| 1 | <HTML |
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| 4 | >SDL_Event</TITLE |
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| 13 | TITLE="SDL Event Structures." |
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| 16 | TITLE="SDL Event Structures." |
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| 19 | TITLE="SDL_ActiveEvent" |
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| 37 | ><TH |
| 38 | COLSPAN="3" |
| 39 | ALIGN="center" |
| 40 | >SDL Library Documentation</TH |
| 41 | ></TR |
| 42 | ><TR |
| 43 | ><TD |
| 44 | WIDTH="10%" |
| 45 | ALIGN="left" |
| 46 | VALIGN="bottom" |
| 47 | ><A |
| 48 | HREF="eventstructures.html" |
| 49 | ACCESSKEY="P" |
| 50 | >Prev</A |
| 51 | ></TD |
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| 56 | ></TD |
| 57 | ><TD |
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| 59 | ALIGN="right" |
| 60 | VALIGN="bottom" |
| 61 | ><A |
| 62 | HREF="sdlactiveevent.html" |
| 63 | ACCESSKEY="N" |
| 64 | >Next</A |
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| 70 | WIDTH="100%"></DIV |
| 71 | ><H1 |
| 72 | ><A |
| 73 | NAME="SDLEVENT" |
| 74 | ></A |
| 75 | >SDL_Event</H1 |
| 76 | ><DIV |
| 77 | CLASS="REFNAMEDIV" |
| 78 | ><A |
| 79 | NAME="AEN3711" |
| 80 | ></A |
| 81 | ><H2 |
| 82 | >Name</H2 |
| 83 | >SDL_Event -- General event structure</DIV |
| 84 | ><DIV |
| 85 | CLASS="REFSECT1" |
| 86 | ><A |
| 87 | NAME="AEN3714" |
| 88 | ></A |
| 89 | ><H2 |
| 90 | >Structure Definition</H2 |
| 91 | ><PRE |
| 92 | CLASS="PROGRAMLISTING" |
| 93 | >typedef union{ |
| 94 | Uint8 type; |
| 95 | SDL_ActiveEvent active; |
| 96 | SDL_KeyboardEvent key; |
| 97 | SDL_MouseMotionEvent motion; |
| 98 | SDL_MouseButtonEvent button; |
| 99 | SDL_JoyAxisEvent jaxis; |
| 100 | SDL_JoyBallEvent jball; |
| 101 | SDL_JoyHatEvent jhat; |
| 102 | SDL_JoyButtonEvent jbutton; |
| 103 | SDL_ResizeEvent resize; |
| 104 | SDL_ExposeEvent expose; |
| 105 | SDL_QuitEvent quit; |
| 106 | SDL_UserEvent user; |
| 107 | SDL_SysWMEvent syswm; |
| 108 | } SDL_Event;</PRE |
| 109 | ></DIV |
| 110 | ><DIV |
| 111 | CLASS="REFSECT1" |
| 112 | ><A |
| 113 | NAME="AEN3717" |
| 114 | ></A |
| 115 | ><H2 |
| 116 | >Structure Data</H2 |
| 117 | ><DIV |
| 118 | CLASS="INFORMALTABLE" |
| 119 | ><A |
| 120 | NAME="AEN3719" |
| 121 | ></A |
| 122 | ><P |
| 123 | ></P |
| 124 | ><TABLE |
| 125 | BORDER="0" |
| 126 | CLASS="CALSTABLE" |
| 127 | ><TBODY |
| 128 | ><TR |
| 129 | ><TD |
| 130 | ALIGN="LEFT" |
| 131 | VALIGN="TOP" |
| 132 | ><TT |
| 133 | CLASS="STRUCTFIELD" |
| 134 | ><I |
| 135 | >type</I |
| 136 | ></TT |
| 137 | ></TD |
| 138 | ><TD |
| 139 | ALIGN="LEFT" |
| 140 | VALIGN="TOP" |
| 141 | >The type of event</TD |
| 142 | ></TR |
| 143 | ><TR |
| 144 | ><TD |
| 145 | ALIGN="LEFT" |
| 146 | VALIGN="TOP" |
| 147 | ><TT |
