scrcpy/app/src/usb/hid_mouse.c

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#include "hid_mouse.h"
#include <assert.h>
#include "input_events.h"
#include "util/log.h"
/** Downcast mouse processor to hid_mouse */
#define DOWNCAST(MP) container_of(MP, struct sc_hid_mouse, mouse_processor)
#define HID_MOUSE_ACCESSORY_ID 2
// 1 byte for buttons + padding, 1 byte for X position, 1 byte for Y position
#define HID_MOUSE_EVENT_SIZE 4
/**
* Mouse descriptor from the specification:
* <https://www.usb.org/sites/default/files/hid1_11.pdf>
*
* Appendix E (p71): §E.10 Report Descriptor (Mouse)
*
* The usage tags (like Wheel) are listed in "HID Usage Tables":
* <https://www.usb.org/sites/default/files/documents/hut1_12v2.pdf>
* §4 Generic Desktop Page (0x01) (p26)
*/
static const unsigned char mouse_report_desc[] = {
// Usage Page (Generic Desktop)
0x05, 0x01,
// Usage (Mouse)
0x09, 0x02,
// Collection (Application)
0xA1, 0x01,
// Usage (Pointer)
0x09, 0x01,
// Collection (Physical)
0xA1, 0x00,
// Usage Page (Buttons)
0x05, 0x09,
// Usage Minimum (1)
0x19, 0x01,
// Usage Maximum (5)
0x29, 0x05,
// Logical Minimum (0)
0x15, 0x00,
// Logical Maximum (1)
0x25, 0x01,
// Report Count (5)
0x95, 0x05,
// Report Size (1)
0x75, 0x01,
// Input (Data, Variable, Absolute): 5 buttons bits
0x81, 0x02,
// Report Count (1)
0x95, 0x01,
// Report Size (3)
0x75, 0x03,
// Input (Constant): 3 bits padding
0x81, 0x01,
// Usage Page (Generic Desktop)
0x05, 0x01,
// Usage (X)
0x09, 0x30,
// Usage (Y)
0x09, 0x31,
// Usage (Wheel)
0x09, 0x38,
// Local Minimum (-127)
0x15, 0x81,
// Local Maximum (127)
0x25, 0x7F,
// Report Size (8)
0x75, 0x08,
// Report Count (3)
0x95, 0x03,
// Input (Data, Variable, Relative): 3 position bytes (X, Y, Wheel)
0x81, 0x06,
// End Collection
0xC0,
// End Collection
0xC0,
};
/**
* A mouse HID event is 3 bytes long:
*
* - byte 0: buttons state
* - byte 1: relative x motion (signed byte from -127 to 127)
* - byte 2: relative y motion (signed byte from -127 to 127)
*
* 7 6 5 4 3 2 1 0
* +---------------+
* byte 0: |0 0 0 . . . . .| buttons state
* +---------------+
* ^ ^ ^ ^ ^
* | | | | `- left button
* | | | `--- right button
* | | `----- middle button
* | `------- button 4
* `--------- button 5
*
* +---------------+
* byte 1: |. . . . . . . .| relative x motion
* +---------------+
* byte 2: |. . . . . . . .| relative y motion
* +---------------+
* byte 3: |. . . . . . . .| wheel motion (-1, 0 or 1)
* +---------------+
*
* As an example, here is the report for a motion of (x=5, y=-4) with left
* button pressed:
*
* +---------------+
* |0 0 0 0 0 0 0 1| left button pressed
* +---------------+
* |0 0 0 0 0 1 0 1| horizontal motion (x = 5)
* +---------------+
* |1 1 1 1 1 1 0 0| relative y motion (y = -4)
* +---------------+
* |0 0 0 0 0 0 0 0| wheel motion
* +---------------+
*/
static bool
sc_hid_mouse_event_init(struct sc_hid_event *hid_event) {
unsigned char *buffer = calloc(1, HID_MOUSE_EVENT_SIZE);
if (!buffer) {
LOG_OOM();
return false;
}
sc_hid_event_init(hid_event, HID_MOUSE_ACCESSORY_ID, buffer,
HID_MOUSE_EVENT_SIZE);
return true;
}
static unsigned char
buttons_state_to_hid_buttons(uint8_t buttons_state) {
unsigned char c = 0;
if (buttons_state & SC_MOUSE_BUTTON_LEFT) {
c |= 1 << 0;
}
if (buttons_state & SC_MOUSE_BUTTON_RIGHT) {
