Object Model
Syntax
| Visual Basic (Declaration) | |
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Public Class DragDropEventData | |
| Visual Basic (Usage) |  Copy Code |
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Dim instance As DragDropEventData | |
| C# | |
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public class DragDropEventData | |
| Delphi | |
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public class DragDropEventData | |
| JScript | |
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public class DragDropEventData | |
| Managed Extensions for C++ | |
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public __gc class DragDropEventData | |
| C++/CLI | |
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public ref class DragDropEventData | |
Remarks
When dealing with drag and drop, it is common to assign a data to be carried during the drag and drop operation. The drag-drop framework in ClientUI also provides this architecture to store the data in multiple formats.
Storing Data
To store the data, you can use the DragInit event or perform the drag-drop manually by using the provided API, then store the data when you call the API.
To learn how to enable drag and drop using API and storing the data using API, see How-to: Drag an UIElement using API.
To learn how to store the data at DragInit event, see How-to: Store DataObject at DragInit event.
Querying a Data Object for Available Formats
Because a single data object can contain an arbitrary number of data formats, data objects include facilities for retrieving a list of available data formats.
The following example code uses the GetFormats overload to get an array of strings denoting all data formats available in a data object.
| GetFormats |  Copy Code |
|---|---|
string sourceData = "Some string data to store...";
byte[] unicodeText = Encoding.Unicode.GetBytes(sourceData);
byte[] utf8Text = Encoding.UTF8.GetBytes(sourceData);
string uniCodeFormat = "Unicode";
string utf8DataFormat = "UTF-8";
DragDropEventData dataObject = e.Data as DragDropEventData;
dataObject.SetData(sourceData);
dataObject.SetData(uniCodeFormat, unicodeText);
dataObject.SetData(utf8DataFormat, utf8Text);
// Get an array of strings, each string denoting a data format
// that is available in the data object. This overload of GetDataFormats
// returns all available data formats, native and auto-convertible.
string[] dataFormats = dataObject.GetFormats();
// Get the number of data formats present in the data object, including both
// auto-convertible and native data formats.
int numberOfDataFormats = dataFormats.Length;
// To enumerate the resulting array of data formats, and take some action when
// a particular data format is found, use a code structure similar to the following.
foreach (string dataFormat in dataFormats)
{
if (dataFormat == uniCodeFormat)
{
// Take some action if/when data in the Text data format is found.
break;
}
else if (dataFormat == utf8DataFormat)
{
// Take some action if/when data in the string data format is found.
break;
}
}
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Retrieving Data from a Data Object
Retrieving data from a data object in a particular format simply involves calling one of the GetData methods and specifying the desired data format. One of the GetDataPresent methods can be used to check for the presence of a particular data format. GetData returns the data in a Object; depending on the data format, this object can be cast to a type-specific container.
The following example code uses the GetDataPresent(String) overload to first check if a specified data format is available (natively or by auto-convert). If the specified format is available, the example retrieves the data by using the GetData(String) method.
| GetData | Copy Code |
|---|---|
string sourceData = "Some string data to store...";
byte[] unicodeText = Encoding.Unicode.GetBytes(sourceData);
byte[] utf8Text = Encoding.UTF8.GetBytes(sourceData);
string uniCodeFormat = "Unicode";
string utf8DataFormat = "UTF-8";
DragDropEventData dataObject = e.Data as DragDropEventData;
dataObject.SetData(sourceData);
dataObject.SetData(uniCodeFormat, unicodeText);
dataObject.SetData(utf8DataFormat, utf8Text);
string desiredFormat = uniCodeFormat;
byte[] data = null;
// Use the GetDataPresent method to check for the presence of a desired data format.
// This particular overload of GetDataPresent looks for both native and auto-convertible
// data formats.
if (dataObject.GetDataPresent(desiredFormat))
{
// If the desired data format is present, use one of the GetData methods to retrieve the
// data from the data object.
data = dataObject.GetData(desiredFormat) as byte[];
}
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Inheritance Hierarchy
Intersoft.Client.UI.Controls.Interactivity.DragDropEventData
Requirements
Target Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, Windows Vista, Windows Server 2008 family