| 148 | CLASS="STRUCTFIELD" |
| 149 | ><I |
| 150 | >active</I |
| 151 | ></TT |
| 152 | ></TD |
| 153 | ><TD |
| 154 | ALIGN="LEFT" |
| 155 | VALIGN="TOP" |
| 156 | ><A |
| 157 | HREF="sdlactiveevent.html" |
| 158 | >Activation event</A |
| 159 | ></TD |
| 160 | ></TR |
| 161 | ><TR |
| 162 | ><TD |
| 163 | ALIGN="LEFT" |
| 164 | VALIGN="TOP" |
| 165 | ><TT |
| 166 | CLASS="STRUCTFIELD" |
| 167 | ><I |
| 168 | >key</I |
| 169 | ></TT |
| 170 | ></TD |
| 171 | ><TD |
| 172 | ALIGN="LEFT" |
| 173 | VALIGN="TOP" |
| 174 | ><A |
| 175 | HREF="sdlkeyboardevent.html" |
| 176 | >Keyboard event</A |
| 177 | ></TD |
| 178 | ></TR |
| 179 | ><TR |
| 180 | ><TD |
| 181 | ALIGN="LEFT" |
| 182 | VALIGN="TOP" |
| 183 | ><TT |
| 184 | CLASS="STRUCTFIELD" |
| 185 | ><I |
| 186 | >motion</I |
| 187 | ></TT |
| 188 | ></TD |
| 189 | ><TD |
| 190 | ALIGN="LEFT" |
| 191 | VALIGN="TOP" |
| 192 | ><A |
| 193 | HREF="sdlmousemotionevent.html" |
| 194 | >Mouse motion event</A |
| 195 | ></TD |
| 196 | ></TR |
| 197 | ><TR |
| 198 | ><TD |
| 199 | ALIGN="LEFT" |
| 200 | VALIGN="TOP" |
| 201 | ><TT |
| 202 | CLASS="STRUCTFIELD" |
| 203 | ><I |
| 204 | >button</I |
| 205 | ></TT |
| 206 | ></TD |
| 207 | ><TD |
| 208 | ALIGN="LEFT" |
| 209 | VALIGN="TOP" |
| 210 | ><A |
| 211 | HREF="sdlmousebuttonevent.html" |
| 212 | >Mouse button event</A |
| 213 | ></TD |
| 214 | ></TR |
| 215 | ><TR |
| 216 | ><TD |
| 217 | ALIGN="LEFT" |
| 218 | VALIGN="TOP" |
| 219 | ><TT |
| 220 | CLASS="STRUCTFIELD" |
| 221 | ><I |
| 222 | >jaxis</I |
| 223 | ></TT |
| 224 | ></TD |
| 225 | ><TD |
| 226 | ALIGN="LEFT" |
| 227 | VALIGN="TOP" |
| 228 | ><A |
| 229 | HREF="sdljoyaxisevent.html" |
| 230 | >Joystick axis motion event</A |
| 231 | ></TD |
| 232 | ></TR |
| 233 | ><TR |
| 234 | ><TD |
| 235 | ALIGN="LEFT" |
| 236 | VALIGN="TOP" |
| 237 | ><TT |
| 238 | CLASS="STRUCTFIELD" |
| 239 | ><I |
| 240 | >jball</I |
| 241 | ></TT |
| 242 | ></TD |
| 243 | ><TD |
| 244 | ALIGN="LEFT" |
| 245 | VALIGN="TOP" |
| 246 | ><A |
| 247 | HREF="sdljoyballevent.html" |
| 248 | >Joystick trackball motion event</A |
| 249 | ></TD |
| 250 | ></TR |
| 251 | ><TR |
| 252 | ><TD |
| 253 | ALIGN="LEFT" |
| 254 | VALIGN="TOP" |
| 255 | ><TT |
| 256 | CLASS="STRUCTFIELD" |
| 257 | ><I |
| 258 | >jhat</I |
| 259 | ></TT |
| 260 | ></TD |
| 261 | ><TD |
| 262 | ALIGN="LEFT" |
| 263 | VALIGN="TOP" |
| 264 | ><A |
| 265 | HREF="sdljoyhatevent.html" |
| 266 | >Joystick hat motion event</A |
| 267 | ></TD |
| 268 | ></TR |
| 269 | ><TR |
| 270 | ><TD |
| 271 | ALIGN="LEFT" |
| 272 | VALIGN="TOP" |
| 273 | ><TT |
| 274 | CLASS="STRUCTFIELD" |
| 275 | ><I |
| 276 | >jbutton</I |
| 277 | ></TT |
| 278 | ></TD |
| 279 | ><TD |
| 280 | ALIGN="LEFT" |
| 281 | VALIGN="TOP" |
| 282 | ><A |
| 283 | HREF="sdljoybuttonevent.html" |
