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With some help from the Lazarus Forum (thank you engkin!), I finally managed to capture mouse wheel movement for controls that do not support it.
In the code below, we define a new class that we hook up to controls to their WindowProc, so we can intercept messages, and relay them the usual way after we're done with them.
The usage is straight forward:
uses
..., Controls, LMessages; type ...
{ TWheelCatcher }
TWheelCatcher=class
public
PrvWindowProc: TWndMethod;
WinControl:TWinControl;
procedure AdjustedWindowProc(var TheMessage: TLMessage);
constructor Create(Target: TWinControl);
end;
...
implementation
...
{ TWheelCatcher }
procedure TWheelCatcher.AdjustedWindowProc(var TheMessage: TLMessage);
begin
if TheMessage.msg = LM_MOUSEWHEEL then
begin
//Do what you want here //Read the "TheMessage" values to determine if the wheel goes up or down ShowMessage('Wheel event!');
end;
PrvWindowProc(TheMessage);
end;
constructor TWheelCatcher.Create(Target: TWinControl);
begin
WinControl := Target;
PrvWindowProc := WinControl.WindowProc;
WinControl.WindowProc := @AdjustedWindowProc;
end;
... // For whatever control you'd like to use it, for example myPanel is a TPanel
// so for that one you do the following during the Form onCreate event.
TWheelCatcher.Create(myPanel);
// or when you create a control during runtime:
tmpPanel := TPanel.Create(ParentPanel);
tmpPanel.Parent := ParentPanel;
...
TWheelCatcher.Create(tmpPanel);
...
...
