How to detect a Windows 8 Slate - c++

Question

I'm looking for a method to programatically detect Windows 8 Slate devices using C/C++. My definition of "Slate" is "a portable computing device equipped with a touchscreen but without a dedicated physical keyboard" (so including devices that come with a keyboard dock, but excluding laptops and tradition tablets where the physical keyboard is attached).
I tried using WMI Win32_SystemEnclosure and checking the ChassisTypes, but one Slate reported the ChassisTypes as being "Hand Held" and another reported "Main System Chassis", so this doesn't seem to be reliable.

Answer 1

I'm not able to provide any code, since I don't have a "slate" device to test it on, but I can offer you some suggestions.
You'll probably want to use a heuristic sort of approach, using several API calls to determine the presence or status of various bits of hardware, then determine if the system matches what you're looking for. The GetSystemMetrics API is likely to be the most useful to you; after looking through some documentation, here are the calls that are likely to help you.
GetSystemMetrics with SM_CONVERTIBLESLATEMODE: returns 0 if the system is in Slate Mode and non-zero otherwise. There's no guarantee this will mean the system is an actual slate device, but it can at least tell you if the device has a slate mode and is using it.
GetSystemMetrics with SM_DIGITIZER: returns a bitfield value that tells you whether the system supports touch or a pen. If GetSystemMetrics(SM_DIGITIZER) & TABLET_CONFIG_NONE evaluates to true, your device probably isn't a slate. You can also make good use of the other bitflags this call gives you access to.
GetSystemMetrics with SM_MOUSEPRESENT: tells you whether a mouse is present. This is a very weak test since the docs say virtual mice or sometimes just a mouse port will be enough to set this flag, but it's still worth testing. If a mouse isn't present, your device has a higher chance of being a slate.
GetSystemMetrics with SM_TABLETPC: similar to the SM_DIGITIZER test, this tells you if the Tablet PC Input service is started or not. If the service isn't started, your device probably isn't a tablet.
GetSystemPowerStatus could provide a few useful heuristics as well. This API returns a SYSTEM_POWER_STATUS structure which you can test in the following ways:
If ACLineStatus is 0, your device isn't connected to AC power, so it's more likely to be a slate.
If BatteryFlag is 128, there is no system battery, so your device probably isn't a slate. If it's any other value (except 255, which is unknown status) there is a battery, which means your device is more likely to be a slate.
You can also look into WMI's Win32_Keyboard, in particular its Availability, ConfigManagerErrorCode, and Status properties. At the end of the day there is no way to determine whether keyboard input is from a physical or virtual keyboard, but you can at least attempt to test for a physical keyboard.
Your WMI Win32_SystemEnclosure test would become another heuristic in the list. See what ChassisTypes returns: Desktop, Low Profile Desktop, Mini Tower, Tower, and Laptop probably mean the device isn't a slate. Pizza Box, Portable, Notebook (although generally notebook == laptop in common verbiage, so this will require testing), Hand Held, Space Saving, and Lunch Box are probably more likely to be slates. You can also try to run calculations on the Depth, Height, Width and Weight properties, since anything over a certain size and weight probably won't be a portable device and therefore won't be a slate.

Answer 2

Sample touch detection code from MSDN:
// test for touch
int value = GetSystemMetrics(SM_DIGITIZER);
if (value & NID_READY){ /* stack ready */}
if (value & NID_MULTI_INPUT){
/* digitizer is multitouch */
MessageBoxW(hWnd, L"Multitouch found", L"IsMulti!", MB_OK);
}
if (value & NID_INTEGRATED_TOUCH){ /* Integrated touch */}

Answer 3

I'm not a specialist when it comes to WinAPI, but since noone else answered, maybe it will be of some help to you. On MSDN, there's a list of functions awailable for Windows store apps, which also specifies whether functions can be used on handheld devices. Seems like the Windows.Devices.Enumeration contains exactly what you need - the DeviceInformation class.
All you have to do is list all the devices (there's code one the page which says how to do that), and search the list for a keyboard.
Please note: I don't own any Windows 8 device, so I can't really test if this is helpful or not. Give it a try, and I'll delete my comment if it won't help you out.