app: update tool widgets on display-shell changes more granularly

Partially revert commit c73710e410,
avoiding updating tool widgets unconditionally on tool resume in
GimpDrawTool -- it's too expensive in general.

Instead, handle display-shell changes in GimpToolWidget, by adding
GimpToolWidget::update_on_{scale,scroll,rotate} flags, which
subclasses can use to request an update on any of these events.

Set the flags as necessary for the affected widgets.

app/display/gimptoolcompass.c

@@ -198,6 +198,8 @@ gimp_tool_compass_class_init (GimpToolCompassClass *klass)
   widget_class->leave_notify     = gimp_tool_compass_leave_notify;
   widget_class->motion_modifier  = gimp_tool_compass_motion_modifier;
   widget_class->get_cursor       = gimp_tool_compass_get_cursor;
+  widget_class->update_on_scale  = TRUE;
+  widget_class->update_on_rotate = TRUE;
 
   compass_signals[CREATE_GUIDES] =
     g_signal_new ("create-guides",

app/display/gimptoolfocus.c

@@ -224,6 +224,7 @@ gimp_tool_focus_class_init (GimpToolFocusClass *klass)
   widget_class->motion_modifier = gimp_tool_focus_motion_modifier;
   widget_class->hover_modifier  = gimp_tool_focus_hover_modifier;
   widget_class->get_cursor      = gimp_tool_focus_get_cursor;
+  widget_class->update_on_scale = TRUE;
 
   g_object_class_install_property (object_class, PROP_TYPE,
                                    g_param_spec_enum ("type", NULL, NULL,

app/display/gimptoolrectangle.c

@@ -463,6 +463,7 @@ gimp_tool_rectangle_class_init (GimpToolRectangleClass *klass)
   widget_class->key_press       = gimp_tool_rectangle_key_press;
   widget_class->motion_modifier = gimp_tool_rectangle_motion_modifier;
   widget_class->get_cursor      = gimp_tool_rectangle_get_cursor;
+  widget_class->update_on_scale = TRUE;
 
   rectangle_signals[CHANGE_COMPLETE] =
     g_signal_new ("change-complete",

app/display/gimptooltransformgrid.c

@@ -232,6 +232,7 @@ gimp_tool_transform_grid_class_init (GimpToolTransformGridClass *klass)
   widget_class->leave_notify    = gimp_tool_transform_grid_leave_notify;
   widget_class->hover_modifier  = gimp_tool_transform_grid_hover_modifier;
   widget_class->get_cursor      = gimp_tool_transform_grid_get_cursor;
+  widget_class->update_on_scale = TRUE;
 
   g_object_class_install_property (object_class, PROP_TRANSFORM,
                                    gimp_param_spec_matrix3 ("transform",

app/display/gimptoolwidget.c

@@ -221,6 +221,7 @@ gimp_tool_widget_constructed (GObject *object)
 {
   GimpToolWidget        *widget  = GIMP_TOOL_WIDGET (object);
   GimpToolWidgetPrivate *private = widget->private;
+  GimpToolWidgetClass   *klass   = GIMP_TOOL_WIDGET_GET_CLASS (widget);
 
   G_OBJECT_CLASS (parent_class)->constructed (object);
 
@@ -229,6 +230,33 @@ gimp_tool_widget_constructed (GObject *object)
   private->item = gimp_canvas_group_new (private->shell);
 
   gimp_canvas_item_set_visible (private->item, private->visible);
+
+  if (klass->changed)
+    {
+      if (klass->update_on_scale)
+        {
+          g_signal_connect_object (private->shell, "scaled",
+                                   G_CALLBACK (klass->changed),
+                                   widget,
+                                   G_CONNECT_SWAPPED);
+        }
+
+      if (klass->update_on_scroll)
+        {
+          g_signal_connect_object (private->shell, "scrolled",
+                                   G_CALLBACK (klass->changed),
+                                   widget,
+                                   G_CONNECT_SWAPPED);
+        }
+
+      if (klass->update_on_rotate)
+        {
+          g_signal_connect_object (private->shell, "rotated",
+                                   G_CALLBACK (klass->changed),
+                                   widget,
+                                   G_CONNECT_SWAPPED);
+        }
+    }
 }
 
 static void

app/display/gimptoolwidget.h

@@ -125,6 +125,10 @@ struct _GimpToolWidgetClass
                                 const GimpCoords      *coords,
                                 GdkModifierType        state,
                                 const gchar          **ui_path);
+
+  gboolean update_on_scale;
+  gboolean update_on_scroll;
+  gboolean update_on_rotate;
 };
 
 

app/tools/gimpdrawtool.c

@@ -217,11 +217,7 @@ gimp_draw_tool_control (GimpTool       *tool,
   switch (action)
     {
     case GIMP_TOOL_ACTION_PAUSE:
-      break;
-
     case GIMP_TOOL_ACTION_RESUME:
-      if (draw_tool->widget)
-        gimp_tool_widget_changed (draw_tool->widget);
       break;
 
     case GIMP_TOOL_ACTION_HALT: