Add intermediate input events layer

This aims to make the key/mouse processors independent of the "screen",
by processing scrcpy-specific input events instead of SDL events.

In particular, these scrcpy events are not impacted by any UI window
scaling or rotation (contrary to SDL events).

app/src/input_events.h

@@ -0,0 +1,378 @@
+#ifndef SC_INPUT_EVENTS_H
+#define SC_INPUT_EVENTS_H
+
+#include "common.h"
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <SDL2/SDL_events.h>
+
+#include "coords.h"
+
+/* The representation of input events in scrcpy is very close to the SDL API,
+ * for simplicity.
+ *
+ * This scrcpy input events API is designed to be consumed by input event
+ * processors (sc_key_processor and sc_mouse_processor, see app/src/trait/).
+ *
+ * One major semantic difference between SDL input events and scrcpy input
+ * events is their frame of reference (for mouse and touch events): SDL events
+ * coordinates are expressed in SDL window coordinates (the visible UI), while
+ * scrcpy events are expressed in device frame coordinates.
+ *
+ * In particular, the window may be visually scaled or rotated (with --rotation
+ * or MOD+Left/Right), but this does not impact scrcpy input events (contrary
+ * to SDL input events). This allows to abstract these display details from the
+ * input event processors (and to make them independent from the "screen").
+ *
+ * For many enums below, the values are purposely the same as the SDL
+ * constants (though not all SDL values are represented), so that the
+ * implementation to convert from the SDL version to the scrcpy version is
+ * straightforward.
+ *
+ * In practice, there are 3 levels of input events:
+ *  1. SDL input events (as received from SDL)
+ *  2. scrcpy input events (this API)
+ *  3. the key/mouse processors input events (Android API or HID events)
+ *
+ * An input event is first received (1), then (if accepted) converted to an
+ * scrcpy input event (2), then submitted to the relevant key/mouse processor,
+ * which (if accepted) is converted to an Android event (to be sent to the
+ * server) or to an HID event (to be sent over USB/AOA directly).
+ */
+
+enum sc_mod {
+    SC_MOD_LSHIFT = KMOD_LSHIFT,
+    SC_MOD_RSHIFT = KMOD_RSHIFT,
+    SC_MOD_LCTRL = KMOD_LCTRL,
+    SC_MOD_RCTRL = KMOD_RCTRL,
+    SC_MOD_LALT = KMOD_LALT,
+    SC_MOD_RALT = KMOD_RALT,
+    SC_MOD_LGUI = KMOD_LGUI,
+    SC_MOD_RGUI = KMOD_RGUI,
+
+    SC_MOD_NUM = KMOD_NUM,
+    SC_MOD_CAPS = KMOD_CAPS,
+    SC_MOD_SCROLL = KMOD_SCROLL,
+};
+
+enum sc_action {
+    SC_ACTION_DOWN, // key or button pressed
+    SC_ACTION_UP, // key or button released
+};
+
+enum sc_keycode {
