[Brass]

Is there any way to query an NSTextView to determine if it is currently in the process of doing a drag operation from itself to itself? Ie, currently performing a drop operation for the purpose of rearranging it's content (without deleting or adding any content).

What I want to be able to do is something like this (using the existing NSTextView delegate method shown below, because it is already working for all the other conditions I have in place):

Code:

- (BOOL)textView:(NSTextView *)aTextView shouldChangeTextInRange:(NSRange)affectedCharRange replacementString:(NSString *)replacementString
{
	if ( [aTextView isDoingSelfContainedDragOperation] || <other coditions> )
		return YES;

	return NO;
}

Where "isDoingSefContainedDragOperation" is a fictitious method of my NSTextView subclass. How could I write such a fictitious method to return YES if the text view is in the process of performing a drop of some of its own dragged text into itself?

[Chuckit]

A dragging destination will receive NSDraggingDestination messages. The argument to these methods can be used to find out the source of the drag.

[Brass]

Thanks Chuckit. I'm now overriding "performDragOperation" and "concludeDragOperation" (and invoking super's implementation in both cases).

However, I can't figure out how to determine the point in the text where the drop is going to happen.

I need to make sure that it can only be dropped in certain places within the text. I'm still scouring the doco for this one, but if anyone can save me the time, I'd be grateful.

[Chuckit]

Sorry I'm late in responding. Don't know if you've figured this out yet, but here is some code for getting a character index from a point in an NSTextView. It's generalized from the highlighting method in Apple's LayoutManagerDemo example. (Note: I actually just recently wrote this, and I haven't had a chance to test it yet in the project it's meant for, but it ought to work.)

Code:
@implementation NSTextView ( PointToCharIndex )
// point is in the view's coordinate system.

// flag indicates whether the point is actually on the character
// or just near the character
- (unsigned)characterIndexForPoint:(NSPoint)point
                     isOnCharacter:(BOOL *)flag
{
    NSLayoutManager *layout = [self layoutManager];
    NSTextContainer *container = [self textContainer);
    unsigned glyphIndex;
    unsigned charIndex;
    
    point.x -= [self textContainerOrigin].x;
    point.y -= [self textContainerOrigin].y;
    
    glyphIndex = [layoutManager glyphIndexForPoint:point
                                   inTextContainer:textContainer];
    if (flag !- NULL)
    {
        *flag = NSPointInRect(point, [layoutManager
                boundingRectForGlyphRange:NSMakeRange(glyphIndex, 1)
                          inTextContainer:textContainer]);
    }

    return [layoutManager characterIndexForGlyphAtIndex:glyphIndex];
}
@end

[Brass]

Thanks Chuckit, you're right on the mark again!

I eventually found the hints I needed (convertPoint:fromView: and the layout manager's glyphIndexForPoint:...) at the old Cocoamamasam archives - there's no way I would have found them in Apple's doco myself (and am surprised there is no single NSTextView method to give the text index of there the drag is potentially about to be dropped).

I used these methods in the "draggingUpdated:" method.

Came up with something similar in function to what you suggested, and it works nicely now!

Code:

- (NSDragOperation)draggingUpdated:(id <NSDraggingInfo>)sender
{
	NSDictionary *attributes;
	NSRange attributeRange;
	float fracGlyph;
	NSPoint dragPoint = [self convertPoint:[sender draggingLocation] fromView:nil];  // nil to convert from window coordinates
	int dragTextIndex = [[self layoutManager] glyphIndexForPoint:dragPoint
												 inTextContainer:[self textContainer]
								  fractionOfDistanceThroughGlyph:&fracGlyph];
	NSAttributedString *theString = [self textStorage];

	if ( fracGlyph > 0.5 && dragTextIndex < [theString length] )
		dragTextIndex++;

	if ( dragTextIndex == [theString length] )  //  at end of all text and cannot use as an index of the text
		return [super draggingUpdated:sender];

	attributes = [theString attributesAtIndex:dragTextIndex effectiveRange:&attributeRange];
	
	if ( ! [[attributes allKeys] containsObject:@"field_name"]						// not in a field attribute
		 || dragTextIndex == ( attributeRange.location + attributeRange.length )	// at end of field
		 || dragTextIndex == attributeRange.location								// at begining of field
		 )
	{
		return [super draggingUpdated:sender];
	}
	
	return NSDragOperationNone;
}

[Chuckit]

Originally posted by Brass:
I eventually found the hints I needed (convertPoint:fromView: and the layout manager's glyphIndexForPoint:...) at the old Cocoamamasam archives - there's no way I would have found them in Apple's doco myself (and am surprised there is no single NSTextView method to give the text index of there the drag is potentially about to be dropped).

Apple is working on making the text system more flexible � and it is a lot more customizeable than it used to be � but there are still a lot of places where it's kind of a black box. NSTextView really doesn't seem meant to be customized very much by hand; only through delegation, and there aren't any delegate methods that need such information.