Re: Controlling line tightening

FROM : John Stiles
DATE : Wed Mar 12 22:20:11 2008

BTW, I've just documented this limitation in Radar:
rdar://5795937    AppKit string tightening should work with
non-truncating line break modes

This one is up to you—if you think it would be a useful addition, great;
if not, I guess you can punt it as "Behaves Correctly" or something.


John Stiles wrote:
> Right, we went over this a month or two ago. But in this case, I
> actually needed finer-grained control over the tightening—for
> instance, I didn't want an ellipsis when the tightening threshold is
> exceeded. Instead, when the tightening threshold is exceeded, I just
> want it to use the maximum tightening value and clip the excess.
> However, NSLineBreakByClipping does not work with AppKit tightening,
> and there is no way to make NSLineBreakByTruncatingTail stop
> displaying an ellipsis.
>
> So in short, I needed to implement my own custom tightening with the
> NSKern attribute. Works like a charm, it's just way more code :)
>
> I didn't even know NSKern existed until now, but it works great.
>
>
> Aki Inoue wrote:

>> John,
>>
>> The tightening is controlled by -[NSParagraphStyle
>> tighteningFactorForTruncation].
>>
>> http://developer.apple.com/documentation/Cocoa/Reference/ApplicationKit/Classes/NSParagraphStyle_Class/Reference/Reference.html#//apple_ref/occ/instm/NSParagraphStyle/tighteningFactorForTruncation
>>
>>
>> Aki
>>
>> On 2008/03/12, at 11:35, John Stiles wrote:

>>> Followup: this requires a bit of math but it works great in
>>> practice. I have a lot more control over the tightening now, which
>>> is just what I needed. Thanks!
>>>
>>> John Stiles wrote:

>>>> Interesting! I didn't think to use kerning directly. Thank you for
>>>> the idea!! It makes sense since obviously I am trying to do
>>>> something a little more sophisticated than the default "tighten"
>>>> functionality.
>>>>
>>>> How does "line tightening" pick an appropriate kerning value? I'm
>>>> thinking you could use -cellSize to get the actual string width,
>>>> and then you could figure out the ratio of cell frame to desired
>>>> size to compute a kerning value... but I've never used kerning
>>>> before so I could be off in the weeds here.
>>>>
>>>>
>>>> glenn andreas wrote:

>>>>>
>>>>> On Mar 11, 2008, at 9:54 PM, John Stiles wrote:
>>>>>

>>>>>> Gah, I spoke too soon.
>>>>>> This "solution" actually disables tightening entirely. So I'm
>>>>>> back to square one. Please help!

>>>>>
>>>>>
>>>>> You could try to manually squeeze the result by setting an
>>>>> attributed string's NSKernAttributeName value, but that would be
>>>>> far from automatic (since you'd have to be constantly measuring
>>>>> the string, redoing the kerning, and, in all likelihood, handle
>>>>> the auto-ellipsification yourself).
>>>>>
>>>>> It could probably be handled by a transformer in a binding, so it
>>>>> may not be too bad, though there's no obvious way for the binding
>>>>> to know the line width it needs to try to shrink the string to...
>>>>>
>>>>>
>>>>> Glenn Andreas                      <email_removed>
>>>>> <http://www.gandreas.com/> wicked fun!
>>>>> quadrium | prime : build, mutate, evolve, animate : the next
>>>>> generation of fractal art
>>>>>
>>>>>
>>>>>

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