internal IntPtr ConvertToMemory()
{
int size = Marshal.SizeOf(typeof(EncoderParameter));
Debug.Assert(size == (16 + 4 + 4 + 4), "wrong size! (" + size + ")");
IntPtr memory = (IntPtr)((long)Marshal.AllocHGlobal(param.Length * size + Marshal.SizeOf(typeof(Int32))));
if (memory == IntPtr.Zero)
{
throw SafeNativeMethods.StatusException(SafeNativeMethods.OutOfMemory);
}
Marshal.WriteInt32(memory, param.Length);
for (int i = 0; i < param.Length; i++)
{
Marshal.StructureToPtr(param[i], (IntPtr)((long)memory + Marshal.SizeOf(typeof(Int32)) + i * size), false);
}
return(memory);
}
/// <devdoc>
/// Copy the EncoderParameters data into a chunk of memory to be consumed by native GDI+ code.
///
/// We need to marshal the EncoderParameters info from/to native GDI+ ourselve since the definition of the managed/unmanaged classes
/// are different and the native class is a bit weird. The native EncoderParameters class is defined in GDI+ as follows:
///
/// class EncoderParameters {
/// UINT Count; // Number of parameters in this structure
/// EncoderParameter Parameter[1]; // Parameter values
/// };
///
/// We don't have the 'Count' field since the managed array contains it. In order for this structure to work with more than one
/// EncoderParameter we need to preallocate memory for the extra n-1 elements, something like this:
///
/// EncoderParameters* pEncoderParameters = (EncoderParameters*) malloc(sizeof(EncoderParameters) + (n-1) * sizeof(EncoderParameter));
///
/// Also, in 64-bit platforms, 'Count' is aligned in 8 bytes (4 extra padding bytes) so we use IntPtr instead of Int32 to account for
/// that (See VSW#451333).
/// </devdoc>
internal IntPtr ConvertToMemory()
{
int size = Marshal.SizeOf(typeof(EncoderParameter));
int length = param.Length;
IntPtr memory = Marshal.AllocHGlobal(checked (length * size + Marshal.SizeOf(typeof(IntPtr))));
if (memory == IntPtr.Zero)
{
throw SafeNativeMethods.Gdip.StatusException(SafeNativeMethods.Gdip.OutOfMemory);
}
Marshal.WriteIntPtr(memory, (IntPtr)length);
long arrayOffset = checked ((long)memory + Marshal.SizeOf(typeof(IntPtr)));
for (int i = 0; i < length; i++)
{
Marshal.StructureToPtr(param[i], (IntPtr)(arrayOffset + i * size), false);
}
return(memory);
}
public SafeHGlobalHandle(object value) : this(Marshal.SizeOf(value))
{
Marshal.StructureToPtr(value, handle, false);
}
