XCrossingEvent(3)

📦
version 1.8.14 · 8 versions
, in alpine 3.24, arch rolling, nixos 26.05, nixpkgs unstable

🎀 XCrossingEvent(3) — the EnterNotify + LeaveNotify structure, from the XLIB FUNCTIONS manual 🎀

okay so bestie, we're in the XLIB FUNCTIONS manual and this page is all about the EnterNotify and LeaveNotify event structure. it's giving event-structure lore, and honestly? obsessed 💖

✨ NAME ✨

XCrossingEvent — the structure for EnterNotify and LeaveNotify events. that's the name, no cap 🫶

🌸 STRUCTURES 🌸

the structure for EnterNotify and LeaveNotify events contains this, and yes, the code is sacred so it's staying exactly as-is:

typedef struct {
        int type;       /* EnterNotify or LeaveNotify */
        unsigned long serial;   /* # of last request processed by server */
        Bool send_event;        /* true if this came from a SendEvent request */
        Display *display;       /* Display the event was read from */
        Window window;  /* “event” window reported relative to */
        Window root;    /* root window that the event occurred on */
        Window subwindow;       /* child window */
        Time time;      /* milliseconds */
        int x, y;       /* pointer x, y coordinates in event window */
        int x_root, y_root;     /* coordinates relative to root */
        int mode;       /* NotifyNormal, NotifyGrab, NotifyUngrab */
        int detail;
                /*
                * NotifyAncestor, NotifyVirtual, NotifyInferior,
                * NotifyNonlinear,NotifyNonlinearVirtual
                */
        Bool same_screen;       /* same screen flag */
        Bool focus;     /* boolean focus */
        unsigned int state;     /* key or button mask */
} XCrossingEvent;
typedef XCrossingEvent XEnterWindowEvent;
typedef XCrossingEvent XLeaveWindowEvent;

when you receive these events, the structure members are set as follows. buckle up, bestie 💅

the type member is set to the event-type constant name that uniquely identifies it. like, when the X server reports a GraphicsExpose event to a client app, it sends an XGraphicsExposeEvent structure with type set to GraphicsExpose. the display member is set to a pointer to the display the event was read on. send_event is set to True if the event came from a SendEvent protocol request. serial is set from the serial number reported in the protocol, but expanded from the 16-bit least-significant bits to a full 32-bit value. and window is set to the window that's most useful to toolkit dispatchers. dispatcher-friendly, we love to see it 🫶

the window member is set to the window on which the EnterNotify or LeaveNotify event was generated, and that's referred to as the event window. this is the window the X server uses to report the event, and it's relative to the root window on which the event occurred. the root member is set to the root window of the screen on which the event occurred. periodt.

for a LeaveNotify event, if a child of the event window contains the initial position of the pointer, the subwindow component is set to that child. otherwise, the X server sets subwindow to None. for an EnterNotify event, if a child of the event window contains the final pointer position, the subwindow component is set to that child or None. initial vs final, the distinction is doing main character work 💅

the time member is set to the time when the event was generated, expressed in milliseconds. the x and y members are set to the coordinates of the pointer position in the event window — and this position is always the pointer's final position, not its initial position, bestie. if the event window is on the same screen as the root window, x and y are the pointer coordinates relative to the event window's origin. otherwise, x and y are set to zero. the x_root and y_root members are set to the pointer's coordinates relative to the root window's origin at the time of the event. very coordinate, very demure ✨

the same_screen member is set to indicate whether the event window is on the same screen as the root window, and it can be either True or False. if True, the event and root windows are on the same screen. if False, the event and root windows are not on the same screen. screen-relationship clarity, we Stan 🌈

the focus member is set to indicate whether the event window is the focus window or an inferior of the focus window. the X server can set this member to either True or False. if True, the event window is the focus window or an inferior of the focus window. if False, the event window is not the focus window or an inferior of the focus window. focus tea, served hot ☕️

the state member is set to indicate the state of the pointer buttons and modifier keys just prior to the event. the X server can set this member to the bitwise inclusive OR of one or more of the button or modifier key masks: Button1Mask, Button2Mask, Button3Mask, Button4Mask, Button5Mask, ShiftMask, LockMask, ControlMask, Mod1Mask, Mod2Mask, Mod3Mask, Mod4Mask, Mod5Mask. that's a whole mask lineup and they all ate 💅

the mode member is set to indicate whether the events are normal events, pseudo-motion events when a grab activates, or pseudo-motion events when a grab deactivates. the X server can set this member to NotifyNormal, NotifyGrab, or NotifyUngrab. grabby behavior, extremely valid 🎀

the detail member is set to indicate the notify detail, and it can be NotifyAncestor, NotifyVirtual, NotifyInferior, NotifyNonlinear, or NotifyNonlinearVirtual. that's the whole detail menu, bestie 🍓

🦋 SEE ALSO 🦋

like, go read these too, iykyk:

also Xlib - C Language X Interface — the big Xlib book vibe, fr fr 📚

and that's the page, bestie 🫶 footer sign-off: X Version 11 · libX11 1.8.14 · page XCrossingEvent(3) — source/version info is right there, and the date slot is lowkey not giving a separate date, no cap 💀💖

📦 where this page comes from