Mercurial > sdl-ios-xcode
diff docs/man3/SDL_Event.3 @ 0:74212992fb08
Initial revision
author | Sam Lantinga <slouken@lokigames.com> |
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date | Thu, 26 Apr 2001 16:45:43 +0000 |
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children | 55f1f1b3e27d |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/docs/man3/SDL_Event.3 Thu Apr 26 16:45:43 2001 +0000 @@ -0,0 +1,175 @@ +.TH "SDL_Event" "3" "Mon 12 Mar 2001, 01:03" "SDL" "SDL API Reference" +.SH "NAME" +SDL_Event\- General event structure +.SH "STRUCTURE DEFINITION" +.PP +.nf +\f(CWtypedef union{ + Uint8 type; + SDL_ActiveEvent active; + SDL_KeyboardEvent key; + SDL_MouseMotionEvent motion; + SDL_MouseButtonEvent button; + SDL_JoyAxisEvent jaxis; + SDL_JoyBallEvent jball; + SDL_JoyHatEvent jhat; + SDL_JoyButtonEvent jbutton; + SDL_ResizeEvent resize; + SDL_QuitEvent quit; + SDL_UserEvent user; + SDL_SywWMEvent syswm; +} SDL_Event;\fR +.fi +.PP +.SH "STRUCTURE DATA" +.TP 20 +\fBtype\fR +The type of event +.TP 20 +\fBactive\fR +\fIActivation event\fR +.TP 20 +\fBkey\fR +\fIKeyboard event\fR +.TP 20 +\fBmotion\fR +\fIMouse motion event\fR +.TP 20 +\fBbutton\fR +\fIMouse button event\fR +.TP 20 +\fBjaxis\fR +\fIJoystick axis motion event\fR +.TP 20 +\fBjball\fR +\fIJoystick trackball motion event\fR +.TP 20 +\fBjhat\fR +\fIJoystick hat motion event\fR +.TP 20 +\fBjbutton\fR +\fIJoystick button event\fR +.TP 20 +\fBresize\fR +\fIApplication window resize event\fR +.TP 20 +\fBquit\fR +\fIApplication quit request event\fR +.TP 20 +\fBuser\fR +\fIUser defined event\fR +.TP 20 +\fBsyswm\fR +\fIUndefined window manager event\fR +.SH "DESCRIPTION" +.PP +The \fBSDL_Event\fR union is the core to all event handling is SDL, its probably the most important structure after \fBSDL_Surface\fR\&. \fBSDL_Event\fR is a union of all event structures used in SDL, using it is a simple matter of knowing which union member relates to which event \fBtype\fR\&. +.PP +.TP 20 +\fBEvent \fBtype\fR\fR +\fBEvent Structure\fR +.TP 20 +\fBSDL_ACTIVEEVENT\fP +\fI\fBSDL_ActiveEvent\fR\fR +.TP 20 +\fBSDL_KEYDOWN/UP\fP +\fI\fBSDL_KeyboardEvent\fR\fR +.TP 20 +\fBSDL_MOUSEMOTION\fP +\fI\fBSDL_MouseMotionEvent\fR\fR +.TP 20 +\fBSDL_MOUSEBUTTONDOWN/UP\fP +\fI\fBSDL_MouseButtonEvent\fR\fR +.TP 20 +\fBSDL_JOYAXISMOTION\fP +\fI\fBSDL_JoyAxisEvent\fR\fR +.TP 20 +\fBSDL_JOYBALLMOTION\fP +\fI\fBSDL_JoyBallEvent\fR\fR +.TP 20 +\fBSDL_JOYHATMOTION\fP +\fI\fBSDL_JoyHatEvent\fR\fR +.TP 20 +\fBSDL_JOYBUTTONDOWN/UP\fP +\fI\fBSDL_JoyButtonEvent\fR\fR +.TP 20 +\fBSDL_QUIT\fP +\fI\fBSDL_QuitEvent\fR\fR +.TP 20 +\fBSDL_SYSWMEVENT\fP +\fI\fBSDL_SysWMEvent\fR\fR +.TP 20 +\fBSDL_VIDEORESIZE\fP +\fI\fBSDL_ResizeEvent\fR\fR +.TP 20 +\fBSDL_USEREVENT\fP +\fI\fBSDL_UserEvent\fR\fR +.SH "USE" +.PP +The \fBSDL_Event\fR structure has two uses +.IP " \(bu" 6 +Reading events on the event queue +.IP " \(bu" 6 +Placing events on the event queue +.PP +Reading events from the event queue is done with either \fI\fBSDL_PollEvent\fP\fR or \fI\fBSDL_PeepEvents\fP\fR\&. We\&'ll use \fBSDL_PollEvent\fP and step through an example\&. +.PP +First off, we create an empty \fBSDL_Event\fR structure\&. +.PP +.nf +\f(CWSDL_Event test_event;\fR +.fi +.PP + \fBSDL_PollEvent\fP removes the next event from the event queue, if there are no events on the queue it returns \fB0\fR otherwise it returns \fB1\fR\&. We use a \fBwhile\fP loop to process each event in turn\&. +.PP +.nf +\f(CWwhile(SDL_PollEvent(&test_event)) {\fR +.fi +.PP + The \fBSDL_PollEvent\fP function take a pointer to an \fBSDL_Event\fR structure that is to be filled with event information\&. We know that if \fBSDL_PollEvent\fP removes an event from the queue then the event information will be placed in our \fBtest_event\fR structure, but we also know that the \fItype\fP of event will be placed in the \fBtype\fR member of \fBtest_event\fR\&. So to handle each event \fBtype\fR seperately we use a \fBswitch\fP statement\&. +.PP +.nf +\f(CW switch(test_event\&.type) {\fR +.fi +.PP + We need to know what kind of events we\&'re looking for \fIand\fP the event \fBtype\fR\&'s of those events\&. So lets assume we want to detect where the user is moving the mouse pointer within our application\&. We look through our event types and notice that \fBSDL_MOUSEMOTION\fP is, more than likely, the event we\&'re looking for\&. A little \fImore\fR research tells use that \fBSDL_MOUSEMOTION\fP events are handled within the \fI\fBSDL_MouseMotionEvent\fR\fR structure which is the \fBmotion\fR member of \fBSDL_Event\fR\&. We can check for the \fBSDL_MOUSEMOTION\fP event \fBtype\fR within our \fBswitch\fP statement like so: +.PP +.nf +\f(CW case SDL_MOUSEMOTION:\fR +.fi +.PP + All we need do now is read the information out of the \fBmotion\fR member of \fBtest_event\fR\&. +.PP +.nf +\f(CW printf("We got a motion event\&. +"); + printf("Current mouse position is: (%d, %d) +", test_event\&.motion\&.x, test_event\&.motion\&.y); + break; + default: + printf("Unhandled Event! +"); + break; + } +} +printf("Event queue empty\&. +");\fR +.fi +.PP +.PP +It is also possible to push events onto the event queue and so use it as a two-way communication path\&. Both \fI\fBSDL_PushEvent\fP\fR and \fI\fBSDL_PeepEvents\fP\fR allow you to place events onto the event queue\&. This is usually used to place a \fBSDL_USEREVENT\fP on the event queue, however you could use it to post fake input events if you wished\&. Creating your own events is a simple matter of choosing the event type you want, setting the \fBtype\fR member and filling the appropriate member structure with information\&. +.PP +.nf +\f(CWSDL_Event user_event; + +user_event\&.type=SDL_USEREVENT; +user_event\&.user\&.code=2; +user_event\&.user\&.data1=NULL; +user_event\&.user\&.data2=NULL; +SDL_PushEvent(&user_event);\fR +.fi +.PP +.SH "SEE ALSO" +.PP +\fI\fBSDL_PollEvent\fP\fR, \fI\fBSDL_PushEvent\fP\fR, \fI\fBSDL_PeepEvents\fP\fR +...\" created by instant / docbook-to-man, Mon 12 Mar 2001, 01:03