| 284 | >Joystick button event</A |
| 285 | ></TD |
| 286 | ></TR |
| 287 | ><TR |
| 288 | ><TD |
| 289 | ALIGN="LEFT" |
| 290 | VALIGN="TOP" |
| 291 | ><TT |
| 292 | CLASS="STRUCTFIELD" |
| 293 | ><I |
| 294 | >resize</I |
| 295 | ></TT |
| 296 | ></TD |
| 297 | ><TD |
| 298 | ALIGN="LEFT" |
| 299 | VALIGN="TOP" |
| 300 | ><A |
| 301 | HREF="sdlresizeevent.html" |
| 302 | >Application window resize event</A |
| 303 | ></TD |
| 304 | ></TR |
| 305 | ><TR |
| 306 | ><TD |
| 307 | ALIGN="LEFT" |
| 308 | VALIGN="TOP" |
| 309 | ><TT |
| 310 | CLASS="STRUCTFIELD" |
| 311 | ><I |
| 312 | >expose</I |
| 313 | ></TT |
| 314 | ></TD |
| 315 | ><TD |
| 316 | ALIGN="LEFT" |
| 317 | VALIGN="TOP" |
| 318 | ><A |
| 319 | HREF="sdlexposeevent.html" |
| 320 | >Application window expose event</A |
| 321 | ></TD |
| 322 | ></TR |
| 323 | ><TR |
| 324 | ><TD |
| 325 | ALIGN="LEFT" |
| 326 | VALIGN="TOP" |
| 327 | ><TT |
| 328 | CLASS="STRUCTFIELD" |
| 329 | ><I |
| 330 | >quit</I |
| 331 | ></TT |
| 332 | ></TD |
| 333 | ><TD |
| 334 | ALIGN="LEFT" |
| 335 | VALIGN="TOP" |
| 336 | ><A |
| 337 | HREF="sdlquitevent.html" |
| 338 | >Application quit request event</A |
| 339 | ></TD |
| 340 | ></TR |
| 341 | ><TR |
| 342 | ><TD |
| 343 | ALIGN="LEFT" |
| 344 | VALIGN="TOP" |
| 345 | ><TT |
| 346 | CLASS="STRUCTFIELD" |
| 347 | ><I |
| 348 | >user</I |
| 349 | ></TT |
| 350 | ></TD |
| 351 | ><TD |
| 352 | ALIGN="LEFT" |
| 353 | VALIGN="TOP" |
| 354 | ><A |
| 355 | HREF="sdluserevent.html" |
| 356 | >User defined event</A |
| 357 | ></TD |
| 358 | ></TR |
| 359 | ><TR |
| 360 | ><TD |
| 361 | ALIGN="LEFT" |
| 362 | VALIGN="TOP" |
| 363 | ><TT |
| 364 | CLASS="STRUCTFIELD" |
| 365 | ><I |
| 366 | >syswm</I |
| 367 | ></TT |
| 368 | ></TD |
| 369 | ><TD |
| 370 | ALIGN="LEFT" |
| 371 | VALIGN="TOP" |
| 372 | ><A |
| 373 | HREF="sdlsyswmevent.html" |
| 374 | >Undefined window manager event</A |
| 375 | ></TD |
| 376 | ></TR |
| 377 | ></TBODY |
| 378 | ></TABLE |
| 379 | ><P |
| 380 | ></P |
| 381 | ></DIV |
| 382 | ></DIV |
| 383 | ><DIV |
| 384 | CLASS="REFSECT1" |
| 385 | ><A |
| 386 | NAME="AEN3791" |
| 387 | ></A |
| 388 | ><H2 |
| 389 | >Description</H2 |
| 390 | ><P |
| 391 | >The <SPAN |
| 392 | CLASS="STRUCTNAME" |
| 393 | >SDL_Event</SPAN |
| 394 | > union is the core to all event handling is SDL, its probably the most important structure after <SPAN |
| 395 | CLASS="STRUCTNAME" |
| 396 | >SDL_Surface</SPAN |
| 397 | >. <SPAN |
| 398 | CLASS="STRUCTNAME" |
| 399 | >SDL_Event</SPAN |
| 400 | > 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 <TT |
| 401 | CLASS="STRUCTFIELD" |
| 402 | ><I |
| 403 | >type</I |
| 404 | ></TT |
| 405 | >.</P |
| 406 | ><P |
| 407 | ><DIV |
| 408 | CLASS="INFORMALTABLE" |
| 409 | ><A |
| 410 | NAME="AEN3799" |
| 411 | ></A |
| 412 | ><P |
| 413 | ></P |
