How do you change a drag-and-dropped image mid-drag?

Question

So I want to drag an object from one source to multiple potential destinations. When the object is over each destination, I want it to 'morph' into a different image. Is there a straightforward way to do this from the NSDragSource perspective?

score 19 · Answer 1 · answered Jun 13 '13 at 08:53

You can do so by using enumerateDraggingItemsWithOptions: method of NSDraggingInfo in your dragging destination's handler methods (i.e. - your implementation of NSDraggingDestination protocol).

For example:

- (NSDragOperation)draggingUpdated:(id < NSDraggingInfo >)sender
{
    NSImage* newDragImage = <take it from wherever>;
    [sender enumerateDraggingItemsWithOptions:0
                                      forView:sender.draggingSource
                                      classes:[NSArray arrayWithObject:[NSPasteboardItem class]]
                                searchOptions:nil
                                   usingBlock:^(NSDraggingItem *draggingItem, NSInteger idx, BOOL *stop) {
                                       NSRect theFrame = draggingItem.draggingFrame;
                                       theFrame.size = newDragImage.size;
                                       [draggingItem setDraggingFrame:theFrame contents:newDragImage];
                                       *stop = NO;
                                   }];
}

score 4 · Answer 2 · answered Nov 27 '09 at 22:05

4

Joshua Nozzi has posted a great way to do this: http://joshua.nozzi.name/2009/10/jlndrageffectmanager/

answered Nov 27 '09 at 22:05

Ben Gottlieb

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Yep. This is a drop-in manager for this particular effect. The download contains a demo app. – Joshua Nozzi Dec 14 '09 at 03:23
1

If you end up using this class, just let me know and I'll add your app to the list on the source page. – Joshua Nozzi Jul 05 '10 at 18:53
The link is dead. – Willeke Jul 26 '22 at 21:25

score 3 · Answer 3 · answered Aug 28 '12 at 23:11

3

Check out NSDraggingInfo's enumerateDraggingItemsWithOptions method.

answered Aug 28 '12 at 23:11

panupan

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13
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Please edit your answer to elaborate: How would you use that method to solve this problem? – Peter Hosey Sep 01 '12 at 02:17

score 3 · Accepted Answer · answered Oct 10 '09 at 05:58

3

There's no way to do this using just the drag source APIs.

If you look at Interface Builder it does something similar to what you want. When you drag a button out of the library the button animates in the middle of the drag.

According to most people the way Apple is doing this is by making the drag image a small transparent image. Then they create a Window and have it follow the mouse. You can then use the window to do any type of animation you want.

answered Oct 10 '09 at 05:58

Leibowitzn

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At least as of 10.7+ the accepted response is no longer correct - see Иван Георгиев answer for the current way to change stuff mid-drag! – cacau Feb 19 '14 at 07:15

How do you change a drag-and-dropped image mid-drag?

4 Answers4