Re: CATextLayer and CAConstraint

FROM : Paul Arthur Henrion
DATE : Thu Nov 22 16:53:15 2007

As it's been said by Apple Documentation the CATextLayer only 
automatically resizes when a default CAConstraintLayoutManager is on.

So Aaron, instead of constraining the layer's width just set its 
layoutManager to [CAConstraintLayoutManager defaultManager] and it'll 
resize to fit your text.

By the way, I'd like to play with my CATextLayer's constraints, but it 
does not work properly: I want my layer width to be constraint but not 
its height and, whenever the string prompted in my layer is too large, 
I want the layer height to increase in order to fit the whole 
phrase... I don't know if you get me, my english is not that correct 
(I'm Frog powered huhu).

Maybe a small schema could help: (I'm sorry if you cannot see it 
properly — font and font size issue — :'/)
+ First:                                      ___________
This is my CATextLayer --> | Hey Apple Li |  st people, how you doin'?
                                                   
¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨          /\
                                                                                        |
                                                                  This 
is hidden because it does not fit the layer (too large)

+ Then it resizes as I want:  ___________
This is my CATextLayer --> | Hey Apple    |
                                                  | List people,  | 
No more hidden text
The layer width stay un-      | how you        |
-changed but the height      | doin'?            |
got bigger.                              ¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨

I've tried a couple techniques (like telling layer and / or superlayer 
to layout, playing with the autoresizing mask, manually setting the 
layer height, etc.) but it never does want I want.

If anyone has an idea, it would be very appreciated :')

Thanks,

Paul

On , Mon Nov 19 10:12:19 2007 Scott Anguish wrote:
> If this is the case, it may be a bug. might be worth reporting
>
> are you notifying the superlayer that it needs to layout its
> sublayers when the string changes?  I don't believe that simply
> changing the string of the textlayer will do that.
>
> CATextLayer does alter its bounds to fit the text exactly when using
> constraints. (this is mentioned in the reference)
>
> On  Sun Nov 18 19:02:15 2007 Aaron Tait wrote:

>> Bill, I tried your solution but it did not help. Fortunately however,
>> I have found a working solution. It looks like the constraints mess
>> with the sizing and bounds of my CATextLayer making it only 1 unit in
>> size. I have added the following constraint and it produces a
>> desirable result:
>>    [fileNameLayer addConstraint:[CAConstraint
>> constraintWithAttribute:kCAConstraintWidth relativeTo:@"superlayer"
>> attribute:kCAConstraintWidth]];
>>
>> -Aaron
>>
>>
>> On 18-Nov-07, at 8:26 AM, Bill Dudney wrote:

>>> Hi Aaron,
>>>
>>> When trying to manipulate layers like this its best if you use a
>>> layer hosting view rather than a layer backed view. If you rely on
>>> the layer the view creates for you its often the case that you get
>>> weird behavior like this.
>>>
>>> Instead in your awakeFromNib method you can make your view layer
>>> hosting;
>>> myLayer = [CALayer layer];
>>> // other myLayer initilization
>>> [myView setLayer:myLayer];
>>> [myView setWantsLayer:YES];
>>>
>>> then you can add sublayers as in your addFileNameLayer: below and
>>> everything should work.
>>>
>>> As an alternative you could simply create a text field as a label
>>> and add it as a subview of your current setup and it will become
>>> layer backed since you are adding it to a view that is layer backed.
>>>
>>> HTH,
>>>
>>> -bd-
>>> http://bill.dudney.net/roller/objc
>>>
>>> On Nov 18, 2007, at 1:00 AM, Aaron Tait wrote:

>>>> I've been pulling my hair out trying to get a CATextLayer to work
>>>> with a couple of CAConstraints. The following is a method
>>>> implemented in a layer backed view and the following call is made
>>>> in the view's awakeFromNib:
>>>> self.layer.layoutManager = [CAConstraintLayoutManager 
>>>> layoutManager];
>>>>
>>>> The method is as follows:
>>>>
>>>> -(void)addFileNameLayer:(NSString *)fileName
>>>> {
>>>>    CATextLayer * fileNameLayer = [CATextLayer layer];
>>>>    fileNameLayer.string = fileName;
>>>>    fileNameLayer.name = @"fileNameLayer";
>>>>    fileNameLayer.fontSize = 14.0;
>>>>    fileNameLayer.alignmentMode = kCAAlignmentCenter;
>>>>    fileNameLayer.wrapped = YES;
>>>>    fileNameLayer.anchorPoint = CGPointMake(0.5, 0.5);
>>>>    fileNameLayer.bounds = CGRectMake(0, 0, 320, 50);
>>>>    [fileNameLayer addConstraint:[CAConstraint
>>>> constraintWithAttribute:kCAConstraintMidX relativeTo:@"superlayer"
>>>> attribute:kCAConstraintMidX]];
>>>>    [fileNameLayer addConstraint:[CAConstraint
>>>> constraintWithAttribute:kCAConstraintMidY relativeTo:@"superlayer"
>>>> attribute:kCAConstraintMidY offset:-100]];
>>>>    [self.layer addSublayer:fileNameLayer];
>>>> }
>>>>
>>>> When the code executes, it displays nothing. I also add another
>>>> plain old CALayer before I call this method with similar
>>>> constraints and it works out fine. Anyone help would be 
>>>> appreciated.
>>>>
>>>> -Aaron