| 414 | ><TABLE |
| 415 | BORDER="1" |
| 416 | CLASS="CALSTABLE" |
| 417 | ><THEAD |
| 418 | ><TR |
| 419 | ><TH |
| 420 | ALIGN="LEFT" |
| 421 | VALIGN="TOP" |
| 422 | >Event <TT |
| 423 | CLASS="STRUCTFIELD" |
| 424 | ><I |
| 425 | >type</I |
| 426 | ></TT |
| 427 | ></TH |
| 428 | ><TH |
| 429 | ALIGN="LEFT" |
| 430 | VALIGN="TOP" |
| 431 | >Event Structure</TH |
| 432 | ></TR |
| 433 | ></THEAD |
| 434 | ><TBODY |
| 435 | ><TR |
| 436 | ><TD |
| 437 | ALIGN="LEFT" |
| 438 | VALIGN="MIDDLE" |
| 439 | ><TT |
| 440 | CLASS="LITERAL" |
| 441 | >SDL_ACTIVEEVENT</TT |
| 442 | ></TD |
| 443 | ><TD |
| 444 | ALIGN="LEFT" |
| 445 | VALIGN="MIDDLE" |
| 446 | ><A |
| 447 | HREF="sdlactiveevent.html" |
| 448 | ><SPAN |
| 449 | CLASS="STRUCTNAME" |
| 450 | >SDL_ActiveEvent</SPAN |
| 451 | ></A |
| 452 | ></TD |
| 453 | ></TR |
| 454 | ><TR |
| 455 | ><TD |
| 456 | ALIGN="LEFT" |
| 457 | VALIGN="TOP" |
| 458 | ><TT |
| 459 | CLASS="LITERAL" |
| 460 | >SDL_KEYDOWN/UP</TT |
| 461 | ></TD |
| 462 | ><TD |
| 463 | ALIGN="LEFT" |
| 464 | VALIGN="TOP" |
| 465 | ><A |
| 466 | HREF="sdlkeyboardevent.html" |
| 467 | ><SPAN |
| 468 | CLASS="STRUCTNAME" |
| 469 | >SDL_KeyboardEvent</SPAN |
| 470 | ></A |
| 471 | ></TD |
| 472 | ></TR |
| 473 | ><TR |
| 474 | ><TD |
| 475 | ALIGN="LEFT" |
| 476 | VALIGN="TOP" |
| 477 | ><TT |
| 478 | CLASS="LITERAL" |
| 479 | >SDL_MOUSEMOTION</TT |
| 480 | ></TD |
| 481 | ><TD |
| 482 | ALIGN="LEFT" |
| 483 | VALIGN="TOP" |
| 484 | ><A |
| 485 | HREF="sdlmousemotionevent.html" |
| 486 | ><SPAN |
| 487 | CLASS="STRUCTNAME" |
| 488 | >SDL_MouseMotionEvent</SPAN |
| 489 | ></A |
| 490 | ></TD |
| 491 | ></TR |
| 492 | ><TR |
| 493 | ><TD |
| 494 | ALIGN="LEFT" |
| 495 | VALIGN="TOP" |
| 496 | ><TT |
| 497 | CLASS="LITERAL" |
| 498 | >SDL_MOUSEBUTTONDOWN/UP</TT |
| 499 | ></TD |
| 500 | ><TD |
| 501 | ALIGN="LEFT" |
| 502 | VALIGN="TOP" |
| 503 | ><A |
| 504 | HREF="sdlmousebuttonevent.html" |
| 505 | ><SPAN |
| 506 | CLASS="STRUCTNAME" |
| 507 | >SDL_MouseButtonEvent</SPAN |
| 508 | ></A |
| 509 | ></TD |
| 510 | ></TR |
| 511 | ><TR |
| 512 | ><TD |
| 513 | ALIGN="LEFT" |
| 514 | VALIGN="TOP" |
| 515 | ><TT |
| 516 | CLASS="LITERAL" |
| 517 | >SDL_JOYAXISMOTION</TT |
| 518 | ></TD |
| 519 | ><TD |
| 520 | ALIGN="LEFT" |
| 521 | VALIGN="TOP" |
| 522 | ><A |
| 523 | HREF="sdljoyaxisevent.html" |
| 524 | ><SPAN |
| 525 | CLASS="STRUCTNAME" |
| 526 | >SDL_JoyAxisEvent</SPAN |
| 527 | ></A |
| 528 | ></TD |
| 529 | ></TR |
| 530 | ><TR |
| 531 | ><TD |
| 532 | ALIGN="LEFT" |
| 533 | VALIGN="TOP" |
| 534 | ><TT |
| 535 | CLASS="LITERAL" |
| 536 | >SDL_JOYBALLMOTION</TT |
| 537 | ></TD |
| 538 | ><TD |
| 539 | ALIGN="LEFT" |
| 540 | VALIGN="TOP" |
| 541 | ><A |
| 542 | HREF="sdljoyballevent.html" |
| 543 | ><SPAN |
| 544 | CLASS="STRUCTNAME" |
