Thread: MAKEPOINTS structure (win32)

I'm very new to C++ and am confused with how the MAKEPOINT structure works.

POINTS MAKEPOINTS(
DWORD dwValue // coordinates of a point
);

The definition of dwValue is as follows:

Specifies the coordinates of a point. The x-coordinate is in the low-order word, and the y-coordinate is in the high-order word.

What are low and high order words? How do I create an instance of MAKEPOINTS with 10, 10?

Thanks for your patience.

If you want a POINTS struct with 10, 10 just do it like any other structure:

Code:

POINTS pts;

pts.x = 10;
pts.y = 10;

or, even easier:

Code:

POINTS pts = { 10, 10 };

The MAKEPOINTS macro is a helper macro that can be used with certain window messages. For example the WM_RBUTTONDOWN passes an x, y value in the lParam:

Originally Posted by MSDN WM_RBUTTONDOWN

lParam
The low-order word(the lower 16 bits) specifies the x-coordinate of the cursor. The coordinate is relative to the upper-left corner of the client area.

The high-order word(the upper 16 bits) specifies the y-coordinate of the cursor. The coordinate is relative to the upper-left corner of the client area.

Now, instead of extracting the x,y values manually, we can just use the MAKEPOINTS macro.

Code:

int x = MAKEPOINTS(lParam).x;
int y = MAKEPOINTS(lParam).y;