This repository has been archived by the owner on Feb 11, 2021. It is now read-only.
sdlseteventfilter.html
1
2
3
4
5
6
<HTML
><HEAD
><TITLE
>SDL_SetEventFilter</TITLE
><META
NAME="GENERATOR"
7
CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
"><LINK
REL="HOME"
TITLE="SDL Library Documentation"
HREF="index.html"><LINK
REL="UP"
TITLE="Event Functions."
HREF="eventfunctions.html"><LINK
REL="PREVIOUS"
TITLE="SDL_PushEvent"
HREF="sdlpushevent.html"><LINK
REL="NEXT"
TITLE="SDL_GetEventFilter"
HREF="sdlgeteventfilter.html"></HEAD
><BODY
CLASS="REFENTRY"
BGCOLOR="#FFF8DC"
TEXT="#000000"
LINK="#0000ee"
VLINK="#551a8b"
ALINK="#ff0000"
><DIV
CLASS="NAVHEADER"
><TABLE
31
SUMMARY="Header navigation table"
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>SDL Library Documentation</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="sdlpushevent.html"
49
ACCESSKEY="P"
50
51
52
53
54
55
56
57
58
59
60
61
62
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
></TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="sdlgeteventfilter.html"
63
ACCESSKEY="N"
64
65
66
67
68
69
70
71
72
73
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><H1
><A
NAME="SDLSETEVENTFILTER"
74
75
></A
>SDL_SetEventFilter</H1
76
77
78
><DIV
CLASS="REFNAMEDIV"
><A
79
NAME="AEN5575"
80
81
82
83
84
85
86
87
></A
><H2
>Name</H2
>SDL_SetEventFilter -- Sets up a filter to process all events before they are posted
to the event queue.</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
88
NAME="AEN5578"
89
90
91
92
93
94
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
95
NAME="AEN5579"
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
></A
><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>void <B
CLASS="FSFUNC"
>SDL_SetEventFilter</B
></CODE
>(SDL_EventFilter filter);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
119
NAME="AEN5585"
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
></A
><H2
>Description</H2
><P
>This function sets up a filter to process all events before they are posted
to the event queue. This is a very powerful and flexible feature. The filter
is prototyped as:
<PRE
CLASS="PROGRAMLISTING"
>typedef int (*SDL_EventFilter)(const SDL_Event *event);</PRE
>
If the filter returns <SPAN
CLASS="RETURNVALUE"
>1</SPAN
>, then the event will be
added to the internal queue. If it returns <SPAN
CLASS="RETURNVALUE"
>0</SPAN
>,
then the event will be dropped from the queue. This allows selective
filtering of dynamically.</P
><P
>There is one caveat when dealing with the <TT
CLASS="LITERAL"
>SDL_QUITEVENT</TT
> event type. The
event filter is only called when the window manager desires to close the
application window. If the event filter returns 1, then the window will
be closed, otherwise the window will remain open if possible.
If the quit event is generated by an interrupt signal, it will bypass the
internal queue and be delivered to the application at the next event poll.</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
>Events pushed onto the queue with <A
HREF="sdlpushevent.html"
><TT
CLASS="FUNCTION"
>SDL_PushEvent</TT
></A
> or <A
HREF="sdlpeepevents.html"
><TT
CLASS="FUNCTION"
>SDL_PeepEvents</TT
></A
> do not get passed through the event filter.</P
></BLOCKQUOTE
></DIV
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
180
181
><SPAN
CLASS="emphasis"
182
183
184
><I
CLASS="EMPHASIS"
>Be Careful!</I
185
></SPAN
186
187
188
189
190
191
192
> The event filter function may run in a different thread so be careful what you do within it.</P
></BLOCKQUOTE
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
193
NAME="AEN5602"
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
></A
><H2
>See Also</H2
><P
><A
HREF="sdlevent.html"
><SPAN
CLASS="STRUCTNAME"
>SDL_Event</SPAN
></A
>,
<A
HREF="sdlgeteventfilter.html"
><TT
CLASS="FUNCTION"
>SDL_GetEventFilter</TT
></A
>,
<A
HREF="sdlpushevent.html"
><TT
CLASS="FUNCTION"
>SDL_PushEvent</TT
></A
></P
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
225
SUMMARY="Footer navigation table"
226
227
228
229
230
231
232
233
234
235
236
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="sdlpushevent.html"
237
ACCESSKEY="P"
238
239
240
241
242
243
244
245
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
246
ACCESSKEY="H"
247
248
249
250
251
252
253
254
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="sdlgeteventfilter.html"
255
ACCESSKEY="N"
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>SDL_PushEvent</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="eventfunctions.html"
271
ACCESSKEY="U"
272
273
274
275
276
277
278
279
280
281
282
283
284
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>SDL_GetEventFilter</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>