編集

DataObject.GetDataPresent Method

  • Reference

Definition

Namespace:
System.Windows
Assembly:
PresentationCore.dll

Determines whether the data is available in, or can be converted to, a specified format.

Overloads

GetDataPresent(String)

Determines whether the data is available in, or can be converted to, a format specified by a string.
GetDataPresent(Type)

Determines whether the data is available in, or can be converted to, a format specified by a Type object.
GetDataPresent(String, Boolean)

Determines whether the data is available in, or can be converted to, a specified format. A Boolean flag indicates whether to check if the data can be converted to the specified format if it is not available in that format.

Remarks

Call GetDataPresent to determine whether a format is available in this data object before calling GetData. Call GetFormats to obtain a list of all the formats that are available in this data object.

GetDataPresent(String)

Determines whether the data is available in, or can be converted to, a format specified by a string.

public:
 virtual bool GetDataPresent(System::String ^ format);
public bool GetDataPresent (string format);
abstract member GetDataPresent : string -> bool
override this.GetDataPresent : string -> bool
Public Function GetDataPresent (format As String) As Boolean

Parameters

format
String

A string that specifies the format for the data. For a set of predefined data formats, see the DataFormats class.

Returns

Boolean

true if the data is in, or can be converted to, the specified format; otherwise, false.

Implements

GetDataPresent(String)

Exceptions

ArgumentNullException

format is null.

Examples

The following example uses this method to query for the presence of a particular data format by descriptor string.

DataObject dataObject = new DataObject("Some string data to store...");

// Query for the presence of Text data in the data object, by a data format descriptor string.
// In this overload of GetDataPresent, the method will return true both for native data formats
// and when the data can automatically be converted to the specifed format.

// In this case, string data is present natively, so GetDataPresent returns "true".
string textData = null;
if (dataObject.GetDataPresent(DataFormats.StringFormat))
{
    textData = dataObject.GetData(DataFormats.StringFormat) as string;
}

// In this case, the Text data in the data object can be autoconverted to 
// Unicode text, so GetDataPresent returns "true".
byte[] unicodeData = null;
if (dataObject.GetDataPresent(DataFormats.UnicodeText))
{
    unicodeData = dataObject.GetData(DataFormats.UnicodeText) as byte[];
}

Dim dataObject As New DataObject("Some string data to store...")

' Query for the presence of Text data in the data object, by a data format descriptor string.
' In this overload of GetDataPresent, the method will return true both for native data formats
' and when the data can automatically be converted to the specifed format.

' In this case, string data is present natively, so GetDataPresent returns "true".
Dim textData As String = Nothing
If dataObject.GetDataPresent(DataFormats.StringFormat) Then
    textData = TryCast(dataObject.GetData(DataFormats.StringFormat), String)
End If

' In this case, the Text data in the data object can be autoconverted to 
' Unicode text, so GetDataPresent returns "true".
Dim unicodeData() As Byte = Nothing
If dataObject.GetDataPresent(DataFormats.UnicodeText) Then
    unicodeData = TryCast(dataObject.GetData(DataFormats.UnicodeText), Byte())
End If

Remarks

Call GetDataPresent to determine whether a format is available in this data object before calling GetData. Call GetFormats to obtain a list of all the formats that are available in this data object.

See also

Applies to

GetDataPresent(Type)

Determines whether the data is available in, or can be converted to, a format specified by a Type object.

public:
 virtual bool GetDataPresent(Type ^ format);
public bool GetDataPresent (Type format);
abstract member GetDataPresent : Type -> bool
override this.GetDataPresent : Type -> bool
Public Function GetDataPresent (format As Type) As Boolean

Parameters

format
Type

A Type that specifies the data format to check. F or a set of predefined data formats, see the DataFormats class.

Returns

Boolean

true if the data is in, or can be converted to, the specified format; otherwise, false.

Implements

GetDataPresent(Type)

Exceptions

ArgumentNullException

format is null.

Examples

The following example uses this method to query for the presence of a particular data format by type.

DataObject dataObject = new DataObject("Some string data to store...");

// Query for the presence of String data in the data object, by type.  In this overload 
// of GetDataPresent, the method will return true both for native data formats
// and when the data can automatically be converted to the specifed format.

