Compare file extension? If you don't trust the file extension then you'll need to read the headers in the file, and detect if it is a valid header for that image type!

You click a listbox or combobox, it returns the index of that item.
You use that index to get the name, or the user data value.

Not the other way around!

I'm not sure what you're asking for. You can get/set the user value associated with a list/combo item.

You can add and remove items.

Just a thought


const float Y1 = (2 * SQRT2) / 7 - 1 / 7;
const float Y2 = (4 * SQRT2) / 7 - 2 / 7;
const float Y3 = SQRT2 / 2;
const float Y4 = (3 * SQRT2) / 7 + 2 / 7;


7 is not 7.0f

Look for something not properly initialized!

Singlestep in the debugger and see if data contains expected values.

Other then that, the specific problem or code needs to be shown from view to...