png size changed in 3.1.52

[Ben Abbott]

On Feb 23, 2009, at 6:06 PM, Ben Abbott wrote:

>
> On Feb 23, 2009, at 11:31 AM, Francesco Potorti` wrote:
>
>>>> Is there a reason why the PNG default print size is forced to
>>>> 576x432
>>>> in 3.1.52?
>>>>
>>>> Before 3.1.52, the default size was the "large" one of gnuplot,
>>>> which
>>>> is a more common 640x480.
>>>
>>> I hope this will change soon. I'm working on a full support of the
>>> figure properties "papersize" and "paperposition". I also hope to
>>> allow the resolution (dpi) to be specified as well.
>>>
>>> My intention is to make the default consistent with Matlab.
>>
>> Thank you.  By a quick glance at the sources, I think I guess that  
>> the
>> size is set by gnuplot_set_term in gnuplot_drawnow.m, and then  
>> "large"
>> is set by print.m.
>>
>> Just removing the "size" setting would bring things back to the
>> default
>> 640x480, but I do not know what would be the side effects for
>> terminals
>> other than PNG.
>
> The commands below would produce a 640x480 size in Matlab ...
>
> 	 set (gcf, "paperunits", "inches")
> 	 set (gcf, "papersize", [6.4, 4.8])
> 	 set (gcf, "paperposition", [0 0 6.4, 4.8])
> 	 print -dpng -r100 myfile.png
>
> At the present time, the developers sources defaults to the resolution
> of your screen ... at least that's my understanding.
>
> You could try
>
> 	 dpi = get (0, "screenpixelsperinch");
> 	 paper_size = round ([640, 480]./dpi);
> 	 set (gcf, "paperunits", "inches")
> 	 set (gcf, "papersize", paper_size)
> 	 set (gcf, "paperposition", [0, 0, paper_size])
> 	 print ("-dpng", sprintf("-r%d", dpi), "myfile.png")
>
> This isn't working for me because, I'm half way though adding the
> compatible behavior.
>
> Please let me know if it does for you.
>
> Ben

Francesco,

I overlooked setting the property "papertype". Once listeners are in  
place to reconcile changes in the "papertype" & "papersize"  
properties, it will not be necessary to set both.

Also the "-r%d" isn't yet supported by Octave, so the proper sequence  
of command is ...

> 	 dpi = get (0, "screenpixelsperinch");
> 	 paper_size = round ([640, 480]./dpi);
> 	 set (gcf, "paperunits", "inches")
> 	 set (gcf, "papertype", "<custom>")
> 	 set (gcf, "papersize", paper_size)
> 	 set (gcf, "paperposition", [0, 0, paper_size])
> 	 print ("-dpng", "myfile.png")

With these I get the expected image. I'm using my modified sources,  
but in this instance I think the current sources should work as well.

Ben