[Qt-interest] How to zoom a particular selected region in QCanvas in Qt-3.3.6

[Brad Howes]

On Oct 5, 2009, at 9:41 AM, Rehan wrote:

>  I am using Qt-3.3.6. My requirement is to select a particular  
> portion of the canvas and zoom in/out the same.
> Could someone please guide me, Is there any QT direct method or I  
> have to customize?


Just use QMatrix (I think it is called that in Qt3). You know the  
dimensions of the area the user wanted, and you know your current view  
port, so just create an appropriate scaling and translation so that  
the new points become the corners of the view. If you want to preserve  
aspect ratio, then you will have to use min or max on the x and y  
scale values.

Brad

-- 
Brad Howes
Group 42
MIT Lincoln Laboratory • 244 Wood St. • Lexington, MA 02173
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