mouse coordinates in a gnome2 canvas

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1.ruby-gnome2 canvas pixbuf scaling

2.annoying problem with gnome2 canvas

Hello,
I'm trying different things with the gnome2canvas, but don't understand
the following behaviour :

#!/usr/bin/env ruby

require 'gtk2'
require 'gnomecanvas2'

def item_event(item, event)
    case event.event_type
    when Gdk::Event::BUTTON_PRESS
        item_x, item_y = item.parent.w2i(event.x, event.y)
      case event.button
      when 1
        if event.state & Gdk::Window::SHIFT_MASK ==
Gdk::Window::SHIFT_MASK
          item.destroy()
        else
          @x = item_x;
          @y = item_y;
          fleur = Gdk::Cursor.new(Gdk::Cursor::FLEUR)
          item.grab(Gdk::Event::POINTER_MOTION_MASK |
Gdk::Event::BUTTON_RELEASE_MASK,
                    fleur,
                    event.time)
          @dragging = true
        end
      when 2
        if event.state & Gdk::Window::SHIFT_MASK ==
Gdk::Window::SHIFT_MASK
          item.lower_to_bottom()
        else
          item.lower(1)
        end
      when 3
        if event.state & Gdk::Window::SHIFT_MASK ==
Gdk::Window::SHIFT_MASK
          item.raise_to_top()
        else
          item.raise(1)
        end
      end
    when Gdk::Event::MOTION_NOTIFY
      item_x, item_y = item.parent.w2i(event.x, event.y)
      if @dragging && (event.state & Gdk::Window::BUTTON1_MASK ==
Gdk::Window::BUTTON1_MASK)
        item.move(item_x - @x, item_y - @y)
        @x = item_x;
        @y = item_y;
      end
    when Gdk::Event::BUTTON_RELEASE
      item.ungrab(event.time)
      @dragging = false;
    end
end

def setup_item(item)
    item.signal_connect("event") do |item, event|
        item_event(item, event)
    end
end

Gtk.init

@ECX = 600
@ECY = 600

@combo1 = Gtk::ComboBox.new(true)
@combo1.append_text("Build")
@combo1.append_text("Move")
@combo1.set_active(0)

@labelcoord = Gtk::Label.new("")

@box1 = Gtk::HBox.new(false,5)
@boxv1 = Gtk::VBox.new(false,5)
@boxv2 = Gtk::VBox.new(false,5)

@canvas = Gnome::Canvas.new(true)

@zoomf = 1
@canvas.set_pixels_per_unit(@zoomf)
@canvas.set_size_request(@ECX, @ECY)
@canvas.set_scroll_region(0, 0, @ECX, @ECY)
@root = @canvas.root

# ScrolledWindow
@scroller = Gtk::ScrolledWindow.new
@scroller.set_policy( Gtk::POLICY_AUTOMATIC, Gtk::POLICY_AUTOMATIC )
@scroller.add( @canvas )

# Main window
window = Gtk::Window.new
window.signal_connect("destroy") {
  puts "Bye."
  Gtk.main_quit
}

@boxv1.pack_start(@combo1,false, false, 0)
@box1.pack_start(@boxv1)
@box1.pack_start(@boxv2)
@boxv1.pack_start(@labelcoord,false, false, 0)
@boxv2.pack_start(@scroller,false, false, 0)
window.border_width = 10
window.add(@box1)
window.show_all
x,y = 200,200
pt = Gnome::CanvasEllipse.new(@root,{:x1 => x-3,
                                    :y1 => y-3,
                                    :x2 => x+3,
                                    :y2 => y+3,
                                    :outline_color => "goldenrod",
                                    :fill_color_rgba => 0x0000ff80,
                                    :width_units => 0.5})
setup_item(pt)

#@canvas.signal_connect("motion-notify-event") do |widget, event|
  #x,y = event.x,event.y
  #@labelcoord.set_text("X= #{x}, Y= #{y}")
#end

Gtk.main

You can move the point with the mouse easily, right?
Now, uncomment the last 4 lines before "Gtk.main" : I can't move the
point anymore, and I don't know why.
Thanks for your replies.

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4.[ruby-gnome2] general memory problems with ruby-gnome2?

 Hi all.

 This is not a message about a concrete error. I need your advice in
 order to explore memory problems with an application using ruby1.8
 and ruby-gnome2 in Linux Debian Sid.

 My application is relatively complex. It generates dinamic windows
 form represnting data in postgres database. Each window has a
 notebook with various pages, and each page has a treeview
 representing detail of data.

 So, in diary work, program creates and destroys windows continually.

 When I worked with ruby-gnome1, there was no memory problems and
 program was speedy. But now, with same estructure of data
 presentation and using ruby-gnome2, memory use grows without limit
 until machine begins to use virtual memory in great amounts, slowing
 work.

 I destroy each window properly when it is closed, but don't know if
 that is enought. Might I do anything more in order to reduce memory
 usage?

 Thanks for your advice. Greets.

 							David

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