// This is the workhorse for figuring out fallback options for HIDs attached to the system.
// If the system cannot find a more specific layout for a given HID, this method will try
// to produce a layout builder on the fly based on the HID descriptor received from
// the device.
internal static string OnFindLayoutForDevice(int deviceId, ref InputDeviceDescription description, string matchedLayout, IInputRuntime runtime)
{
// If the system found a matching layout, there's nothing for us to do.
if (!string.IsNullOrEmpty(matchedLayout))
{
return(null);
}
// If the device isn't a HID, we're not interested.
if (description.interfaceName != kHIDInterface)
{
return(null);
}
// Read HID descriptor.
var hidDeviceDescriptor = ReadHIDDeviceDescriptor(deviceId, ref description, runtime);
// Determine if there's any usable elements on the device.
var hasUsableElements = false;
if (hidDeviceDescriptor.elements != null)
{
foreach (var element in hidDeviceDescriptor.elements)
{
if (element.DetermineLayout() != null)
{
hasUsableElements = true;
break;
}
}
}
// If not, there's nothing we can do with the device.
if (!hasUsableElements)
{
return(null);
}
// Determine base layout.
var baseLayout = "HID";
if (hidDeviceDescriptor.usagePage == UsagePage.GenericDesktop)
{
/*
* ////TODO: there's some work to be done to make the HID *actually* compatible with these devices
* if (hidDeviceDescriptor.usage == (int)GenericDesktop.Joystick)
* baseLayout = "Joystick";
* else if (hidDeviceDescriptor.usage == (int)GenericDesktop.Gamepad)
* baseLayout = "Gamepad";
* else if (hidDeviceDescriptor.usage == (int)GenericDesktop.Mouse)
* baseLayout = "Mouse";
* else if (hidDeviceDescriptor.usage == (int)GenericDesktop.Pointer)
* baseLayout = "Pointer";
* else if (hidDeviceDescriptor.usage == (int)GenericDesktop.Keyboard)
* baseLayout = "Keyboard";
*/
}
////TODO: match HID layouts by vendor and product ID
////REVIEW: this probably works fine for most products out there but I'm not sure it works reliably for all cases
// Come up with a unique template name. HIDs are required to have product and vendor IDs.
// We go with the string versions if we have them and with the numeric versions if we don't.
string layoutName;
if (!string.IsNullOrEmpty(description.product) && !string.IsNullOrEmpty(description.manufacturer))
{
layoutName = string.Format("{0}::{1} {2}", kHIDNamespace, description.manufacturer, description.product);
}
else
{
// Sanity check to make sure we really have the data we expect.
if (hidDeviceDescriptor.vendorId == 0)
{
return(null);
}
layoutName = string.Format("{0}::{1:X}-{2:X}", kHIDNamespace, hidDeviceDescriptor.vendorId,
hidDeviceDescriptor.productId);
}
// Register layout builder that will turn the HID descriptor into an
// InputControlLayout instance.
var layout = new HIDLayoutBuilder {
hidDescriptor = hidDeviceDescriptor
};
InputSystem.RegisterLayoutBuilder(() => layout.Build(),
layoutName, baseLayout, InputDeviceMatcher.FromDeviceDescription(description));
return(layoutName);
}
// This is the workhorse for figuring out fallback options for HIDs attached to the system.
// If the system cannot find a more specific layout for a given HID, this method will try
// to produce a layout builder on the fly based on the HID descriptor received from
// the device.
internal static unsafe string OnFindControlLayoutForDevice(int deviceId, ref InputDeviceDescription description, string matchedLayout, IInputRuntime runtime)
{
// If the system found a matching layout, there's nothing for us to do.
if (!string.IsNullOrEmpty(matchedLayout))
{
return(null);
}
// If the device isn't a HID, we're not interested.
if (description.interfaceName != kHIDInterface)
{
return(null);
}
// See if we have to request a HID descriptor from the device.
// We support having the descriptor directly as a JSON string in the `capabilities`
// field of the device description.
var needToRequestDescriptor = true;
var hidDeviceDescriptor = new HIDDeviceDescriptor();
if (!string.IsNullOrEmpty(description.capabilities))
{
try
{
hidDeviceDescriptor = HIDDeviceDescriptor.FromJson(description.capabilities);
// If there's elements in the descriptor, we're good with the descriptor. If there aren't,
// we go and ask the device for a full descriptor.
if (hidDeviceDescriptor.elements != null && hidDeviceDescriptor.elements.Length > 0)
{
needToRequestDescriptor = false;
}
}
catch (Exception exception)
{
Debug.Log(string.Format("Could not parse HID descriptor (exception: {0})", exception));
}
}
////REVIEW: we *could* switch to a single path here that supports *only* parsed descriptors but it'd
//// mean having to switch *every* platform supporting HID to the hack we currently have to do
//// on Windows
// Request descriptor, if necessary.
if (needToRequestDescriptor)
{
// If the device has no assigned ID yet, we can't perform IOCTLs on the
// device so no way to get a report descriptor.
if (deviceId == kInvalidDeviceId)
{
return(null);
}
// Try to get the size of the HID descriptor from the device.
