On Monday, 4 January 2016 at 16:13:50 UTC, TheDGuy wrote:
Thanks for your example code. Do i need those extern (C) function?
Yes, you need it. The extern (C) function is what GDK invokes on idle. In any GUI application there is a lot of idle time waiting for events, what the addThreadIdle allows you to do is take advantage of this and tell GTK that whenever it's sitting around doing nothing, give this function a call.
The idea is that you spawn a thread that does your work and when GTK invokes your thread idle callback where you can check the status of the thread and update the UI accordingly. For example, let's say you need to render a highly complicated graph that takes a few minutes to complete. You could spawn a thread that renders it into an off-line buffer of some sort and once completed sends a message to the GTK main thread using std.concurrency. At some point GTK calls your thread idle callback and you simply invoke the std.concurrency.receive and see a message saying the graph has been rendered is available, and if so, copy it into the appropriate GTK widget.
The important thing to understand is that the thread idle callback happens in the GTK main thread so it is completely safe to update GTK widgets from here. The other thing to understand is that whatever you work you do in the callback must be short, if you don't return in a reasonable amount of time you are blocking the main GTK thread. As a result it really should only be used as a mechanism to track work progress in whatever threads you have spawned.
The GTK thread idle callback works beautifully with D's std.concurrency send and receive mechanism.
Note the code I pointed you to in that D github Issue abstracts the extern (C) function from you and allows you to use normal D delegates as callbacks. The issue was created to get this incorporated into GtkD as I agree the framework should abstract this.
Why is it not possible to write the value to the TreeView in D?
I don't understand what you mean as of course it's possible to update value's in a TreeView. Do you mean why am I updating it from the callback (i.e. the C function)? The code here is an artificial example where it is simply updating the treeview with an iterating number generated in a separate thread. The results being posted to the TreeView could just as easily be a resultset from a long running database query, a complicated mathematical expression, etc. Hopefully the previous explanation helps you understand what the callback is doing.
You can see a more real world example of GtkD multi-threading in this application I wrote called Visual Grep (https://github.com/gnunn1/vgrep), it puts a GTK GUI around grep with all searches running in background threads and updating Gtk TreeView as results come in. It also uses the delegate code linked in that issue which originally came from an application called grestful.
Note Visual Grep was my first ever D/GtkD program so there is some ugh code in there, but hopefully it can act as an additional source of info for you.
