BXThreadQueue Class Reference

Defines a class that manages the threads using Barcode Xpress to perform recognition and decoding of images. More...

#import <BXThreadQueue.h>

Inheritance diagram for BXThreadQueue:

Instance Methods
(id)	- init
	Initializes an empty thread queue. More...
(id)	- initWithInfo:threadcount:sender:executioncallback:processingcallback:
	Initializes the thread control data structures. More...
(void)	- dispatch:
	Creates a new thread to perform recognition on an image, if a thread in the queue is available. More...
(bool)	- canDispatch
	Tests if there is a slot in the thread queue that is not being used by an active thread. More...
(bool)	- canDispatch:
	Tests if there is a slot in the thread queue that is not being used by an active thread. More...

Protected Attributes
int	m_threadCount
	An int specifying the maximum number of threads to use.
bool *	m_threadUsed
	A boolean array of length m_threadCount. More...
NSLock *	m_captureMutex
	Mutex used to synchronize access to thread control data structures.
id	m_sender
	Object instance that will execute callbacks.
NSString *	m_name
	A string representing the name of the thread queue. Set any arbitrary name.
SEL	m_executionCallback
	Callback function to be executed to perform recognition.
SEL	m_processingCallback
	Callback function to be executed before recognition is performed.

Detailed Description

Defines a class that manages the threads using Barcode Xpress to perform recognition and decoding of images.

Method Documentation

- (bool) canDispatch

Tests if there is a slot in the thread queue that is not being used by an active thread.

Returns

TRUE if there is an open slot, FALSE otherwise.

- (bool) canDispatch:

(int*)

pIndex

Tests if there is a slot in the thread queue that is not being used by an active thread.

Parameters

pIndex

Address of an int that will contain the first available queue slot number if any are not being used by active threads. This return parameter will not be changed if the method returns FALSE.

Returns

TRUE if there is an open slot, FALSE otherwise.

- (void) dispatch:

(BXThreadData*)

threadData

Creates a new thread to perform recognition on an image, if a thread in the queue is available.

Parameters

threadData

This object contains a pointer to an image captured from the video camera, information about the image, and the ID of the thread that this is executing on. See BXThreadData. The image is byte data in YUV420p (planar) format. This format provides grayscale data without having to perform a conversion before calling the Barcode Xpress recognition methods.

- (id) init

Initializes an empty thread queue.

Without any callbacks, and with a maximum thread count of zero, it won't be useful to call this method. Call initWithInfo:threadcount:sender:executioncallback:processingcallback: instead.

Returns

The Object ID.

The Object ID.

- (id) initWithInfo:		(NSString*)	name
threadcount:		(int)	threadCount
sender:		(id)	sender
executioncallback:		(SEL)	executionCallback
processingcallback:		(SEL)	processingCallback

Initializes the thread control data structures.

Parameters

name	An abitrary name for the thread queue.
threadCount	Maximum number of active threads.
sender	Object instance that will execute callbacks.
executionCallback	Callback executed to perform recognition.
processingCallback	Callback executed before recognition is performed.

Returns

The Object ID.

Member Data Documentation

- (bool*) m_threadUsed

protected

A boolean array of length m_threadCount.

Each boolean is TRUE if a thread is currently performing an executionCallback.