About the WM_LBUTTONDOWN

Question

The question is simple, I have a code that's using the PostMessage function like so :

public enum WMessages : int
        {
            WM_MOUSEMOVE=                    0x0200,

            WM_LBUTTONDOWN = 0x201,
            WM_LBUTTONUP = 0x202,
            WM_RBUTTONDOWN = 0x0204,
            WM_RBUTTONUP = 0x0205,

            WM_KEYDOWN = 0x100,
            WM_KEYUP = 0x101,

            WH_KEYBOARD_LL = 13,
            WH_MOUSE_LL = 14,
        }
[DllImport("User32.Dll", EntryPoint = "PostMessageA")]
        static extern bool PostMessage(IntPtr hWnd, uint msg, int wParam, int lParam);
        private int MAKELPARAM(int p, int p_2)
        {
            return (p_2 * 0x10000 + p);
        }
        public void SendClick(WMessages type, Point pos, IntPtr hwnd)
        {
            switch (type)
            {
                case WMessages.WM_LBUTTONDOWN:
                    PostMessage(hwnd,
                        (int)0x201, 1,
                        MAKELPARAM(pos.X, pos.Y));//(IntPtr)((pos.Y << 16) | (pos.X & 0xFFFF)));
                    return;
                case WMessages.WM_LBUTTONUP:
                    PostMessage(hwnd,
                        (int)WMessages.WM_LBUTTONUP, 0, // <--(2) but you are telling to do WM_LBUTTONDOWN
                        MAKELPARAM(pos.X, pos.Y));//(IntPtr)((pos.Y << 16) | (pos.X & 0xFFFF)));
                    return;
                default:
                    return;
            }
        }

The only problem is that it clicks in a wrong place. For example, if i input the point 50,50 it'll click in 70,70 for example, offsetted to the window handle.

I wonder why it happens? Hope to get an answer.

Thanks in advance.

Example :

IntPtr atat = (IntPtr)0x00010870;
SendRClick(WMessages.WM_RBUTTONDOWN, new Point(50, 50), atat);
SendRClick(WMessages.WM_RBUTTONUP, new Point(50, 50), atat);

Edit :

I've found something interesting, apparently it happens only in 1 of my screens (I have 2), in the other one its not happening.

The screen that it happens in's resolution is 1920/1080, the screen that does it correctly's resolution is 1280/1024 (my main screen, does it correctly).

Edit 2 :

Also another thing that I've forgot to mention, the ratio between the resulted point to the inserted point is 1.5 in X and also in Y.

For example, if I've entered X=100,Y=100, it'll be resulted in 150 X and 150 Y offset from the window handle.

Edit 3 :

An alternative would be to devide the x and y by 1.5 and then it'll be multiplied again by default... but its not really an answer

Edit 4 :

If it's a duplicate then give me a link to an original thread then.

Edit 5 :

I've solved it. Adding a manifest didn't help, but then i got to know this file:

https://github.com/Microsoft/WPF-Samples/blob/master/PerMonitorDPI/Developer%20Guide%20-%20Per%20Monitor%20DPI%20-%20WPF%20Preview.docx

By adding to the manifest file this line:

<dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings"> PerMonitor</dpiAwareness>

in the <windowsSettings> area I've solved the problem.