var sizeOfDescriptorCommand = new InputDeviceCommand(QueryHIDReportDescriptorSizeDeviceCommandType);
var sizeOfDescriptorInBytes = runtime.DeviceCommand(deviceId, ref sizeOfDescriptorCommand);
if (sizeOfDescriptorInBytes > 0)
{
// Now try to fetch the HID descriptor.
using (var buffer =
InputDeviceCommand.AllocateNative(QueryHIDReportDescriptorDeviceCommandType, (int)sizeOfDescriptorInBytes))
{
var commandPtr = (InputDeviceCommand *)NativeArrayUnsafeUtility.GetUnsafePtr(buffer);
if (runtime.DeviceCommand(deviceId, ref *commandPtr) != sizeOfDescriptorInBytes)
{
return(null);
}
// Try to parse the HID report descriptor.
if (!HIDParser.ParseReportDescriptor((byte *)commandPtr->payloadPtr, (int)sizeOfDescriptorInBytes, ref hidDeviceDescriptor))
{
return(null);
}
}
// Update the descriptor on the device with the information we got.
description.capabilities = hidDeviceDescriptor.ToJson();
}
else
{
// The device may not support binary descriptors but may support parsed descriptors so
// try the IOCTL for parsed descriptors next.
//
// This path exists pretty much only for the sake of Windows where it is not possible to get
// unparsed/binary descriptors from the device (and where getting element offsets is only possible
// with some dirty hacks we're performing in the native runtime).
const int kMaxDescriptorBufferSize = 2 * 1024 * 1024; ////TODO: switch to larger buffer based on return code if request fails
using (var buffer =
InputDeviceCommand.AllocateNative(QueryHIDParsedReportDescriptorDeviceCommandType, kMaxDescriptorBufferSize))
{
var commandPtr = (InputDeviceCommand *)NativeArrayUnsafeUtility.GetUnsafePtr(buffer);
var utf8Length = runtime.DeviceCommand(deviceId, ref *commandPtr);
if (utf8Length < 0)
{
return(null);
}
// Turn UTF-8 buffer into string.
////TODO: is there a way to not have to copy here?
var utf8 = new byte[utf8Length];
fixed(byte *utf8Ptr = utf8)
{
UnsafeUtility.MemCpy(utf8Ptr, commandPtr->payloadPtr, utf8Length);
}
var descriptorJson = Encoding.UTF8.GetString(utf8, 0, (int)utf8Length);
// Try to parse the HID report descriptor.
try
{
hidDeviceDescriptor = HIDDeviceDescriptor.FromJson(descriptorJson);
}
catch (Exception exception)
{
Debug.Log(string.Format("Could not parse HID descriptor JSON returned from runtime (exception: {0})", exception));
return(null);
}
// Update the descriptor on the device with the information we got.
description.capabilities = descriptorJson;
}
}
}
// Determine if there's any usable elements on the device.
var hasUsableElements = false;
if (hidDeviceDescriptor.elements != null)
{
foreach (var element in hidDeviceDescriptor.elements)
{
if (element.DetermineLayout() != null)
{
hasUsableElements = true;
break;
}
}
}
// If not, there's nothing we can do with the device.
if (!hasUsableElements)
{
return(null);
}
// Determine base layout.
var baseLayout = "HID";
if (hidDeviceDescriptor.usagePage == UsagePage.GenericDesktop)
{
/*
* ////TODO: there's some work to be done to make the HID *actually* compatible with these devices
* if (hidDeviceDescriptor.usage == (int)GenericDesktop.Joystick)
* baseLayout = "Joystick";
* else if (hidDeviceDescriptor.usage == (int)GenericDesktop.Gamepad)
* baseLayout = "Gamepad";
* else if (hidDeviceDescriptor.usage == (int)GenericDesktop.Mouse)
* baseLayout = "Mouse";
* else if (hidDeviceDescriptor.usage == (int)GenericDesktop.Pointer)
* baseLayout = "Pointer";
* else if (hidDeviceDescriptor.usage == (int)GenericDesktop.Keyboard)
* baseLayout = "Keyboard";
*/
}
////TODO: match HID layouts by vendor and product ID
////REVIEW: this probably works fine for most products out there but I'm not sure it works reliably for all cases
// Come up with a unique template name. HIDs are required to have product and vendor IDs.
// We go with the string versions if we have them and with the numeric versions if we don't.
string layoutName;
if (!string.IsNullOrEmpty(description.product) && !string.IsNullOrEmpty(description.manufacturer))
{
layoutName = string.Format("{0}::{1} {2}", kHIDNamespace, description.manufacturer, description.product);
}
else
{
// Sanity check to make sure we really have the data we expect.
if (hidDeviceDescriptor.vendorId == 0)
{
return(null);
}
layoutName = string.Format("{0}::{1:X}-{2:X}", kHIDNamespace, hidDeviceDescriptor.vendorId,
hidDeviceDescriptor.productId);
}
// Register layout builder that will turn the HID descriptor into an
// InputControlLayout instance.
var layout = new HIDLayoutBuilder {
hidDescriptor = hidDeviceDescriptor
};
InputSystem.RegisterControlLayoutBuilder(() => layout.Build(),
layoutName, baseLayout, InputDeviceMatcher.FromDeviceDescription(description));
return(layoutName);
}
