Class

CGDataProvider

An abstraction for data-reading tasks that eliminates the need to manage a raw memory buffer.

Declaration

class CGDataProvider

Overview

Some Core Graphics routines supply blocks of data to your program. Rather than reading through a raw memory buffer, data provider objects of type CGDataProviderRef allow you to supply Core Graphics functions with data.

CGDataProviderRef is derived from CFTypeRef and inherits the properties that all Core Foundation types have in common.

Topics

Creating Sequential-Access Data Providers

init?(sequentialInfo: UnsafeMutableRawPointer?, callbacks: UnsafePointer<CGDataProviderSequentialCallbacks>)

Creates a sequential-access data provider.

struct CGDataProviderSequentialCallbacks

Defines a structure containing pointers to client-defined callback functions that manage the sending of data for a sequential-access data provider.

typealias CGDataProviderRewindCallback

A callback function that moves the current position in the data stream back to the beginning.

typealias CGDataProviderGetBytesCallback

A callback function that copies from a provider data stream into a Core Graphics buffer.

typealias CGDataProviderSkipForwardCallback

A callback function that advances the current position in the data stream supplied by the provider.

typealias CGDataProviderReleaseInfoCallback

A callback function that releases any private data or resources associated with the data provider.

Creating Direct-Access Data Providers

init?(directInfo: UnsafeMutableRawPointer?, size: off_t, callbacks: UnsafePointer<CGDataProviderDirectCallbacks>)

Creates a direct-access data provider.

init?(data: CFData)

Creates a data provider that reads from a CFData object.

init?(url: CFURL)

Creates a direct-access data provider that uses a URL to supply data.

init?(dataInfo: UnsafeMutableRawPointer?, data: UnsafeRawPointer, size: Int, releaseData: CGDataProviderReleaseDataCallback)

Creates a direct-access data provider that uses data your program supplies.

init?(filename: UnsafePointer<Int8>)

Creates a direct-access data provider that uses a file to supply data.

struct CGDataProviderDirectCallbacks

Defines pointers to client-defined callback functions that manage the sending of data for a direct-access data provider.

typealias CGDataProviderGetBytePointerCallback

A callback function that returns a generic pointer to the provider data.

typealias CGDataProviderGetBytesAtPositionCallback

A callback function that copies data from the provider into a Core Graphics buffer.

typealias CGDataProviderReleaseBytePointerCallback

A callback function that releases the pointer Core Graphics obtained by calling CGDataProviderGetBytePointerCallback.

typealias CGDataProviderReleaseInfoCallback

A callback function that releases any private data or resources associated with the data provider.

typealias CGDataProviderReleaseDataCallback

A callback function that releases data you supply to the function init(dataInfo:data:size:releaseData:).

Getting Data from a Data Provider

var data: CFData?

Returns a copy of the provider’s data.

Working with Core Foundation Types

class var typeID: CFTypeID

Returns the Core Foundation type identifier for data providers.

Instance Properties

var info: UnsafeMutableRawPointer?