I have developed a functionality where user can drag drop email attachments on my application.I am extracting the dropped attachment names passing "FileGroupDescriptor" format and using "FileContents" format for extracting the attachment stream.It works fine on my system, but on some other guys system this functionality is not able to extract attachment data.So, I was thinking of implementing a functionality where I don't hard code the type format and retrieve it from the IDataObject itself.Is there any way of doing it? Please, find below the code that I am using:
public object GetData(string format, bool autoConvert)
{
try
{
//handle the "FileGroupDescriptor" and "FileContents" format request in this class otherwise pass through to underlying IDataObject
switch (format)
{
case "FileGroupDescriptor":
//override the default handling of FileGroupDescriptor which returns a
//MemoryStream and instead return a string array of file names
IntPtr fileGroupDescriptorAPointer = IntPtr.Zero;
try
{
//use the underlying IDataObject to get the FileGroupDescriptor as a MemoryStream
Object o = underlyingDataObject.GetData(typeof(Object));
MemoryStream fileGroupDescriptorStream = (MemoryStream)this.underlyingDataObject.GetData("FileGroupDescriptor", autoConvert);
byte[] fileGroupDescriptorBytes = new byte[fileGroupDescriptorStream.Length];
fileGroupDescriptorStream.Read(fileGroupDescriptorBytes, 0, fileGroupDescriptorBytes.Length);
fileGroupDescriptorStream.Close();
//copy the file group descriptor into unmanaged memory
fileGroupDescriptorAPointer = Marshal.AllocHGlobal(fileGroupDescriptorBytes.Length);
Marshal.Copy(fileGroupDescriptorBytes, 0, fileGroupDescriptorAPointer, fileGroupDescriptorBytes.Length);
//marshal the unmanaged memory to to FILEGROUPDESCRIPTORA struct
object fileGroupDescriptorObject = Marshal.PtrToStructure(fileGroupDescriptorAPointer, typeof(NativeMethods.FILEGROUPDESCRIPTORA));
NativeMethods.FILEGROUPDESCRIPTORA fileGroupDescriptor = (NativeMethods.FILEGROUPDESCRIPTORA)fileGroupDescriptorObject;
//create a new array to store file names in of the number of items in the file group descriptor
string[] fileNames = new string[fileGroupDescriptor.cItems];
//get the pointer to the first file descriptor
IntPtr fileDescriptorPointer = (IntPtr)((long)fileGroupDescriptorAPointer + Marshal.SizeOf(fileGroupDescriptorAPointer));
//loop for the number of files acording to the file group descriptor
for (int fileDescriptorIndex = 0; fileDescriptorIndex < fileGroupDescriptor.cItems; fileDescriptorIndex++)
{
//marshal the pointer top the file descriptor as a FILEDESCRIPTORA struct and get the file name
NativeMethods.FILEDESCRIPTORA fileDescriptor = (NativeMethods.FILEDESCRIPTORA)Marshal.PtrToStructure(fileDescriptorPointer, typeof(NativeMethods.FILEDESCRIPTORA));
fileNames[fileDescriptorIndex] = fileDescriptor.cFileName;
//move the file descriptor pointer to the next file descriptor
fileDescriptorPointer = (IntPtr)((long)fileDescriptorPointer + Marshal.SizeOf(fileDescriptor));
}
//return the array of filenames
return fileNames;
}
finally
{
//free unmanaged memory pointer
Marshal.FreeHGlobal(fileGroupDescriptorAPointer);
}
case "FileGroupDescriptorW":
//override the default handling of FileGroupDescriptorW which returns a
//MemoryStream and instead return a string array of file names
IntPtr fileGroupDescriptorWPointer = IntPtr.Zero;
try
{
//use the underlying IDataObject to get the FileGroupDescriptorW as a MemoryStream
