Hans-Joachim Ott wrote 21 lines
Hi,
I found a bug in TWinControl, wincontrol.inc date 00/04/03.
Symptom: When a text is assigned to a TEdit (with MyEdit.Text :=
'...')before its handle is allocated (e.g. immediately after its
creation), this text is not displayed when the control gets visible.
Reason: TEdit.Text is TWinControl.SetText, where the text is stored in
fCaption when the handle is not allocated. When later on in
TWinControl.CreateWnd the component is created, InitializeWnd is called
which tries to retrieve the text from Caption and put it to the control
with SetText. But: Caption is a property which is read by
TControl.GetText, and in case of csEdit and HandleAllocated (which is
now true) the text is read from the control (with LM_GETTEXT, which
returns an empty string) instead of fCaption, so the empty string is
used in SetText.
Proposed solution: use fCaption instead of Caption in
TWinControl.InitializeWnd, this should be correct always when the
control is being created.
HHmm.... typo? Thanks I'll fix it.
Additional remarks: - I find it very strange that TControl.GetText has a decision on the ControlStyle. Should this not be implemented by defining GetText as virtual and overriding it in descendant classes?
Looking at delphi:
GetText is private. It calls gettextbuf and here the text is retrieved throug an WM_GETTEXT.
This way it is in fact virtual.
- GetText should return fCaption if HandleAllocated = false, instead of 'Edit' (see TControl.GetText).
OK, this is a result of our change a while ago in the way controls are created. Not all controls have been
BTW: I would volunteer to work on a control, especially on Grids, but I don't have much spare time, so I fear it would take months to finish one :-(.
At least there will be a control :-)
Marc