Path: utzoo!attcan!uunet!cme!durer!warsaw
From: warsaw@cme.nist.gov (Barry A. Warsaw)
Newsgroups: comp.windows.x
Subject: Re: XView: Help w/ attaching client data
Message-ID: <WARSAW.90Mar15105024@rtg.cme.nist.gov>
Date: 15 Mar 90 15:50:24 GMT
References: <WARSAW.90Mar14121813@rtg.cme.nist.gov>
Sender: news@cme.nist.gov
Organization: National Institute of Standards and Technology
Lines: 134
In-reply-to: warsaw@cme.nist.gov's message of 14 Mar 90 17:18:13 GMT


>>>>> "Barry" == Barry A. Warsaw <cme!durer!warsaw> writes:

Barry> I'm trying to attach client data to PANEL_LIST type panel items
Barry> in XView, but I can't quite figure out how to set and later
Barry> retrieve the data in the notify procedure.

I spent some time scanning through the source (after all those years
of sunview hacking with no source, its a real treat to have the xview
source! Thanks, Sun) and came up with a few routines that help with
attaching and retrieving data on PANEL_LIST items.  These aren't the
best solutions (I still think the data should hang off of some
attribute, or the list item should be passed to the notify proc), but
they do the job...

Say you have a PANEL_LIST item created as such:

	list = xv_create(panel, PANEL_LIST,
		PANEL_NOTIFY_PROC,	my_list_notify_proc,
		...
		NULL);

And later you add items to the list:

	xv_set(list,
		PANEL_LIST_INSERT,  	insert_index,
		PANEL_LIST_STRING,  	insert_index, string_name,
		PANEL_LIST_CLIENT_DATA,	insert_index, client_data,
		NULL);

When an item is selected, this function is called:

	void my_list_notify_proc(item, op, event)
	Panel_item  	item;
	Panel_list_op	op;
	Event       	*event;
		{
		int     	row = get_pli_row(item);
		Xv_opaque	client_data = get_pli_client_data(item);
		Panel_item	list = get_pli_parent_list(item);
		}

Here are the three useful routines:

	#include <xview_private/p_lst_impl.h> /* very important */

	int get_pli_row(item)
	Panel_item	item;
		{
		Panel_list_info	*pli;
		Row_info    	*row;
	
		pli = (Panel_list_info *) xv_get(item, PANEL_CLIENT_DATA);
	
		for (row = pli->rows; row; row = row->next)
			if (row->string_item == item) break;
	
		if (!row) return -1;
		return row->row;
		}


	Xv_opaque get_pli_client_data(item)
	Panel_item	item;
		{
		Panel_list_info	*pli;
	
		pli = (Panel_list_info *) xv_get(item, PANEL_CLIENT_DATA);
		return xv_get(pli->public_self, PANEL_LIST_CLIENT_DATA,
			get_pli_row(item));
		}


	Panel_item get_pli_parent_list(item)
	Panel_item	item;
		{
		Panel_list_info	*pli;
	
		pli = (Panel_list_info *) xv_get(item, PANEL_CLIENT_DATA);
		return pli->public_self;
		}


Barry> 1) In the notify proc we can't find the row number
Barry> corresponding to the PANEL_MESSAGE item selected so that we
Barry> could do an xv_get(list, PANEL_LIST_CLIENT_DATA, row).  We have
Barry> to brute-force to find the row number of the selected item.
Barry> Something like PANEL_LIST_ROW_SELECTED on the PANEL_LIST would
Barry> do the trick.

Still need to brute force it (see get_pli_row above), but you can cut
down on the number of globals needed by using some xview "secrets".

Barry> 2) Can't find the total number of rows in the PANEL_LIST item,
Barry> so we don't bomb out "for" loops when brute-force searching for
Barry> the message item.  We'd have to keep a global variable for
Barry> this.  Something like PANEL_LIST_ROWS_N would be needed.

Sorry, should have read TFM a little more closely, try attribute
PANEL_LIST_NROWS.

Barry> 3) Also in the notify proc, we can't find the PANEL_LIST item
Barry> which contains the PANEL_MESSAGE item selected, forcing me to
Barry> keep "list" around as a global variable.  Something like
Barry> PANEL_LIST_PARENT_LIST would be appropriate here.

See get_pli_parent_list above.

Barry> 4) The client data set on the list via PANEL_LIST_CLIENT_DATA
Barry> could be placed on the item's PANEL_CLIENT_DATA attribute so
Barry> that it can be retrieved in the notify proc.

I see why this can't be done, since xview uses the item's
PANEL_CLIENT_DATA attribute to store a structure of data pertaining to
the parent PANEL_LIST item.

Barry> 5) Really, the parameters passed to the notify procedure are
Barry> not the right ones.  Ideally it should be passed the PANEL_LIST
Barry> item containing the selection, the row number of the selected
Barry> item and a pointer to the event, much like PANEL_CHOICE
Barry> notification.

I still think this is the preferred way of notification since its
highly likely that the notification proc will need info about the
parent list.

Hope this helps...

-Barry

NAME: Barry A. Warsaw                USMAIL: National Institute of Standards
TELE: (301) 975-3460                         and Technology (formerly NBS)
UUCP: {...}!uunet!cme-durer!warsaw           Rm. B-124, Bldg. 220
ARPA: warsaw@cme.nist.gov                    Gaithersburg, MD 20899