| 545 | >SDL_JoyBallEvent</SPAN |
| 546 | ></A |
| 547 | ></TD |
| 548 | ></TR |
| 549 | ><TR |
| 550 | ><TD |
| 551 | ALIGN="LEFT" |
| 552 | VALIGN="TOP" |
| 553 | ><TT |
| 554 | CLASS="LITERAL" |
| 555 | >SDL_JOYHATMOTION</TT |
| 556 | ></TD |
| 557 | ><TD |
| 558 | ALIGN="LEFT" |
| 559 | VALIGN="TOP" |
| 560 | ><A |
| 561 | HREF="sdljoyhatevent.html" |
| 562 | ><SPAN |
| 563 | CLASS="STRUCTNAME" |
| 564 | >SDL_JoyHatEvent</SPAN |
| 565 | ></A |
| 566 | ></TD |
| 567 | ></TR |
| 568 | ><TR |
| 569 | ><TD |
| 570 | ALIGN="LEFT" |
| 571 | VALIGN="TOP" |
| 572 | ><TT |
| 573 | CLASS="LITERAL" |
| 574 | >SDL_JOYBUTTONDOWN/UP</TT |
| 575 | ></TD |
| 576 | ><TD |
| 577 | ALIGN="LEFT" |
| 578 | VALIGN="TOP" |
| 579 | ><A |
| 580 | HREF="sdljoybuttonevent.html" |
| 581 | ><SPAN |
| 582 | CLASS="STRUCTNAME" |
| 583 | >SDL_JoyButtonEvent</SPAN |
| 584 | ></A |
| 585 | ></TD |
| 586 | ></TR |
| 587 | ><TR |
| 588 | ><TD |
| 589 | ALIGN="LEFT" |
| 590 | VALIGN="TOP" |
| 591 | ><TT |
| 592 | CLASS="LITERAL" |
| 593 | >SDL_QUIT</TT |
| 594 | ></TD |
| 595 | ><TD |
| 596 | ALIGN="LEFT" |
| 597 | VALIGN="TOP" |
| 598 | ><A |
| 599 | HREF="sdlquitevent.html" |
| 600 | ><SPAN |
| 601 | CLASS="STRUCTNAME" |
| 602 | >SDL_QuitEvent</SPAN |
| 603 | ></A |
| 604 | ></TD |
| 605 | ></TR |
| 606 | ><TR |
| 607 | ><TD |
| 608 | ALIGN="LEFT" |
| 609 | VALIGN="TOP" |
| 610 | ><TT |
| 611 | CLASS="LITERAL" |
| 612 | >SDL_SYSWMEVENT</TT |
| 613 | ></TD |
| 614 | ><TD |
| 615 | ALIGN="LEFT" |
| 616 | VALIGN="TOP" |
| 617 | ><A |
| 618 | HREF="sdlsyswmevent.html" |
| 619 | ><SPAN |
| 620 | CLASS="STRUCTNAME" |
| 621 | >SDL_SysWMEvent</SPAN |
| 622 | ></A |
| 623 | ></TD |
| 624 | ></TR |
| 625 | ><TR |
| 626 | ><TD |
| 627 | ALIGN="LEFT" |
| 628 | VALIGN="TOP" |
| 629 | ><TT |
| 630 | CLASS="LITERAL" |
| 631 | >SDL_VIDEORESIZE</TT |
| 632 | ></TD |
| 633 | ><TD |
| 634 | ALIGN="LEFT" |
| 635 | VALIGN="TOP" |
| 636 | ><A |
| 637 | HREF="sdlresizeevent.html" |
| 638 | ><SPAN |
| 639 | CLASS="STRUCTNAME" |
| 640 | >SDL_ResizeEvent</SPAN |
| 641 | ></A |
| 642 | ></TD |
| 643 | ></TR |
| 644 | ><TR |
| 645 | ><TD |
| 646 | ALIGN="LEFT" |
| 647 | VALIGN="TOP" |
| 648 | ><TT |
| 649 | CLASS="LITERAL" |
| 650 | >SDL_VIDEOEXPOSE</TT |
| 651 | ></TD |
| 652 | ><TD |
| 653 | ALIGN="LEFT" |
| 654 | VALIGN="TOP" |
| 655 | ><A |
| 656 | HREF="sdlexposeevent.html" |
| 657 | ><SPAN |
| 658 | CLASS="STRUCTNAME" |
| 659 | >SDL_ExposeEvent</SPAN |
| 660 | ></A |
| 661 | ></TD |
| 662 | ></TR |
| 663 | ><TR |
| 664 | ><TD |
| 665 | ALIGN="LEFT" |
| 666 | VALIGN="TOP" |
| 667 | ><TT |
| 668 | CLASS="LITERAL" |
| 669 | >SDL_USEREVENT</TT |
| 670 | ></TD |
| 671 | ><TD |
| 672 | ALIGN="LEFT" |
| 673 | VALIGN="TOP" |
| 674 | ><A |
| 675 | HREF="sdluserevent.html" |
| 676 | ><SPAN |
| 677 | CLASS="STRUCTNAME" |
| 678 | >SDL_UserEvent</SPAN |
