Could somebody explain me the sizing mechanism in the LCL? I can't figure out how it…
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Hi,
Could somebody explain me the sizing mechanism in the LCL? I can't figure
out how it works, ie. I set Form1.Height := 300; What happens? I am
particularly interested in the messages sent to the interface that do the
actual job, so to say.
The LCL sends LM_SETSIZE messages to the interface in TWinControl.InitializeWnd and TWinControl.RealizeBounds. The InitializeWnd is called at the end of the handle creation, right before the LM_SHOWHIDE message. The TWinControl.RealizeBounds is called whenever the LCL is ready to commit. That means it does not send LM_SETSIZE messages during loading, or the handle is not created, or while autosizing, or it already sent a size message with the current bounds. The LCL therefore sends less size messages than the VCL.
A Form1.Height:=300; first changes the width of the LCL control, without sending a message. Then the autosizing is invoked (align, anchors, constraints). If this changes the bounds the LM_SETSIZE message is sent.
Mattias