Re: [Pythoncard-users] [newbie] drawing over a bitmap

[Alex T. <al...@tw...>]

Mauro Cherubini wrote:

> Thanks Alex for the quick answer!
>
> Actually, when I say existing bitmap I mean an external png file that  
> represent a geographical map.
> What I want to do is to add to this map some "dots" and "lines" at  
> specific locations according to some logic I have in the rest of the  
> program.
>
> I did this using PIL, editing the existing bitmap and saving the  
> results into a new file. I was hoping to do the same with PythonCard,  
> maybe working on a transparent canvas which should overlay the  
> existing bitmap. But I cannot figure out the way to do it.
>
Is the end result just to display it ?  Or do you need to save a new PNG 
file ?

If display on screen is what you want, then it should (maybe) be easy.

I doubt if your idea of using an Image and a bitmapCanvas will work - 
you'd need transparency of the bitmapCanvas which I don't think is 
supported.

What you should be able to do is something like
(you'll need  "from PythonCard import graphic" if you don't already have 
it).
        backimage = graphic.Bitmap('D:/Our Documents/Alex/a.png')
        self.components.bufOff.drawBitmap(backimage, (0,0))
       

and then do additional drawing on top of that.

If you then need to save that to a new PNG file, it can probably be done 
- investigate the functions within graphic.py - though I've not done 
anything like that.

-- 
Alex Tweedly       http://www.tweedly.net



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