| 679 | ></A |
| 680 | ></TD |
| 681 | ></TR |
| 682 | ></TBODY |
| 683 | ></TABLE |
| 684 | ><P |
| 685 | ></P |
| 686 | ></DIV |
| 687 | ></P |
| 688 | ></DIV |
| 689 | ><DIV |
| 690 | CLASS="REFSECT1" |
| 691 | ><A |
| 692 | NAME="AEN3885" |
| 693 | ></A |
| 694 | ><H2 |
| 695 | >Use</H2 |
| 696 | ><P |
| 697 | >The <SPAN |
| 698 | CLASS="STRUCTNAME" |
| 699 | >SDL_Event</SPAN |
| 700 | > structure has two uses</P |
| 701 | ><P |
| 702 | ></P |
| 703 | ><UL |
| 704 | COMPACT="COMPACT" |
| 705 | ><LI |
| 706 | ><P |
| 707 | >Reading events on the event queue</P |
| 708 | ></LI |
| 709 | ><LI |
| 710 | ><P |
| 711 | >Placing events on the event queue</P |
| 712 | ></LI |
| 713 | ></UL |
| 714 | ><P |
| 715 | >Reading events from the event queue is done with either <A |
| 716 | HREF="sdlpollevent.html" |
| 717 | ><TT |
| 718 | CLASS="FUNCTION" |
| 719 | >SDL_PollEvent</TT |
| 720 | ></A |
| 721 | > or <A |
| 722 | HREF="sdlpeepevents.html" |
| 723 | ><TT |
| 724 | CLASS="FUNCTION" |
| 725 | >SDL_PeepEvents</TT |
| 726 | ></A |
| 727 | >. We'll use <TT |
| 728 | CLASS="FUNCTION" |
| 729 | >SDL_PollEvent</TT |
| 730 | > and step through an example.</P |
| 731 | ><P |
| 732 | >First off, we create an empty <SPAN |
| 733 | CLASS="STRUCTNAME" |
| 734 | >SDL_Event</SPAN |
| 735 | > structure. |
| 736 | <PRE |
| 737 | CLASS="PROGRAMLISTING" |
| 738 | >SDL_Event test_event;</PRE |
| 739 | > |
| 740 | <TT |
| 741 | CLASS="FUNCTION" |
| 742 | >SDL_PollEvent</TT |
| 743 | > removes the next event from the event queue, if there are no events on the queue it returns <SPAN |
| 744 | CLASS="RETURNVALUE" |
| 745 | >0</SPAN |
| 746 | > otherwise it returns <SPAN |
| 747 | CLASS="RETURNVALUE" |
| 748 | >1</SPAN |
| 749 | >. We use a <TT |
| 750 | CLASS="FUNCTION" |
| 751 | >while</TT |
| 752 | > loop to process each event in turn. |
| 753 | <PRE |
| 754 | CLASS="PROGRAMLISTING" |
| 755 | >while(SDL_PollEvent(&test_event)) {</PRE |
| 756 | > |
| 757 | The <TT |
| 758 | CLASS="FUNCTION" |
| 759 | >SDL_PollEvent</TT |
| 760 | > function take a pointer to an <SPAN |
| 761 | CLASS="STRUCTNAME" |
| 762 | >SDL_Event</SPAN |
| 763 | > structure that is to be filled with event information. We know that if <TT |
| 764 | CLASS="FUNCTION" |
| 765 | >SDL_PollEvent</TT |
| 766 | > removes an event from the queue then the event information will be placed in our <SPAN |
| 767 | CLASS="STRUCTNAME" |
| 768 | >test_event</SPAN |
| 769 | > structure, but we also know that the <SPAN |
| 770 | CLASS="emphasis" |
| 771 | ><I |
| 772 | CLASS="EMPHASIS" |
| 773 | >type</I |
| 774 | ></SPAN |
| 775 | > of event will be placed in the <TT |
| 776 | CLASS="STRUCTFIELD" |
| 777 | ><I |
| 778 | >type</I |
| 779 | ></TT |
| 780 | > member of <SPAN |
| 781 | CLASS="STRUCTNAME" |
| 782 | >test_event</SPAN |
