Re: canvas.render doesn't accept None as second parameter

[Damon Chaplin <damonachaplin gmail com>]

On Sun, 2016-03-27 at 16:27 -0300, John Coppens wrote:
> Hi all,
>
> From a demo I found on the 'net, I used:
>
>         surface = cairo.SVGSurface("demo.svg", 9 * 72, 10 * 72)
>         cr = cairo.Context(surface)
>         self.canvas.render(cr, None, 1)
>
> This prints:
>
> Traceback (most recent call last):
>   File "necview.py", line 351, in save_SVG
>     self.canvas.render(cr, None, 1)
>   File "/usr/lib64/python2.7/site-packages/gi/types.py", line 44, in function
>     return info.invoke(*args)
> TypeError: argument 2: Must be GooCanvas.CanvasBounds, not NoneType
>
> According to https://lazka.github.io/pgi-docs/GooCanvas-2.0/classes/Canvas.html#GooCanvas.Canvas.render
> render should accept None as second parameter.
>
> 1) Is this a doc error or a GI/Goocanvas regression?

It looks like there should be an (allow-none) annotation for
introspection. Though it isn't too important as you usually want to use
a bounds rectangle. Or just use the entire canvas bounds.


> 2) I couldn't find a working demo which uses 'render' and SVG|PNG...surfaces in python. 

I don't think I've ever tried SVG or PNG surfaces.

Can you get it to work with a PDF surface? The write_pdf_clicked()
function in goocanvas/demo/demo.c shows how to do that in C. (And it
still seems to work!)

Damon