c |= 1 << 1;
}
if (buttons_state & SC_MOUSE_BUTTON_MIDDLE) {
c |= 1 << 2;
}
if (buttons_state & SC_MOUSE_BUTTON_X1) {
c |= 1 << 3;
}
if (buttons_state & SC_MOUSE_BUTTON_X2) {
c |= 1 << 4;
}
return c;
}
static void
sc_mouse_processor_process_mouse_motion(struct sc_mouse_processor *mp,
const struct sc_mouse_motion_event *event) {
struct sc_hid_mouse *mouse = DOWNCAST(mp);
struct sc_hid_event hid_event;
if (!sc_hid_mouse_event_init(&hid_event)) {
return;
}
unsigned char *buffer = hid_event.buffer;
buffer[0] = buttons_state_to_hid_buttons(event->buttons_state);
buffer[1] = CLAMP(event->xrel, -127, 127);
buffer[2] = CLAMP(event->yrel, -127, 127);
buffer[3] = 0; // wheel coordinates only used for scrolling
if (!sc_aoa_push_hid_event(mouse->aoa, &hid_event)) {
sc_hid_event_destroy(&hid_event);
LOGW("Could not request HID event (mouse motion)");
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}
}
static void
sc_mouse_processor_process_mouse_click(struct sc_mouse_processor *mp,
const struct sc_mouse_click_event *event) {
struct sc_hid_mouse *mouse = DOWNCAST(mp);
struct sc_hid_event hid_event;
if (!sc_hid_mouse_event_init(&hid_event)) {
return;
}
unsigned char *buffer = hid_event.buffer;
buffer[0] = buttons_state_to_hid_buttons(event->buttons_state);
buffer[1] = 0; // no x motion
buffer[2] = 0; // no y motion
buffer[3] = 0; // wheel coordinates only used for scrolling
if (!sc_aoa_push_hid_event(mouse->aoa, &hid_event)) {
sc_hid_event_destroy(&hid_event);
LOGW("Could not request HID event (mouse click)");
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}
}
static void
sc_mouse_processor_process_mouse_scroll(struct sc_mouse_processor *mp,
const struct sc_mouse_scroll_event *event) {
struct sc_hid_mouse *mouse = DOWNCAST(mp);
struct sc_hid_event hid_event;
if (!sc_hid_mouse_event_init(&hid_event)) {
return;
}
unsigned char *buffer = hid_event.buffer;
buffer[0] = 0; // buttons state irrelevant (and unknown)
buffer[1] = 0; // no x motion
buffer[2] = 0; // no y motion
// In practice, vscroll is always -1, 0 or 1, but in theory other values
// are possible
buffer[3] = CLAMP(event->vscroll, -127, 127);
// Horizontal scrolling ignored
if (!sc_aoa_push_hid_event(mouse->aoa, &hid_event)) {
sc_hid_event_destroy(&hid_event);
LOGW("Could not request HID event (mouse scroll)");
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}
}
bool
sc_hid_mouse_init(struct sc_hid_mouse *mouse, struct sc_aoa *aoa) {
mouse->aoa = aoa;
bool ok = sc_aoa_setup_hid(aoa, HID_MOUSE_ACCESSORY_ID, mouse_report_desc,
ARRAY_LEN(mouse_report_desc));
if (!ok) {
LOGW("Register HID mouse failed");
return false;
}
static const struct sc_mouse_processor_ops ops = {
.process_mouse_motion = sc_mouse_processor_process_mouse_motion,
.process_mouse_click = sc_mouse_processor_process_mouse_click,
.process_mouse_scroll = sc_mouse_processor_process_mouse_scroll,
// Touch events not supported (coordinates are not relative)
.process_touch = NULL,
};
mouse->mouse_processor.ops = &ops;
mouse->mouse_processor.relative_mode = true;
return true;
}
void
sc_hid_mouse_destroy(struct sc_hid_mouse *mouse) {
bool ok = sc_aoa_unregister_hid(mouse->aoa, HID_MOUSE_ACCESSORY_ID);
if (!ok) {
LOGW("Could not unregister HID mouse");
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}
}