| 783 | >. So to handle each event <TT |
| 784 | CLASS="STRUCTFIELD" |
| 785 | ><I |
| 786 | >type</I |
| 787 | ></TT |
| 788 | > seperately we use a <TT |
| 789 | CLASS="FUNCTION" |
| 790 | >switch</TT |
| 791 | > statement. |
| 792 | <PRE |
| 793 | CLASS="PROGRAMLISTING" |
| 794 | > switch(test_event.type) {</PRE |
| 795 | > |
| 796 | We need to know what kind of events we're looking for <SPAN |
| 797 | CLASS="emphasis" |
| 798 | ><I |
| 799 | CLASS="EMPHASIS" |
| 800 | >and</I |
| 801 | ></SPAN |
| 802 | > the event <TT |
| 803 | CLASS="STRUCTFIELD" |
| 804 | ><I |
| 805 | >type</I |
| 806 | ></TT |
| 807 | >'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 <TT |
| 808 | CLASS="LITERAL" |
| 809 | >SDL_MOUSEMOTION</TT |
| 810 | > is, more than likely, the event we're looking for. A little <A |
| 811 | HREF="sdlmousemotionevent.html" |
| 812 | >more</A |
| 813 | > research tells use that <TT |
| 814 | CLASS="LITERAL" |
| 815 | >SDL_MOUSEMOTION</TT |
| 816 | > events are handled within the <A |
| 817 | HREF="sdlmousemotionevent.html" |
| 818 | ><SPAN |
| 819 | CLASS="STRUCTNAME" |
| 820 | >SDL_MouseMotionEvent</SPAN |
| 821 | ></A |
| 822 | > structure which is the <TT |
| 823 | CLASS="STRUCTFIELD" |
| 824 | ><I |
| 825 | >motion</I |
| 826 | ></TT |
| 827 | > member of <SPAN |
| 828 | CLASS="STRUCTNAME" |
| 829 | >SDL_Event</SPAN |
| 830 | >. We can check for the <TT |
| 831 | CLASS="LITERAL" |
| 832 | >SDL_MOUSEMOTION</TT |
| 833 | > event <TT |
| 834 | CLASS="STRUCTFIELD" |
| 835 | ><I |
| 836 | >type</I |
| 837 | ></TT |
| 838 | > within our <TT |
| 839 | CLASS="FUNCTION" |
| 840 | >switch</TT |
| 841 | > statement like so: |
| 842 | <PRE |
| 843 | CLASS="PROGRAMLISTING" |
| 844 | > case SDL_MOUSEMOTION:</PRE |
| 845 | > |
| 846 | All we need do now is read the information out of the <TT |
| 847 | CLASS="STRUCTFIELD" |
| 848 | ><I |
| 849 | >motion</I |
| 850 | ></TT |
| 851 | > member of <SPAN |
| 852 | CLASS="STRUCTNAME" |
| 853 | >test_event</SPAN |
| 854 | >. |
| 855 | <PRE |
| 856 | CLASS="PROGRAMLISTING" |
| 857 | > printf("We got a motion event.\n"); |
| 858 | printf("Current mouse position is: (%d, %d)\n", test_event.motion.x, test_event.motion.y); |
| 859 | break; |
| 860 | default: |
| 861 | printf("Unhandled Event!\n"); |
| 862 | break; |
| 863 | } |
| 864 | } |
| 865 | printf("Event queue empty.\n");</PRE |
| 866 | ></P |
| 867 | ><P |
| 868 | >It is also possible to push events onto the event queue and so use it as a two-way communication path. Both <A |
| 869 | HREF="sdlpushevent.html" |
| 870 | ><TT |
| 871 | CLASS="FUNCTION" |
| 872 | >SDL_PushEvent</TT |
| 873 | ></A |
| 874 | > and <A |
| 875 | HREF="sdlpeepevents.html" |
| 876 | ><TT |
| 877 | CLASS="FUNCTION" |
| 878 | >SDL_PeepEvents</TT |
| 879 | ></A |
