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<HTML><HEAD><TITLE>Xlib Programming Manual: Window Entry/Exit Events</TITLE></HEAD><BODY><H1 ALIGN=center>10.6 Window Entry/Exit Events</H1><!.IN "Events" "EnterNotify"><!.IN "Events" "LeaveNotify">This section describes the processing that occurs for the window crossing events<B>EnterNotify</B>and<B>LeaveNotify</B>.<!.IN "EnterNotify" "" "@DEF@"><!.IN "LeaveNotify" "" "@DEF@">If a pointer motion or a window hierarchy change causes thepointer to be in a different window than before, the X server reports<B>EnterNotify</B>or<B>LeaveNotify</B>events to clients who have selected for these events.All <B>EnterNotify</B>and <B>LeaveNotify</B>events caused by a hierarchy change aregenerated after any hierarchy event(<B><A HREF="../window-state-change/unmap.html">UnmapNotify</A></B>,<B><A HREF="../window-state-change/map.html">MapNotify</A></B>,<B><A HREF="../window-state-change/configure.html">ConfigureNotify</A></B>,<B><A HREF="../window-state-change/gravity.html">GravityNotify</A></B>,<B><A HREF="../window-state-change/circulate.html">CirculateNotify</A></B>)caused by that change;however, the X protocol does not constrain the ordering of <B>EnterNotify</B>and <B>LeaveNotify</B>events with respect to<B><A HREF="../input-focus/">FocusOut</A></B>, <B><A HREF="../window-state-change/visibility.html">VisibilityNotify</A></B>,and <B><A HREF="../exposure/expose.html">Expose</A></B> events.<P>This contrasts with<B><A HREF="../keyboard-pointer/keyboard-pointer.html">MotionNotify</A></B>events, which are also generated when the pointer movesbut only when the pointer motion begins and ends in a single window.An<B>EnterNotify</B>or<B>LeaveNotify</B>event also can be generated when some client application calls<B><A HREF="../../input/XGrabPointer.html">XGrabPointer()</A></B>and<B><A HREF="/toto/XUngrabPointer.html">XUngrabPointer()</A></B>.<P>To receive<B>EnterNotify</B>or<B>LeaveNotify</B>events, set the<B>EnterWindowMask</B>or<B>LeaveWindowMask</B>bits of the <A HREF="../../window/attributes/event-and-do-not-propagate.html">event-mask</A> attribute of the window.<P>The structure for these event types contains:<P><A NAME="XCrossingEvent"></A><A NAME="XEnterWindowEvent"></A><A NAME="XLeaveWindowEvent"></A><!.IN "XCrossingEvent" "" "@DEF@"><!.IN "XEnterWindowEvent" "" "@DEF@"><!.IN "XLeaveWindowEvent" "" "@DEF@"><CODE><PRE>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 <B><A HREF="../../appendix/a.html#SendEvent">SendEvent</A></B> 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;</PRE></CODE><P>The <B>window</B> member is set to the window on which the<B>EnterNotify</B>or<B>LeaveNotify</B>event was generated and is referred to as the event window. This is the window used by the X server to report the event, and is relative to the rootwindow on which the event occurred. The <B>root</B> member is set to the root window of the screenon which the event occurred.<P>For a<B>LeaveNotify</B>event,if a child of the event window contains the initial position of the pointer,the <B>subwindow</B> component is set to that child.Otherwise, the X server sets the <B>subwindow</B> member to<B>None</B>.For an<B>EnterNotify</B>event, if a child of the event window contains the final pointer position, the <B>subwindow</B> component is set to that child or<B>None</B>.<P>The <B>time</B> member is set to the time when the event was generatedand is expressed in milliseconds.The <B>x</B> and <B>y</B> members are set to the coordinates of the pointer position in the event window.This position is always the pointer's final position,not its initial position.If the event window is on the samescreen as the root window, <B>x</B> and <B>y</B> are the pointer coordinatesrelative to the event window's origin. Otherwise, <B>x</B> and <B>y</B> are set to zero.The <B>x_root</B> and <B>y_root</B> members are set to the pointer's coordinates relative to theroot window's origin at the time of the event.<P>The <B>same_screen</B> member is set to indicate whether the event window is on the same screenas the root window and can be either<B>True</B> or<B>False</B>.If<B>True</B>,the event and root windows are on the same screen.If<B>False</B>,the event and root windows are not on the same screen.<P>The <B>focus</B> member is set to indicate whether the event window is the focus window or aninferior of the focus window.The X server can set this member to either<B>True</B> or<B>False</B>.If<B>True</B>,the event window is the focus window or an inferior of the focus window.If<B>False</B>,the event window is not the focus window or an inferior of the focus window.<P>The <B>state</B> member is set to indicate the state of the pointer buttons andmodifier keys just prior to theevent.The X server can set this member to the bitwise inclusive OR of one or more of the button or modifier key masks:<B>Button1Mask</B>,<B>Button2Mask</B>,<B>Button3Mask</B>,<B>Button4Mask</B>,<B>Button5Mask</B>,<B>ShiftMask</B>,<B>LockMask</B>,<B>ControlMask</B>,<B>Mod1Mask</B>,<B>Mod2Mask</B>,<B>Mod3Mask</B>,<B>Mod4Mask</B>,<B>Mod5Mask</B>.<P>The <B>mode</B> member is set to indicate whether the events are normal events, <A HREF="grab-ungrab.html">pseudo-motion</A> eventswhen a grab activates, or <A HREF="grab-ungrab.html">pseudo-motion</A> events when a grab deactivates.The X server can set this member to <B>NotifyNormal</B>,<B>NotifyGrab</B>,or<B>NotifyUngrab</B>.<P>The <B>detail</B> member is set to indicate the notify detail and can be<B>NotifyAncestor</B>,<B>NotifyVirtual</B>,<B>NotifyInferior</B>,<B>NotifyNonlinear</B>,or<B>NotifyNonlinearVirtual</B>.<H5 ALIGN=right><I>Next: <A HREF="normal.html">Normal Entry/Exit Events</A></I></H5><HR><ADDRESS><A HREF="http://tronche.com/">Christophe Tronche</A>, <A HREF="mailto:ch.tronche@computer.org">ch.tronche@computer.org</A></ADDRESS></BODY></HTML>⌨️ 快捷键说明
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