relative-mouse-mode

This will allow the mouse processor to handle relative motion easily.

app/meson.build

@@ -77,6 +77,7 @@ if aoa_hid_support
     src += [
         'src/aoa_hid.c',
         'src/hid_keyboard.c',
+        'src/hid_mouse.c',
     ]
 endif
 

app/src/common.h

@@ -7,6 +7,7 @@
 #define ARRAY_LEN(a) (sizeof(a) / sizeof(a[0]))
 #define MIN(X,Y) (X) < (Y) ? (X) : (Y)
 #define MAX(X,Y) (X) > (Y) ? (X) : (Y)
+#define CLAMP(V,X,Y) MIN( MAX((V),(X)), (Y) )
 
 #define container_of(ptr, type, member) \
     ((type *) (((char *) (ptr)) - offsetof(type, member)))

app/src/hid_mouse.c

@@ -0,0 +1,267 @@
+#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 request HID event");
+    }
+}
+
+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 request HID event");
+    }
+}
+
+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 request HID event");
+    }
+}
+
+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");
+    }
+}

app/src/hid_mouse.h

@@ -0,0 +1,23 @@
+#ifndef HID_MOUSE_H
+#define HID_MOUSE_H
+
+#include "common.h"
+
+#include <stdbool.h>
+
+#include "aoa_hid.h"
+#include "trait/mouse_processor.h"
+
+struct sc_hid_mouse {
+    struct sc_mouse_processor mouse_processor; // mouse processor trait
+
+    struct sc_aoa *aoa;
+};
+
+bool
+sc_hid_mouse_init(struct sc_hid_mouse *mouse, struct sc_aoa *aoa);
+
+void
+sc_hid_mouse_destroy(struct sc_hid_mouse *mouse);
+
+#endif

app/src/input_events.h

@@ -366,6 +366,8 @@ struct sc_mouse_scroll_event {
 
 struct sc_mouse_motion_event {
     struct sc_position position;
+    int32_t xrel;
+    int32_t yrel;
     uint8_t buttons_state; // bitwise-OR of sc_mouse_button values
 };
 

app/src/input_manager.c

@@ -4,6 +4,7 @@
 #include <SDL2/SDL_keycode.h>
 
 #include "input_events.h"
+#include "screen.h"
 #include "util/log.h"
 
 static inline uint16_t
@@ -121,24 +122,22 @@ is_shortcut_mod(struct input_manager *im, uint16_t sdl_mod) {
 }
 
 void
-input_manager_init(struct input_manager *im, struct controller *controller,
-                   struct screen *screen, struct sc_key_processor *kp,
-                   struct sc_mouse_processor *mp,
-                   const struct scrcpy_options *options) {
-    assert(!options->control || (kp && kp->ops));
-    assert(!options->control || (mp && mp->ops));
+input_manager_init(struct input_manager *im,
+                   const struct input_manager_params *params) {
+    assert(!params->control || (params->kp && params->kp->ops));
+    assert(!params->control || (params->mp && params->mp->ops));
 
-    im->controller = controller;
-    im->screen = screen;
-    im->kp = kp;
-    im->mp = mp;
+    im->controller = params->controller;
+    im->screen = params->screen;
+    im->kp = params->kp;
+    im->mp = params->mp;
 
-    im->control = options->control;
-    im->forward_all_clicks = options->forward_all_clicks;
-    im->legacy_paste = options->legacy_paste;
-    im->clipboard_autosync = options->clipboard_autosync;
+    im->control = params->control;
+    im->forward_all_clicks = params->forward_all_clicks;
+    im->legacy_paste = params->legacy_paste;
+    im->clipboard_autosync = params->clipboard_autosync;
 
-    const struct sc_shortcut_mods *shortcut_mods = &options->shortcut_mods;
+    const struct sc_shortcut_mods *shortcut_mods = params->shortcut_mods;
     assert(shortcut_mods->count);
     assert(shortcut_mods->count < SC_MAX_SHORTCUT_MODS);
     for (unsigned i = 0; i < shortcut_mods->count; ++i) {
@@ -639,10 +638,10 @@ input_manager_process_mouse_motion(struct input_manager *im,
     if (im->forward_all_clicks) {
         mask |= SDL_BUTTON_MMASK | SDL_BUTTON_RMASK;
     }
-    if (!(event->state & mask)) {
-        // do not send motion events when no click is pressed
-        return;
-    }
+    //if (!(event->state & mask)) {
+    //    // do not send motion events when no click is pressed
+    //    return;
+    //}
     if (event->which == SDL_TOUCH_MOUSEID) {
         // simulated from touch events, so it's a duplicate
         return;
@@ -654,6 +653,8 @@ input_manager_process_mouse_motion(struct input_manager *im,
             .point = screen_convert_window_to_frame_coords(im->screen,
                                                            event->x, event->y),
         },
+        .xrel = event->xrel,
+        .yrel = event->yrel,
         .buttons_state =
             sc_mouse_buttons_state_from_sdl(event->state,
                                             im->forward_all_clicks),
@@ -775,6 +776,12 @@ input_manager_process_mouse_button(struct input_manager *im,
     assert(im->mp->ops->process_mouse_click);
     im->mp->ops->process_mouse_click(im->mp, &evt);
 
