Canvas show=True doesn't work about vispy HOT 7 CLOSED

Yeah, I found this too. show=True only really works when you are not subclassing Canvas.

How do other toolkits deal with this? I would be surprised if the deffered the showing till the app is run.

A solution (I think) is to do the Canvas.init(self) at the end of your new init.

from vispy.

atom.py now demonstrates how you would do this. Dereferencing the showing until the app is run is non-trivial at best.

from vispy.

I think it is not really fixed even though the atom example show a workaround.

from vispy.

But I do not think it is a bug of vispy. This behaviour is inherent to how window creation works.

In theory, we could keep a list of windows-to-show on the app. The Canvas can add itself to the list. On app.run() all canvas objects in the list are shown. However, this will fail if a Canvas is created while the mainloop is running, for instance when a button is pressed and a popup with a visualization is shown.

from vispy.

But this means we cannot make the windows visible by default, no ?

On Aug 29, 2013, at 10:22 AM, Almar Klein [email protected] wrote:

But I do not think it is a bug of vispy. This behaviour is inherent to how window creation works.

In theory, we could keep a list of windows-to-show on the app. The Canvas can add itself to the list. On app.run() all canvas objects in the list are shown. However, this will fail if a Canvas is created while the mainloop is running, for instance when a button is pressed and a popup with a visualization is shown.

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#39 (comment)

from vispy.

We can, but when subclassing Canvas, you need to take into account that the call to Canvas.__init__(self, **kwargs) may invoke a call to some of the event handlers. So you probably want to do that after you've initialized stuff (as shown in atom.py).

And this should also just work:

MyCanvas(app.Canvas):
    def __init__(self):
        app.Canvas.__init__(self) # No show here
        .... init stuff
        self.show()

    def on_paint(self):
        ... etc.

And so does this:

canvas = Canvas(show=True)

@canvas.connect
def on_paint(event):
    ....

from vispy.

Ok, great. I think we can close it.

Nicolas

On Aug 29, 2013, at 11:24 AM, Almar Klein [email protected] wrote:

We can, but when subclassing Canvas, you need to take into account that the call to Canvas.__init__(self, **kwargs) may invoke a call to some of the event handlers. So you probably want to do that after you've initialized stuff (as shown in atom.py).

And this should also just work:

MyCanvas(app.Canvas):
def init(self):
app.Canvas.init(self) # No show here
.... init stuff
self.show()

   def on_paint(self):
       ... etc.

And so does this:

canvas = Canvas(show=True)

@canvas.connect
def on_paint(event):
....

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Reply to this email directly or view it on GitHub:
#39 (comment)

from vispy.