Files
scrcpy/app/src/hid_keyboard.c
Romain Vimont d2cdf2f507 Use scrcpy input events for key processors
Pass scrcpy input events instead of SDL input events to key processors.

This makes the source code of key processors independent of the SDL API.
2021-12-31 10:49:54 +01:00

438 lines
13 KiB
C

#include "hid_keyboard.h"
#include <assert.h>
#include "input_events.h"
#include "util/log.h"
/** Downcast key processor to hid_keyboard */
#define DOWNCAST(KP) container_of(KP, struct sc_hid_keyboard, key_processor)
#define HID_KEYBOARD_ACCESSORY_ID 1
#define HID_MODIFIER_NONE 0x00
#define HID_MODIFIER_LEFT_CONTROL (1 << 0)
#define HID_MODIFIER_LEFT_SHIFT (1 << 1)
#define HID_MODIFIER_LEFT_ALT (1 << 2)
#define HID_MODIFIER_LEFT_GUI (1 << 3)
#define HID_MODIFIER_RIGHT_CONTROL (1 << 4)
#define HID_MODIFIER_RIGHT_SHIFT (1 << 5)
#define HID_MODIFIER_RIGHT_ALT (1 << 6)
#define HID_MODIFIER_RIGHT_GUI (1 << 7)
#define HID_KEYBOARD_INDEX_MODIFIER 0
#define HID_KEYBOARD_INDEX_KEYS 2
// USB HID protocol says 6 keys in an event is the requirement for BIOS
// keyboard support, though OS could support more keys via modifying the report
// desc. 6 should be enough for scrcpy.
#define HID_KEYBOARD_MAX_KEYS 6
#define HID_KEYBOARD_EVENT_SIZE (2 + HID_KEYBOARD_MAX_KEYS)
#define HID_RESERVED 0x00
#define HID_ERROR_ROLL_OVER 0x01
/**
* For HID over AOAv2, only report descriptor is needed.
*
* The specification is available here:
* <https://www.usb.org/sites/default/files/hid1_11.pdf>
*
* In particular, read:
* - 6.2.2 Report Descriptor
* - Appendix B.1 Protocol 1 (Keyboard)
* - Appendix C: Keyboard Implementation
*
* Normally a basic HID keyboard uses 8 bytes:
* Modifier Reserved Key Key Key Key Key Key
*
* You can dump your device's report descriptor with:
*
* sudo usbhid-dump -m vid:pid -e descriptor
*
* (change vid:pid' to your device's vendor ID and product ID).
*/
static const unsigned char keyboard_report_desc[] = {
// Usage Page (Generic Desktop)
0x05, 0x01,
// Usage (Keyboard)
0x09, 0x06,
// Collection (Application)
0xA1, 0x01,
// Usage Page (Key Codes)
0x05, 0x07,
// Usage Minimum (224)
0x19, 0xE0,
// Usage Maximum (231)
0x29, 0xE7,
// Logical Minimum (0)
0x15, 0x00,
// Logical Maximum (1)
0x25, 0x01,
// Report Size (1)
0x75, 0x01,
// Report Count (8)
0x95, 0x08,
// Input (Data, Variable, Absolute): Modifier byte
0x81, 0x02,
// Report Size (8)
0x75, 0x08,
// Report Count (1)
0x95, 0x01,
// Input (Constant): Reserved byte
0x81, 0x01,
// Usage Page (LEDs)
0x05, 0x08,
// Usage Minimum (1)
0x19, 0x01,
// Usage Maximum (5)
0x29, 0x05,
// Report Size (1)
0x75, 0x01,
// Report Count (5)
0x95, 0x05,
// Output (Data, Variable, Absolute): LED report
0x91, 0x02,
// Report Size (3)
0x75, 0x03,
// Report Count (1)
0x95, 0x01,
// Output (Constant): LED report padding
0x91, 0x01,
// Usage Page (Key Codes)
0x05, 0x07,
// Usage Minimum (0)
0x19, 0x00,
// Usage Maximum (101)
0x29, SC_HID_KEYBOARD_KEYS - 1,
// Logical Minimum (0)
0x15, 0x00,
// Logical Maximum(101)
0x25, SC_HID_KEYBOARD_KEYS - 1,
// Report Size (8)
0x75, 0x08,
// Report Count (6)
0x95, HID_KEYBOARD_MAX_KEYS,
// Input (Data, Array): Keys
0x81, 0x00,
// End Collection
0xC0
};
/**
* A keyboard HID event is 8 bytes long:
*
* - byte 0: modifiers (1 flag per modifier key, 8 possible modifier keys)
* - byte 1: reserved (always 0)
* - bytes 2 to 7: pressed keys (6 at most)
*
* 7 6 5 4 3 2 1 0
* +---------------+
* byte 0: |. . . . . . . .| modifiers
* +---------------+
* ^ ^ ^ ^ ^ ^ ^ ^
* | | | | | | | `- left Ctrl
* | | | | | | `--- left Shift
* | | | | | `----- left Alt
* | | | | `------- left Gui
* | | | `--------- right Ctrl
* | | `----------- right Shift
* | `------------- right Alt
* `--------------- right Gui
*
* +---------------+
* byte 1: |0 0 0 0 0 0 0 0| reserved
* +---------------+
*
* +---------------+
* bytes 2 to 7: |. . . . . . . .| scancode of 1st key pressed
* +---------------+
* |. . . . . . . .| scancode of 2nd key pressed
* +---------------+
* |. . . . . . . .| scancode of 3rd key pressed
* +---------------+
* |. . . . . . . .| scancode of 4th key pressed
* +---------------+
* |. . . . . . . .| scancode of 5th key pressed
* +---------------+
* |. . . . . . . .| scancode of 6th key pressed
* +---------------+
*
* If there are less than 6 keys pressed, the last items are set to 0.
