转载自：http://developer.apple.com/library/mac/#documentation/Carbon/Reference/CTFramesetterRef/Reference/reference.html#//apple_ref/c/func/CTFramesetterSuggestFrameSizeWithConstraints

CTFramesetter Reference

Derived from

CFType

Framework

ApplicationServices/CoreText

Declared in

CTFramesetter.h

Overview

The CTFramesetter opaque type is used to generate text frames. That is, CTFramesetter is an object factory for CTFrame objects.

The framesetter takes an attributed string object and a shape descriptor object and calls into the typesetter to create line objects that fill that shape. The output is a frame object containing an array of lines. The frame can then draw itself directly into the current graphic context.

Functions by Task

Creating a Framesetter

• CTFramesetterCreateWithAttributedString

Creating Frames

• CTFramesetterCreateFrame
• CTFramesetterGetTypesetter

Frame Sizing

• CTFramesetterSuggestFrameSizeWithConstraints

Getting the Type Identifier

• CTFramesetterGetTypeID

Functions

CTFramesetterCreateFrame

Creates an immutable frame using a framesetter.

CTFrameRef CTFramesetterCreateFrame( CTFramesetterRef framesetter, CFRange stringRange, CGPathRef path, CFDictionaryRef frameAttributes );

Parameters

framesetter

The framesetter used to create the frame.

stringRange

The range, of the attributed string that was used to create the framesetter, that is to be typeset in lines fitted into the frame. If the length portion of the range is set to 0, then the framesetter continues to add lines until it runs out of text or space.

path

A CGPath object that specifies the shape of the frame.

frameAttributes

Additional attributes that control the frame filling process can be specified here, or NULL if there are no such attributes.

Return Value

A reference to a new CTFrame object if the call was successful; otherwise, NULL.

Discussion

This call creates a frame full of glyphs in the shape of the path provided by the path parameter. The framesetter continues to fill the frame until it either runs out of text or it finds that text no longer fits.

Availability

• Available in OS X v10.5 and later.

Related Sample Code

• CoreTextRTF
• CoreTextTest

Declared In

CTFramesetter.h

CTFramesetterCreateWithAttributedString

Creates an immutable framesetter object from an attributed string.

CTFramesetterRef CTFramesetterCreateWithAttributedString( CFAttributedStringRef string );

Parameters

string

The attributed string with which to construct the framesetter object.

Return Value

A reference to a CTFramesetter object if the call was successful; otherwise, NULL.

Discussion

The resultant framesetter object can be used to create and fill text frames with the CTFramesetterCreateFrame call.

Availability

• Available in OS X v10.5 and later.

Related Sample Code

• CoreTextRTF
• CoreTextTest

Declared In

CTFramesetter.h

CTFramesetterGetTypeID

Returns the Core Foundation type identifier of the framesetter object.

CFTypeID CTFramesetterGetTypeID( void );

Availability

• Available in OS X v10.5 and later.

Declared In

CTFramesetter.h

CTFramesetterGetTypesetter

Returns the typesetter object being used by the framesetter.

CTTypesetterRef CTFramesetterGetTypesetter( CTFramesetterRef framesetter );

Parameters

framesetter

The framesetter from which a typesetter is requested.

Return Value

A reference to a CTTypesetter object if the call was successful; otherwise, NULL. The framesetter maintains a reference to the returned object, which should not be released by the caller.

Discussion

Each framesetter uses a typesetter internally to perform line breaking and other contextual analysis based on the characters in a string; this function returns the typesetter being used by a particular framesetter in case the caller would like to perform other operations on that typesetter.

Availability

• Available in OS X v10.5 and later.

Declared In

CTFramesetter.h

CTFramesetterSuggestFrameSizeWithConstraints

Determines the frame size needed for a string range.

CGSize CTFramesetterSuggestFrameSizeWithConstraints(   CTFramesetterRef framesetter,   CFRange stringRange,   CFDictionaryRef frameAttributes,   CGSize constraints,   CFRange* fitRange);

Parameters

framesetter

The framesetter used for measuring the frame size.

stringRange

The string range to which the frame size applies. The string range is a range over the string used to create the framesetter. If the length portion of the range is set to 0, then the framesetter continues to add lines until it runs out of text or space.

frameAttributes

Additional attributes that control the frame filling process, or NULL if there are no such attributes.

constraints

The width and height to which the frame size is constrained. A value of CGFLOAT_MAX for either dimension indicates that it should be treated as unconstrained.

fitRange

On return, contains the range of the string that actually fit in the constrained size.

Return Value

The actual dimensions for the given string range and constraints.

Discussion

This function can be used to determine how much space is needed to display a string, optionally by constraining the space along either dimension.

Availability

• Available in OS X v10.6 and later.

Declared In

CTFramesetter.h

Data Types

CTFramesetterRef

A reference to a Core Foundation framesetter object.

typedef const struct __CTFramesetter *CTFramesetterRef;

Availability

• Available in OS X v10.5 and later.

Declared In

CTFramesetter.h

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