/[thuban]/branches/WIP-pyshapelib-bramz/Thuban/UI/mainwindow.py

Diff of /branches/WIP-pyshapelib-bramz/Thuban/UI/mainwindow.py

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-revision 2531 by bernhard,
Thu Jan 20 18:47:26 2005 UTC
+revision 2544 by bh,
Mon Jan 24 11:19:53 2005 UTC
 Line 1
- # Copyright (C) 2001, 2002, 2003, 2004 by Intevation GmbH
+ # Copyright (C) 2001, 2002, 2003, 2004, 2005 by Intevation GmbH
  # Authors:
  # Jan-Oliver Wagner <[email protected]>
  # Bernhard Herzog <[email protected]>
 Line 23 
 from wxPython.wx import *
  import Thuban
  from Thuban import _
- from Thuban.Model.messages import TITLE_CHANGED
+ from Thuban.Model.messages import TITLE_CHANGED, LAYER_PROJECTION_CHANGED, \
+      MAP_PROJECTION_CHANGED, MAP_LAYERS_ADDED, MAP_LAYERS_REMOVED
  from Thuban.Model.session import create_empty_session
  from Thuban.Model.layer import Layer, RasterLayer
  from Thuban.Model.postgisdb import PostGISShapeStore, has_postgis_support
-Line 75 
 class MainWindow(DockFrame):
+Line 77 
 class MainWindow(DockFrame):
                           "SelectedShapes": "canvas",
                           }
+     # Messages from the canvas that may require a status bar update.
+     # The update_status_bar method will be subscribed to these messages.
+     update_status_bar_messages = (VIEW_POSITION, LAYER_PROJECTION_CHANGED,
+                                   MAP_PROJECTION_CHANGED, MAP_LAYERS_ADDED,
+                                   MAP_LAYERS_REMOVED)
      def __init__(self, parent, ID, title, application, interactor,
                   initial_message = None, size = wxSize(-1, -1)):
          DockFrame.__init__(self, parent, ID, title, wxDefaultPosition, size)
-Line 101 
 class MainWindow(DockFrame):
+Line 109 
 class MainWindow(DockFrame):
          # Create the map canvas
          canvas = view.MapCanvas(self, -1)
-         canvas.Subscribe(VIEW_POSITION, self.view_position_changed)
          canvas.Subscribe(SHAPES_SELECTED, self.identify_view_on_demand)
          self.canvas = canvas
          self.canvas.Subscribe(TITLE_CHANGED, self.title_changed)
+         for channel in self.update_status_bar_messages:
+             self.canvas.Subscribe(channel, self.update_status_bar)
          self.SetMainWindow(self.canvas)
          self.SetAutoLayout(True)
-Line 334 
 class MainWindow(DockFrame):
+Line 344 
 class MainWindow(DockFrame):
      def get_open_dialog(self, name):
          return self.dialogs.get(name)
-     def view_position_changed(self):
+     def update_status_bar(self, *args):
-         """Put current position in status bar after a mouse move."""
+         """Handler for a bunch of messages that may require a status bar update
+         Currently this handles the canvas' VIEW_POSITION_CHANGED
+         messages as well as several messages about changes in the map
+         which may affect whether and how projections are used.
+         These messages affect the text in the status bar in the following way:
+         When VIEW_POSITION_CHANGED messages are sent and the mouse is
+         actually in the canvas window, display the current mouse
+         coordinates as defined by the canvas' CurrentPosition method.
+         If there is no current position to show, check whether there is
+         a potential problem with the map and layer projections and
+         display a message about it.  Otherwise the status bar will
+         become empty.
+         The text is displayed in the status bar using the
+         set_position_text method.
+         """
+         # Implementation note: We do not really have to know which
+         # message was sent.  We can simply call the canvas'
+         # CurrentPosition method and if that returns a tuple, it was a
+         # VIEW_POSITION_CHANGED message and we have to display it.
+         # Otherwise it was a VIEW_POSITION_CHANGED message where the
+         # mouse has left the canvas or it was a message about a change
+         # to the map, in which case we check the projections.
+         #
+         # When changing this method, keep in mind that the
+         # VIEW_POSITION_CHANGED message are sent for every mouse move in
+         # the canvas window, that is they happen very often, so the path
+         # taken in that case has to be fast.
+         text = ""
          pos = self.canvas.CurrentPosition()
          if pos is not None:
              text = "(%10.10g, %10.10g)" % pos
          else:
-             text = ""
+             for layer in self.canvas.Map().Layers():
-             # XXX This is a hack until we find a better place for this code.
-             # (BER 20050120)
-             # BH wrote (20050120):
-             # this branch is only executed when the mouse
-             # leaves the canvas window, so it's not that often [..]
-             # [Here] not the right place to put this code.
-             # I don't have a better solution at hand,
-             # but the view_position_changed is only there to update
-             # the current position.  If other information is to
-             # be shown in the status bar it should
-             # be handled in a different way and
-             # by other methods.
-             #
-             # The status bar widget supports some kind of stack of texts.
-             # maybe that can be used to distinguis
-             # between short-lived information such as the mouse position
-             # and more permanent information such as the hint
-             # about the projections.
-             map = self.canvas.Map()
-             for layer in map.layers:
                  bbox = layer.LatLongBoundingBox()
                  if bbox:
                      left, bottom, right, top = bbox
                      if not (-180 <= left <= 180 and
-                         -180 <= right <= 180 and
+                             -180 <= right <= 180 and
-                         -90 <= top <= 90 and
+                             -90 <= top <= 90 and
-                         -90 <= bottom <= 90):
+                             -90 <= bottom <= 90):
-                         text = ("Select '"+layer.title+"' and pick a " +
+                         text = _("Select layer '%s' and pick a projection "
-                             "projection using Layer/Projection...")
+                                  "using Layer/Projection...") % layer.title
                          break
          self.set_position_text(text)
      def set_position_text(self, text):
-         """Set the statusbar text showing the current position.
+         """Set the statusbar text to that created by update_status_bar
          By default the text is shown in field 0 of the status bar.
          Override this method in derived classes to put it into a
          different field of the statusbar.
-         """
+         For historical reasons this method is called set_position_text
+         because at first the text was always either the current position
+         or the empty string.  Now it can contain other messages as well.
+         The method will be renamed at one point.
+         """
+         # Note: If this method is renamed we should perhaps think about
+         # some backwards compatibility measures for projects like
+         # GREAT-ER which override this method.
          self.SetStatusText(text)
      def OpenOrRaiseDialog(self, name, dialog_class, *args, **kw):
-Line 472 
 class MainWindow(DockFrame):
+Line 502 
 class MainWindow(DockFrame):
              # FIXME: it would be better to tie the unsubscription to
              # wx's destroy event, but that isn't implemented for wxGTK
              # yet.
-             self.canvas.Unsubscribe(VIEW_POSITION, self.view_position_changed)
+             for channel in self.update_status_bar_messages:
+                 self.canvas.Unsubscribe(channel, self.update_status_bar)
              DockFrame.OnClose(self, event)
              for dlg in self.dialogs.values():
                  dlg.Destroy()

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