I need to access the VScrollBar of a TListBox in TComboBox and TComboEdit in order to find a TThumb inside of it (using the EnumControls method) and set custom OnMouseEnter, OnMouseLeave, OnMouseDown and OnMouseUp events, like this:
class TScrollThumb : public TCppInterfacedObject<TFunc__2<TControl*, TEnumControlsResult>> {
public:
TEnumControlsResult __fastcall Invoke(TControl* Control) {
if (Control->ClassNameIs("TThumb")) {
Control->OnMouseEnter = MouseEnter;
Control->OnMouseLeave = MouseLeave;
Control->OnMouseDown = MouseDown;
Control->OnMouseUp = MouseUp;
return TEnumControlsResult::Stop;
}
return TEnumControlsResult::Continue;
}
};
if (ComboBox->ListBox->VScrollBar) ComboBox->ListBox->VScrollBar->EnumControls(new TScrollThumb);
// TScrollBar *scrollbar = ComboBox->ListBox->GetVScrollBar();
// if (scrollbar) scrollBar->EnumControls(new TScrollThumb);
The VScrollBar property is a protected member of Fmx::Layouts::TCustomScrollBox and GetVScrollBar() is a private member of Fmx::Layouts::TCustomScrollBox, but even making them public does nothing, I still can't access the VScrollBar.
The same approach works great for TThumb inside a TVertScrollBox. What can I do in this case?
I seem to have found a solution myself. A bit tricky, but it works like a charm. So I'll just post it here as is:
class TScrollThumb : public TCppInterfacedObject<TFunc__2<TControl*, TEnumControlsResult>> {
public:
TEnumControlsResult __fastcall Invoke(TControl* Control) {
if (Control->ClassNameIs("TThumb")) {
Control->OnMouseEnter = MouseEnter;
Control->OnMouseLeave = MouseLeave;
Control->OnMouseDown = MouseDown;
Control->OnMouseUp = MouseUp;
return TEnumControlsResult::Stop;
}
return TEnumControlsResult::Continue;
}
};
void __fastcall ListBoxMouseEnter(TObject *Sender) {
((TControl*)Sender)->EnumControls(new TScrollThumb);
// The tricky part: working with a ListBox inside of its own event handler;
}
ComboBox->ListBox->OnMouseEnter = ListBoxMouseEnter;
// Assign an auxiliary event handler to a ListBox that has already been displayed;
ComboEdit->Presentation->ListBox->OnMouseEnter = ListBoxMouseEnter;
// Same trick for ComboEdit;