Nelissen, M. wrote:
> Can someone tell me how non-visual components are drawn on forms in the
> designer in gtk/lazarus ? Is it done in designer/, or in the interface?
designer
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> In win32, they are clickable, but not visible.
Ok, did some research myself. It seems that the gtk interface sends a
designer specific INTERNALPAINT message from gtkobject.inc:1176 to the
lcl, which is then handled by designer.pp and passed on to
controlselection for drawing grid and grabbers etc.
Please, is there no other way? This is real ugly; having to send this
from the interface with specific non-documented behaviour for the
lazarus ide.
Can the designer form override the Paint method and do it that way?
The designer can't override any method, because any component can also do so. But this is not required anyway, because the designer is using the message queue of the form (like Delphi). It uses all paint messages (PAINT and INTERNALPAINT). The reason for the extra INTERNALPAINT messages is simple: The paint messages from the gtk interface are not sufficient. A LCL control can consist of several internal widgets in the gtk-interface. The normal paint message is only sent for the main widget. But the designer wants to paint on everything, so the gtk-interface has to send special paint messages for the internal widgets. (Another solution would be to create one special paint message for all widgets of the control. But this is an optimization for the gtk-interface. The designer should not bother.)
For win32 the normal paint messages should be enough. Please test, if the designer is getting the paint messages and if they are handled at the right time (after letting the control draw itself).
Maybe we need to adapt the BeginPaint, EndPaint to the designer.
Mattias
