[postr] Allow image list to be re-ordered using D&D (#601536)

[Germán Poó Caamaño <gpoo src gnome org>]

commit 130b9f5eb2187e3249a3a550f6c62b1dae746bc6
Author: Francisco Rojas <frojas alumnos utalca cl>
Date:   Wed Nov 11 13:28:59 2009 -0300

    Allow image list to be re-ordered using D&D (#601536)
    
    Allows the user organize the photo list, once the images are in
    the list through the use of Drag and Drop.
    
    Signed-off-by: Germán Póo-Caamaño <gpoo gnome org>

 src/ImageList.py |   17 ++++++++++++-----
 src/postr.py     |   47 ++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 58 insertions(+), 6 deletions(-)
---
diff --git a/src/ImageList.py b/src/ImageList.py
index d5334ae..c1706c0 100644
--- a/src/ImageList.py
+++ b/src/ImageList.py
@@ -48,11 +48,18 @@ class ImageList(gtk.TreeView):
         selection.set_mode(gtk.SELECTION_MULTIPLE)
 
         # Setup the drag and drop
-        self.drag_dest_set (gtk.DEST_DEFAULT_ALL, (), gtk.gdk.ACTION_COPY)
-        targets = self.drag_dest_get_target_list()
-        targets = gtk.target_list_add_image_targets (targets, DRAG_IMAGE, False)
-        targets = gtk.target_list_add_uri_targets (targets, DRAG_URI)
-        self.drag_dest_set_target_list (targets)
+        self.targets = self.drag_dest_get_target_list()
+        self.targets = gtk.target_list_add_image_targets (self.targets, DRAG_IMAGE, False)
+        self.targets = gtk.target_list_add_uri_targets (self.targets, DRAG_URI)
+        self.drag_dest_set (gtk.DEST_DEFAULT_ALL, self.targets, gtk.gdk.ACTION_COPY)
+
+    def enable_targets(self):
+        """Enable the drag and drop destination. """
+        self.drag_dest_set(gtk.DEST_DEFAULT_ALL, self.targets, gtk.gdk.ACTION_COPY)
+
+    def unable_targets(self):
+        """Unable the drag and drop destination. """
+        self.drag_dest_unset()
 
     def data_func(self, column, cell, model, it):
         from xml.sax.saxutils import escape
diff --git a/src/postr.py b/src/postr.py
index 6fce813..fdbe5ff 100644
--- a/src/postr.py
+++ b/src/postr.py
@@ -115,16 +115,30 @@ class Postr(UniqueApp):
         self.model.connect("row-deleted", self.on_model_changed)
         
         self.thumbview.set_model(self.model)
-        self.thumbview.connect("drag_data_received", self.on_drag_data_received)
 
         self.set_combo.connect("changed", self.on_set_combo_changed)
         
         selection = self.thumbview.get_selection()
         selection.connect("changed", self.on_selection_changed)
 
+        self.drag_signals = []
+        self.drag_signals.append((self.thumbview, self.thumbview.connect(
+                            "drag_data_received", self.on_drag_data_received)))
+
         self.thumbview.connect("row-activated",
                                self.on_row_activated,
                                self.title_entry)
+
+        self.drop_disabled = False
+        self.drag_started = False
+
+        self.thumbview.connect("button_press_event",
+                                self.on_button_press_cb)
+        self.thumbview.connect("button_release_event",
+                                self.on_button_release_cb)
+        self.thumbview.connect("drag_begin", self.drag_begin_cb)
+        self.thumbview.connect("drag_end", self.drag_end_cb)
+
         if has_gtkspell:
           gtkspell.Spell(self.desc_view)
 
@@ -941,6 +955,37 @@ class Postr(UniqueApp):
             one row is activated."""
         entry.grab_focus()
 
+    def drag_begin_cb(self, thumbview, context, data=None):
+        self.drag_started = True
+
+    def drag_end_cb(self, thumbview, context, data=None):
+        self.drop_disabled = False
+        self.drag_started = False
+        self.thumbview.set_reorderable(False)
+
+        self.thumbview.enable_targets()
+        [obj.handler_unblock(i) for obj,i in self.drag_signals]
+
+    def on_button_press_cb(self, thumbview, event, data=None):
+        if self.drop_disabled:
+            return
+        self.thumbview.unable_targets()
+
+        self.drop_disabled = True
+        [obj.handler_block(i) for obj,i in self.drag_signals]
+        thumbview.set_reorderable(True)
+        return
+
+    def on_button_release_cb(self, thumbview, event, data=None):
+
+        if self.drop_disabled and (not self.drag_started):
+            self.drop_disabled = False
+            thumbview.set_reorderable(False)
+            self.thumbview.enable_targets()
+            [obj.handler_unblock(i) for obj,i in self.drag_signals]
+        return False
+
+
     def save_upload_set(self):
         dialog = gtk.FileChooserDialog(title=None,
                                        action=gtk.FILE_CHOOSER_ACTION_SAVE,