| 880 | > allow you to place events onto the event queue. This is usually used to place a <TT |
| 881 | CLASS="LITERAL" |
| 882 | >SDL_USEREVENT</TT |
| 883 | > 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 <TT |
| 884 | CLASS="STRUCTFIELD" |
| 885 | ><I |
| 886 | >type</I |
| 887 | ></TT |
| 888 | > member and filling the appropriate member structure with information. |
| 889 | <PRE |
| 890 | CLASS="PROGRAMLISTING" |
| 891 | >SDL_Event user_event; |
| 892 | |
| 893 | user_event.type=SDL_USEREVENT; |
| 894 | user_event.user.code=2; |
| 895 | user_event.user.data1=NULL; |
| 896 | user_event.user.data2=NULL; |
| 897 | SDL_PushEvent(&user_event);</PRE |
| 898 | ></P |
| 899 | ></DIV |
| 900 | ><DIV |
| 901 | CLASS="REFSECT1" |
| 902 | ><A |
| 903 | NAME="AEN3942" |
| 904 | ></A |
| 905 | ><H2 |
| 906 | >See Also</H2 |
| 907 | ><P |
| 908 | ><A |
| 909 | HREF="sdlpollevent.html" |
| 910 | ><TT |
| 911 | CLASS="FUNCTION" |
| 912 | >SDL_PollEvent</TT |
| 913 | ></A |
| 914 | >, |
| 915 | <A |
| 916 | HREF="sdlpushevent.html" |
| 917 | ><TT |
| 918 | CLASS="FUNCTION" |
| 919 | >SDL_PushEvent</TT |
| 920 | ></A |
| 921 | >, |
| 922 | <A |
| 923 | HREF="sdlpeepevents.html" |
| 924 | ><TT |
| 925 | CLASS="FUNCTION" |
| 926 | >SDL_PeepEvents</TT |
| 927 | ></A |
| 928 | ></P |
| 929 | ></DIV |
| 930 | ><DIV |
| 931 | CLASS="NAVFOOTER" |
| 932 | ><HR |
| 933 | ALIGN="LEFT" |
| 934 | WIDTH="100%"><TABLE |
| 935 | SUMMARY="Footer navigation table" |
| 936 | WIDTH="100%" |
| 937 | BORDER="0" |
| 938 | CELLPADDING="0" |
| 939 | CELLSPACING="0" |
| 940 | ><TR |
| 941 | ><TD |
| 942 | WIDTH="33%" |
| 943 | ALIGN="left" |
| 944 | VALIGN="top" |
| 945 | ><A |
| 946 | HREF="eventstructures.html" |
| 947 | ACCESSKEY="P" |
| 948 | >Prev</A |
| 949 | ></TD |
| 950 | ><TD |
| 951 | WIDTH="34%" |
| 952 | ALIGN="center" |
| 953 | VALIGN="top" |
| 954 | ><A |
| 955 | HREF="index.html" |
| 956 | ACCESSKEY="H" |
| 957 | >Home</A |
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| 960 | WIDTH="33%" |
| 961 | ALIGN="right" |
| 962 | VALIGN="top" |
| 963 | ><A |
| 964 | HREF="sdlactiveevent.html" |
| 965 | ACCESSKEY="N" |
| 966 | >Next</A |
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| 969 | ><TR |
| 970 | ><TD |
| 971 | WIDTH="33%" |
| 972 | ALIGN="left" |
| 973 | VALIGN="top" |
| 974 | >SDL Event Structures.</TD |
| 975 | ><TD |
| 976 | WIDTH="34%" |
| 977 | ALIGN="center" |
| 978 | VALIGN="top" |
| 979 | ><A |
| 980 | HREF="eventstructures.html" |
| 981 | ACCESSKEY="U" |
| 982 | >Up</A |
| 983 | ></TD |
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| 985 | WIDTH="33%" |
| 986 | ALIGN="right" |
| 987 | VALIGN="top" |
| 988 | >SDL_ActiveEvent</TD |
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| 990 | ></TABLE |
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| 994 | > |