Real Time Drawing

[Athanasios Anastasiou <thanos atmail com>]

Hello All

I am building an application that monitors a signal that is being 
digitized and the samples are delivered to the serial port.

There are two threads of execution, one is handling reading and decoding 
of the incoming stream of data and the other is handling processing. For 
the time processing involves only plotting the data to the surface of a 
widget. There is a double linked list with mutex protection so that two 
buffer areas can not be accessed concurrently. A simpler way to 
visualize the operation of these two threads is taking the Read and 
decode thread as the producer of buffers and the processing thread as 
the consumer of buffers. For the time, when a buffer becomes available 
it gets drawn immediately.

The reading and decoding thread works OK but problems gloom when i try 
to plot the function. The problems are as follows:

1. Several captured frames are printed one on top of the other
2. Some times i get some error messages from the X Window Server and 
some times i get Critical Errors from GDK.

I am more inclined towards believing that my problems are focused in the 
plotting procedure. This is a very simple procedure where i draw a 
simple black rectangle around the widget and then set up an array of 
GdkPoints and then call the function that draws lines from these 
points...When this function is put to the OnClick of a button it works 
with no problems...Also i believe that its also going to work if i hook 
it up on a timer, but i dont like this solution, i would like to be able 
to plot the data as soon as i have it available.

Additionaly i can not find a way to invalidate the widget (as i would do 
in Win for example). (I have read the official and unofficial docs, 
Tutorials, i have tested some code which is supposed to invalidate the 
region, but no luck)

If that makes sense, is there anyone out there with any suggestions on 
this problem?

Thanks in advance for any help you wish to provide
thanOS

P.S. I really like the concept of GTK but i believe that the project 
would be highly benefited from a document that describes its 
architecture and gives the bigger picture about the operation of Gtk / 
Gdk. Just by reading the documentation it is not obvious which fields in 
all these structures need to be modified in order to achieve 
something...In case i have not searched enough....is there anything like 
this available on the internet? (Or in any format, book, scribled 
stones....anything)