UIKit's [NSString sizeWithFont:constrainedToSize:] in AppKit

问题

Is there any equivalent method in AppKit (for Cocoa on Mac OS X) that does the same thing as UIKit's [NSString sizeWithFont:constrainedToSize:]?

If not, how could I go about getting the amount of space needed to render a particular string constrained to a width/height?

Update: Below is a snippet of code I'm using that I expect would produce the results I'm after.

NSDictionary *attributes = [NSDictionary dictionaryWithObjectsAndKeys:
                            [NSFont systemFontOfSize: [NSFont smallSystemFontSize]], NSFontAttributeName,
                            [NSParagraphStyle defaultParagraphStyle], NSParagraphStyleAttributeName,
                            nil];
NSSize size = NSMakeSize(200.0, MAXFLOAT);
NSRect bounds;

bounds = [@"This is a really really really really really really really long string that won't fit on one line"
             boundingRectWithSize: size
             options: NSStringDrawingUsesFontLeading
             attributes: attributes];

NSLog(@"height: %02f, width: %02f", bounds.size.height, bounds.size.width);

I would expect that the output width would be 200 and the height would be something greater than the height of a single line, however it produces:

height: 14.000000, width: 466.619141

Thanks!

回答1:

EDIT: You should be able to do things the normal way in Lion and later. The problems described below have been fixed.

There is no way to accurately measure text among the current Mac OS X APIs.

There are several APIs that promise to work but don't. That's one of them; Core Text's function for this purpose is another. Some methods return results that are close but wrong; some return results that seem to mean nothing at all. I haven't filed any bugs on these yet, but when I do, I'll edit the Radar numbers into this answer. You should file a bug as well, and include your code in a small sample project.

[Apparently I have already filed the Core Text one: 8666756. It's closed as a duplicate of an unspecified other bug. For Cocoa, I filed 9022238 about the method Dave suggested, and will file two NSLayoutManager bugs tomorrow.]

This is the closest solution I've found.

回答2:

Try this one:

bounds = [value boundingRectWithSize:size options:NSLineBreakByWordWrapping | NSStringDrawingUsesLineFragmentOrigin attributes:attributes];

回答3:

The newer NSExtendedStringDrawing category API (methods with the NSStringDrawingOptions argument) behaves in the single line mode. If you want to measure/render in multi line mode, want to specify NSStringDrawingUsesLineFragmentOrigin.

回答4:

If you want to constrain the string to a certain size, you use -[NSString boundingRectWithSize:options:attributes:]. The .size of the returned NSRect is the size you're looking for.

回答5:

Here is a more complete example of how you can do this using boundingRectWithSize.

// get the text field
NSTextField* field = (NSTextField*)view;

// create the new font for the text field
NSFont* newFont = [NSFont fontWithName:@"Trebuchet MS" size:11.0];

// set the font on the text field
[field setFont:newFont];

// calculate the size the textfield needs to be in order to display the text properly
NSString* text      = field.stringValue;
NSInteger maxWidth  = field.frame.size.width;
NSInteger maxHeight = 20000;
CGSize constraint   = CGSizeMake(maxWidth, maxHeight);
NSDictionary* attrs = [NSDictionary dictionaryWithObjectsAndKeys:NSFontAttributeName,newFont, nil];
NSRect newBounds    = [text boundingRectWithSize:constraint
                                         options:NSLineBreakByWordWrapping | NSStringDrawingUsesLineFragmentOrigin
                                      attributes:attrs];

// set the size of the text field to the calculated size
field.frame = NSMakeRect(field.frame.origin.x, field.frame.origin.y, field.frame.size.width, newBounds.size.height);

Of course, for additional info, take a look at the Apple documentation:

Options for the attributes dictionary
boundingRectWithSize

回答6:

If you search the documentation for NSString, you will find the "NSString Application Kit Additions Reference", which is pretty much analogous to the UIKit counterpart.

-[NSString sizeWithAttributes:]

is the method you are looking for.

来源：https://stackoverflow.com/questions/5033598/uikits-nsstring-sizewithfontconstrainedtosize-in-appkit

标签

cocoa

nsstring

appkit