* For example, if A and W are pressed:
*
* +---------------+
* bytes 2 to 7: |0 0 0 0 0 1 0 0| A is pressed (scancode = 4)
* +---------------+
* |0 0 0 1 1 0 1 0| W is pressed (scancode = 26)
* +---------------+
* |0 0 0 0 0 0 0 0| ^
* +---------------+ | only 2 keys are pressed, the
* |0 0 0 0 0 0 0 0| | remaining items are set to 0
* +---------------+ |
* |0 0 0 0 0 0 0 0| |
* +---------------+ |
* |0 0 0 0 0 0 0 0| v
* +---------------+
*
* Pressing more than 6 keys is not supported. If this happens (typically,
* never in practice), report a "phantom state":
*
* +---------------+
* bytes 2 to 7: |0 0 0 0 0 0 0 1| ^
* +---------------+ |
* |0 0 0 0 0 0 0 1| | more than 6 keys pressed:
* +---------------+ | the list is filled with a special
* |0 0 0 0 0 0 0 1| | rollover error code (0x01)
* +---------------+ |
* |0 0 0 0 0 0 0 1| |
* +---------------+ |
* |0 0 0 0 0 0 0 1| |
* +---------------+ |
* |0 0 0 0 0 0 0 1| v
* +---------------+
*/
static unsigned char
sdl_keymod_to_hid_modifiers(uint16_t mod) {
unsigned char modifiers = HID_MODIFIER_NONE;
if (mod & SC_MOD_LCTRL) {
modifiers |= HID_MODIFIER_LEFT_CONTROL;
}
if (mod & SC_MOD_LSHIFT) {
modifiers |= HID_MODIFIER_LEFT_SHIFT;
}
if (mod & SC_MOD_LALT) {
modifiers |= HID_MODIFIER_LEFT_ALT;
}
if (mod & SC_MOD_LGUI) {
modifiers |= HID_MODIFIER_LEFT_GUI;
}
if (mod & SC_MOD_RCTRL) {
modifiers |= HID_MODIFIER_RIGHT_CONTROL;
}
if (mod & SC_MOD_RSHIFT) {
modifiers |= HID_MODIFIER_RIGHT_SHIFT;
}
if (mod & SC_MOD_RALT) {
modifiers |= HID_MODIFIER_RIGHT_ALT;
}
if (mod & SC_MOD_RGUI) {
modifiers |= HID_MODIFIER_RIGHT_GUI;
}
return modifiers;
}
static bool
sc_hid_keyboard_event_init(struct sc_hid_event *hid_event) {
unsigned char *buffer = malloc(HID_KEYBOARD_EVENT_SIZE);
if (!buffer) {
LOG_OOM();
return false;
}
buffer[HID_KEYBOARD_INDEX_MODIFIER] = HID_MODIFIER_NONE;
buffer[1] = HID_RESERVED;
memset(&buffer[HID_KEYBOARD_INDEX_KEYS], 0, HID_KEYBOARD_MAX_KEYS);
sc_hid_event_init(hid_event, HID_KEYBOARD_ACCESSORY_ID, buffer,
HID_KEYBOARD_EVENT_SIZE);
return true;
}
static inline bool
scancode_is_modifier(enum sc_scancode scancode) {
return scancode >= SC_SCANCODE_LCTRL && scancode <= SC_SCANCODE_RGUI;
}
static bool
convert_hid_keyboard_event(struct sc_hid_keyboard *kb,
struct sc_hid_event *hid_event,
const struct sc_key_event *event) {
enum sc_scancode scancode = event->scancode;
assert(scancode >= 0);
// SDL also generates events when only modifiers are pressed, we cannot
// ignore them totally, for example press 'a' first then press 'Control',
// if we ignore 'Control' event, only 'a' is sent.
