matplotlib-devel Mailing List for matplotlib

A few weeks ago I reported a double draw problem in the qt backends. They
both have a draw() method that looked like this:
 def draw( self ):
 self.replot = True
 FigureCanvasAgg.draw(self)
 self.repaint( False )
It turned out that FCA::draw() and self.repaint() both did a draw which
slowed everything down. Commenting out the FCA draw call seemed to work
fine:
 def draw( self ):
 self.replot = True
 self.repaint( False )
However, this breaks when running code like this:
import pylab as p
p.plot( [1,2,3] )
p.savefig( 'image.png' )
The image is never drawn in this case. If you do a show() and save the
image from the gui, then everything is fine. I did some experimenting and
the solution may be to do this:
 def draw( self ):
 self.replot = True
 FigureCanvasAgg.draw(self)
Which does seem to work for the cases I have. Could someone else take a
look and see if this doesn't break anything (You'll have to edit your local
backends, I haven't changed anything).
Ted

On Thu, Apr 3, 2008 at 8:40 AM, Manuel Metz <mm...@as...> wrote:
> Hi,
>
> in matplotlib 0.91 there was a function draw_point for the backends.
> This seems to be gone (except for backend_agg2.py and backend_emf.py
> !?). I guess it wasn't used very often; instead I see that there is now
> a function draw_point in lines.py. Is it possible to re-add this
> functionality to the backends ??? What I would need is a function that
> draws a single pixel to a device.
The markerstyle for drawing a pixel is ',' and it is supported across
backends AFAIK
In [1]: plot(rand(1000), ',')
Out[1]: [<matplotlib.lines.Line2D instance at 0x8e6c12c>]
In [2]: savefig('test.png')
In [3]: savefig('test.pdf')
In [4]: savefig('test.eps')
In [5]: savefig('test.svg')
JDH

Hi,
in matplotlib 0.91 there was a function draw_point for the backends. 
This seems to be gone (except for backend_agg2.py and backend_emf.py 
!?). I guess it wasn't used very often; instead I see that there is now 
a function draw_point in lines.py. Is it possible to re-add this 
functionality to the backends ??? What I would need is a function that 
draws a single pixel to a device.
The reason why I'm asking is that I have thought about an additional 
scatter marker m=(0,0) that draws single pixels (as fast as possible). 
Such a marker might be very useful when drawing lots and lots of 
data-point on in a single plot. A typical application might be to draw 
the positions of particles in an N-Body simulation. My current best 
approach is to use "scatter(x,y, s=0.1)", but I think that an optimized 
routine would be very helpful.
So my main questions are:
- Why was draw_point removed ?
- Can it be re-added again?
Manuel