When I used to develop Excel mini-applications for use by others in my department, I often needed to know the user’s display settings at runtime so that I could adjust my UI accordingly. I learned to do that the hard way, when users started complaining about my dialogs being too big for their screens or too small for them to work with.

The GetDeviceCaps API function can supply all kinds of metrics about any output device, although I’ve only used it for display settings. The functions I use are provided below:

The basic approach is to get the handle of the Device Context (in this case the screen) using GetDC(0), and then passing the handle to the GetDeviceCaps function with the appropriate parameter to retrieve the desired metric. There seem to be differing opinions on whether or not ReleaseDC is needed in this case, but I’ve included it for neatness (and because Bob Phillips insists that it’s necessary).

Of course, all of these functions can be wrapped up in a single sub, but I prefer to use functions so that I can use their return values directly in other procedures.

Since I hadn’t used these functions in a few years, I had to update the return type for the Colors function from a Long to a Single, since many displays now support 32 bits per pixel, or 4.3 billion colors. The old 24-bit standard was a paltry 16.7 million colors.

Needless to say, nothing in these functions is original material. It’s pretty basic API stuff, hopefully useful to users who may be thinking about getting their feet wet with APIs.