General zoom algorithm for drawing program

Posted by Steven Sproat on Stack Overflow See other posts from Stack Overflow or by Steven Sproat
Published on 2010-04-18T21:49:04Z Indexed on 2010/04/18 21:53 UTC
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wxpython

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zoom

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draw

My GUI toolkit, wxPython provides some methods for implementing a user zoom factor, however the quality isn't too good. I'm looking for ideas on how to create a zooming feature, which I know is complicated.

I have a bitmap representing my canvas which is drawn to. This is displayed inside a scrolled window.

Problems I forsee: - performance when zoomed in and panning around the canvas - difficulties with "real" coordinates and zoomed in coordinates - image quality not degrading with the zoom

Using wxPython's SetUserScale() on its device contexts presents image quality like this - this is with a 1px line, at 30% zoomed in.

I'm just wondering the general steps I'll need to take and the challenges I'll encounter. Thanks for any suggestions

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