+    SC_KEYCODE_UNKNOWN = SDLK_UNKNOWN,
+
+    SC_KEYCODE_RETURN = SDLK_RETURN,
+    SC_KEYCODE_ESCAPE = SDLK_ESCAPE,
+    SC_KEYCODE_BACKSPACE = SDLK_BACKSPACE,
+    SC_KEYCODE_TAB = SDLK_TAB,
+    SC_KEYCODE_SPACE = SDLK_SPACE,
+    SC_KEYCODE_EXCLAIM = SDLK_EXCLAIM,
+    SC_KEYCODE_QUOTEDBL = SDLK_QUOTEDBL,
+    SC_KEYCODE_HASH = SDLK_HASH,
+    SC_KEYCODE_PERCENT = SDLK_PERCENT,
+    SC_KEYCODE_DOLLAR = SDLK_DOLLAR,
+    SC_KEYCODE_AMPERSAND = SDLK_AMPERSAND,
+    SC_KEYCODE_QUOTE = SDLK_QUOTE,
+    SC_KEYCODE_LEFTPAREN = SDLK_LEFTPAREN,
+    SC_KEYCODE_RIGHTPAREN = SDLK_RIGHTPAREN,
+    SC_KEYCODE_ASTERISK = SDLK_ASTERISK,
+    SC_KEYCODE_PLUS = SDLK_PLUS,
+    SC_KEYCODE_COMMA = SDLK_COMMA,
+    SC_KEYCODE_MINUS = SDLK_MINUS,
+    SC_KEYCODE_PERIOD = SDLK_PERIOD,
+    SC_KEYCODE_SLASH = SDLK_SLASH,
+    SC_KEYCODE_0 = SDLK_0,
+    SC_KEYCODE_1 = SDLK_1,
+    SC_KEYCODE_2 = SDLK_2,
+    SC_KEYCODE_3 = SDLK_3,
+    SC_KEYCODE_4 = SDLK_4,
+    SC_KEYCODE_5 = SDLK_5,
+    SC_KEYCODE_6 = SDLK_6,
+    SC_KEYCODE_7 = SDLK_7,
+    SC_KEYCODE_8 = SDLK_8,
+    SC_KEYCODE_9 = SDLK_9,
+    SC_KEYCODE_COLON = SDLK_COLON,
+    SC_KEYCODE_SEMICOLON = SDLK_SEMICOLON,
+    SC_KEYCODE_LESS = SDLK_LESS,
+    SC_KEYCODE_EQUALS = SDLK_EQUALS,
+    SC_KEYCODE_GREATER = SDLK_GREATER,
+    SC_KEYCODE_QUESTION = SDLK_QUESTION,
+    SC_KEYCODE_AT = SDLK_AT,
+
+    SC_KEYCODE_LEFTBRACKET = SDLK_LEFTBRACKET,
+    SC_KEYCODE_BACKSLASH = SDLK_BACKSLASH,
+    SC_KEYCODE_RIGHTBRACKET = SDLK_RIGHTBRACKET,
+    SC_KEYCODE_CARET = SDLK_CARET,
+    SC_KEYCODE_UNDERSCORE = SDLK_UNDERSCORE,
+    SC_KEYCODE_BACKQUOTE = SDLK_BACKQUOTE,
+    SC_KEYCODE_a = SDLK_a,
+    SC_KEYCODE_b = SDLK_b,
+    SC_KEYCODE_c = SDLK_c,
+    SC_KEYCODE_d = SDLK_d,
+    SC_KEYCODE_e = SDLK_e,
+    SC_KEYCODE_f = SDLK_f,
+    SC_KEYCODE_g = SDLK_g,
+    SC_KEYCODE_h = SDLK_h,
+    SC_KEYCODE_i = SDLK_i,
+    SC_KEYCODE_j = SDLK_j,
+    SC_KEYCODE_k = SDLK_k,
+    SC_KEYCODE_l = SDLK_l,
+    SC_KEYCODE_m = SDLK_m,
+    SC_KEYCODE_n = SDLK_n,
+    SC_KEYCODE_o = SDLK_o,
+    SC_KEYCODE_p = SDLK_p,
+    SC_KEYCODE_q = SDLK_q,
+    SC_KEYCODE_r = SDLK_r,
+    SC_KEYCODE_s = SDLK_s,
+    SC_KEYCODE_t = SDLK_t,
+    SC_KEYCODE_u = SDLK_u,
+    SC_KEYCODE_v = SDLK_v,
+    SC_KEYCODE_w = SDLK_w,
+    SC_KEYCODE_x = SDLK_x,
+    SC_KEYCODE_y = SDLK_y,
+    SC_KEYCODE_z = SDLK_z,
+
+    SC_KEYCODE_CAPSLOCK = SDLK_CAPSLOCK,
+
+    SC_KEYCODE_F1 = SDLK_F1,
+    SC_KEYCODE_F2 = SDLK_F2,
+    SC_KEYCODE_F3 = SDLK_F3,
+    SC_KEYCODE_F4 = SDLK_F4,
+    SC_KEYCODE_F5 = SDLK_F5,
+    SC_KEYCODE_F6 = SDLK_F6,
+    SC_KEYCODE_F7 = SDLK_F7,
+    SC_KEYCODE_F8 = SDLK_F8,
+    SC_KEYCODE_F9 = SDLK_F9,
