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Updated SDL HTML documentation
author Sam Lantinga <slouken@libsdl.org>
date Tue, 10 Feb 2004 15:15:40 +0000
parents e5bc29de3f0a
children
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802:3c609d54f100 803:355632dca928
2 ><HEAD 2 ><HEAD
3 ><TITLE 3 ><TITLE
4 >Input handling</TITLE 4 >Input handling</TITLE
5 ><META 5 ><META
6 NAME="GENERATOR" 6 NAME="GENERATOR"
7 CONTENT="Modular DocBook HTML Stylesheet Version 1.64 7 CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
8 "><LINK 8 "><LINK
9 REL="HOME" 9 REL="HOME"
10 TITLE="SDL Library Documentation" 10 TITLE="SDL Library Documentation"
11 HREF="index.html"><LINK 11 HREF="index.html"><LINK
12 REL="UP" 12 REL="UP"
26 VLINK="#551a8b" 26 VLINK="#551a8b"
27 ALINK="#ff0000" 27 ALINK="#ff0000"
28 ><DIV 28 ><DIV
29 CLASS="NAVHEADER" 29 CLASS="NAVHEADER"
30 ><TABLE 30 ><TABLE
31 SUMMARY="Header navigation table"
31 WIDTH="100%" 32 WIDTH="100%"
32 BORDER="0" 33 BORDER="0"
33 CELLPADDING="0" 34 CELLPADDING="0"
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35 ><TR 36 ><TR
43 WIDTH="10%" 44 WIDTH="10%"
44 ALIGN="left" 45 ALIGN="left"
45 VALIGN="bottom" 46 VALIGN="bottom"
46 ><A 47 ><A
47 HREF="guidevideoopengl.html" 48 HREF="guidevideoopengl.html"
49 ACCESSKEY="P"
48 >Prev</A 50 >Prev</A
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59 ><A 61 ><A
60 HREF="guideinputkeyboard.html" 62 HREF="guideinputkeyboard.html"
63 ACCESSKEY="N"
61 >Next</A 64 >Next</A
62 ></TD 65 ></TD
63 ></TR 66 ></TR
64 ></TABLE 67 ></TABLE
65 ><HR 68 ><HR
68 ><DIV 71 ><DIV
69 CLASS="CHAPTER" 72 CLASS="CHAPTER"
70 ><H1 73 ><H1
71 ><A 74 ><A
72 NAME="GUIDEINPUT" 75 NAME="GUIDEINPUT"
73 >Chapter 3. Input handling</A 76 ></A
74 ></H1 77 >Chapter 3. Input handling</H1
75 ><DIV 78 ><DIV
76 CLASS="TOC" 79 CLASS="TOC"
77 ><DL 80 ><DL
78 ><DT 81 ><DT
79 ><B 82 ><B
95 CLASS="SECT1" 98 CLASS="SECT1"
96 ><H1 99 ><H1
97 CLASS="SECT1" 100 CLASS="SECT1"
98 ><A 101 ><A
99 NAME="GUIDEINPUTJOYSTICK" 102 NAME="GUIDEINPUTJOYSTICK"
100 >Handling Joysticks</A 103 ></A
101 ></H1 104 >Handling Joysticks</H1
102 ><DIV 105 ><DIV
103 CLASS="SECT2" 106 CLASS="SECT2"
104 ><H2 107 ><H2
105 CLASS="SECT2" 108 CLASS="SECT2"
106 ><A 109 ><A
107 NAME="AEN135" 110 NAME="AEN135"
108 >Initialization</A 111 ></A
109 ></H2 112 >Initialization</H2
110 ><P 113 ><P
111 >The first step in using a joystick in a SDL program is to initialize the Joystick subsystems of SDL. This done by passing the <TT 114 >The first step in using a joystick in a SDL program is to initialize the Joystick subsystems of SDL. This done by passing the <TT
112 CLASS="LITERAL" 115 CLASS="LITERAL"
113 >SDL_INIT_JOYSTICK</TT 116 >SDL_INIT_JOYSTICK</TT
114 > flag to <A 117 > flag to <A
142 CLASS="SECT2" 145 CLASS="SECT2"
143 ><H2 146 ><H2
144 CLASS="SECT2" 147 CLASS="SECT2"
145 ><A 148 ><A
146 NAME="AEN145" 149 NAME="AEN145"
147 >Querying</A 150 ></A
148 ></H2 151 >Querying</H2
149 ><P 152 ><P
150 >If we have reached this point then we can safely assume that the SDL library has been initialized and that the Joystick subsystem is active. We can now call some video and/or sound functions to get things going before we need the joystick. Eventually we have to make sure that there is actually a joystick to work with. It's wise to always check even if you know a joystick will be present on the system because it can also help detect when the joystick is unplugged. The function used to check for joysticks is <A 153 >If we have reached this point then we can safely assume that the SDL library has been initialized and that the Joystick subsystem is active. We can now call some video and/or sound functions to get things going before we need the joystick. Eventually we have to make sure that there is actually a joystick to work with. It's wise to always check even if you know a joystick will be present on the system because it can also help detect when the joystick is unplugged. The function used to check for joysticks is <A
151 HREF="sdlnumjoysticks.html" 154 HREF="sdlnumjoysticks.html"
152 ><TT 155 ><TT
