/*
GUIBEGIN

STRING STRING1
List Item 1
List Item 2
List Item 3
List Item 4
DEND

WINDOW , 52, 106, 400, 200, POPUP|CAPTION|SYSMENU|MINBOX|MAXBOX|THICK, , Drag List example
	FONT 8, 400, MS Shell Dlg
	LIST 3, 3, 94, 81, NOTIFY|BORDER|VSCROLL|TABSTOP, , MyList, , STRING1
DEND
GUIEND
*/

/* This is an example of a "Drag List box". It allows the user to grab
 * one of the items in a listbox, and drag it to a new position.
 */

DO
	/* FUNCDEF some C structures that we'll have to convert
	 * to a REXX Stem variable.
	 */
	FUNCDEF("DRAGLISTINFO", "32u, 32u, 32, 32")

	/* FUNCDEF some Windows APIs we need */
	FUNCDEF("MakeDragList",", void", "comctl32")
	FUNCDEF("RegisterWindowMessage","32u, str","user32")
	FUNCDEF("LBItemFromPt","32, void, 32, 32, 32u", "comctl32")
	FUNCDEF("DrawInsert",", void, void, 32u", "comctl32")
	FUNCDEF("LoadStdCursor", "void, void, 32u", "user32", "LoadCursor")
	FUNCDEF("SetCursor", "void, void", "user32")

	CATCH FAILURE
		CONDITION('M')
		RETURN
END

/* Get a few standard mouse pointers we'll use */
CrossHairCursor = LoadStdCursor(, 32513)
NoDropCursor = LoadStdCursor(, 32648)

LIBRARY rexxgui
GuiErr = "SYNTAX"
GuiHeading = 1
GuiCreateWindow('NORMAL')
Again:
DO FOREVER
	GuiGetMsg()
	CATCH SYNTAX
			CONDITION('M')
			SIGNAL Again
	CATCH HALT
	FINALLY
		GuiDestroyWindow()
END
RETURN


/* Called by Reginald after our main window, and all its
 * controls are created, but not yet shown.
 */
WM_INITDIALOG:
	/* Get the handle to our listbox */
	handle = GuiInfo("HANDLE", "MyList")

	/* Call the Windows API MakeDragList to turn this into a
	 * drag listbox
	 */
	MakeDragList(handle)

	/* Get the special message that Windows sends us when the user
	 * drags an item in the listbox
	 */
	DragMessage = RegisterWindowMessage("commctrl_DragListMsg")

	/* Don't let Rexx Gui process this event. */
	RETURN ""


/* Called by Reginald when our main window receives a
 * message that REXX GUI doesn't know how to handle.
 * Such a message would be the "commctrl_DragListMsg"
 * message, whose message number we have stored in the
 * variable "DragMessage".
 */
WM_EXTRA:
	/* Is this a DragMessage for our listbox? */
	IF ARG(3) = DragMessage THEN DO

		 /* ARG(2) is a C structure that we have to convert
		  * to a REXX stem variable. We use CONVERTDATA() to
		  * do that, using one of the struct types we
		  * FUNCDEF'ed.
		  */
		CONVERTDATA(ARG(2), "DRAGLISTINFO", "struct DRAGLISTINFO")

		/* dragListInfo.2 is now the handle
		 * for the list box whose item is being dragged.
		 * If we had several listboxes we set to be drag
		 * lists, then we'd pass this handle to GuiInfo,
		 * using a "VARIABLE" arg, to get the variable
		 * name we associated with this listbox. But since
		 * we have only 1 drag list in this example, we
		 * know it's "MyList".
		 */

		/* Figure out which drag operation */
		SELECT dragListInfo.1

			/* Has the user just clicked on an item to drag it? */
			WHEN 1157 /* DL_BEGINDRAG */ THEN DO

				/* Get the 0-based position of the item that is being dragged. This is
				 * the original position of the item in the list. Save it in a variable
				 * so we'll have it later when we process DL_DROPPED
				 */
				OldPosition = LBItemFromPt(dragListInfo.2, dragListInfo.3, dragListInfo.4)

				/* Display the drag mouse pointer */
				DrawInsert(GuiWindow, ARG(1), 1)

				/* User hasn't yet dragged the item anywhere */
				DragDrop = 0

				/* Allow dragging to continue. Returning nothing aborts the drag operation,
				 * so we can choose which items we allow to be dragged.
				 */
				RETURN 1
			END

			/* Did the user start dragging the item? */
			WHEN 1158 /* DL_DRAGGING */ THEN DO

				/* Get the 0-based position he has dragged the item to. NOTE: He hasn't
				 * dropped it yet
				 */
				NewPosition = LBItemFromPt(dragListInfo.2, dragListInfo.3, dragListInfo.4)

				/* Make sure he draagged to a legal position */
				IF NewPosition \= -1 THEN DO

					/* Display a crosshair mouse pointer to
					 * let him know he can drio the item here
					 */
					SetCursor(CrossHairCursor)

					/* Allow if he drops here */
					DragDrop = 1
				END
				ELSE DO

					/* Display a "no drop" mouse pointer to let him know he can't drop here
					 */
					SetCursor(NoDropCursor)

					/* Ignore if he drops here */
					DragDrop = 0
				END
			END

			/* Did he drop the item? */
			WHEN 1159 /* DL_DROPPED */ THEN DO

				/* Did he drag it to an allowable position? */
				IF DragDrop == 1 THEN DO

					/* Yes. Get the final position where he dropped it */
					NewPosition = LBItemFromPt(dragListInfo.2, dragListInfo.3, dragListInfo.4)

					/* Just make sure it's legal */
					IF NewPosition \= -1 THEN DO

						/* NOTE: The drag list box doesn't reorder the items. We
						 * need to do that. We have the original position of the
						 * item (where 0 = first item), and its new position.
						 * We need to delete at its old position, and insert at
						 * the new position. There's one problem here. If the new
						 * position is greater than the original position, then
						 * after we delete, the new position will be off by one.
						 * So let's check first and readjust 
						 */

						/* Get the string at the original position */
						GuiSendMsg("MyList", "GETLBTEXT", OldPosition + 1, "text")

						IF NewPosition > OldPosition THEN NewPosition = NewPosition - 1

						/* Delete the original position */
						GuiSendMsg("MyList", "DELETESTRING", OldPosition + 1)

						/* Insert at the new position */
						GuiSendMsg("MyList", "INSERTSTRING", NewPosition + 1, text)
					END
				END
			END
		END

		/* Return 0 for DL_DRAG and DL_DROPPED */
		RETURN 0

	END
	
	/* Don't let Rexx Gui process this event. */
	RETURN ""