+    SC_KEYCODE_F10 = SDLK_F10,
+    SC_KEYCODE_F11 = SDLK_F11,
+    SC_KEYCODE_F12 = SDLK_F12,
+
+    SC_KEYCODE_PRINTSCREEN = SDLK_PRINTSCREEN,
+    SC_KEYCODE_SCROLLLOCK = SDLK_SCROLLLOCK,
+    SC_KEYCODE_PAUSE = SDLK_PAUSE,
+    SC_KEYCODE_INSERT = SDLK_INSERT,
+    SC_KEYCODE_HOME = SDLK_HOME,
+    SC_KEYCODE_PAGEUP = SDLK_PAGEUP,
+    SC_KEYCODE_DELETE = SDLK_DELETE,
+    SC_KEYCODE_END = SDLK_END,
+    SC_KEYCODE_PAGEDOWN = SDLK_PAGEDOWN,
+    SC_KEYCODE_RIGHT = SDLK_RIGHT,
+    SC_KEYCODE_LEFT = SDLK_LEFT,
+    SC_KEYCODE_DOWN = SDLK_DOWN,
+    SC_KEYCODE_UP = SDLK_UP,
+
+    SC_KEYCODE_KP_DIVIDE = SDLK_KP_DIVIDE,
+    SC_KEYCODE_KP_MULTIPLY = SDLK_KP_MULTIPLY,
+    SC_KEYCODE_KP_MINUS = SDLK_KP_MINUS,
+    SC_KEYCODE_KP_PLUS = SDLK_KP_PLUS,
+    SC_KEYCODE_KP_ENTER = SDLK_KP_ENTER,
+    SC_KEYCODE_KP_1 = SDLK_KP_1,
+    SC_KEYCODE_KP_2 = SDLK_KP_2,
+    SC_KEYCODE_KP_3 = SDLK_KP_3,
+    SC_KEYCODE_KP_4 = SDLK_KP_4,
+    SC_KEYCODE_KP_5 = SDLK_KP_5,
+    SC_KEYCODE_KP_6 = SDLK_KP_6,
+    SC_KEYCODE_KP_7 = SDLK_KP_7,
+    SC_KEYCODE_KP_8 = SDLK_KP_8,
+    SC_KEYCODE_KP_9 = SDLK_KP_9,
+    SC_KEYCODE_KP_0 = SDLK_KP_0,
+    SC_KEYCODE_KP_PERIOD = SDLK_KP_PERIOD,
+    SC_KEYCODE_KP_EQUALS = SDLK_KP_EQUALS,
+    SC_KEYCODE_KP_LEFTPAREN = SDLK_KP_LEFTPAREN,
+    SC_KEYCODE_KP_RIGHTPAREN = SDLK_KP_RIGHTPAREN,
+
+    SC_KEYCODE_LCTRL = SDLK_LCTRL,
+    SC_KEYCODE_LSHIFT = SDLK_LSHIFT,
+    SC_KEYCODE_LALT = SDLK_LALT,
+    SC_KEYCODE_LGUI = SDLK_LGUI,
+    SC_KEYCODE_RCTRL = SDLK_RCTRL,
+    SC_KEYCODE_RSHIFT = SDLK_RSHIFT,
+    SC_KEYCODE_RALT = SDLK_RALT,
+    SC_KEYCODE_RGUI = SDLK_RGUI,
+};
+
+enum sc_scancode {
+    SC_SCANCODE_UNKNOWN = SDL_SCANCODE_UNKNOWN,
+
+    SC_SCANCODE_A = SDL_SCANCODE_A,
+    SC_SCANCODE_B = SDL_SCANCODE_B,
+    SC_SCANCODE_C = SDL_SCANCODE_C,
+    SC_SCANCODE_D = SDL_SCANCODE_D,
+    SC_SCANCODE_E = SDL_SCANCODE_E,
+    SC_SCANCODE_F = SDL_SCANCODE_F,
+    SC_SCANCODE_G = SDL_SCANCODE_G,
+    SC_SCANCODE_H = SDL_SCANCODE_H,
+    SC_SCANCODE_I = SDL_SCANCODE_I,
+    SC_SCANCODE_J = SDL_SCANCODE_J,
+    SC_SCANCODE_K = SDL_SCANCODE_K,
+    SC_SCANCODE_L = SDL_SCANCODE_L,
+    SC_SCANCODE_M = SDL_SCANCODE_M,
+    SC_SCANCODE_N = SDL_SCANCODE_N,
+    SC_SCANCODE_O = SDL_SCANCODE_O,
+    SC_SCANCODE_P = SDL_SCANCODE_P,
+    SC_SCANCODE_Q = SDL_SCANCODE_Q,
+    SC_SCANCODE_R = SDL_SCANCODE_R,
+    SC_SCANCODE_S = SDL_SCANCODE_S,
+    SC_SCANCODE_T = SDL_SCANCODE_T,
+    SC_SCANCODE_U = SDL_SCANCODE_U,
+    SC_SCANCODE_V = SDL_SCANCODE_V,
+    SC_SCANCODE_W = SDL_SCANCODE_W,
+    SC_SCANCODE_X = SDL_SCANCODE_X,
+    SC_SCANCODE_Y = SDL_SCANCODE_Y,
+    SC_SCANCODE_Z = SDL_SCANCODE_Z,
+
