scrcpy/app/src/hid_keyboard.c
Romain Vimont e4163321f0 Delay HID events on Ctrl+v
When Ctrl+v is pressed, a control is sent to the device to set the
device clipboard before injecting Ctrl+v.

With the InputManager method, it is guaranteed that the device
synchronization is executed before handling Ctrl+v, since the commands
are executed on the device in sequence.

However, HID are injected from the computer, so there is no such
guarantee. As a consequence, on Android, Ctrl+v triggers a paste with
the old clipboard content.

To workaround the issue, wait a bit (2 milliseconds) from the AOA
thread before injecting the event, to leave enough time for the
clipboard to be set before injecting Ctrl+v.
2021-10-26 21:30:04 +02:00

363 lines
10 KiB
C

#include "hid_keyboard.h"
#include <assert.h>
#include <SDL2/SDL_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
};
static unsigned char
sdl_keymod_to_hid_modifiers(SDL_Keymod mod) {
unsigned char modifiers = HID_MODIFIER_NONE;
if (mod & KMOD_LCTRL) {
modifiers |= HID_MODIFIER_LEFT_CONTROL;
}
if (mod & KMOD_LSHIFT) {
modifiers |= HID_MODIFIER_LEFT_SHIFT;
}
if (mod & KMOD_LALT) {
modifiers |= HID_MODIFIER_LEFT_ALT;
}
if (mod & KMOD_LGUI) {
modifiers |= HID_MODIFIER_LEFT_GUI;
}
if (mod & KMOD_RCTRL) {
modifiers |= HID_MODIFIER_RIGHT_CONTROL;
}
if (mod & KMOD_RSHIFT) {
modifiers |= HID_MODIFIER_RIGHT_SHIFT;
}
if (mod & KMOD_RALT) {
modifiers |= HID_MODIFIER_RIGHT_ALT;
}
if (mod & KMOD_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) {
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(SDL_Scancode scancode) {
return scancode >= SDL_SCANCODE_LCTRL && scancode <= SDL_SCANCODE_RGUI;
}
static bool
convert_hid_keyboard_event(struct sc_hid_keyboard *kb,
struct sc_hid_event *hid_event,
const SDL_KeyboardEvent *event) {
SDL_Scancode scancode = event->keysym.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->keysym.mod);
if (scancode < SC_HID_KEYBOARD_KEYS) {
// Pressed is true and released is false
kb->keys[scancode] = (event->type == SDL_KEYDOWN);
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) {
// Pantom 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->type == SDL_KEYDOWN ? "down" : "up", event->keysym.scancode,
event->keysym.scancode, modifiers);
return true;
}
static bool
push_mod_lock_state(struct sc_hid_keyboard *kb, uint16_t sdl_mod) {
bool capslock = sdl_mod & KMOD_CAPS;
bool numlock = sdl_mod & KMOD_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;
}
#define SC_SCANCODE_CAPSLOCK SDL_SCANCODE_CAPSLOCK
#define SC_SCANCODE_NUMLOCK SDL_SCANCODE_NUMLOCKCLEAR
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 SDL_KeyboardEvent *event) {
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->keysym.mod)) {
kb->mod_lock_synchronized = true;
}
}
SDL_Keycode keycode = event->keysym.sym;
bool down = event->type == SDL_KEYDOWN;
bool ctrl = event->keysym.mod & KMOD_CTRL;
bool shift = event->keysym.mod & KMOD_SHIFT;
if (ctrl && !shift && keycode == SDLK_v && down) {
// Ctrl+v is pressed, so clipboard synchronization has been
// requested. Wait a bit so that the clipboard is set before
// injecting Ctrl+v via HID, otherwise it would paste the old
// clipboard content.
hid_event.delay = SC_TICK_FROM_MS(2);
}
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 SDL_TextInputEvent *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,
};
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");
}
}