MemoryStream fileGroupDescriptorStream = (MemoryStream)this.underlyingDataObject.GetData("FileGroupDescriptorW");
byte[] fileGroupDescriptorBytes = new byte[fileGroupDescriptorStream.Length];
fileGroupDescriptorStream.Read(fileGroupDescriptorBytes, 0, fileGroupDescriptorBytes.Length);
fileGroupDescriptorStream.Close();
//copy the file group descriptor into unmanaged memory
fileGroupDescriptorWPointer = Marshal.AllocHGlobal(fileGroupDescriptorBytes.Length);
Marshal.Copy(fileGroupDescriptorBytes, 0, fileGroupDescriptorWPointer, fileGroupDescriptorBytes.Length);
//marshal the unmanaged memory to to FILEGROUPDESCRIPTORW struct
object fileGroupDescriptorObject = Marshal.PtrToStructure(fileGroupDescriptorWPointer, typeof(NativeMethods.FILEGROUPDESCRIPTORW));
NativeMethods.FILEGROUPDESCRIPTORW fileGroupDescriptor = (NativeMethods.FILEGROUPDESCRIPTORW)fileGroupDescriptorObject;
//create a new array to store file names in of the number of items in the file group descriptor
string[] fileNames = new string[fileGroupDescriptor.cItems];
//get the pointer to the first file descriptor
IntPtr fileDescriptorPointer = (IntPtr)((int)fileGroupDescriptorWPointer + Marshal.SizeOf(fileGroupDescriptorWPointer));
//loop for the number of files acording to the file group descriptor
for (int fileDescriptorIndex = 0; fileDescriptorIndex < fileGroupDescriptor.cItems; fileDescriptorIndex++)
{
//marshal the pointer top the file descriptor as a FILEDESCRIPTORW struct and get the file name
NativeMethods.FILEDESCRIPTORW fileDescriptor = (NativeMethods.FILEDESCRIPTORW)Marshal.PtrToStructure(fileDescriptorPointer, typeof(NativeMethods.FILEDESCRIPTORW));
fileNames[fileDescriptorIndex] = fileDescriptor.cFileName;
//move the file descriptor pointer to the next file descriptor
fileDescriptorPointer = (IntPtr)((int)fileDescriptorPointer + Marshal.SizeOf(fileDescriptor));
}
//return the array of filenames
return fileNames;
}
finally
{
//free unmanaged memory pointer
Marshal.FreeHGlobal(fileGroupDescriptorWPointer);
}
case "FileContents":
//override the default handling of FileContents which returns the
//contents of the first file as a memory stream and instead return
//a array of MemoryStreams containing the data to each file dropped
//get the array of filenames which lets us know how many file contents exist
string[] fileContentNames = (string[])this.GetData("FileGroupDescriptor");
//create a MemoryStream array to store the file contents
MemoryStream[] fileContents = new MemoryStream[fileContentNames.Length];
//loop for the number of files acording to the file names
for (int fileIndex = 0; fileIndex < fileContentNames.Length; fileIndex++)
{
//get the data at the file index and store in array
fileContents[fileIndex] = this.GetData(format, fileIndex);
}
//return array of MemoryStreams containing file contents
return fileContents;
}
//use underlying IDataObject to handle getting of data
return this.underlyingDataObject.GetData(format, autoConvert);
}
catch (Exception ex)
{
}
}
I call the above function using the following code:
if (e.Data.GetDataPresent(DataFormats.FileDrop))
// drag drop from explorer to outlook DM Repository
filenames = (string[])(e.Data.GetData(DataFormats.FileDrop));
else
{
OutlookDataObject dataObject = new OutlookDataObject(e.Data);
filenames = (string[])dataObject.GetData("FileGroupDescriptor");
filestreams = (MemoryStream[])dataObject.GetData("FileContents");
}
Use IDataObject::EnumFormatEtc method - see https://msdn.microsoft.com/en-us/library/windows/desktop/ms683979(v=vs.85).aspx