Mercurial > sdl-ios-xcode
annotate docs/html/event.html @ 1259:36f24cdfcda7
te: Thu, 17 Apr 2003 11:25:26 -0700
From: "Jim"
Subject: [SDL] Frame buffer patches...
Would seem that GCC 3.2.2 promotes all signed values to unsigned if any single vlaue is unsigned in an expression...
for instance when calculating an elo touch position....evertyhign is an (int) except for cach_vinfo.xres which is unsigned. THerefore if y
ou reverse the SDL_ELO_MIN_X and SDL_ELO_MAX_X values the resulging negative value pegs the expression to it's max. Attached it the accumu
lated patch to typecast the unsigned values to (int)
- *dx = (cache_vinfo.xres - (cache_vinfo.xres * (input_x - ELO_MIN_X)) / width);
+ *dx = ((int)cache_vinfo.xres - ((int)cache_vinfo.xres * (input_x - ELO_MIN_X)) / width);
and also to provide quite failure to operations which have the screen currently locked...
The touch screen I'm using the original values were exactly opposite of any position I touched on the screen - evaluating the math the expr
ession SHOULD have handled reversing the min and max values - and after casting the unsigned .xres and .yres to a signed int - worked well.
..
Jim
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Tue, 24 Jan 2006 06:36:43 +0000 |
| parents | 355632dca928 |
| children |
| rev | line source |
|---|---|
| 0 | 1 <HTML |
| 2 ><HEAD | |
| 3 ><TITLE | |
| 4 >Events</TITLE | |
| 5 ><META | |
| 6 NAME="GENERATOR" | |
|
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7 CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ |
| 0 | 8 "><LINK |
| 9 REL="HOME" | |
| 10 TITLE="SDL Library Documentation" | |
| 11 HREF="index.html"><LINK | |
| 12 REL="UP" | |
| 13 TITLE="SDL Reference" | |
| 14 HREF="reference.html"><LINK | |
| 15 REL="PREVIOUS" | |
| 16 TITLE="SDL_WM_GrabInput" | |
| 17 HREF="sdlwmgrabinput.html"><LINK | |
| 18 REL="NEXT" | |
| 19 TITLE="SDL Event Structures." | |
| 20 HREF="eventstructures.html"><META | |
| 21 NAME="KEYWORD" | |
| 22 CONTENT="events"><META | |
| 23 NAME="KEYWORD" | |
| 24 CONTENT="function"></HEAD | |
| 25 ><BODY | |
| 26 CLASS="CHAPTER" | |
| 27 BGCOLOR="#FFF8DC" | |
| 28 TEXT="#000000" | |
| 29 LINK="#0000ee" | |
| 30 VLINK="#551a8b" | |
| 31 ALINK="#ff0000" | |
| 32 ><DIV | |
| 33 CLASS="NAVHEADER" | |
| 34 ><TABLE | |
|
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35 SUMMARY="Header navigation table" |
| 0 | 36 WIDTH="100%" |
| 37 BORDER="0" | |
| 38 CELLPADDING="0" | |
| 39 CELLSPACING="0" | |
| 40 ><TR | |
| 41 ><TH | |
| 42 COLSPAN="3" | |
| 43 ALIGN="center" | |
| 44 >SDL Library Documentation</TH | |
| 45 ></TR | |
| 46 ><TR | |
| 47 ><TD | |
| 48 WIDTH="10%" | |
| 49 ALIGN="left" | |
| 50 VALIGN="bottom" | |
| 51 ><A | |
| 52 HREF="sdlwmgrabinput.html" | |
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53 ACCESSKEY="P" |
| 0 | 54 >Prev</A |
| 55 ></TD | |
| 56 ><TD | |
| 57 WIDTH="80%" | |
| 58 ALIGN="center" | |
| 59 VALIGN="bottom" | |
| 60 ></TD | |
| 61 ><TD | |
| 62 WIDTH="10%" | |
| 63 ALIGN="right" | |
| 64 VALIGN="bottom" | |
| 65 ><A | |
| 66 HREF="eventstructures.html" | |
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67 ACCESSKEY="N" |
| 0 | 68 >Next</A |
| 69 ></TD | |
| 70 ></TR | |
| 71 ></TABLE | |
| 72 ><HR | |
| 73 ALIGN="LEFT" | |
| 74 WIDTH="100%"></DIV | |
| 75 ><DIV | |
| 76 CLASS="CHAPTER" | |
| 77 ><H1 | |
| 78 ><A | |
| 79 NAME="EVENT" | |
|
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80 ></A |
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81 >Chapter 8. Events</H1 |
| 0 | 82 ><DIV |
| 83 CLASS="TOC" | |
| 84 ><DL | |
| 85 ><DT | |
| 86 ><B | |
| 87 >Table of Contents</B | |
| 88 ></DT | |
| 89 ><DT | |
| 90 ><A | |
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91 HREF="event.html#AEN3691" |
