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Re: how to convert view point to logic point [message #55838 is a reply to message #55837]

Sun, 20 December 2020 09:43

mirek
Messages: 14257
Registered: November 2005

Ultimate Member

zouql wrote on Sun, 20 December 2020 08:45

Hi all:
when using Painter's scale/translate/rotate, it convert the user's
point to view point. So when mouse event LeftDown(Point p,dword flags),
the Point p is view point, Is there any way to convert this viewpoint
to user point for user's comparison and judgment logic?

If you need to handle this in really generic way, I think the best is to use the transformation matrix - Xform2D.

I would probably stopped using scale/translate/rotate and instead created a method that creates Xform2D (by multiplying with Xform2D::Scale, Rotate, Translate), then assign this whole matrix to Painter (using Transform method). Then, to convert view point back, compute Inverse matrix and use Xform2D::Transform...

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