Home » U++ Library support » Draw, Display, Images, Bitmaps, Icons » how to convert view point to logic point (Painter point convert)
| how to convert view point to logic point [message #55837] |
Sun, 20 December 2020 08:45  |
zouql
Messages: 19
Registered: December 2020
Location: China
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Promising Member |
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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?
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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  |
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mirek
Messages: 14271
Registered: November 2005
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Ultimate Member |
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zouql wrote on Sun, 20 December 2020 08:45Hi 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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