/* The IntPtr passed in here is a blob returned from
* GdipImageGetEncoderParameterList. Its internal pointers
* (i.e. the Value pointers in the EncoderParameter entries)
* point to areas within this block of memeory; this means
* that we need to free it as a whole, and also means that
* we can't Marshal.PtrToStruct our way to victory.
*/
internal static EncoderParameters FromNativePtr(IntPtr epPtr)
{
if (epPtr == IntPtr.Zero)
{
return(null);
}
IntPtr ptr = epPtr;
int count = Marshal.ReadInt32(ptr);
ptr = (IntPtr)(ptr.ToInt64() + 4);
if (count == 0)
{
return(null);
}
EncoderParameters result = new EncoderParameters(count);
for (int i = 0; i < count; i++)
{
result.parameters[i] = EncoderParameter.FromNativePtr(ptr);
ptr = (IntPtr)(ptr.ToInt64() + EncoderParameter.NativeSize());
}
return(result);
}
internal IntPtr ToNativePtr()
{
IntPtr result;
IntPtr ptr;
// 4 is the initial int32 "count" value
result = Marshal.AllocHGlobal(4 + parameters.Length * EncoderParameter.NativeSize());
ptr = result;
Marshal.WriteInt32(ptr, parameters.Length);
ptr = (IntPtr)(ptr.ToInt64() + 4);
for (int i = 0; i < parameters.Length; i++)
{
parameters[i].ToNativePtr(ptr);
ptr = (IntPtr)(ptr.ToInt64() + EncoderParameter.NativeSize());
}
return(result);
}
