltip();
 }
 
 void TooltipManagerGtk::ShowKeyboardTooltip(View* view) {
-  NOTIMPLEMENTED();
+  if (view == keyboard_view_)
+    return;  // We're already showing the tip for the specified view.
+
+  // We have to hide the current tooltip, then show again.
+  HideKeyboardTooltip();
+
+  std::wstring tooltip_text;
+  if (!view->GetTooltipText(0, 0, &tooltip_text))
+    return;  // The view doesn't have a tooltip, nothing to do.
+
+  keyboard_view_ = view;
+  if (!SendShowHelpSignal()) {
+    keyboard_view_ = NULL;
+    return;
+  }
 }
 
 void TooltipManagerGtk::HideKeyboardTooltip() {
-  NOTIMPLEMENTED();
+  if (!keyboard_view_)
+    return;
+
+  SendShowHelpSignal();
+  keyboard_view_ = NULL;
+}
+
+bool TooltipManagerGtk::SendShowHelpSignal() {
+  GtkWidget* widget = widget_->window_contents();
+  GType itype = G_TYPE_FROM_INSTANCE(G_OBJECT(widget));
+  guint signal_id;
+  GQuark detail;
+  if (!g_signal_parse_name("show_help", itype, &signal_id, &detail, FALSE)) {
+    NOTREACHED();
+    return false;
+  }
+  gboolean result;
+  g_signal_emit(widget, signal_id, 0, GTK_WIDGET_HELP_TOOLTIP, &result);
+  return true;
 }
 
 }  // namespace views