Coordinate space transformations
lazarus / 7-LCL

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tk · 2009-10-04 22:42

Hi,
in order to create the printing support (not just) for KGrid I would
appreciate the SetWindowExtEx, SetViewPortExtEx and SetMapMode
functions in Lazarus. Of course i can map manually but especially in
controls with custom painting I'd like to use something "hidden" in
the Canvas/device context. Are the transformations on the roadmap or
even implementable for the other widget sets? Thanks

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Paul Ishenin · 2009-10-05 01:27

Some functions are available in LCLIntf unit. For example
SetWindowOrgEx. You can try to implement missing in a similar way and
to send us a patch.

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tk · 2009-10-05 07:34

OK. I'll give it a try because I really need them. At least for GTKx
and QT where I can test it.

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tk · 2009-10-05 10:50

I made a brief research about how this could be implemented under QT
and GTKx. QT seems to be very easy by utilizing the QPainter_Scale
function. But GTK does not natively support these transformations
(Cairo does sth but would be too hard to implement). I'll have to make
major modifications to the GTK interfaces by introducing eg. FScaleX
and FScaleY fields (Double type) to TGTKDeviceContext and modify ALL
painting methods. I can do this but the question is, will such huge
change be accepted by the Lazarus development team and the community?
I'm asking because of course I cannot test everything myself and thus
cannot guarantee that the new feature will work for every possible
case (but I think I can guarantee the default behavior remains
unchanged if the three new functions will not be used).