On 2/18/13 11:06 PM, "Graham Cox" <graham....@bigpond.com> wrote:
>On 19/02/2013, at 11:09 AM, Chuck Soper <chu...@veladg.com> wrote: > >> Does anyone know the steps to allow custom dragging of a table column to >> another table? Is this possible? If I was dealing with an NSView >>subclass, >> I think this would be straightforward. I want to show the entire column >> (header + row) when dragging. I believe that the dragging implementation >> could go in my NSTableHeaderCell subclass, but I'm not sure how to get >> started. > > >It's definitely possible, but you'll have to do a bit of subclassing. I >suspect you're going to need to subclass the overall NSTableView so that >you can receive a private drag type and do the necessary graphics work as >part of NSDraggingDestination. > >There are two parts to a drag - the drag source and the drag destination. >The source can be your custom table header cell, but the destination is >probably going to have to be a subclass of the table view itself. The two >parts can be programmed fairly independently, once you've settled on how >they are going to communicate in terms of the column data you pass from >to the other. > >Having subclassed your table header cell, kicking off the drag shouldn't >be too hard - just handle the mouseDown or mouseDragged and capture an >image of the column as the drag image. NSView's method for capturing part >of a view to a bitmap rep is invaluable here. Declare a private drag type >and use whatever data makes sense to pass the column content through the >drag pasteboard mechanism - you might not need to actually transfer any >data, you could just store enough info in shared variables (e.g. just >make a note of the source column somewhere) that your custom table class >can access - as it's all private there's no need to consider dragging to >other apps or supporting standard data formats. > >The hardest part as I see it is in receiving the drag. Your custom table >class will register for the private drag type, and implement >NSDraggingDestination methods to do whatever is needed to provide >feedback and validation of the drag. You will need for example to >highlight the place where the column can be dropped, and maybe animate >moving other columns apart to "make room". You'll want to pass anything >else up to super's implementation to continue supporting all the standard >dragging that the table can handle. > >On a drop, you just need to remove the column from the source, use the >private data to recreate it at the destination and insert it into the >table view. > >--Graham Thanks for your very thorough response. It sounds possible, but quite labor intensive. So much so, that I think that I should not be using NSTableView. I was using NSTableView, with one row, as way to horizontally scroll custom views. To auto adjust the height of the single row I added an observer for NSViewFrameDidChangeNotification on the NSTableView object. Then called setRowHeight: to scrollView.documentVisibleRect.size.height as the table was resized. This was pretty fast to implement and worked fine. I think that this could have been a good way to make use of a table view except for needing to customize the headerCell and implement custom column dragging. I think that I'll just use an NSScrollView and avoid customizing NSTableView. Chuck _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