+    SC_SCANCODE_1 = SDL_SCANCODE_1,
+    SC_SCANCODE_2 = SDL_SCANCODE_2,
+    SC_SCANCODE_3 = SDL_SCANCODE_3,
+    SC_SCANCODE_4 = SDL_SCANCODE_4,
+    SC_SCANCODE_5 = SDL_SCANCODE_5,
+    SC_SCANCODE_6 = SDL_SCANCODE_6,
+    SC_SCANCODE_7 = SDL_SCANCODE_7,
+    SC_SCANCODE_8 = SDL_SCANCODE_8,
+    SC_SCANCODE_9 = SDL_SCANCODE_9,
+    SC_SCANCODE_0 = SDL_SCANCODE_0,
+
+    SC_SCANCODE_RETURN = SDL_SCANCODE_RETURN,
+    SC_SCANCODE_ESCAPE = SDL_SCANCODE_ESCAPE,
+    SC_SCANCODE_BACKSPACE = SDL_SCANCODE_BACKSPACE,
+    SC_SCANCODE_TAB = SDL_SCANCODE_TAB,
+    SC_SCANCODE_SPACE = SDL_SCANCODE_SPACE,
+
+    SC_SCANCODE_MINUS = SDL_SCANCODE_MINUS,
+    SC_SCANCODE_EQUALS = SDL_SCANCODE_EQUALS,
+    SC_SCANCODE_LEFTBRACKET = SDL_SCANCODE_LEFTBRACKET,
+    SC_SCANCODE_RIGHTBRACKET = SDL_SCANCODE_RIGHTBRACKET,
+    SC_SCANCODE_BACKSLASH = SDL_SCANCODE_BACKSLASH,
+    SC_SCANCODE_NONUSHASH = SDL_SCANCODE_NONUSHASH,
+    SC_SCANCODE_SEMICOLON = SDL_SCANCODE_SEMICOLON,
+    SC_SCANCODE_APOSTROPHE = SDL_SCANCODE_APOSTROPHE,
+    SC_SCANCODE_GRAVE = SDL_SCANCODE_GRAVE,
+    SC_SCANCODE_COMMA = SDL_SCANCODE_COMMA,
+    SC_SCANCODE_PERIOD = SDL_SCANCODE_PERIOD,
+    SC_SCANCODE_SLASH = SDL_SCANCODE_SLASH,
+
+    SC_SCANCODE_CAPSLOCK = SDL_SCANCODE_CAPSLOCK,
+
+    SC_SCANCODE_F1 = SDL_SCANCODE_F1,
+    SC_SCANCODE_F2 = SDL_SCANCODE_F2,
+    SC_SCANCODE_F3 = SDL_SCANCODE_F3,
+    SC_SCANCODE_F4 = SDL_SCANCODE_F4,
+    SC_SCANCODE_F5 = SDL_SCANCODE_F5,
+    SC_SCANCODE_F6 = SDL_SCANCODE_F6,
+    SC_SCANCODE_F7 = SDL_SCANCODE_F7,
+    SC_SCANCODE_F8 = SDL_SCANCODE_F8,
+    SC_SCANCODE_F9 = SDL_SCANCODE_F9,
+    SC_SCANCODE_F10 = SDL_SCANCODE_F10,
+    SC_SCANCODE_F11 = SDL_SCANCODE_F11,
+    SC_SCANCODE_F12 = SDL_SCANCODE_F12,
+
+    SC_SCANCODE_PRINTSCREEN = SDL_SCANCODE_PRINTSCREEN,
+    SC_SCANCODE_SCROLLLOCK = SDL_SCANCODE_SCROLLLOCK,
+    SC_SCANCODE_PAUSE = SDL_SCANCODE_PAUSE,
+    SC_SCANCODE_INSERT = SDL_SCANCODE_INSERT,
+    SC_SCANCODE_HOME = SDL_SCANCODE_HOME,
+    SC_SCANCODE_PAGEUP = SDL_SCANCODE_PAGEUP,
+    SC_SCANCODE_DELETE = SDL_SCANCODE_DELETE,
+    SC_SCANCODE_END = SDL_SCANCODE_END,
+    SC_SCANCODE_PAGEDOWN = SDL_SCANCODE_PAGEDOWN,
+    SC_SCANCODE_RIGHT = SDL_SCANCODE_RIGHT,
+    SC_SCANCODE_LEFT = SDL_SCANCODE_LEFT,
+    SC_SCANCODE_DOWN = SDL_SCANCODE_DOWN,
+    SC_SCANCODE_UP = SDL_SCANCODE_UP,
+
+    SC_SCANCODE_NUMLOCK = SDL_SCANCODE_NUMLOCKCLEAR,
+    SC_SCANCODE_KP_DIVIDE = SDL_SCANCODE_KP_DIVIDE,
+    SC_SCANCODE_KP_MULTIPLY = SDL_SCANCODE_KP_MULTIPLY,
+    SC_SCANCODE_KP_MINUS = SDL_SCANCODE_KP_MINUS,
+    SC_SCANCODE_KP_PLUS = SDL_SCANCODE_KP_PLUS,
+    SC_SCANCODE_KP_ENTER = SDL_SCANCODE_KP_ENTER,
+    SC_SCANCODE_KP_1 = SDL_SCANCODE_KP_1,
