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Control picture zoom

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Hi guys,

I am trying  to make a picture controler on my interface. I can drag and zoom my picture but my zoom is too bad ....

My picture is big and I didn't find the way to make a zoom on the center of my indicator image with the zoomfactor. All my calculate tries failed and my reseachs on the web failed ...

I am not really sure if i am clear but I can answer your questions.





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This is an imperfect solution from a project of mine. A scroll of the mouse wheel zooms in or out by a factor sqrt(sqrt(2)), centering the zoom on the pixel upon which the cursor lies. The arithmetics of that is easy, it just involves that {ox,oy}->{px,py}-{px-ox,py-oy}*z1/z2, where {ox,oy} is the origin and {px, py} are the image coordinates of the pixel pointed at. That is, the new origin is just moved proportionally along the line connecting the old origin and the current pixel, all in image coordinates.

Differently than you, I haven't implemented limits on the zoom factor based on the image size and position, perhaps one should.



Edited by ensegre
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As an aside: I realize that the computation of the current pixel coordinates could be avoided using, like you did,


however it seems that these coordinates are not always polled at the right time; for instance I get {-1,-1} during mouse scroll. That might be part of the problem...

Edited by ensegre
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