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This class allows Realbasic developers to preview and/or record data from external devices.





The QTPlgGrabber class constructors are called when you create a new instance of the class, while the ˜QTPlgGrabber class destructor, is called automatically when the class is no more in use. Also, you can invoke the class destructor by setting the instance of the class to nil.
Once a new class instance is returned, it is good practice to check the class property to be sure that the new object can be used. See the super class to information about the validity of a QTPlgGrabber class instance.

The class provides you with the following initializer methods:
()
the default constructor. The instance class will try to open a connection to the first sequence grabbber component found, if any; if no sequence grabber component can be found the class property is set to false and you should dispose of the class instance; otherwise the object will be initialized in the following way:
  • =kstatus_stopped
  • =0
  • =the default sequence grabber component record settings
none
(fSettings as folderitem)
using this class constructor version, the class will be instantiated with the settings previously stored in the file specified by the fSettings parameter; these settings comprise both the sequence grabbber component , and its channels, if any. If you set this parameter is nil, the cosntructor behaviour is the same as the default constructor
none
(component as as )
using this version of the class constructor, you can instruct the class instance to open a connection to the sequence grabber component specified by the component parameter; if you set this parameter is nil, the cosntructor behaviour is the same as the default constructor
none

determines if the acquisition of sound streams will be performed by using the newest sound channel component; this component allows capture of high–resolution audio, supporting multi–channel, high sample rate, high accuracy sound
this property is effective only with QuickTime 7 or later and MacOS X; otherwise it will be ignored and the grabber instance will create an old style sound channel component instance
enables or disables the automatic idling of data during playback. If this property is set to true, then you do not need anymore to use a Timer control to call repeatedly the method to provide processing time to the grabber and the channels associated to it. If possible, the internal timer interval is set up to a value that best fits the characteristics of the data to play (based on time scale and sample duration values); otherwise the interval is set up to a default value of 40 milliseconds
returns information about the current status of the grabber. The value returned can be one of the constant values defined in to the section
returns the number of channels associated to the grabber
a 0–based list of channels allocated by the grabber (that is you can use values for i ranging from 0 to 1). You can use this list to retrieve and configure as appropriate for you any channel associated to the grabber
specifies the set of parameters to be used in the next record session. This property should be set to any valid object instance before starting a new record session
lets your application obtain an image from a sequence grabber component and display it using a data presentation context
specifies the list of channels currently allocated by the grabber. You can use this list to retrieve and configure as appropriate for you any associated to the grabber

(channelType as )
use this function to instantiate a new object and associate it to the grabber; you determines the type of the channel to be allocated by specifying its type into the channelType parameter. Using the , you can retrieve later a reference to this channel and inspect and modify its configuration using the properties and methods of the class
returns nothing. You can check the class property for errors.
()
use this function to instantiate a new object and associate it to the grabber. Using the , you can retrieve later a reference to this channel and inspect and modify its configuration using the properties and methods of the class
returns nothing. You can check the class property for errors.
()
use this function to instantiate a new object and associate it to the grabber. If the property is set to true, this method will instantiate a object instead. Using the , you can retrieve later a reference to this channel and inspect and modify its configuration using the properties and methods of the class
returns nothing. You can check the class property for errors.
()
use this function to instantiate a new object and associate it to the grabber. Using the , you can retrieve later a reference to this channel and inspect and modify its configuration using the properties and methods of the class
returns nothing. You can check the class property for errors.
(i as integer)
use this function to remove a object from the . You specify the channel to remove by providing its index i in the list
returns nothing. You can check the class property for errors.
(w as window, r as )
You establish where the grabber will display visual data in preview mode using the w and r parameters. The destination rectangle r is defined into the graphics world specified by the w parameter and specifies the maximum display area in wich any visual channel set for preview mode will be displayed; its coordinates are intended to be relatives to the destination graphics world. If a visual channel’s display boundary does not fit into the destination rectangle, it will be scaled and centered as apropriate.
If you do not call this function before previewing data, the current graphics world will be used as destination of previewed data.
If you have not allocated any channel that display visual data you can ignore this function
returns nothing. You can check the class property for errors.
(context as canvas, [r as ])
You establish where the grabber will display visual data in preview mode using the context and r parameters. The destination rectangle r is defined into the graphics world associated to the context parameter and specifies the maximum display area in wich any visual channel set for preview mode will be displayed; its coordinates are intended to be local to the destination canvas control. If you do not specify a destination rectangle, the display boundary of the canvas control will be used for display. If a visual channel’s display boundary does not fit into the destination rectangle, it will be scaled and centered as apropriate.
If you do not call this function before previewing data, the current graphics world will be used as destination of previewed data.
If you have not allocated any channel that display visual data you can ignore this function
returns nothing. You can check the class property for errors.
(r as ) as picture
if some visual data is available, this function allows you to obtain an image from the grabber. You can specify the resulting image dimensions by setting the and properties of the r parameter as appropriate. If the original image dimensions do not fit into the destination rectangle defined by r, the image wil be scaled and centered into this rectangle as appropriate
if some visual data is available returns a RealBasic picture, otherwise returns nil. You can check the class property for errors.
() as boolean
instructs the grabber to begin processing data from its channels, if any. The grabber immediately presents the data to the user in the appropriate format according to the channel configuration parameters you have specified by using the appropriate methods and properties of the and its derived classes ( , and ).
Video data is displayed in the destination display region (as specified by the class method; sound data is played at the specified volume settings.
if the command has been executed with success returns true, otherwise returns false. You can check the class property for errors.
() as boolean
instructs the grabber to begin collecting data from its channels. The grabber stores the collected data according to the recording parameters you specified with the class property
if the command has been executed with success returns true, otherwise returns false. You can check the class property for errors.
() as boolean
this function provides processing time to the grabber and the channels associated to it. After starting a preview or record operation, you should call this function as often as possible, until you stop the operation by calling class method. If this function encounter some error during its execution, it will the current operation automatically and set the class property to the returned error code. This is true even if you have established a limit of some type to a record operation providing the appropriate parameters to the class property
if the command has been executed with success returns true, otherwise returns false. You can check the class property for errors.
() as boolean
this function allows you to tell the grabber that it must refresh its display. You should call this function whenever you receive an update event for a window that contains a sequence grabber display.
if the command has been executed with success returns true, otherwise returns false. You can check the class property for errors.
() as boolean
instructs the grabber to suspend the current operation. This function does not release any system resources or temporary memory associated with the current operation. Consequently, it is generally much faster than using the class method to suspend an operation. When you restart the operation, the sequence grabber component may be unable to satisfy your request. This can occur, for example, if the user has moved the display window to a location that the digitizing hardware cannot support.
if the command has been executed with success returns true, otherwise returns false. You can check the class property for errors.
() as boolean
instructs the grabber to restart the current operation.
if the command has been executed with success returns true, otherwise returns false. You can check the class property for errors.
() as boolean
use this function to stop a preview or record operation. The grabber releases any system resources it used during the operation, such as temporary memory. In the case of a record operation, the grabber stores the collected movie data as specified by the class property
if the command has been executed with success returns true, otherwise returns false. You can check the class property for errors.


the grabber is in idle status
the grabber is previewing data
the grabber is recording data
the grabber is paused