153 CLASS="FUNCTION" 156 CLASS="FUNCTION"
189 CLASS="SECT2" 192 CLASS="SECT2"
190 ><H2 193 ><H2
191 CLASS="SECT2" 194 CLASS="SECT2"
192 ><A 195 ><A
193 NAME="AEN157" 196 NAME="AEN157"
194 >Opening a Joystick and Receiving Joystick Events</A 197 ></A
195 ></H2 198 >Opening a Joystick and Receiving Joystick Events</H2
196 ><P 199 ><P
197 >SDL's event driven architecture makes working with joysticks a snap. Joysticks can trigger 4 different types of events: 200 >SDL's event driven architecture makes working with joysticks a snap. Joysticks can trigger 4 different types of events:
198 <P 201 <P
199 ></P 202 ></P
200 ><TABLE 203 ><TABLE
431 CLASS="SECT2" 434 CLASS="SECT2"
432 ><H2 435 ><H2
433 CLASS="SECT2" 436 CLASS="SECT2"
434 ><A 437 ><A
435 NAME="AEN214" 438 NAME="AEN214"
436 >Advanced Joystick Functions</A 439 ></A
437 ></H2 440 >Advanced Joystick Functions</H2
438 ><P 441 ><P
439 >That takes care of the controls that you can count on being on every joystick under the sun, but there are a few extra things that SDL can support. Joyballs are next on our list, they are alot like axis with a few minor differences. Joyballs store relative changes unlike the the absolute postion stored in a axis event. Also one trackball event contains both the change in x and they change in y. Our case for it is as follows:</P 442 >That takes care of the controls that you can count on being on every joystick under the sun, but there are a few extra things that SDL can support. Joyballs are next on our list, they are alot like axis with a few minor differences. Joyballs store relative changes unlike the the absolute postion stored in a axis event. Also one trackball event contains both the change in x and they change in y. Our case for it is as follows:</P
440 ><DIV 443 ><DIV
441 CLASS="EXAMPLE" 444 CLASS="EXAMPLE"
442 ><A 445 ><A
567 >Example 3-8. Joystick Hat Events</B 570 >Example 3-8. Joystick Hat Events</B
568 ></P 571 ></P
569 ><PRE 572 ><PRE
570 CLASS="PROGRAMLISTING" 573 CLASS="PROGRAMLISTING"
571 > case SDL_JOYHATMOTION: /* Handle Hat Motion */ 574 > case SDL_JOYHATMOTION: /* Handle Hat Motion */
572 if ( event.jhat.hat &#38; SDL_HAT_UP ) 575 if ( event.jhat.value &#38; SDL_HAT_UP )
573 { 576 {
574 /* Do up stuff here */ 577 /* Do up stuff here */
575 } 578 }
576 579
577 if ( event.jhat.hat &#38; SDL_HAT_LEFT ) 580 if ( event.jhat.value &#38; SDL_HAT_LEFT )
578 { 581 {
579 /* Do left stuff here */ 582 /* Do left stuff here */
580 } 583 }
581 584
582 if ( event.jhat.hat &#38; SDL_HAT_RIGHTDOWN ) 585 if ( event.jhat.value &#38; SDL_HAT_RIGHTDOWN )
583 { 586 {
584 /* Do right and down together stuff here */ 587 /* Do right and down together stuff here */
585 } 588 }
586 break;</PRE 589 break;</PRE
587 ></DIV 590 ></DIV
672 ><DIV 675 ><DIV
673 CLASS="NAVFOOTER" 676 CLASS="NAVFOOTER"
674 ><HR 677 ><HR
675 ALIGN="LEFT" 678 ALIGN="LEFT"
676 WIDTH="100%"><TABLE 679 WIDTH="100%"><TABLE
680 SUMMARY="Footer navigation table"
677 WIDTH="100%" 681 WIDTH="100%"
678 BORDER="0" 682 BORDER="0"
679 CELLPADDING="0" 683 CELLPADDING="0"
680 CELLSPACING="0" 684 CELLSPACING="0"
681 ><TR 685 ><TR
683 WIDTH="33%" 687 WIDTH="33%"
684 ALIGN="left" 688 ALIGN="left"
685 VALIGN="top" 689 VALIGN="top"
686 ><A 690 ><A
687 HREF="guidevideoopengl.html" 691 HREF="guidevideoopengl.html"
692 ACCESSKEY="P"
688 >Prev</A 693 >Prev</A
689 ></TD 694 ></TD
690 ><TD 695 ><TD
691 WIDTH="34%" 696 WIDTH="34%"
692 ALIGN="center" 697 ALIGN="center"
693 VALIGN="top" 698 VALIGN="top"
694 ><A 699 ><A
695 HREF="index.html" 700 HREF="index.html"
701 ACCESSKEY="H"
696 >Home</A 702 >Home</A
697 ></TD 703 ></TD
698 ><TD 704 ><TD
699 WIDTH="33%" 705 WIDTH="33%"
700 ALIGN="right" 706 ALIGN="right"
701 VALIGN="top" 707 VALIGN="top"
702 ><A 708 ><A
703 HREF="guideinputkeyboard.html" 709 HREF="guideinputkeyboard.html"
710 ACCESSKEY="N"
704 >Next</A 711 >Next</A
705 ></TD 712 ></TD
706 ></TR 713 ></TR
707 ><TR 714 ><TR
708 ><TD 715 ><TD
714 WIDTH="34%" 721 WIDTH="34%"
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718 HREF="guide.html" 725 HREF="guide.html"
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