UglyBlackHighlightRectWhenDraggingToNSTableView

last edited April 2, 2008 20:23:09 (71.190.26.183)
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I looked all over the NSCell class but can't figure out what to change to modify that ugly black highlight rectangle that you get when you drag something onto it (eg onto a tableview row). What I want is something like the Finder in Panther, a nice cell highlight. What a strange choice for default behaviour in this class with no apparent way to overrule it!

EcumeDesJours

It looks like you might be able to do it by overriding NSTableView's -drawRow:clipRect:

no luck with that one - EcumeDesJours

I was reminded of this ongoing and unresolved issue by the revival of the RoundedRectRowHighlighting thread...

Has anyone found a solution? Clearly Apple is doing it somehow in Mail.app and Address Book -- the black highlight is killing me!

- (void) _drawDropHighlightBetweenUpperRow: (int) parameter1 andLowerRow: (int) parameter2 atOffset: (float) parameter3

...maybe? --RyanStevens

I seem to have it working using the following. Feel free to make changes to anything (especially the colors, I just did it by eye). -- AustinSarner 

static float widthOffset = 5.0;
static float heightOffset = 3.0;

-(void)_drawDropHighlightOnRow:(int)rowIndex
{
	[self lockFocus];
	
	NSRect drawRect = [self rectOfRow:rowIndex];
	
	drawRect.size.width -= widthOffset;
	drawRect.origin.x += widthOffset/2.0;

	drawRect.size.height -= heightOffset;
	drawRect.origin.y += heightOffset/2.0;
	
	[[[NSColor blueColor]colorWithAlphaComponent:0.2]set];
	[NSBezierPath fillRoundRectInRect:drawRect radius:4.0];

	[[[NSColor blueColor]colorWithAlphaComponent:0.8]set];
	[NSBezierPath setDefaultLineWidth:2.0];
	[NSBezierPath strokeRoundRectInRect:drawRect radius:4.0];

	[self unlockFocus];
}

adding that to my NSCell subclass gives me 'invalid initializer' errors when it goes to compile. Anyone else get this to work?

It should be in your NSTableView subclass. :)

Just to be clear: the above is overriding a private method, so may well break with future versions.

Also: the above uses +fillRoundRectInRect which is a NSBezierPath Category Method found on the NSBezierPathCategory page.

It worked for me, and has been a longstanding issue so I am very grateful to Ryan and the others for this solution - EcumeDesJours

I'm sorry to emphasize this again, but "worked for me" is really not the issue here. This is using an internal detail of the NSTableView implementation, so cannot be relied on. If you can deal with the consequences, then fine, but it's important to realize what's going on. Every time you use a private method, you limit Apple's ability to improve the frameworks.

of course, it would be best if we didnt have to hack apple's stuff but no 'legit' way to override this has surfaced...:-/

Using undocumented API (/internal details) does not limit Apple's ability to improve the frameworks. If I was Adobe or Microsoft (neither of which ship Cocoa apps but whatever), it might affect their framework design decisions but even then I think they'd continue doing what they're doing. The original disclaimer was good enough -- It could break in future versions. If it breaks you'll know and if you're smart your app will continue to work regardless. Good thing it's not a "critical" feature.

How do I make the drag function not highlight the table or any cells?

Why? they highlight for a reason (to indicate they're valid drop targets). Try turning the focus ring off.

I highlight the cell itself instead.

This is unfortunately a longstanding unsolved problem, as discussed above

EcumeDesJours

I have a possible solution:

Subclass NSTableView and leave setDropRow:dropOperation: blank

and a second solution:

override this one:

(private)

- (void) _drawDropHighlightBetweenUpperRow: (int) parameter1 andLowerRow: (int) parameter2 atOffset: (float) parameter3 {}

did this work for anyone?

Obligatory warning about overriding private methods...

sure enough, _highlightColorForCell is gone in Leopard... back to the drawing board!

shockingly, there is a new private method that get rid of those black rectangles in Leopard, which is never a good idea as things may break in the future. However, for educational purposes, you can try overriding the following in your NSTableView subclass: _drawDropHighlightBackgroundForRow: as in

- (id)_drawDropHighlightBackgroundForRow:(id)unObject{ return nil; }