Re: NSTextContainer subclass question

FROM : Douglas Davidson
DATE : Wed Nov 27 20:04:09 2002

On Wednesday, November 27, 2002, at 10:40  AM, Brock Brandenberg wrote:

> In a quick sample project, I have a subclass of NSTextContainer that
> overrides the lineFragmentRectForProposedRect: method, returning
> appropriate
> rects for a custom shape. In an NSApplication delegate, I'm simply
> replacing
> the default NSTextContainer for a NSTextView that is instantiated from
> a nib
> with my subclass. When text is entered into the NSTextView and the
> shape
> will no longer hold all of the text, the subclass method will return a
> NSZeroRect. In this case, the NSTextView no longer draws the text. As
> long
> as the text is short enough to fit the shape, however, it draws.
>
> Is it a requirement that an NSLayoutManager has enough text containers
> to
> hold all the text before drawing occurs? In my example, I'm hacking
> the sole
> NSTextContainer for a NSTextView, so I assume that I'm breaking its
> usual
> operation in some way. However, I would assume that there is some way
> to
> catch the end of layout for this sole container and at least tell the
> NSTextView to draw what it can to make this sample work. I'm familiar
> with
> the NSLayoutManager delegate methods, so in my particular application,
> I can
> insure that extra containers are added to hold the text. However, I'd
> like
> to avoid having to do so and would rather ignore any overflowed text.
> The
> docs are pretty thin around NSTextContainer subclasses and their
> interaction
> with the rest of the text system, so any assistance with handling text
> container overflow would be helpful.

It should not be necessary for there to be sufficient containers to
hold all of the text.  Yes, you can use the layout manager delegate
methods (as TextEdit does) to add additional text containers if those
present are full, but there is no requirement that you do so.  However,
it's possible that there's a bug here for which adding an additional
large undisplayed text container would be a workaround.  Let me ask--is
the text you are drawing all one paragraph?  Does inserting explicit
line breaks into the text change the result?

Douglas Davidson
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