Add UHID mouse support

Use the following command:

    scrcpy --mouse=uhid

app/src/cli.c

@@ -468,8 +468,10 @@ static const struct sc_option options[] = {
                 "events to applications.\n"
                 "\"aoa\" simulates a physical mouse using the AOAv2 protocol\n"
                 "It may only work over USB.\n"
-                "In \"aoa\" mode, the computer mouse is captured to control "
-                "the device directly (relative mouse mode).\n"
+                "\"uhid\" simulates a physical HID mouse using the Linux UHID "
+                "kernel module on the device."
+                "In \"aoa\" and \"uhid\" modes, the computer mouse is captured "
+                "to control the device directly (relative mouse mode).\n"
                 "LAlt, LSuper or RSuper toggle the capture mode, to give "
                 "control of the mouse back to the computer.\n"
                 "Also see --keyboard.",
@@ -1989,7 +1991,12 @@ parse_mouse(const char *optarg, enum sc_mouse_input_mode *mode) {
 #endif
     }
 
-    LOGE("Unsupported mouse: %s (expected disabled, sdk or aoa)", optarg);
+    if (!strcmp(optarg, "uhid")) {
+        *mode = SC_MOUSE_INPUT_MODE_UHID;
+        return true;
+    }
+
+    LOGE("Unsupported mouse: %s (expected disabled, sdk, aoa or uhid)", optarg);
     return false;
 }
 

app/src/options.h

@@ -152,6 +152,7 @@ enum sc_mouse_input_mode {
     SC_MOUSE_INPUT_MODE_DISABLED,
     SC_MOUSE_INPUT_MODE_SDK,
     SC_MOUSE_INPUT_MODE_AOA,
+    SC_MOUSE_INPUT_MODE_UHID,
 };
 
 enum sc_key_inject_mode {

app/src/scrcpy.c

@@ -26,6 +26,7 @@
 #include "screen.h"
 #include "server.h"
 #include "uhid/keyboard_uhid.h"
+#include "uhid/mouse_uhid.h"
 #ifdef HAVE_USB
 # include "usb/aoa_hid.h"
 # include "usb/keyboard_aoa.h"
@@ -76,6 +77,7 @@ struct scrcpy {
 #ifdef HAVE_USB
         struct sc_mouse_aoa mouse_aoa;
 #endif
+        struct sc_mouse_uhid mouse_uhid;
     };
     struct sc_timeout timeout;
 };
@@ -681,6 +683,12 @@ aoa_hid_end:
         if (options->mouse_input_mode == SC_MOUSE_INPUT_MODE_SDK) {
             sc_mouse_sdk_init(&s->mouse_sdk, &s->controller);
             mp = &s->mouse_sdk.mouse_processor;
+        } else if (options->mouse_input_mode == SC_MOUSE_INPUT_MODE_UHID) {
+            bool ok = sc_mouse_uhid_init(&s->mouse_uhid, &s->controller);
+            if (!ok) {
+                goto end;
+            }
+            mp = &s->mouse_uhid.mouse_processor;
         }
 
         sc_controller_configure(&s->controller, acksync, uhid_devices);

app/src/uhid/mouse_uhid.c

@@ -0,0 +1,89 @@
+#include "mouse_uhid.h"
+
+#include "hid/hid_mouse.h"
+#include "input_events.h"
+#include "util/log.h"
+
+/** Downcast mouse processor to mouse_uhid */
+#define DOWNCAST(MP) container_of(MP, struct sc_mouse_uhid, mouse_processor)
+
+#define UHID_MOUSE_ID 2
+
+static void
+sc_mouse_uhid_send_input(struct sc_mouse_uhid *mouse,
+                         const struct sc_hid_event *event, const char *name) {
+    struct sc_control_msg msg;
+    msg.type = SC_CONTROL_MSG_TYPE_UHID_INPUT;
+    msg.uhid_input.id = UHID_MOUSE_ID;
+
+    assert(event->size <= SC_HID_MAX_SIZE);
+    memcpy(msg.uhid_input.data, event->data, event->size);
+    msg.uhid_input.size = event->size;
+
+    if (!sc_controller_push_msg(mouse->controller, &msg)) {
+        LOGE("Could not send UHID_INPUT message (%s)", name);
+    }
+}
+
+static void
+sc_mouse_processor_process_mouse_motion(struct sc_mouse_processor *mp,
+                                    const struct sc_mouse_motion_event *event) {
+    struct sc_mouse_uhid *mouse = DOWNCAST(mp);
+
+    struct sc_hid_event hid_event;
+    sc_hid_mouse_event_from_motion(&hid_event, event);
+
+    sc_mouse_uhid_send_input(mouse, &hid_event, "mouse motion");
+}
+
+static void
+sc_mouse_processor_process_mouse_click(struct sc_mouse_processor *mp,
+                                   const struct sc_mouse_click_event *event) {
+    struct sc_mouse_uhid *mouse = DOWNCAST(mp);
+
+    struct sc_hid_event hid_event;
+    sc_hid_mouse_event_from_click(&hid_event, event);
+
+    sc_mouse_uhid_send_input(mouse, &hid_event, "mouse click");
+}
+
+static void
+sc_mouse_processor_process_mouse_scroll(struct sc_mouse_processor *mp,
+                                    const struct sc_mouse_scroll_event *event) {
+    struct sc_mouse_uhid *mouse = DOWNCAST(mp);
+
+    struct sc_hid_event hid_event;
+    sc_hid_mouse_event_from_scroll(&hid_event, event);
+
+    sc_mouse_uhid_send_input(mouse, &hid_event, "mouse scroll");
+}
+
+bool
+sc_mouse_uhid_init(struct sc_mouse_uhid *mouse,
+                   struct sc_controller *controller) {
+    mouse->controller = controller;
+
+    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;
+
+    struct sc_control_msg msg;
+    msg.type = SC_CONTROL_MSG_TYPE_UHID_CREATE;
+    msg.uhid_create.id = UHID_MOUSE_ID;
+    msg.uhid_create.report_desc = SC_HID_MOUSE_REPORT_DESC;
+    msg.uhid_create.report_desc_size = SC_HID_MOUSE_REPORT_DESC_LEN;
+    if (!sc_controller_push_msg(controller, &msg)) {
+        LOGE("Could not send UHID_CREATE message (mouse)");
+        return false;
+    }
+
+    return true;
+}

app/src/uhid/mouse_uhid.h

@@ -0,0 +1,19 @@
+#ifndef SC_MOUSE_UHID_H
+#define SC_MOUSE_UHID_H
+
+#include <stdbool.h>
+
+#include "controller.h"
+#include "trait/mouse_processor.h"
+
+struct sc_mouse_uhid {
+    struct sc_mouse_processor mouse_processor; // mouse processor trait
+
+    struct sc_controller *controller;
+};
+
+bool
+sc_mouse_uhid_init(struct sc_mouse_uhid *mouse,
+                   struct sc_controller *controller);
+
+#endif