+    if (im->mp->relative_mode) {
+        assert(!im->vfinger_down); // vfinger must not be used in relative mode
+        // No pinch-to-zoom simulation
+        return;
+    }
+
     // Pinch-to-zoom simulation.
     //
     // If Ctrl is hold when the left-click button is pressed, then

app/src/input_manager.h

@@ -10,10 +10,11 @@
 #include "controller.h"
 #include "fps_counter.h"
 #include "options.h"
-#include "screen.h"
 #include "trait/key_processor.h"
 #include "trait/mouse_processor.h"
 
+struct screen; // forward declaration to avoid cycle
+
 struct input_manager {
     struct controller *controller;
     struct screen *screen;
@@ -43,11 +44,22 @@ struct input_manager {
     uint64_t next_sequence; // used for request acknowledgements
 };
 
+struct input_manager_params {
+    struct controller *controller;
+    struct screen *screen;
+    struct sc_key_processor *kp;
+    struct sc_mouse_processor *mp;
+
+    bool control;
+    bool forward_all_clicks;
+    bool legacy_paste;
+    bool clipboard_autosync;
+    const struct sc_shortcut_mods *shortcut_mods;
+};
+
 void
-input_manager_init(struct input_manager *im, struct controller *controller,
-                   struct screen *screen, struct sc_key_processor *kp,
-                   struct sc_mouse_processor *mp,
-                   const struct scrcpy_options *options);
+input_manager_init(struct input_manager *im,
+                   const struct input_manager_params *params);
 
 bool
 input_manager_handle_event(struct input_manager *im, SDL_Event *event);

app/src/mouse_inject.c

@@ -151,4 +151,6 @@ sc_mouse_inject_init(struct sc_mouse_inject *mi,
     };
 
     mi->mouse_processor.ops = &ops;
+
+    mi->mouse_processor.relative_mode = false;
 }

app/src/scrcpy.c

@@ -17,9 +17,9 @@
 #include "decoder.h"
 #include "events.h"
 #include "file_handler.h"
-#include "input_manager.h"
 #ifdef HAVE_AOA_HID
 # include "hid_keyboard.h"
+# include "hid_mouse.h"
 #endif
 #include "keyboard_inject.h"
 #include "mouse_inject.h"
@@ -56,8 +56,12 @@ struct scrcpy {
         struct sc_hid_keyboard keyboard_hid;
 #endif
     };
-    struct sc_mouse_inject mouse_inject;
-    struct input_manager input_manager;
+    union {
+        struct sc_mouse_inject mouse_inject;
+#ifdef HAVE_AOA_HID
+        struct sc_hid_mouse mouse_hid;
+#endif
+    };
 };
 
 static inline void
@@ -189,11 +193,6 @@ handle_event(struct scrcpy *s, const struct scrcpy_options *options,
     }
 
     bool consumed = screen_handle_event(&s->screen, event);
-    if (consumed) {
-        goto end;
-    }
-
-    consumed = input_manager_handle_event(&s->input_manager, event);
     (void) consumed;
 
 end:
@@ -450,6 +449,9 @@ scrcpy(struct scrcpy_options *options) {
         stream_add_sink(&s->stream, &rec->packet_sink);
     }
 
+    struct sc_key_processor *kp = NULL;
+    struct sc_mouse_processor *mp = NULL;
+
     if (options->control) {
 #ifdef HAVE_AOA_HID
         if (options->keyboard_input_mode == SC_KEYBOARD_INPUT_MODE_HID) {
@@ -481,59 +483,7 @@ scrcpy(struct scrcpy_options *options) {
                 LOGW("Could not request 'set screen power mode'");
             }
         }
-    }
 
