Microsoft DirectX 8.0

IScanningTuner Interface

IScanningTuner inherits from ITuner and permits direct control of a tuner that supports searching for valid programming. The client must provide a valid tuning space (via ITuner::put_TuningSpace or ITuner::put_TuneRequest) before calling any of the methods in this interface. This interface is meant to be used in conjunction with the ITunerEvents outbound interface.

MethodNameDescription
ITuner Methods 
get_TuningSpaceGets the Tuning Space currently in effect for the tuner.
put_TuningSpaceSets the Tuning Space currently in effect for the tuner.
EnumTuningSpacesCreates an enumerator for the Tuning Spaces preferred by this implementation.
get_TuneRequestGets the Tune Request currently in effect for the tuner.
put_TuneRequestSets the Tune Request currently in effect for the tuner.
ValidateReturns a value indicating that the Tune Request can be carried out.
get_PreferredComponentTypesGets the collection of ComponentType objects used for default component selection.
put_PreferredComponentTypesSets the collection of ComponentType objects used for default component selection.
get_SignalStrengthRetrieves the tuner-specific signal strength metric.
TriggerSignalEventsPuts the tuner into a mode where ISignalEvents::OnSignal will be repeatedly called.
IScanningTuner Methods 
SeekUpChanges the channel to the next higher channel with valid programming.
SeekDownChanges the channel to the next lower channel with valid programming.
ScanUpChanges the channel to the next higher channel with valid programming, pauses for the specified number of milliseconds, then repeats until canceled.
ScanDownChanges the channel to the next lower channel with valid programming, pauses for the specified number of milliseconds, then repeats… until canceled.
AutoProgramScans for all channels with valid programming.

IScanningTuner::SeekUp

IScanningTuner Interface

Changes the channel to the next higher channel with valid programming.

Syntax

HRESULT SeekUp();

Return Value

Returns S_OK if successful. If the method fails, error information can be retrieved using the standard COM IErrorInfo interface.

Remarks

This method returns immediately, and the seek continues in the background. The seek can be canceled by calling any other tuning operation.

IScanningTuner::SeekDown

IScanningTuner Interface

Changes the channel to the next lower channel with valid programming.

Syntax

HRESULT SeekDown();

Return Value

Returns S_OK if successful. If the method fails, error information can be retrieved using the standard COM IErrorInfo interface.

Remarks

This method returns immediately, and the seek continues in the background. The seek can be canceled by calling any other tuning operation.

IScanningTuner::ScanUp

IScanningTuner Interface

Changes the channel to the next higher channel with valid programming, pauses for the specified number of milliseconds, then repeats until canceled.

Syntax

HRESULT ScanUp(
    long MillisecondsPause
    );

Parameters

MillisecondsPause
[in] Variable of type long that specifies the number of milliseconds to pause.

Return Value

Returns S_OK if successful. If the method fails, error information can be retrieved using the standard COM IErrorInfo interface.

Remarks

The call returns immediately, while the scan continues in the background. The scan can be canceled by calling any other tuning operation.

IScanningTuner::ScanDown

IScanningTuner Interface

Changes the channel to the next lower channel with valid programming, pauses for the specified number of milliseconds, then repeats until canceled.

Syntax

HRESULT ScanDown(
    long MillisecondsPause
    );

Parameters

MillisecondsPause
[in] Variable of type long that specifies the number of milliseconds to pause.

Return Value

Returns S_OK if successful. If the method fails, error information can be retrieved using the standard COM IErrorInfo interface.

Remarks

The call returns immediately, while the scan continues in the background. The scan can be canceled by calling any other tuning operation.

IScanningTuner::AutoProgram

IScanningTuner Interface

Scans for all channels with valid programming.

Syntax

HRESULT AutoProgram();

Return Value

Returns S_OK if successful. If the method fails, error information can be retrieved using the standard COM IErrorInfo interface.

Remarks

This method returns immediately, and the scan continues in the background. If the device allows it, the scan can be canceled by calling any other tuning operation. Otherwise, the scan will complete once all channels have been visited once. Internal devices will likely have a software implementation of this feature, and will collect fine-tuning information resulting from the scan. External devices will likely implement this feature, so this is just a means to trigger the process.