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annotate docs/man3/SDL_Event.3 @ 4159:a1b03ba2fcd0 SDL-1.2
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author | Sam Lantinga <slouken@libsdl.org> |
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date | Mon, 08 Dec 2008 00:25:42 +0000 |
parents | 4e3b250c950e |
children | 1238da4a7112 |
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1 .TH "SDL_Event" "3" "Tue 11 Sep 2001, 22:59" "SDL" "SDL API Reference" |
0 | 2 .SH "NAME" |
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3 SDL_Event \- General event structure |
0 | 4 .SH "STRUCTURE DEFINITION" |
5 .PP | |
6 .nf | |
7 \f(CWtypedef union{ | |
8 Uint8 type; | |
9 SDL_ActiveEvent active; | |
10 SDL_KeyboardEvent key; | |
11 SDL_MouseMotionEvent motion; | |
12 SDL_MouseButtonEvent button; | |
13 SDL_JoyAxisEvent jaxis; | |
14 SDL_JoyBallEvent jball; | |
15 SDL_JoyHatEvent jhat; | |
16 SDL_JoyButtonEvent jbutton; | |
17 SDL_ResizeEvent resize; | |
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18 SDL_ExposeEvent expose; |
0 | 19 SDL_QuitEvent quit; |
20 SDL_UserEvent user; | |
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21 SDL_SysWMEvent syswm; |
0 | 22 } SDL_Event;\fR |
23 .fi | |
24 .PP | |
25 .SH "STRUCTURE DATA" | |
26 .TP 20 | |
27 \fBtype\fR | |
28 The type of event | |
29 .TP 20 | |
30 \fBactive\fR | |
31 \fIActivation event\fR | |
32 .TP 20 | |
33 \fBkey\fR | |
34 \fIKeyboard event\fR | |
35 .TP 20 | |
36 \fBmotion\fR | |
37 \fIMouse motion event\fR | |
38 .TP 20 | |
39 \fBbutton\fR | |
40 \fIMouse button event\fR | |
41 .TP 20 | |
42 \fBjaxis\fR | |
43 \fIJoystick axis motion event\fR | |
44 .TP 20 | |
45 \fBjball\fR | |
46 \fIJoystick trackball motion event\fR | |
47 .TP 20 | |
48 \fBjhat\fR | |
49 \fIJoystick hat motion event\fR | |
50 .TP 20 | |
51 \fBjbutton\fR | |
52 \fIJoystick button event\fR | |
53 .TP 20 | |
54 \fBresize\fR | |
55 \fIApplication window resize event\fR | |
56 .TP 20 | |
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57 \fBexpose\fR |
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58 \fIApplication window expose event\fR |
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59 .TP 20 |
0 | 60 \fBquit\fR |
61 \fIApplication quit request event\fR | |
62 .TP 20 | |
63 \fBuser\fR | |
64 \fIUser defined event\fR | |
65 .TP 20 | |
66 \fBsyswm\fR | |
67 \fIUndefined window manager event\fR | |
68 .SH "DESCRIPTION" | |
69 .PP | |
70 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\&. | |
71 .PP | |
72 .TP 20 | |
73 \fBEvent \fBtype\fR\fR | |
74 \fBEvent Structure\fR | |
75 .TP 20 | |
76 \fBSDL_ACTIVEEVENT\fP | |
77 \fI\fBSDL_ActiveEvent\fR\fR | |
78 .TP 20 | |
79 \fBSDL_KEYDOWN/UP\fP | |
80 \fI\fBSDL_KeyboardEvent\fR\fR | |
81 .TP 20 | |
82 \fBSDL_MOUSEMOTION\fP | |
83 \fI\fBSDL_MouseMotionEvent\fR\fR | |
84 .TP 20 | |
85 \fBSDL_MOUSEBUTTONDOWN/UP\fP | |
86 \fI\fBSDL_MouseButtonEvent\fR\fR | |
