Re: GTK Queue Draw Subtle Question

Thomas Dineen <tdineen@xxxxxxxxxxxxx> · Fri, 17 Feb 2017 14:03:38 -0800



    Eric:

      
         Thanks for the response!

      
         The long running function involves repeatedly loading data from
      a disk cache and if necessary the internet

      based on a user selected list of Stock Ticker Symbols. Then once
      loaded performing a modest amount of

      processing, and then display. Most of the latency by far is caused
      by the Internet server loads.

      
         The previous response mentioned a thread based solution which
      sounds interesting. Where the long latency

      read will be moved off to a separate thread which ends in a gtk_widget_queue_draw of its
        own. What do you

        think?

      
      Thomas Dineen

      
      On 2/17/2017 10:41 AM, cecashon@xxxxxxx wrote:

    
            Hi Thomas,

            
            What is in your long running function? Are there calls to
            GTK/GDK functions? Is it calculating a long running math
            function for a simulation? Complex drawing, etc?

            
            GTK has a few different ways to help out with long running
            functions depending on what the code is doing. A little more
            info would help to target a good solution.

            
            Eric 

        
        -----Original
          Message-----

          From: Thomas Dineen <tdineen@xxxxxxxxxxxxx>

          To: gtk-list <gtk-list@xxxxxxxxx>; tdineen
          <tdineen@xxxxxxxxxxxxx>

          Sent: Wed, Feb 15, 2017 2:41 pm

          Subject: GTK Queue Draw Subtle Question

          
          Gentle People:

          
          I have a rather large project in progress based on the
          GTK2/Cairo 

          packages.

          Which brings me to the following question about
          gtk_widget_queue_draw:

          For each Menu Function, meaning a C function, which is called
          by a menu 

          event handle,

          in response to a Menu Selection. I place a
          gtk_widget_queue_draw at the 

          end of the function

          to cause the screen to update in response to the command.
          Learned 

          behavior from examples

          and experience. This seems to work great.

          
          Now the question: If the menu function is complex, requiring
          seconds or 

          minutes to execute

          the screen freezes or if windows are moved fails to update and
          we are 

          left with a default

          grey screen. Is there any way to cause a queue draw and screen
          up date 

          from within this

          long latency function.

          
          My experience indicates that calling gtk_widget_queue_draw
          from within 

          this long latency

          function dose not cause a screen update.

          
          Thomas Dineen

          
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