[gnome-boxes] display-page: Show drag and drop message

[Felipe Borges <felipeborges src gnome org>]

commit 49d32e2764304f888ee85f3eb732db60b0a0ed04
Author: Visarion Alexandru <viorel visarion gmail com>
Date:   Sat Nov 11 17:58:43 2017 +0200

    display-page: Show drag and drop message
    
    Currently, when transferring files through DnD, the user
    isn't aware of the actual destination of the files and doesn't
    receive any visual feedback.
    
    Let's show a message when the user is hovering with a file over a
    display which can receive files(currently only SPICE), informing him
    that he is about to send files to the machine and pointing to him
    the destination of the files.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=762321

 data/ui/display-page.ui | 84 +++++++++++++++++++++++++++++++++++++++++++++++++
 src/display-page.vala   | 42 ++++++++++++++++++++++++-
 2 files changed, 125 insertions(+), 1 deletion(-)
---
diff --git a/data/ui/display-page.ui b/data/ui/display-page.ui
index 24da3be8..cf2b3aee 100644
--- a/data/ui/display-page.ui
+++ b/data/ui/display-page.ui
@@ -41,6 +41,90 @@
               </object>
             </child>
 
+            <child type="overlay">
+              <object class="GtkBox" id="transfer_message_box">
+                <property name="can_focus">False</property>
+                <property name="halign">fill</property>
+                <property name="valign">fill</property>
+                <property name="hexpand">True</property>
+                <property name="vexpand">True</property>
+                <style>
+                  <class name="app-notification"/>
+                </style>
+                <child>
+                  <object class="GtkImage">
+                    <property name="visible">True</property>
+                    <property name="can_focus">False</property>
+                    <property name="halign">end</property>
+                    <property name="valign">center</property>
+                    <property name="margin_right">24</property>
+                    <property name="stock">gtk-save</property>
+                    <property name="icon_size">6</property>
+                  </object>
+                  <packing>
+                    <property name="expand">True</property>
+                    <property name="fill">True</property>
+                    <property name="position">0</property>
+                  </packing>
+                </child>
+                <child type="center">
+                  <object class="GtkBox">
+                    <property name="visible">True</property>
+                    <property name="can_focus">False</property>
+                    <property name="halign">start</property>
+                    <property name="valign">center</property>
+                    <property name="hexpand">True</property>
+                    <property name="vexpand">True</property>
+                    <property name="orientation">vertical</property>
+                    <child>
+                      <object class="GtkLabel">
+                        <property name="visible">True</property>
+                        <property name="can_focus">False</property>
+                        <property name="halign">start</property>
+                        <property name="margin_left">4</property>
+                        <property name="label" translatable="yes">Ready to Receive File</property>
+                        <property name="justify">center</property>
+                        <style>
+                          <class name="tooltip"/>
+                        </style>
+                        <attributes>
+                          <attribute name="weight" value="bold"/>
+                        </attributes>
+                      </object>
+                      <packing>
+                        <property name="expand">False</property>
+                        <property name="fill">True</property>
+                        <property name="position">0</property>
+                      </packing>
+                    </child>
+                    <child>
+                      <object class="GtkLabel">
+                        <property name="visible">True</property>
+                        <property name="can_focus">False</property>
+                        <property name="vexpand">True</property>
+                        <property name="label" translatable="yes">You will find your file in the Downloads 
directory.</property>
+                        <property name="wrap">True</property>
+                        <property name="max_width_chars">25</property>
+                        <style>
+                          <class name="dim-label"/>
+                        </style>
+                      </object>
+                      <packing>
+                        <property name="expand">False</property>
+                        <property name="fill">True</property>
+                        <property name="position">1</property>
+                      </packing>
+                    </child>
+                  </object>
+                  <packing>
+                    <property name="expand">False</property>
+                    <property name="fill">True</property>
+                    <property name="position">2</property>
+                  </packing>
+                </child>
+              </object>
+            </child>
+
             <child>
               <object class="GtkEventBox" id="event_box">
                 <property name="visible">True</property>
diff --git a/src/display-page.vala b/src/display-page.vala
index cfbb2e8e..3515bf60 100644
--- a/src/display-page.vala
+++ b/src/display-page.vala
@@ -12,6 +12,8 @@
     [GtkChild]
     public Gtk.Label size_label;
 
+    [GtkChild]
+    public Gtk.Box transfer_message_box;
     [GtkChild]
     private EventBox event_box;
     [GtkChild]
@@ -21,6 +23,9 @@
     private uint toolbar_hide_id;
     private uint toolbar_show_id;
     private ulong cursor_id;
+    private ulong widget_drag_motion_id = 0;
+    private ulong transfer_message_box_drag_leave_id = 0;
+    private ulong transfer_message_box_drag_motion_id = 0;
 
     private uint overlay_toolbar_invisible_timeout;
     private uint size_label_timeout;
@@ -67,6 +72,12 @@ public void setup_ui (AppWindow window) {
 
         toolbar.setup_ui (window);
         overlay_toolbar.setup_ui (window);
+
+        Gtk.TargetEntry[] target_list = {};
+        Gtk.TargetEntry urilist_entry = { "text/uri-list", 0, 0 };
+        target_list += urilist_entry;
+
+        drag_dest_set (transfer_message_box, Gtk.DestDefaults.DROP, target_list, DragAction.ASK);
     }
 
      private void update_toolbar_visible() {
@@ -127,6 +138,20 @@ public void replace_display (Boxes.Display display, Widget widget) {
 
         remove_display ();
 
+        if (display.can_transfer_files) {
+            widget_drag_motion_id = widget.drag_motion.connect (() => {
+                transfer_message_box.visible = true;
+
+                return true;
+            });
+            transfer_message_box_drag_motion_id = transfer_message_box.drag_motion.connect (() => {
+                return true;
+            });
+            transfer_message_box_drag_leave_id = transfer_message_box.drag_leave.connect (() => {
+                transfer_message_box.hide ();
+            });
+        }
+
         this.display = display;
         mouse_grabbed_id = display.notify["mouse-grabbed"].connect(() => {
             // In some cases this is sent inside size_allocate (see bug #692465)
@@ -197,8 +222,23 @@ public void replace_display (Boxes.Display display, Widget widget) {
             cursor_id = 0;
         }
 
-        if (widget != null)
+        if (transfer_message_box_drag_leave_id != 0) {
+            transfer_message_box.disconnect (transfer_message_box_drag_leave_id);
+            transfer_message_box_drag_leave_id = 0;
+        }
+        if (transfer_message_box_drag_motion_id != 0) {
+            transfer_message_box.disconnect (transfer_message_box_drag_motion_id);
+            transfer_message_box_drag_motion_id = 0;
+        }
+
+        if (widget != null) {
+            if (widget_drag_motion_id != 0) {
+                widget.disconnect (widget_drag_motion_id);
+                widget_drag_motion_id = 0;
+            }
+
             event_box.remove (widget);
+        }
 
         return widget;
     }