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Re: Text height for printing (fixed width)



Jérôme,

What you (and others) are observing here is the typesetter behavior difference between measurement and rendering.

You're using one of string drawing convenience to render text, but using NSLayoutManager for measurement.

Currently the string drawing convenience methods defined in NSStringDrawing.h are using NSTypesetterBehavior_10_2_WithCompatibility whereas the default setting for NSLayoutManager is NSTypesetterLatestBehavior.

This causes line height calculation mismatch.

A easy solution for your problem is to add the following line in - heightForStringDrawingV1:withFont:andWitdh:.
[layoutManager setTypesetterBehavior:NSTypesetterBehavior_10_2_WithCompatibility];


Ideally, you should use the same layout manager you used to measure for rendering (especially for performance).

Aki

Le 3 janv. 06, à 17:12, Jerry Krinock a écrit :

Sorry I have not read these or your project, but it sounds similar to the
question in this recent thread:


http://www.cocoabuilder.com/archive/message/cocoa/2005/12/20/152875


You're right, it was my question. You gave the Apple NSLayout Guide method. But it didn't really satisfy me, because you said :

You may find that you need to add a little margin.  I don't know why,
but to guarantee no wrapping I have to add 15 pixels to the returned
measurement.  The required margin may depend on your font, size, etc.

It's true : sometimes (and only sometimes !), it needs a margin. To have a font independent margin , I just add a breakline at the end of the string when there isn't :


		if( ! [aString hasSuffix:@"\n"])
		aString = [NSString stringWithFormat:@"%@\n", aString];

It's isn't perfect because there is sometimes a small extra vertical space.

The complete method :
// from Apple Text NSLayout Programming Guide
- (float) heightForStringDrawingV1:(NSString *)aString withFont: (NSFont *)aFont andWitdh:(float)myWidth
{
if( ! [aString hasSuffix:@"\n"])
aString = [NSString stringWithFormat:@"%@\n", aString];

NSTextStorage *textStorage = [[[NSTextStorage alloc] initWithString:aString] autorelease];
NSTextContainer *textContainer = [[[NSTextContainer alloc] initWithContainerSize:NSMakeSize(myWidth,1e7)] autorelease];
NSLayoutManager *layoutManager = [[[NSLayoutManager alloc] init] autorelease];
[layoutManager addTextContainer:textContainer];
[textStorage addLayoutManager:layoutManager];

[textStorage addAttribute:NSFontAttributeName value:aFont range:NSMakeRange(0,[textStorage length])];
[textContainer setLineFragmentPadding:0.0];

(void) [layoutManager glyphRangeForTextContainer:textContainer];
return [layoutManager usedRectForTextContainer:textContainer].size.height;
}


Thanks for your help Jerry, it's your post which gave me this idea ! _______________________________________________
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References: 
 >Re: Text height for printing (fixed width) (From: Jérôme Jaglale <email@hidden>)



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