Core Text is a Core Foundation

Core Foundation

Core Foundation is a C application programming interface in Mac OS X & iOS, and is a mix of low-level routines and wrapper functions...

 style API in Mac OS X

Mac OS X

Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...

, first introduced in Mac OS X 10.4 Tiger

Mac OS X v10.4

Mac OS X v10.4 Tiger is the fifth major release of Mac OS X, Apple's desktop and server operating system for Macintosh computers. Tiger was released to the public on 29 April 2005 for US$129.95 as the successor to Mac OS X Panther , which had been released 18 months earlier...

, made public in Mac OS X 10.5 Leopard

Mac OS X v10.5

Mac OS X Leopard is the sixth major release of Mac OS X, Apple's desktop and server operating system for Macintosh computers. Leopard was released on 26 October 2007 as the successor of Tiger , and is available in two variants: a desktop version suitable for personal computers, and a...

, and introduced for the iPad

IPad

The iPad is a line of tablet computers designed, developed and marketed by Apple Inc., primarily as a platform for audio-visual media including books, periodicals, movies, music, games, and web content. The iPad was introduced on January 27, 2010 by Apple's then-CEO Steve Jobs. Its size and...

 with iPhone SDK 3.2. Exposing a C API, it replaces the text rendering abilities of the now-deprecated QuickDraw

QuickDraw

QuickDraw is the 2D graphics library and associated Application Programming Interface which is a core part of the classic Apple Macintosh operating system. It was initially written by Bill Atkinson and Andy Hertzfeld. QuickDraw still exists as part of the libraries of Mac OS X, but has been...

 and ATSUI frameworks in previous versions of Mac OS X. According to Apple, Core Text is "designed for high performance and ease of use" and its layout API is "simple, consistent, and tightly integrated with Core Foundation, Core Graphics, and Cocoa."

Features

Core Text provides the following opaque types:

• CTFramesetter - creates CTFrame objects from given attributed string object and CGPath object using CTTypesetter.
• CTTypesetter - performs line layouts; e.g., line breaking
• CTFrame - represents an array of lines (i.e., CTLine objects).
• CTLine - represents an array of glyph runs.
• CTRun - an ordered collection of glyphs sharing the same attribute.
• CTFont - represents a font.

Example

The following code displays the text "Hello, World!" to the given graphics context.

// Prepare font

CTFontRef font = CTFontCreateWithName(CFSTR("Times"), 48, NULL);



// Create an attributed string

CFStringRef keys[] = { kCTFontAttributeName };

CFTypeRef values[] = { font };

CFDictionaryRef attr = CFDictionaryCreate(NULL, (const void **)&keys, (const void **)&values,

					  sizeof(keys) / sizeof(keys[0]), &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);

CFAttributedStringRef attrString = CFAttributedStringCreate(NULL, CFSTR("Hello, World!"), attr);

CFRelease(attr);



// Draw the string

CTLineRef line = CTLineCreateWithAttributedString(attrString);

CGContextSetTextMatrix(context, CGAffineTransformIdentity);  //Use this one when using standard view coordinates

//CGContextSetTextMatrix(context, CGAffineTransformMakeScale(1.0, -1.0)); //Use this one if the view's coordinates are flipped



CGContextSetTextPosition(context, 10, 20);

CTLineDraw(line, context);



// Clean up

CFRelease(line);

CFRelease(attrString);

CFRelease(font);

External links

• Overview at Apple's Developer Connection