+    SC_SCANCODE_KP_2 = SDL_SCANCODE_KP_2,
+    SC_SCANCODE_KP_3 = SDL_SCANCODE_KP_3,
+    SC_SCANCODE_KP_4 = SDL_SCANCODE_KP_4,
+    SC_SCANCODE_KP_5 = SDL_SCANCODE_KP_5,
+    SC_SCANCODE_KP_6 = SDL_SCANCODE_KP_6,
+    SC_SCANCODE_KP_7 = SDL_SCANCODE_KP_7,
+    SC_SCANCODE_KP_8 = SDL_SCANCODE_KP_8,
+    SC_SCANCODE_KP_9 = SDL_SCANCODE_KP_9,
+    SC_SCANCODE_KP_0 = SDL_SCANCODE_KP_0,
+    SC_SCANCODE_KP_PERIOD = SDL_SCANCODE_KP_PERIOD,
+
+    SC_SCANCODE_LCTRL = SDL_SCANCODE_LCTRL,
+    SC_SCANCODE_LSHIFT = SDL_SCANCODE_LSHIFT,
+    SC_SCANCODE_LALT = SDL_SCANCODE_LALT,
+    SC_SCANCODE_LGUI = SDL_SCANCODE_LGUI,
+    SC_SCANCODE_RCTRL = SDL_SCANCODE_RCTRL,
+    SC_SCANCODE_RSHIFT = SDL_SCANCODE_RSHIFT,
+    SC_SCANCODE_RALT = SDL_SCANCODE_RALT,
+    SC_SCANCODE_RGUI = SDL_SCANCODE_RGUI,
+};
+
+// On purpose, only use the "mask" values (1, 2, 4, 8, 16) for a single button,
+// to avoid unnecessary conversions (and confusion).
+enum sc_mouse_button {
+    SC_MOUSE_BUTTON_UNKNOWN = 0,
+    SC_MOUSE_BUTTON_LEFT = SDL_BUTTON(SDL_BUTTON_LEFT),
+    SC_MOUSE_BUTTON_RIGHT = SDL_BUTTON(SDL_BUTTON_RIGHT),
+    SC_MOUSE_BUTTON_MIDDLE = SDL_BUTTON(SDL_BUTTON_MIDDLE),
+    SC_MOUSE_BUTTON_X1 = SDL_BUTTON(SDL_BUTTON_X1),
+    SC_MOUSE_BUTTON_X2 = SDL_BUTTON(SDL_BUTTON_X2),
+};
+
+static_assert(sizeof(enum sc_mod) >= sizeof(SDL_Keymod),
+              "SDL_Keymod must be convertible to sc_mod");
+
+static_assert(sizeof(enum sc_keycode) >= sizeof(SDL_Keycode),
+              "SDL_Keycode must be convertible to sc_keycode");
+
+static_assert(sizeof(enum sc_scancode) >= sizeof(SDL_Scancode),
+              "SDL_Scancode must be convertible to sc_scancode");
+
+enum sc_touch_action {
+    SC_TOUCH_ACTION_MOVE,
+    SC_TOUCH_ACTION_DOWN,
+    SC_TOUCH_ACTION_UP,
+};
+
+struct sc_key_event {
+    enum sc_action action;
+    enum sc_keycode keycode;
+    enum sc_scancode scancode;
+    uint16_t mods_state; // bitwise-OR of sc_mod values
+    bool repeat;
+};
+
+struct sc_text_event {
+    const char *text; // not owned
+};
+
+struct sc_mouse_click_event {
+    struct sc_position position;
+    enum sc_action action;
+    enum sc_mouse_button button;
+    uint8_t buttons_state; // bitwise-OR of sc_mouse_button values
+};
+
+struct sc_mouse_scroll_event {
+    struct sc_position position;
+    int32_t hscroll;
+    int32_t vscroll;
+};
+
+struct sc_mouse_motion_event {
+    struct sc_position position;
+    uint8_t buttons_state; // bitwise-OR of sc_mouse_button values
+};
+
+struct sc_touch_event {
+    struct sc_position position;
+    enum sc_touch_action action;
+    uint64_t pointer_id;
+    float pressure;
+};
+
+#endif