RE: Glyph Generator & hiding glyphs -> _NSBlockNumberForIndex() errors
RE: Glyph Generator & hiding glyphs -> _NSBlockNumberForIndex() errors
- Subject: RE: Glyph Generator & hiding glyphs -> _NSBlockNumberForIndex() errors
- From: Keith Blount <email@hidden>
- Date: Sat, 8 Mar 2008 10:41:05 -0800 (PST)
Just to add a little info to my previous message, which was a little misleading:a
My custom glyph generator replaces each glyph that is supposed to be hidden with NSNullGlyph (it doesn't just insert one NSNullGlyph for the lot of them), so I would expect the one-to-one mapping on this first pass of glyph generation to be maintained. I'm therefore really not sure why I'm getting all of these errors - it seems that the presence of a group of null glyphs completely breaks things at the typesetting stage (I'm guessing)? Hmm, given that there is so little documentation about this sort of thing and most glyph generation threads seem to have been unanswered, I don't hold out much hope...
In case there is a better way of doing things: I am basically trying to implement hidden text, so that text with a given custom attribute does not get displayed in the text view. One way I could have done this was via a custom text storage subclass that maintained two representations of its text - one with the hidden text displayed, one with it, um, hidden - but this is no good for what I want, as the same text storage can be displayed in two different text views, and there is more than one attribute type that can be hidden separately.
Hence the custom glyph generator, which isn't working...
Thanks in advance for any help or pointers.
All the best,
Keith
--- ORIGINAL MESSAGE ---
Hi,
I have a custom glyph generator (NSGlyphGenerator subclass) that is used to hide glyphs for text with certain attributes. It does this by inserting a single NSNullGlyph for a range of glyphs representing text with these hidden attributes. (This is basically a hidden text toggle.) This all works brilliantly - I can completely hide whole ranges of text - but only so long as the text is viewed in a single text view.
If I have the same text storage shared between two text views, and one view has the text hidden whilst the other doesn't, I get array out of bounds errors under the following circumstances: If, in the view where no text is hidden, I click in the range of text that IS hidden in the other view, and then I hit return a couple of times, I get these errors:
Exception raised during background layout: *** NSRunStorage, _NSBlockNumberForIndex(): index (345) beyond array bounds (335)
2008-03-08 10:28:00.042 HiddenTextTest[42350:813] *** NSRunStorage, _NSBlockNumberForIndex(): index (345)
Clearly, these errors are caused because my hidden-text view has less glyphs in it than the non-hidden-text view, but they both share the same text storage. So my question is, how do I fix this? Somewhere it seems that I need to tell something else - other than my glyph generator - that some text is hidden. The errors seem to indicate that I might need to tell my text storage about this... But where and how? But then, I can't tell the text storage, because it has hidden text in one view but not the other...
The method of hiding text by inserting a null glyph was recommended to me by DTS, but there is very little documentation on actually achieving something like this, so I'm hoping some text expert here will be able to give me some clues. :)
Many thanks in advance and all the best,
Keith
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