Accessing the Interfaces directly

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Revision as of 15:46, 6 February 2006 by Sekelsenmat (talk | contribs)

This page describes, how to write a new LCL control, using the various LCL interfaces for the platform dependent implementations.

OpenGL is a platform independent language for 3D graphics. The platform dependent part is to get a OpenGL context. Under linux/freebsd/X you use glx for that, under windows you use WGL and under MacOSX you can use AGL.

Every TWinControl has a Handle, and the LCL does not need to know, what a Handle is. The meaning of the Handle is totally up to the LCL interface:

  • under gtk a Handle is often a PGtkWidget
  • under windows a Handle is often a HWnd.
  • under carbon a Handle is often a ControlRef
  • under Qt, a Handle is often a pointer to a Qt object. For example, the Handle of a TCustomButton is a pointer to a QPushButton object.

Be aware that you should avoid relying on any widgetset specials. This page is for people improving the widgetsets and for people writting components that need to access the widgets directly.

List of Handles on various LCL classes


On Win32: HBITMAP On Gtk: PGDIObject

You can access this on Gtk using:

  GDIObject: PGDIObject;
  Bitmap: TBitmap;

  GDIObject := PgdiObject(Bitmap.Handle);

  gtk_image_set_from_pixmap(MyGtkImage, GDIObject^.GDIPixmapObject,