| 0 | 92 >Introduction</A |
| 93 ></DT | |
| 94 ><DT | |
| 95 ><A | |
| 96 HREF="eventstructures.html" | |
| 97 >SDL Event Structures.</A | |
| 98 ></DT | |
| 99 ><DT | |
| 100 ><A | |
| 101 HREF="eventfunctions.html" | |
| 102 >Event Functions.</A | |
| 103 ></DT | |
| 104 ></DL | |
| 105 ></DIV | |
| 106 ><DIV | |
| 107 CLASS="SECT1" | |
| 108 ><H1 | |
| 109 CLASS="SECT1" | |
| 110 ><A | |
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111 NAME="AEN3691" |
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112 ></A |
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113 >Introduction</H1 |
| 0 | 114 ><P |
| 115 >Event handling allows your application to receive input from the user. Event handling is initalised (along with video) with a call to: | |
| 116 <PRE | |
| 117 CLASS="PROGRAMLISTING" | |
| 118 >SDL_Init(SDL_INIT_VIDEO);</PRE | |
| 119 > | |
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181
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120 Internally, SDL stores all the events waiting to be handled in an event queue. Using functions like <A |
| 0 | 121 HREF="sdlpollevent.html" |
| 122 ><TT | |
| 123 CLASS="FUNCTION" | |
| 124 >SDL_PollEvent</TT | |
| 125 ></A | |
| 126 > and <A | |
| 127 HREF="sdlpeepevents.html" | |
| 128 ><TT | |
| 129 CLASS="FUNCTION" | |
| 130 >SDL_PeepEvents</TT | |
| 131 ></A | |
| 132 > you can observe and handle waiting input events.</P | |
| 133 ><P | |
| 134 >The key to event handling in SDL is the <A | |
| 135 HREF="sdlevent.html" | |
| 136 ><SPAN | |
| 137 CLASS="STRUCTNAME" | |
| 138 >SDL_Event</SPAN | |
| 139 ></A | |
| 140 > union. The event queue itself is composed of a series of <SPAN | |
| 141 CLASS="STRUCTNAME" | |
| 142 >SDL_Event</SPAN | |
| 143 > unions, one for each waiting event. <SPAN | |
| 144 CLASS="STRUCTNAME" | |
| 145 >SDL_Event</SPAN | |
| 146 > unions are read from the queue with the <TT | |
| 147 CLASS="FUNCTION" | |
| 148 >SDL_PollEvent</TT | |
| 149 > function and it is then up to the application to process the information stored with them.</P | |
| 150 ></DIV | |
| 151 ></DIV | |
| 152 ><DIV | |
| 153 CLASS="NAVFOOTER" | |
| 154 ><HR | |
| 155 ALIGN="LEFT" | |
| 156 WIDTH="100%"><TABLE | |
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157 SUMMARY="Footer navigation table" |
| 0 | 158 WIDTH="100%" |
| 159 BORDER="0" | |
| 160 CELLPADDING="0" | |
| 161 CELLSPACING="0" | |
| 162 ><TR | |
| 163 ><TD | |
| 164 WIDTH="33%" | |
| 165 ALIGN="left" | |
| 166 VALIGN="top" | |
| 167 ><A | |
| 168 HREF="sdlwmgrabinput.html" | |
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169 ACCESSKEY="P" |
| 0 | 170 >Prev</A |
| 171 ></TD | |
| 172 ><TD | |
| 173 WIDTH="34%" | |
| 174 ALIGN="center" | |
| 175 VALIGN="top" | |
| 176 ><A | |
| 177 HREF="index.html" | |
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178 ACCESSKEY="H" |
| 0 | 179 >Home</A |
| 180 ></TD | |
| 181 ><TD | |
| 182 WIDTH="33%" | |
| 183 ALIGN="right" | |
| 184 VALIGN="top" | |
| 185 ><A | |
| 186 HREF="eventstructures.html" | |
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187 ACCESSKEY="N" |
| 0 | 188 >Next</A |
| 189 ></TD | |
| 190 ></TR | |
| 191 ><TR | |
| 192 ><TD | |
| 193 WIDTH="33%" | |
| 194 ALIGN="left" | |
| 195 VALIGN="top" | |
| 196 >SDL_WM_GrabInput</TD | |
| 197 ><TD | |
| 198 WIDTH="34%" | |
| 199 ALIGN="center" | |
| 200 VALIGN="top" | |
| 201 ><A | |
| 202 HREF="reference.html" | |
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203 ACCESSKEY="U" |
| 0 | 204 >Up</A |
| 205 ></TD | |
| 206 ><TD | |
| 207 WIDTH="33%" | |
| 208 ALIGN="right" | |
| 209 VALIGN="top" | |
| 210 >SDL Event Structures.</TD | |
| 211 ></TR | |
| 212 ></TABLE | |
| 213 ></DIV | |
| 214 ></BODY | |
| 215 ></HTML | |
| 216 > |