CGPattern Reference

Overview

The CGPatternRef opaque type represents a pattern that you can use to stroke along or fill in a graphics path. Quartz tiles the pattern cell for you, based on parameters you specify when you call CGPatternCreate.

To create a dashed line, see CGContextSetLineDash in CGContext Reference.

Functions by Task

Creating a Pattern

• CGPatternCreate

Getting the CFType ID

• CGPatternGetTypeID

Retaining and Releasing a Pattern

• CGPatternRetain
• CGPatternRelease

Functions

CGPatternCreate

Creates a pattern object.

CGPatternRef CGPatternCreate (
   void *info,
   CGRect bounds,
   CGAffineTransform matrix,
   CGFloat xStep,
   CGFloat yStep,
   CGPatternTiling tiling,
   bool isColored,
   const CGPatternCallbacks *callbacks
);

CGPatternGetTypeID

Returns the type identifier for Quartz patterns.

CFTypeID CGPatternGetTypeID (
   void
);

CGPatternRelease

Decrements the retain count of a Quartz pattern.

void CGPatternRelease (
   CGPatternRef pattern
);

CGPatternRetain

Increments the retain count of a Quartz pattern.

CGPatternRef CGPatternRetain (
   CGPatternRef pattern
);

Callbacks

CGPatternDrawPatternCallback

Draws a pattern cell.

typedef void (*CGPatternDrawPatternCallback) (
   void * info,
   CGContextRef context
);
   

If you name your function MyDrawPattern, you would declare it like this:

void MyDrawPattern (
   void * info,
   CGContextRef context
);

CGPatternReleaseInfoCallback

Release private data or resources associated with the pattern.

typedef void (*CGPatternReleaseInfoCallback) (
   void * info
);
   

If you name your function MyCGPatternReleaseInfo, you would declare it like this:

void MyCGPatternReleaseInfo (
   void * info
);

Data Types

CGPatternRef

An opaque type that represents a pattern.

typedef struct CGPattern * CGPatternRef;

CGPatternCallbacks

A structure that holds a version and two callback functions for drawing a custom pattern.

struct CGPatternCallbacks {
   unsigned int version;
   CGPatternDrawPatternCallback drawPattern;
   CGPatternReleaseInfoCallback releaseInfo;
};
typedef struct CGPatternCallbacks CGPatternCallbacks;

Fields

version

The version of the structure passed in as a parameter to the CGPatternCreate. For this version of the structure, you should set this value to zero.

drawPattern

A pointer to a custom function that draws the pattern. For information about this callback function, see CGPatternDrawPatternCallback.

releaseInfo

An optional pointer to a custom function that’s invoked when the pattern is released. CGPatternReleaseInfoCallback.

Constants

Tiling Patterns

Different methods for rendering a tiled pattern.

enum CGPatternTiling {
   kCGPatternTilingNoDistortion,
   kCGPatternTilingConstantSpacingMinimalDistortion,
   kCGPatternTilingConstantSpacing
};
typedef enum CGPatternTiling CGPatternTiling;

Constants

kCGPatternTilingNoDistortion

The pattern cell is not distorted when painted. The spacing between pattern cells may vary by as much as 1 device pixel.

Available in iOS 2.0 and later.

Declared in CGPattern.h.

kCGPatternTilingConstantSpacingMinimalDistortion

Pattern cells are spaced consistently. The pattern cell may be distorted by as much as 1 device pixel when the pattern is painted.

Available in iOS 2.0 and later.

Declared in CGPattern.h.

kCGPatternTilingConstantSpacing

Pattern cells are spaced consistently, as with kCGPatternTilingConstantSpacingMinimalDistortion. The pattern cell may be distorted additionally to permit a more efficient implementation.

Available in iOS 2.0 and later.

Declared in CGPattern.h.