animations in macosx/wxagg

Community matplotlib-users
1

Hi,

I want to visualise a live data-stream by a number of plots (3d,
line drawings, scatter plots etc). I've been using the simpler
animation techniques (using gobject.idle_add and wx.EVT_IDLE to
redraw updates).

Some plots have static backgrounds that may benefit from the blit
techniques and I have been trying to get this approach to work in
GTKAgg and WXAgg. GTKAgg on linux seems to be coming along fine.
WXAgg on linux or macos, I'm not getting very far with.

So can anyone help with a few questions?

- can the native macos backend be used for animation? What's the
equivalent of gobject.idle_add or gobject.timeout_add? Anything
special needed for the blitting approach to work?

- What needs to be done to get WXAgg blitting? I have code like this:
...
matplotlib.use('WXAgg')
...
def update():
  ...
  # restore, blit etc
  wx.WakeUpIdle()

...
wx.EVT_IDLE(wx.GetApp(), update)
...

On Linux this draws the first screen and pauses. If I move the mouse
around I see the updates. As soon as I stop, so do the updates. What
am I missing? (BTW I get the same behaviour from animation_blit_wx.py
from the examples page). This is 1.0.1 on Linux, although I'm still
using 0.99.1 as well.

thanks for any help,

cheers, chris

···

--
Chris Higgins, Omnisense Ltd, 3rd Floor, St. Andrews House,
59 St Andrews Street, Cambridge, CB2 3BZ
Office: +44 (0) 1223 651394
Mobile: +44 (0) 780 490 8562
Skype: chiggins99
http://www.omnisense.co.uk

Omnisense Ltd is a company registered in England and Wales. Registered number: 6779286.
Registered office: St. Andrews House, 59 St Andrews Street, Cambridge, CB2 3BZ

2

Dear Chris,

- can the native macos backend be used for animation?

Yes.

What's the
equivalent of gobject.idle_add or gobject.timeout_add?

If you use the recent backend-independent animation code, you won't need those. See examples/animation/simple_anim.py on github for an example (this code is not yet in an official release). However, blitting won't work, so you'll need to switch that off.

Anything special needed for the blitting approach to work?

Currently it won't work with the MacOSX backend. For blitting to work with the MacOSX backend, we won't just need changes to the backend code (which is relatively straightforward) but also to the upstream lib/matplotlib/animation.py code. We will need to rethink the logic of blitting with animation, in particular when to store the figure to be blitted, and when to do the actual blitting. In the current version of lib/matplotlib/animation.py, the figure to be blitted gets stored after the figure is modified but before the screen is updated. With the other backends, this results in the unmodified figure being stored; with the MacOSX backend, this results in the modified figure being stored, so if you then blit it you will see an incorrect background.

--Michiel.

···

- What needs to be done to get WXAgg blitting? I have code
like this:
...
matplotlib.use('WXAgg')
...
def update():
...
# restore, blit etc
wx.WakeUpIdle()

...
wx.EVT_IDLE(wx.GetApp(), update)
...

On Linux this draws the first screen and pauses. If I move
the mouse
around I see the updates. As soon as I stop, so do the
updates. What
am I missing? (BTW I get the same behaviour from
animation_blit_wx.py
from the examples page). This is 1.0.1 on Linux, although
I'm still
using 0.99.1 as well.

thanks for any help,

cheers, chris

--
Chris Higgins, Omnisense Ltd, 3rd Floor, St. Andrews
House,
59 St Andrews Street, Cambridge, CB2 3BZ
Office: +44 (0) 1223 651394
Mobile: +44 (0) 780 490 8562
Skype: chiggins99
http://www.omnisense.co.uk

Omnisense Ltd is a company registered in England and Wales.
Registered number: 6779286.
Registered office: St. Andrews House, 59 St Andrews Street,
Cambridge, CB2 3BZ

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