Receive double value in WndProc from legacy

Question

I'm trying to send double/float values from my MFC legacy code to WPF window. WPF WndProc procedure receives the arugments in LParam and WParam as ints (truncates the decimal values).

private IntPtr WndProc(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)

How can I do this?

Thanks in advance

Answer 1

You could create a structure to store your float/double values and pass the address of that structure in the lParam value. If you are Posting the message rather than Sending it, you will need to get the recipient to free the memory occupied by the structure.

#define MYMESSAGECODE (WM_APP + 123 )
typedef struct
{
    float f;
    double d;
} MyDataStruct;

MyDataStruct data;
data.f = 1.0;
data.d = 2.0;
pWpfWnd->SendMessage( MYMESSAGECODE, 0, (LPARAM) &data );