87 .TP 20 | |
88 \fBSDL_JOYAXISMOTION\fP | |
89 \fI\fBSDL_JoyAxisEvent\fR\fR | |
90 .TP 20 | |
91 \fBSDL_JOYBALLMOTION\fP | |
92 \fI\fBSDL_JoyBallEvent\fR\fR | |
93 .TP 20 | |
94 \fBSDL_JOYHATMOTION\fP | |
95 \fI\fBSDL_JoyHatEvent\fR\fR | |
96 .TP 20 | |
97 \fBSDL_JOYBUTTONDOWN/UP\fP | |
98 \fI\fBSDL_JoyButtonEvent\fR\fR | |
99 .TP 20 | |
100 \fBSDL_QUIT\fP | |
101 \fI\fBSDL_QuitEvent\fR\fR | |
102 .TP 20 | |
103 \fBSDL_SYSWMEVENT\fP | |
104 \fI\fBSDL_SysWMEvent\fR\fR | |
105 .TP 20 | |
106 \fBSDL_VIDEORESIZE\fP | |
107 \fI\fBSDL_ResizeEvent\fR\fR | |
108 .TP 20 | |
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109 \fBSDL_VIDEOEXPOSE\fP |
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110 \fI\fBSDL_ExposeEvent\fR\fR |
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111 .TP 20 |
0 | 112 \fBSDL_USEREVENT\fP |
113 \fI\fBSDL_UserEvent\fR\fR | |
114 .SH "USE" | |
115 .PP | |
116 The \fBSDL_Event\fR structure has two uses | |
117 .IP " \(bu" 6 | |
118 Reading events on the event queue | |
119 .IP " \(bu" 6 | |
120 Placing events on the event queue | |
121 .PP | |
122 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\&. | |
123 .PP | |
124 First off, we create an empty \fBSDL_Event\fR structure\&. | |
125 .PP | |
126 .nf | |
127 \f(CWSDL_Event test_event;\fR | |
128 .fi | |
129 .PP | |
130 \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\&. | |
131 .PP | |
132 .nf | |
133 \f(CWwhile(SDL_PollEvent(&test_event)) {\fR | |
134 .fi | |
135 .PP | |
136 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\&. | |
137 .PP | |
138 .nf | |
139 \f(CW switch(test_event\&.type) {\fR | |
140 .fi | |
141 .PP | |
142 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: | |
143 .PP | |
144 .nf | |
145 \f(CW case SDL_MOUSEMOTION:\fR | |
146 .fi | |
147 .PP | |
148 All we need do now is read the information out of the \fBmotion\fR member of \fBtest_event\fR\&. | |
149 .PP | |
150 .nf | |
151 \f(CW printf("We got a motion event\&. | |
152 "); | |
153 printf("Current mouse position is: (%d, %d) | |
154 ", test_event\&.motion\&.x, test_event\&.motion\&.y); | |
155 break; | |
156 default: | |
157 printf("Unhandled Event! | |
158 "); | |
159 break; | |
160 } | |
161 } | |
162 printf("Event queue empty\&. | |
163 ");\fR | |
164 .fi | |
165 .PP | |
166 .PP | |
167 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\&. | |
168 .PP | |
169 .nf | |
170 \f(CWSDL_Event user_event; | |
171 | |
172 user_event\&.type=SDL_USEREVENT; | |
173 user_event\&.user\&.code=2; | |
174 user_event\&.user\&.data1=NULL; | |
175 user_event\&.user\&.data2=NULL; | |
176 SDL_PushEvent(&user_event);\fR | |
177 .fi | |
178 .PP | |
179 .SH "SEE ALSO" | |
180 .PP | |
181 \fI\fBSDL_PollEvent\fP\fR, \fI\fBSDL_PushEvent\fP\fR, \fI\fBSDL_PeepEvents\fP\fR | |
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182 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:59 |