Layout manager's -rectArrayForCharacterRange:::: returns zero rectangles??
-
I'm trying to write some code which figures out where the insertion
point is located, every time the selection changes. (Imagine a text
editor which has a "current line number" indicator at the bottom of the
screen that stays updated as the user types.)
To do this, in my text view's delegate, I have implemented the delegate
method -textViewDidChangeSelection:. From there I call -selectedRange
and then ask the layout manager for the rectangles via:
NSRectArray rects = [[myTextView layoutManager]
rectArrayForCharacterRange:selection
withinSelectedCharacterRange:NSMakeRange(NSNotFound, 0)
inTextContainer:[myTextView textContainer]
rectCount:&rectCount];
Normally, this works perfectly.
However, if I go to the very end of the document and start making
insertions or deletions, I don't get a rectangle backââ¬â"rectCount" is
zero. I've checked [[[TextView() textStorage] string] length] and
compared it against the selection, so I'm pretty confident that I'm not
querying past the end of the text, which in the past is the only time
I've seen behavior like this up until now.
Any ideas as to what's wrong? This seems pretty straightforward to me so
I'm not sure what I'm missing. -
Hmm. I tried another approach and it's still no good. This produces
NSZeroRect:
NSLayoutManager* layout = [myTextView layoutManager];
NSRange glyphRange = [layout glyphRangeForCharacterRange:selection
actualCharacterRange:NULL];
rect = [layout boundingRectForGlyphRange:glyphRange
inTextContainer:[myTextView
textContainer]];
Interestingly, this only happens in the -textViewDidChangeSelection:
delegate. If I defer the call until after -textViewDidChangeSelection:
completes, then I can call the exact same function with the exact same
inputs, and get a valid result.
If no one else has any ideas, maybe that's what I'll end up doingââ¬Â¦
John Stiles wrote:> I'm trying to write some code which figures out where the insertion
> point is located, every time the selection changes. (Imagine a text
> editor which has a "current line number" indicator at the bottom of
> the screen that stays updated as the user types.)
>
> To do this, in my text view's delegate, I have implemented the
> delegate method -textViewDidChangeSelection:. From there I call
> -selectedRange and then ask the layout manager for the rectangles via:
>
> NSRectArray rects = [[myTextView layoutManager]
> rectArrayForCharacterRange:selection
>
> withinSelectedCharacterRange:NSMakeRange(NSNotFound, 0)
>
> inTextContainer:[myTextView textContainer]
>
> rectCount:&rectCount];
>
> Normally, this works perfectly.
>
> However, if I go to the very end of the document and start making
> insertions or deletions, I don't get a rectangle backââ¬â"rectCount" is
> zero. I've checked [[[TextView() textStorage] string] length] and
> compared it against the selection, so I'm pretty confident that I'm
> not querying past the end of the text, which in the past is the only
> time I've seen behavior like this up until now.
>
> Any ideas as to what's wrong? This seems pretty straightforward to me
> so I'm not sure what I'm missing. -
I managed to reproduce this in a small test app so it's filed as:
rdar://5764057 NSLayoutManager cannot get bounding rect of glyph
when deleting at end of text
For now I will use -performSelector:inMainThread:afterDelay: to kludge
around it. It's better than nothing.
John Stiles wrote:> Hmm. I tried another approach and it's still no good. This produces
> NSZeroRect:
>
> NSLayoutManager* layout = [myTextView layoutManager];
>
> NSRange glyphRange = [layout glyphRangeForCharacterRange:selection
> actualCharacterRange:NULL];
> rect = [layout boundingRectForGlyphRange:glyphRange
> inTextContainer:[myTextView
> textContainer]];
>
> Interestingly, this only happens in the -textViewDidChangeSelection:
> delegate. If I defer the call until after -textViewDidChangeSelection:
> completes, then I can call the exact same function with the exact same
> inputs, and get a valid result.
>
> If no one else has any ideas, maybe that's what I'll end up doingââ¬Â¦
>
>
> John Stiles wrote:
>> I'm trying to write some code which figures out where the insertion
>> point is located, every time the selection changes. (Imagine a text
>> editor which has a "current line number" indicator at the bottom of
>> the screen that stays updated as the user types.)
>>
>> To do this, in my text view's delegate, I have implemented the
>> delegate method -textViewDidChangeSelection:. From there I call
>> -selectedRange and then ask the layout manager for the rectangles via:
>>
>> NSRectArray rects = [[myTextView layoutManager]
>> rectArrayForCharacterRange:selection
>>
>> withinSelectedCharacterRange:NSMakeRange(NSNotFound, 0)
>>
>> inTextContainer:[myTextView textContainer]
>>
>> rectCount:&rectCount];
>>
>> Normally, this works perfectly.
>>
>> However, if I go to the very end of the document and start making
>> insertions or deletions, I don't get a rectangle backââ¬â"rectCount" is
>> zero. I've checked [[[TextView() textStorage] string] length] and
>> compared it against the selection, so I'm pretty confident that I'm
>> not querying past the end of the text, which in the past is the only
>> time I've seen behavior like this up until now.
>>
>> Any ideas as to what's wrong? This seems pretty straightforward to me
>> so I'm not sure what I'm missing.
