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evdev: Detect whether input devices are accelerometers 

Anything with X, Y and Z axes but no buttons is probably an
accelerometer (this is the assumption made in udev).

Signed-off-by: Simon McVittie <smcv@collabora.com>
Simon McVittie 2020-11-11 19:15:09 -08:00
parent fdd945f2af
commit aae53d5972
2 changed files with 20 additions and 1 deletions
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18
src/core/linux/SDL_evdev_capabilities.c
View File

@ -33,6 +33,24 @@ SDL_EVDEV_GuessDeviceClass(unsigned long bitmask_ev[NBITS(EV_MAX)],
int devclass = 0;
unsigned long keyboard_mask;
/* X, Y, Z axes but no buttons probably means an accelerometer */
if (test_bit(EV_ABS, bitmask_ev) &&
test_bit(ABS_X, bitmask_abs) &&
test_bit(ABS_Y, bitmask_abs) &&
test_bit(ABS_Z, bitmask_abs) &&
!test_bit(EV_KEY, bitmask_ev)) {
return SDL_UDEV_DEVICE_ACCELEROMETER;
}
/* RX, RY, RZ axes but no buttons also probably means an accelerometer */
if (test_bit(EV_ABS, bitmask_ev) &&
test_bit(ABS_RX, bitmask_abs) &&
test_bit(ABS_RY, bitmask_abs) &&
test_bit(ABS_RZ, bitmask_abs) &&
!test_bit(EV_KEY, bitmask_ev)) {
return SDL_UDEV_DEVICE_ACCELEROMETER;
}
if (test_bit(EV_ABS, bitmask_ev) &&
test_bit(ABS_X, bitmask_abs) && test_bit(ABS_Y, bitmask_abs)) {
if (test_bit(BTN_STYLUS, bitmask_key) || test_bit(BTN_TOOL_PEN, bitmask_key)) {

3
src/core/linux/SDL_evdev_capabilities.h
View File

@ -37,7 +37,8 @@ typedef enum
SDL_UDEV_DEVICE_KEYBOARD = 0x0002,
SDL_UDEV_DEVICE_JOYSTICK = 0x0004,
SDL_UDEV_DEVICE_SOUND = 0x0008,
SDL_UDEV_DEVICE_TOUCHSCREEN = 0x0010
SDL_UDEV_DEVICE_TOUCHSCREEN = 0x0010,
SDL_UDEV_DEVICE_ACCELEROMETER = 0x0020
} SDL_UDEV_deviceclass;
#define BITS_PER_LONG (sizeof(unsigned long) * 8)