if (scancode >= SC_HID_KEYBOARD_KEYS && !scancode_is_modifier(scancode)) {
// Scancode to ignore
return false;
}
if (!sc_hid_keyboard_event_init(hid_event)) {
LOGW("Could not initialize HID keyboard event");
return false;
}
unsigned char modifiers = sdl_keymod_to_hid_modifiers(event->mods_state);
if (scancode < SC_HID_KEYBOARD_KEYS) {
// Pressed is true and released is false
kb->keys[scancode] = (event->action == SC_ACTION_DOWN);
LOGV("keys[%02x] = %s", scancode,
kb->keys[scancode] ? "true" : "false");
}
hid_event->buffer[HID_KEYBOARD_INDEX_MODIFIER] = modifiers;
unsigned char *keys_buffer = &hid_event->buffer[HID_KEYBOARD_INDEX_KEYS];
// Re-calculate pressed keys every time
int keys_pressed_count = 0;
for (int i = 0; i < SC_HID_KEYBOARD_KEYS; ++i) {
if (kb->keys[i]) {
// USB HID protocol says that if keys exceeds report count, a
// phantom state should be reported
if (keys_pressed_count >= HID_KEYBOARD_MAX_KEYS) {
// Phantom state:
// - Modifiers
// - Reserved
// - ErrorRollOver * HID_MAX_KEYS
memset(keys_buffer, HID_ERROR_ROLL_OVER, HID_KEYBOARD_MAX_KEYS);
goto end;
}
keys_buffer[keys_pressed_count] = i;
++keys_pressed_count;
}
}
end:
LOGV("hid keyboard: key %-4s scancode=%02x (%u) mod=%02x",
event->action == SC_ACTION_DOWN ? "down" : "up", event->scancode,
event->scancode, modifiers);
return true;
}
static bool
push_mod_lock_state(struct sc_hid_keyboard *kb, uint16_t mods_state) {
bool capslock = mods_state & SC_MOD_CAPS;
bool numlock = mods_state & SC_MOD_NUM;
if (!capslock && !numlock) {
// Nothing to do
return true;
}
struct sc_hid_event hid_event;
if (!sc_hid_keyboard_event_init(&hid_event)) {
LOGW("Could not initialize HID keyboard event");
return false;
}
unsigned i = 0;
if (capslock) {
hid_event.buffer[HID_KEYBOARD_INDEX_KEYS + i] = SC_SCANCODE_CAPSLOCK;
++i;
}
if (numlock) {
hid_event.buffer[HID_KEYBOARD_INDEX_KEYS + i] = SC_SCANCODE_NUMLOCK;
++i;
}
if (!sc_aoa_push_hid_event(kb->aoa, &hid_event)) {
sc_hid_event_destroy(&hid_event);
LOGW("Could request HID event");
return false;
}
LOGD("HID keyboard state synchronized");
return true;
}
static void
sc_key_processor_process_key(struct sc_key_processor *kp,
const struct sc_key_event *event,
uint64_t ack_to_wait) {
if (event->repeat) {
// In USB HID protocol, key repeat is handled by the host (Android), so
// just ignore key repeat here.
return;
}
struct sc_hid_keyboard *kb = DOWNCAST(kp);
struct sc_hid_event hid_event;
// Not all keys are supported, just ignore unsupported keys
if (convert_hid_keyboard_event(kb, &hid_event, event)) {
if (!kb->mod_lock_synchronized) {
// Inject CAPSLOCK and/or NUMLOCK if necessary to synchronize
// keyboard state
if (push_mod_lock_state(kb, event->mods_state)) {
kb->mod_lock_synchronized = true;
}
}
if (ack_to_wait) {
// Ctrl+v is pressed, so clipboard synchronization has been
// requested. Wait until clipboard synchronization is acknowledged
// by the server, otherwise it could paste the old clipboard
// content.
hid_event.ack_to_wait = ack_to_wait;
}
if (!sc_aoa_push_hid_event(kb->aoa, &hid_event)) {
sc_hid_event_destroy(&hid_event);
LOGW("Could request HID event");
}
}
}
static void
sc_key_processor_process_text(struct sc_key_processor *kp,
const struct sc_text_event *event) {
(void) kp;
(void) event;
// Never forward text input via HID (all the keys are injected separately)
}
bool
sc_hid_keyboard_init(struct sc_hid_keyboard *kb, struct sc_aoa *aoa) {
kb->aoa = aoa;
bool ok = sc_aoa_setup_hid(aoa, HID_KEYBOARD_ACCESSORY_ID,
keyboard_report_desc,
ARRAY_LEN(keyboard_report_desc));
if (!ok) {
LOGW("Register HID keyboard failed");
return false;
}
// Reset all states
memset(kb->keys, false, SC_HID_KEYBOARD_KEYS);
kb->mod_lock_synchronized = false;
static const struct sc_key_processor_ops ops = {
.process_key = sc_key_processor_process_key,
.process_text = sc_key_processor_process_text,
};
// Clipboard synchronization is requested over the control socket, while HID
// events are sent over AOA, so it must wait for clipboard synchronization
// to be acknowledged by the device before injecting Ctrl+v.
kb->key_processor.async_paste = true;
kb->key_processor.ops = &ops;
return true;
}
void
sc_hid_keyboard_destroy(struct sc_hid_keyboard *kb) {
// Unregister HID keyboard so the soft keyboard shows again on Android
bool ok = sc_aoa_unregister_hid(kb->aoa, HID_KEYBOARD_ACCESSORY_ID);
if (!ok) {
LOGW("Could not unregister HID keyboard");
}
}