Re: Displaying one NSTextStorage with two sets of temporary attributes
Re: Displaying one NSTextStorage with two sets of temporary attributes
- Subject: Re: Displaying one NSTextStorage with two sets of temporary attributes
- From: Ross Carter <email@hidden>
- Date: Fri, 2 May 2008 13:38:09 -0400
Hi Adam,
I guess that the approach you will take depends on how the textStorage
string is set up. Sorry, I don't know anything about TEI, so I can
only offer general comments.
If the textStorage series are sequential and the number and sequence
of series are known in advance, and the text has no page break
characters (NSFormFeedCharacter), you could insert a page break at the
end of each series. That will throw layout over to the next
textContainer. If you have a textContainer/textView set up for each
series, then the text will flow into the textViews that you have set
up to show the content of each series.
If you know the character range of each series, you could override
NSLayoutManager drawGlyphsForGlyphRange:atPoint: and have it send the
message to super only if the glyphs in glyphRange are in the character
range you want to display.
In short, if the question is "Is there a simple way to tell
NSLayoutManager not to display certain character ranges," then the
answer is: I don't think so. Personally, I wouldn't adopt either of
the approaches I mentioned because of the complications in
coordinating the various displays using one textStorage. For example,
if the user pasted in some text that contains a form feed character,
it could throw off everything.
XML is easy to parse. I think you'll find it simpler in the end to
split the original string into separate series, make each series the
textStorage for a textView, let the user edit each series as he
desires, and then reassemble the series into a single string when you
archive. Even if there were a way to tell the layoutManagers to be
selective about what they display, you've still got a lot of work to
do in keeping them all synchronized as the user adds and removes text.
That's just my opinion, though. Text experts like Douglas and Martin
might have a better idea. I'd be happy to continue this discussion
offline if you to want to kick around some more ideas.
Ross
On May 2, 2008, at 12:47 PM, Adam C.M. Solove wrote:
Actually, you're right that merely suppressing display is all I need.
I was assuming this would have to be done with temporary attributes,
but is there an easier way?
THank you,
Adam Solove
On Fri, May 2, 2008 at 7:57 AM, Ross Carter <email@hidden>
wrote:
I'm not sure whether you need to change a particular set of
attributes
(font, line spacing, tabs, etc) in each layout manager or merely
suppress
the display of text in other series. If the former, I would think
that the
layout manager is not best place to handle the attribute fixing.
I'd think
about either subclassing NSTextStorage and have it modify the
attributes
that it receives from and sends to the various layout managers, or
subclassing the typesetter and overriding setAttributedString: to
change the
attributes as needed. I haven't ever done either of those things,
mind you,
so I don't know whether they would work.
It just seems to me that by the time the layout manager goes to
work, it's
difficult to change the attributes (except for things that don't
affect the
layout, such as underlining) because of the complex interaction
between the
layout manager and the typesetter. You probably want to intervene
before the
attributedString gets converted into glyphs.
On May 1, 2008, at 8:25 PM, Adam C.M. Solove wrote:
Hello all,
In the episode of Late Night Cocoa on the text system, [
http://www.macdevnet.com/index.php/shows/latenightcocoa/37-latenightcocoa/93-lnc005
] Juan Pablo Claude described a setup with multiple NSLayoutManagers
editing text from the same NSTextStorage and then said, off-hand,
that
you might do this if you wanted to display the same text with
different fonts. I am curious if anyone could discuss how this might
be done: displaying the same underlying attributed string, but
formatting it before the NSLayoutManager tries to lay it out and
formatting it back when the NSTextView sends back changes. I cannot
find specific information on subclassing NSLayoutManager to make
these
sorts of changes.
(I know there is an Apple demo [TextViewConfig,
http://developer.apple.com/samplecode/TextViewConfig/index.html]
which
shows multiple layout managers, but these both render the exact same
attributed string (except that one view has been essentially
zoomed to
twice the size). I am curious if it is possible to actually change
temporary attributes in one LayoutManager but not the other, and
then
change them back appropriately before sending events to the
NSTextStorage.)
End technical discussion
----
Begin back story for those interested:
I am a relatively new Cocoa developer working on an open-source
project for academics. I recently spent considerable time working
on
a web-based version of this application before learning that the
hardest part was technically infeasible because of some
limitations in
HTML's designmode. In starting with Cocoa, I will be happy if the
project and required learning takes many years, so long as there
is an
answer in advance to this one difficult question.
The application is an editor for a specific subset of the TEI XML
guidelines for encoding literary works and scholarly commentaries on
them. The underlying data maps very nicely into an attributed
string,
because it is a single text divided up into separate 'series' (main
text, footnotes, cross-links) The series are all anchored together,
but would best be displayed apart, with first the main text, then
each
series of notes. I believe the easiest way to do this would be to
have
a single underlying NSTextStorage, to attribute every range of
text to
one series, and then to create various subclasses (or formatters)
for
NSLayoutManager that each display only text in one particular
series.
I suspect this could also be done with a custom Typesetter and the
method setNotShownAttribute:forGlyphAtIndex:, but am curious if
there
is a more general hook to set attributes on the string before
layout.
Thank you,
Adam Solove
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