LCL Interface Redesign Idea
Why would we want this ?
This is current Idea for the structure of the interface and how it relates to handles
Overview:
- Fork a branch of lazarus/
- Replace TWinControl.Handle with TWinControl.LCLHandle (there should exist no Handle yet)
- Try to get the LCL compiled and maybe the IDE so it doesn't use the (inefficient) .Handle anymore
- Introduce .Handle again, now as WSclass call
- Merge the branches
The change to .Handle will not break existing code.
TWSxxWinControl.CreateHandle Returns a TLCLHandle
TLCLHandle = IInterface; // interfaces as com objects
TxxPrivate = class(TPrivate, TLCLHandle);
TGtkPrivateButton = class(TGtkBin, TLCLHandle);
All TWSxx. methods should be moved to the private class. for instance:
class procedure TWSGtkWinControl.SetText(const AWinControl; const AText: String); var PrivWinControl: TGtkPrivateWinControl; begin PrivWinControl := TGtkPrivateWinControl(AWinControl.LCLHandle); PrivWinControl.SetText(AText); end;
Other possibilities
For accessing widgetset native handles or IDs from the LCL, in the current situation, ppl have to cast the handle. In the case of gtk, to retrieve the XID, one needs the following cast:
PGdkPrivateWindow(PGtkWidget(Handle)^.window)^.XID
When interfaces are used, one can imagine the following code
{$IFDEF GtkHasX} TGtkPrivateWidget = class(TGtkPrivate, ILCLHandle, IX11Handle);
(AWinControl.LCLHandle as IX11Handle).XID
or maybe better:
if Supports(AWinControl.LCLHandle, IX11Handle, X11Handle) then ... DoSomething with X11Handle
Which leads to cleaner constructs, without the need of internal knowledge of the handle.
Note that for this we need COM interfaces and not CORBA, however we don't need reference counting, so AddRef and ReleseRef can be implemented by just returning -1