// In this case, the Text data present in the data object can be autoconverted
// to type string (also represented by DataFormats.String), so GetDataPresent returns "true".
string stringData = null;
if (dataObject.GetDataPresent(typeof(string)))
{
    stringData = dataObject.GetData(DataFormats.Text) as string;
}

Dim dataObject As New DataObject("Some string data to store...")

' Query for the presence of String data in the data object, by type.  In this overload 
' of GetDataPresent, the method will return true both for native data formats
' and when the data can automatically be converted to the specifed format.

' In this case, the Text data present in the data object can be autoconverted
' to type string (also represented by DataFormats.String), so GetDataPresent returns "true".
Dim stringData As String = Nothing
If dataObject.GetDataPresent(GetType(String)) Then
    stringData = TryCast(dataObject.GetData(DataFormats.Text), String)
End If

Remarks

Call GetDataPresent to determine whether a format is available in this data object before calling GetData. Call GetFormats to obtain a list of all the formats that are available in this data object.

See also

Applies to

GetDataPresent(String, Boolean)

Determines whether the data is available in, or can be converted to, a specified format. A Boolean flag indicates whether to check if the data can be converted to the specified format if it is not available in that format.

public:
 virtual bool GetDataPresent(System::String ^ format, bool autoConvert);
public bool GetDataPresent (string format, bool autoConvert);
abstract member GetDataPresent : string * bool -> bool
override this.GetDataPresent : string * bool -> bool
Public Function GetDataPresent (format As String, autoConvert As Boolean) As Boolean

Parameters

format
String

A string that specifies the data format to check. For a set of predefined data formats, see the DataFormats class.

autoConvert
Boolean

false to check only for the specified format; true to also check whether data stored in this data object can be converted to the specified format.

Returns

Boolean

true if the data is in, or can be converted to, the specified format; otherwise, false.

Implements

GetDataPresent(String, Boolean)

Exceptions

ArgumentNullException

format is null.

Examples

The following example uses this method to query for data by descriptor string, and specifies how to treat auto-convertible data formats.

DataObject dataObject = new DataObject("Some string data to store...");

// Query for the presence of Text data in the data object, by data format descriptor string,
// and specifying whether auto-convertible data formats are acceptable.  

// In this case, Text data is present natively, so GetDataPresent returns "true".
string textData = null;
if (dataObject.GetDataPresent(DataFormats.Text, false /* Auto-convert? */))
{
    textData = dataObject.GetData(DataFormats.Text) as string;
}

// In this case, the Text data in the data object can be autoconverted to 
// Unicode text, but it is not available natively, so GetDataPresent returns "false".
byte[] unicodeData = null;
if (dataObject.GetDataPresent(DataFormats.UnicodeText, false /* Auto-convert? */))
{
    unicodeData = dataObject.GetData(DataFormats.UnicodeText) as byte[];
}

// In this case, the Text data in the data object can be autoconverted to 
// Unicode text, so GetDataPresent returns "true".
if (dataObject.GetDataPresent(DataFormats.UnicodeText, true /* Auto-convert? */))
{
    unicodeData = dataObject.GetData(DataFormats.UnicodeText) as byte[];
}

Dim dataObject As New DataObject("Some string data to store...")

' Query for the presence of Text data in the data object, by data format descriptor string,
' and specifying whether auto-convertible data formats are acceptable.  

' In this case, Text data is present natively, so GetDataPresent returns "true".
Dim textData As String = Nothing
If dataObject.GetDataPresent(DataFormats.Text, False) Then ' Auto-convert? 
    textData = TryCast(dataObject.GetData(DataFormats.Text), String)
End If

' In this case, the Text data in the data object can be autoconverted to 
' Unicode text, but it is not available natively, so GetDataPresent returns "false".
Dim unicodeData() As Byte = Nothing
If dataObject.GetDataPresent(DataFormats.UnicodeText, False) Then ' Auto-convert? 
    unicodeData = TryCast(dataObject.GetData(DataFormats.UnicodeText), Byte())
End If

' In this case, the Text data in the data object can be autoconverted to 
' Unicode text, so GetDataPresent returns "true".
If dataObject.GetDataPresent(DataFormats.UnicodeText, True) Then ' Auto-convert? 
    unicodeData = TryCast(dataObject.GetData(DataFormats.UnicodeText), Byte())
End If

Remarks

Call GetDataPresent to determine whether a format is available in this data object before calling GetData. Call GetFormats to obtain a list of all the formats that are available in this data object.

See also

Applies to