A Qui, 2004-02-26 �s 01:48, Alexandre Strube escreveu:
> Hello list,
>
> I'm trying to write a kind of webcam application in Python, using as
> user interface a .glade file. Until there, nothing difficult.
>
> My problem is with getting the data from the webcam and putting it to
> screen. I can grab images from camera and save it to files, but I don't
> know how to put it on a gtk widget.
>
> I have a drawingArea widget, called "janela1". I'm receiving data from
> video4linux to the variable "im", and converting this to a string again
> for putting it on the window, as stated at
> " http://www.daa.com.au/pipermail/pygtk/2004-January/006731.html "
>
> The code follows:
>
> janela1=xml.get_widget('drawingarea1') # gets drawingarea widget
> gc=janela1.window.new_gc() # creates a new window context
> vid=inicializavideo() # initializes video4linux stuff
> im=Image.fromstring("RGB",(WIDTH,HEIGHT),vid.getImage(0)) # grab image
> im.save("foo.png","PNG") # Saves image file (it works)
> buff=im.tostring()
> janela1.window.draw_rgb_image(gc, 1, 1, WIDTH, HEIGHT,
> gtk.gdk.RGB_DITHER_NONE, buff)
> gtk.main()
>
>
> The file "foo.png" is saved correctly, which means the capture stuff is
> ok. However, nothing shows up on "janela1". What am I doing wrong?
You are not understanding correctly the philosophy of GTK (or X)
programming. In GTK, you never draw directly to a widget. Instead, you
tell the X server the widget needs to be redrawn, then the X server
calls you back telling you to draw an area of your widget.
To summarise, you should:
1. connect a handler to 'expose-event' signal. The handler has the
following signature:
def expose_event_cb(widget, event): ....
event is a structure containing the fields: x, y, width, height.
These fields define the area that actually needs to be painted, which
might be different from the entire widget area if, for example, there is
a window on top of the widget, partially obscuring it.
2. call widget.queue_draw() whenever you want to repaint your widget.
You might want to read a GTK tutorial, to better understand these
issues.
Regards.
--
Gustavo Jo�o Alves Marques Carneiro
<[EMAIL PROTECTED]> <[EMAIL PROTECTED]>
The universe is always one step beyond logic.
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