Ascertaining the top line in a view
-
Hi there
I have a requirement for drawing line numbers next to a text view.
Obviously the easiest way to do this in Cocoa is by means of a subclass
of NSRuler. How all this works I can figure out, what is confusing me
is how to ascertain the line number that is currently at the top of the
NSTextView. In the case of unformatted text, i.e. one line == one
paragraph, the number of paragraphs in the NSTextStorage is the number
of lines, but how does one ascertain the relative positions of
paragraphs with respect to the top of the NSTextView. I have spent
hours reading NSTextStorage, NSLayoutManager, NSTextContainer, NSText,
and NSTextView documentation without being able to figure this out. Has
anyone any more in-depth knowledge on this subject that perhaps
suggested a route ?
Thanks
Vincent
_______________________________________________
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For the first character of each paragraph,
charRange is NSMakeRange(first char offset, 1)
noRange is NSMakeRange(NSNotFound, 0)
container is [theTextView container]
layoutManager is [theTextView layoutManager]
unsigned rectCount
NSRect * rects = [layoutManager rectArrayForCharacterRange: charRange
withinSelectedCharacterRange: noRange
inTextContainer: container rectCount: &rectCount
rectCount will always be 1. NSMinY(rects[0]) will be the top of the
first line in the paragraph.
For all the line-fragment rectangles,
allChars is NSMakeRange(0, [textStorage length])
allGlyphs is allChars converted to a glyph range by layoutManager
currRange starts at NSMakeRange(0, 0)
while NSMaxRange(currRange) < NSMaxRange(allGlyphs)
currFragmentRect is [layoutManager lineFragmentRectForGlyphAtIndex:
currRange.location
effectiveRange: &currRange];
process currFragmentRect. There may be more than one per line; look
for the rect at the left margin
currRange.location = NSMaxRange(currRange)
currRange.length = 0;
-- F
On 7 Nov 2003, at 1:11 AM, Vincent Coetzee wrote:
> Hi there_______________________________________________
>
> I have a requirement for drawing line numbers next to a text view.
> Obviously the easiest way to do this in Cocoa is by means of a
> subclass of NSRuler. How all this works I can figure out, what is
> confusing me is how to ascertain the line number that is currently at
> the top of the NSTextView. In the case of unformatted text, i.e. one
> line == one paragraph, the number of paragraphs in the NSTextStorage
> is the number of lines, but how does one ascertain the relative
> positions of paragraphs with respect to the top of the NSTextView. I
> have spent hours reading NSTextStorage, NSLayoutManager,
> NSTextContainer, NSText, and NSTextView documentation without being
> able to figure this out. Has anyone any more in-depth knowledge on
> this subject that perhaps suggested a route ?
cocoa-dev mailing list | <cocoa-dev...>
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Do not post admin requests to the list. They will be ignored. -
Hi there
Thanks for your help guys, but I found a reference to the exact
solution I was looking for on MamaSan, thanks to Koen van der Drift and
Jim Derry. Thanks for publishing the source guys.
Vince
On Nov 07, 2003, at 19:05, Fritz Anderson wrote:
> For the first character of each paragraph,_______________________________________________
> charRange is NSMakeRange(first char offset, 1)
> noRange is NSMakeRange(NSNotFound, 0)
> container is [theTextView container]
> layoutManager is [theTextView layoutManager]
> unsigned rectCount
> NSRect * rects = [layoutManager rectArrayForCharacterRange: charRange
> withinSelectedCharacterRange: noRange
> inTextContainer: container rectCount: &rectCount
>
> rectCount will always be 1. NSMinY(rects[0]) will be the top of the
> first line in the paragraph.
>
> For all the line-fragment rectangles,
>
> allChars is NSMakeRange(0, [textStorage length])
> allGlyphs is allChars converted to a glyph range by layoutManager
> currRange starts at NSMakeRange(0, 0)
> while NSMaxRange(currRange) < NSMaxRange(allGlyphs)
> currFragmentRect is [layoutManager lineFragmentRectForGlyphAtIndex:
> currRange.location
> effectiveRange: &currRange];
> process currFragmentRect. There may be more than one per line; look
> for the rect at the left margin
> currRange.location = NSMaxRange(currRange)
> currRange.length = 0;
>
> -- F
>
> On 7 Nov 2003, at 1:11 AM, Vincent Coetzee wrote:
>
>> Hi there
>>
>> I have a requirement for drawing line numbers next to a text view.
>> Obviously the easiest way to do this in Cocoa is by means of a
>> subclass of NSRuler. How all this works I can figure out, what is
>> confusing me is how to ascertain the line number that is currently at
>> the top of the NSTextView. In the case of unformatted text, i.e. one
>> line == one paragraph, the number of paragraphs in the NSTextStorage
>> is the number of lines, but how does one ascertain the relative
>> positions of paragraphs with respect to the top of the NSTextView. I
>> have spent hours reading NSTextStorage, NSLayoutManager,
>> NSTextContainer, NSText, and NSTextView documentation without being
>> able to figure this out. Has anyone any more in-depth knowledge on
>> this subject that perhaps suggested a route ?
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