I wrote a simple image viewer that will load a photo image into a Gtk.Image widget using a Gdk.Pixbuf. I then added a tool bar with four clickable icons. Zoom out, zoom in, fit to window and original size.
All but the fit to window worked well. When I pulled the width and height from image1.GetSizeRequest(out width, out height), width & height were returned as -1. Not helpful. Google didn’t give me many clues either 
What I needed was something that would provide the visible area of the Gdk.Image widget:
In order to get the visible area, we need to:
- upcast Gtk.Image to a Gtk.GdkWindow
- retrieve a Gdk.Region from the VisibleRegion method
- retrieve the first Gdk.Rectangle from the array returned from the visibleRegion.GetRectangles method
- extract the Height and Width from the Gdk.Rectangle
Now that we have the height and the width of the visible area of the Gtk.Image widget, we need to scale the image (Gdk.Pixbuf) while keeping the aspect. Assigning the image to the Gtk.Image widget will automatically redraw itself.
protected virtual void zoomToWindow
(object sender,
System.EventArgs e
)
{
if (image1
.Pixbuf != null) {
int new_width, new_height
;
int height
= image1
.Pixbuf.Height;
int width
= image1
.Pixbuf.Width;
Gdk.Region visibleRegion = image1.GdkWindow.VisibleRegion;
Gdk.Rectangle rectangle = visibleRegion.GetRectangles()[0];
new_height = rectangle.Height;
new_width = rectangle.Width;
scaleImage(height, width, ref new_height, ref new_width, 0);
image1.Pixbuf = pictureBuf.ScaleSimple(new_width, new_height, Gdk.InterpType.Bilinear);
}
}
There we go 
While the code above is C#, the same principle goes for any language that uses Gtk.
A while back I removed the Beagle and Tracker desktop search engines from my Ubuntu 8.04. As I’ve been consolidating more and more information into my home directory, I thought I would be able to simply install Beagle.
Boy was I wrong! When I started up beagle search, I was rewarded with it dying on me:
$ beagle-search
Debug: Done reading conf from /etc/beagle/config-files/BeagleSearch.xml
Debug: Done reading conf from /home/jason/.beagle/config/Daemon.xml
Debug: Done reading conf from /etc/beagle/config-files/Daemon.xml
Exception in Gtk# callback delegate
Note: Applications can use GLib.ExceptionManager.UnhandledException to handle the exception.
System.DllNotFoundException: libgalago
at (wrapper managed-to-native) Galago.Global:galago_init (intptr,int)
at Galago.Global.Init (System.String name, InitFlags flags) [0×00000]
at Galago.Global.Init (System.String name) [0×00000]
at Beagle.Util.GalagoTools.GetPresence (System.String service_id, System.String username) [0×00000]
at Search.Tiles.IMLog.GetBuddyStatus () [0×00000]
at Search.Tiles.IMLog.GetDetails () [0×00000]
at Search.Tiles.Tile.get_Details () [0×00000]
at Search.MainWindow.ShowInformation (Search.Tiles.Tile tile) [0×00000]
at Search.GroupView.OnTileSelected (System.Object tile, System.EventArgs args) [0×00000]
at Search.Tiles.Tile.OnFocusInEvent (Gdk.EventFocus f) [0×00000]
at Gtk.Widget.focusinevent_cb (IntPtr widget, IntPtr evnt) [0×00000]
at GLib.ExceptionManager.RaiseUnhandledException(System.Exception e, Boolean is_terminal)
at Gtk.Widget.focusinevent_cb(IntPtr widget, IntPtr evnt)
at Gtk.Widget.focusinevent_cb(IntPtr , IntPtr )
at Gtk.Widget.gtk_widget_grab_focus(IntPtr )
at Gtk.Widget.gtk_widget_grab_focus(IntPtr )
at Gtk.Widget.GrabFocus()
at Search.Category.Select(Boolean focus, Boolean extended)
at Search.GroupView.Finished(Boolean grabFocus)
at Search.MainWindow.OnFinished(Beagle.FinishedResponse response)
at Beagle.Query.OnFinished(Beagle.ResponseMessage r)
at Beagle.RequestMessage.OnAsyncResponse(Beagle.ResponseMessage response)
at Beagle.Transport+EventThrowingClosure.ThrowEvent()
at GLib.Idle+IdleProxy.Handler()
at GLib.Idle+IdleProxy.Handler()
at Gtk.Application.gtk_main()
at Gtk.Application.gtk_main()
at Gtk.Application.Run()
at Gnome.Program.Run()
at Search.MainWindow.Main(System.String[] args)
I not so quickly determined I was missing libgalago-gtk1 and libgalago-gtk1.0-cil. Once I installed them, everything was working properly!
There still seems to be a steep learning curve when it comes to Sybase’s PowerBuilder. In this specific case, PB11 is no easier.
What *I* personally would like to see is:
- step by step online tutorials to create a multitude of projects – from simple ‘hello world’ applications to database connected applications to .NET to AJAX enabled .NET web apps
- online videos for the new and experienced developers rather than just feature highlights
- more books… from the “Beginning PowerBuilder 11″ (perhaps a ‘for Dummies’ series type book) to super advanced PB11
- more podcasts ( take a look at Meet the Gimp for example format )
- PowerBuilder gallery of open source and commercial PB applications (please don’t just point to the abomination known as codexchange) and online pb communities
- A better tiered licensing model: Free version (take a look at Microsoft’s VB Express for a model of what should be included for free), Student (K-university) edition, Professional / Small Business, Enterprise. There should be NO feature differences between the student and enterprise editions – the only difference should be in what PB can be used for (licensing).
- Open source & hobby-ist development should be actively promoted to help rebuild the PB community
Can anyone think of anything else to help new developers learn PowerBuilder?
