[pygtk] Reload gtk.Image contents

[Daniil Baturin]

No doubt it's bad idea, but time.sleep(1) was the simplest dirty hack to 
rule out any timing issues I could think of. :)
I think I'll just invoke gnuplot on any replot request and update the 
image when process exists, as this program has no performance 
requirements and process spawning overhead isn't so much of a problem.
If it causes any problems or I get an unused evening, will play with 
gtk.gdk.Pixbuf.


On 01/29/2013 04:06 AM, Niklas Koep wrote:
> Glad to hear it, although I must say manually adding a delay sounds 
> like an unreliable workaround. Putting a file monitor in place might 
> look like an overkill solution, but it should work more reliably. Take 
> a look at gio.FileMonitor. If you add a montior for a directory (or a 
> specific file) and listen for events indicating metadata changes you 
> should be able to determine when it's safe to read the image. Just a 
> suggestion. Another solution I could think of would be to call gnuplot 
> manually, setting its output to stdout and connecting to the process 
> via pipe. That way you could get the raw image data and then manually 
> construct a gtk.gdk.Pixbuf from that which you can in turn feed to a 
> gtk.Image. Again, that's all just speculation though as I've never 
> tried any of this myself. Best of luck.
>
> Cheers.
>
>
> 2013/1/28 Daniil Baturin <daniil at baturin.org <mailto:daniil at baturin.org>>
>
>     Niklas, you were right. Thanks a lot!
>     I was using a gnuplot module and a quick look at it gave me
>     impression it did take care of time issues and its method don't
>     return until gnuplot task if finished. In fact it didn't, but
>     sleep() inserted before set_from_file() fixed the issue.
>
>     That module is not so perfect in other aspects too, so I guess I
>     should either improve it and send patches back to the author or
>     make a less general purpose synchronous interface myself. :)
>
>
>     On 01/29/2013 03:28 AM, Niklas Koep wrote:
>>     I've tested the what I described earlier today and it works. If
>>     there are two distinct images on disk, then calling
>>     gtk.Image.set_from_file() will automatically update the image gtk
>>     displays. This leads me to believe that it's a timing issue
>>     you're facing. The plotter.plot() method wouldn't happen to be
>>     asynchronous, would it? Because if it is it might just be the
>>     case that you update the gtk.Image before the entire image
>>     generated by gnuplot has been written to disk. Obviously, that's
>>     just a guess since I don't know how your plot() method works
>>     internally. But it would explain why the first update of your
>>     image (sometimes) doesn't take and the image on disk actually
>>     appears correct if you look at it after a certain time.
>>
>>
>>     2013/1/28 Daniil Baturin <daniil at baturin.org
>>     <mailto:daniil at baturin.org>>
>>
>>         I'm using set_from_file(), and it kind of works. The problem
>>         is that the image is updated only second time event handler
>>         that replots and invokes set_from_file() is triggered. I
>>         double checked replot occurs every time event is caught, when
>>         I open the image file manually it contains the updated plot.
>>
>>         I added queue_redraw() after set_from_file(), but it didn't help.
>>
>>         This is what I have there now:
>>           def apply_equations(self, widget, data):
>>                 x_equation = data[0].get_text()
>>                 y_equation = data[1].get_text()
>>                 image = data[2]
>>                 print "Equations: x=%s, y=%s" % (x_equation, y_equation)
>>                 expression = x_equation + "," + y_equation
>>                 plotter.set_expression(expression)
>>                 plotter.plot()
>>                 image.set_from_file("test.png")
>>                 image.queue_draw()
>>
>>         self.equations_apply.connect("clicked", self.apply_equations,
>>         (self.x_expression, self.y_expression, self.image) )
>>
>>
>>
>>
>>         On 01/28/2013 10:02 PM, Niklas Koep wrote:
>>>         If you're updating your gtk.Image contents via its
>>>         set_from_file() method you don't need to request an update
>>>         at all -- it happens automatically. Generally speaking,
>>>         however, gtk.Widget implements a queue_draw() method which
>>>         can be used to invalidate the entire visible area of a
>>>         widget which in turn causes it to be redrawn. For your use
>>>         this doesn't seem to be required though. Hope this helps.
>>>
>>>
>>>
>>>         2013/1/27 Daniil Baturin <daniil at baturin.org
>>>         <mailto:daniil at baturin.org>>
>>>
>>>             Hi,
>>>             What is the proper way to reload gtk.Image contents?
>>>
>>>             I want to make a simple educational gnuplot frontend
>>>             that would allow playing with parametric curve
>>>             coefficients by using spin buttons, expressions with
>>>             substituted constants will be passed to gnuplot and
>>>             generated png displayed in a gtk.Image. But I'm not sure
>>>             how to request update of displayed image if the image
>>>             has changed.
>>>
>>>
>>>             -- 
>>>             #!/usr/bin/env perl
>>>             @a=split(//, "daniil @ baturin  .  org" );# Daniil Baturin
>>>             @b=split(//,q/Px%!+o0Q6lh*7dp$. at 8#%|y{/);while($i<24){$_.=
>>>             chr((ord(@b[$i])-ord(@a[$i])+62)%94+32);$i++};print"$_\n"#
>>>
>>>             _______________________________________________
>>>             pygtk mailing list pygtk at daa.com.au
>>>             <mailto:pygtk at daa.com.au>
>>>             http://www.daa.com.au/mailman/listinfo/pygtk
>>>             Read the PyGTK FAQ: http://faq.pygtk.org/
>>>
>>>
>>
>>
>>         -- 
>>         #!/usr/bin/env perl
>>         @a=split(//, "daniil @ baturin  .  org" );# Daniil Baturin
>>         @b=split(//,q/Px%!+o0Q6lh*7dp$. at 8#%|y{/);while($i<24){$_.=
>>         chr((ord(@b[$i])-ord(@a[$i])+62)%94+32);$i++};print"$_\n"#
>>
>>
>>         _______________________________________________
>>         pygtk mailing list pygtk at daa.com.au <mailto:pygtk at daa.com.au>
>>         http://www.daa.com.au/mailman/listinfo/pygtk
>>         Read the PyGTK FAQ: http://faq.pygtk.org/
>>
>>
>
>
>     -- 
>     #!/usr/bin/env perl
>     @a=split(//, "daniil @ baturin  .  org" );# Daniil Baturin
>     @b=split(//,q/Px%!+o0Q6lh*7dp$. at 8#%|y{/);while($i<24){$_.=
>     chr((ord(@b[$i])-ord(@a[$i])+62)%94+32);$i++};print"$_\n"#
>
>
>     _______________________________________________
>     pygtk mailing list pygtk at daa.com.au <mailto:pygtk at daa.com.au>
>     http://www.daa.com.au/mailman/listinfo/pygtk
>     Read the PyGTK FAQ: http://faq.pygtk.org/
>
>


-- 
#!/usr/bin/env perl
@a=split(//, "daniil @ baturin  .  org" );# Daniil Baturin
@b=split(//,q/Px%!+o0Q6lh*7dp$. at 8#%|y{/);while($i<24){$_.=
chr((ord(@b[$i])-ord(@a[$i])+62)%94+32);$i++};print"$_\n"#

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