-    if (options->display) {
-        const char *window_title =
-            options->window_title ? options->window_title : info->device_name;
-
-        struct screen_params screen_params = {
-            .window_title = window_title,
-            .frame_size = info->frame_size,
-            .always_on_top = options->always_on_top,
-            .window_x = options->window_x,
-            .window_y = options->window_y,
-            .window_width = options->window_width,
-            .window_height = options->window_height,
-            .window_borderless = options->window_borderless,
-            .rotation = options->rotation,
-            .mipmaps = options->mipmaps,
-            .fullscreen = options->fullscreen,
-            .buffering_time = options->display_buffer,
-        };
-
-        if (!screen_init(&s->screen, &screen_params)) {
-            goto end;
-        }
-        screen_initialized = true;
-
-        decoder_add_sink(&s->decoder, &s->screen.frame_sink);
-    }
-
-#ifdef HAVE_V4L2
-    if (options->v4l2_device) {
-        if (!sc_v4l2_sink_init(&s->v4l2_sink, options->v4l2_device,
-                               info->frame_size, options->v4l2_buffer)) {
-            goto end;
-        }
-
-        decoder_add_sink(&s->decoder, &s->v4l2_sink.frame_sink);
-
-        v4l2_sink_initialized = true;
-    }
-#endif
-
-    // now we consumed the header values, the socket receives the video stream
-    // start the stream
-    if (!stream_start(&s->stream)) {
-        goto end;
-    }
-    stream_started = true;
-
-    struct sc_key_processor *kp = NULL;
-    struct sc_mouse_processor *mp = NULL;
-
-    if (options->control) {
         if (options->keyboard_input_mode == SC_KEYBOARD_INPUT_MODE_HID) {
 #ifdef HAVE_AOA_HID
             bool aoa_hid_ok = false;
@@ -581,12 +531,65 @@ aoa_hid_end:
             kp = &s->keyboard_inject.key_processor;
         }
 
-        sc_mouse_inject_init(&s->mouse_inject, &s->controller);
-        mp = &s->mouse_inject.mouse_processor;
+        //sc_mouse_inject_init(&s->mouse_inject, &s->controller);
+        sc_hid_mouse_init(&s->mouse_hid, &s->aoa);
+        mp = &s->mouse_hid.mouse_processor;
     }
 
-    input_manager_init(&s->input_manager, &s->controller, &s->screen, kp, mp,
-                       options);
+    if (options->display) {
+        const char *window_title =
+            options->window_title ? options->window_title : info->device_name;
+
+        struct screen_params screen_params = {
+            .controller = &s->controller,
+            .kp = kp,
+            .mp = mp,
+            .control = options->control,
+            .forward_all_clicks = options->forward_all_clicks,
+            .legacy_paste = options->legacy_paste,
+            .clipboard_autosync = options->clipboard_autosync,
+            .shortcut_mods = &options->shortcut_mods,
+            .window_title = window_title,
+            .frame_size = info->frame_size,
+            .always_on_top = options->always_on_top,
+            .window_x = options->window_x,
+            .window_y = options->window_y,
+            .window_width = options->window_width,
+            .window_height = options->window_height,
+            .window_borderless = options->window_borderless,
+            .rotation = options->rotation,
+            .mipmaps = options->mipmaps,
+            .fullscreen = options->fullscreen,
+            .buffering_time = options->display_buffer,
+        };
+
+        if (!screen_init(&s->screen, &screen_params)) {
+            goto end;
+        }
+        screen_initialized = true;
+
+        decoder_add_sink(&s->decoder, &s->screen.frame_sink);
+    }
+
+#ifdef HAVE_V4L2
+    if (options->v4l2_device) {
+        if (!sc_v4l2_sink_init(&s->v4l2_sink, options->v4l2_device,
+                               info->frame_size, options->v4l2_buffer)) {
+            goto end;
+        }
+
+        decoder_add_sink(&s->decoder, &s->v4l2_sink.frame_sink);
+
+        v4l2_sink_initialized = true;
+    }
+#endif
+
+    // now we consumed the header values, the socket receives the video stream
+    // start the stream
+    if (!stream_start(&s->stream)) {
+        goto end;
+    }
+    stream_started = true;
 
     ret = event_loop(s, options);
     LOGD("quit...");

app/src/screen.c

@@ -156,6 +156,17 @@ get_initial_optimal_size(struct sc_size content_size, uint16_t req_width,
     return window_size;
 }
 
+static inline void
+screen_capture_mouse(struct screen *screen, bool capture) {
+    if (SDL_SetRelativeMouseMode(capture)) {
+        LOGE("Could not set relative mouse mode to %s: %s",
+             capture ? "true" : "false", SDL_GetError());
+        return;
+    }
+
+    screen->mouse_captured = capture;
+}
+
 static void
 screen_update_content_rect(struct screen *screen) {
     int dw;
@@ -354,6 +365,7 @@ screen_init(struct screen *screen, const struct screen_params *params) {
     screen->fullscreen = false;
     screen->maximized = false;
     screen->event_failed = false;
+    screen->mouse_captured = false;
 
     static const struct sc_video_buffer_callbacks cbs = {
         .on_new_frame = sc_video_buffer_on_new_frame,
@@ -470,6 +482,20 @@ screen_init(struct screen *screen, const struct screen_params *params) {
         goto error_destroy_texture;
     }
 
+    struct input_manager_params im_params = {
+        .controller = params->controller,
+        .screen = screen,
+        .kp = params->kp,
+        .mp = params->mp,
+        .control = params->control,
+        .forward_all_clicks = params->forward_all_clicks,
+        .legacy_paste = params->legacy_paste,
+        .clipboard_autosync = params->clipboard_autosync,
+        .shortcut_mods = params->shortcut_mods,
+    };
+
+    input_manager_init(&screen->im, &im_params);
+
     // Reset the window size to trigger a SIZE_CHANGED event, to workaround
     // HiDPI issues with some SDL renderers when several displays having
     // different HiDPI scaling are connected
@@ -769,11 +795,33 @@ screen_handle_event(struct screen *screen, SDL_Event *event) {
                     apply_pending_resize(screen);
                     screen_render(screen, true);
                     break;
+                case SDL_WINDOWEVENT_FOCUS_LOST:
+                    if (screen->im.mp->relative_mode) {
+                        screen_capture_mouse(screen, false);
+                    }
+                    break;
+            }
+            return true;
+        case SDL_MOUSEWHEEL:
+        case SDL_MOUSEMOTION:
+        case SDL_MOUSEBUTTONDOWN:
+        case SDL_FINGERMOTION:
+        case SDL_FINGERDOWN:
+        case SDL_FINGERUP:
+            if (screen->im.mp->relative_mode && !screen->mouse_captured) {
+                // Do not forward to input manager, the mouse will be captured
+                // on SDL_MOUSEBUTTONUP
+                return true;
+            }
+            break;
+        case SDL_MOUSEBUTTONUP:
+            if (screen->im.mp->relative_mode && !screen->mouse_captured) {
+                screen_capture_mouse(screen, true);
             }
             return true;
     }
 
-    return false;
+    return input_manager_handle_event(&screen->im, event);
 }
 
 struct sc_point

app/src/screen.h

@@ -7,10 +7,14 @@
 #include <SDL2/SDL.h>
 #include <libavformat/avformat.h>
 
+#include "controller.h"
 #include "coords.h"
 #include "fps_counter.h"
+#include "input_manager.h"
 #include "opengl.h"
+#include "trait/key_processor.h"
 #include "trait/frame_sink.h"
+#include "trait/mouse_processor.h"
 #include "video_buffer.h"
 
 struct screen {
@@ -20,6 +24,7 @@ struct screen {
     bool open; // track the open/close state to assert correct behavior
 #endif
 
+    struct input_manager im;
     struct sc_video_buffer vb;
     struct fps_counter fps_counter;
 
@@ -46,10 +51,22 @@ struct screen {
 
     bool event_failed; // in case SDL_PushEvent() returned an error
 
+    bool mouse_captured; // only relevant in relative mouse mode
+
     AVFrame *frame;
 };
 
 struct screen_params {
+    struct controller *controller;
+    struct sc_key_processor *kp;
+    struct sc_mouse_processor *mp;
+
+    bool control;
+    bool forward_all_clicks;
+    bool legacy_paste;
+    bool clipboard_autosync;
+    const struct sc_shortcut_mods *shortcut_mods;
+
     const char *window_title;
     struct sc_size frame_size;
     bool always_on_top;

app/src/trait/mouse_processor.h

@@ -16,6 +16,13 @@
  */
 struct sc_mouse_processor {
     const struct sc_mouse_processor_ops *ops;
+
+    /**
+     * If set, the mouse processor works in relative mode (the absolute
+     * position is irrelevant). In particular, it indicates that the mouse
+     * pointer must be "captured" by the UI.
+     */
+    bool relative_mode;
 };
 
 struct sc_mouse_processor_ops {