From 9682c8870b8ff5e4ac2e4c70b759f791c6f38c1f Mon Sep 17 00:00:00 2001 From: Jesse Hall Date: Mon, 9 Jul 2012 11:27:07 -0700 Subject: Import SDL release-1.2.15 Change-Id: I505c4aea24325cad475f217db5589814b4c75dbf --- distrib/sdl-1.2.15/docs/html/sdlevent.html | 994 +++++++++++++++++++++++++++++ 1 file changed, 994 insertions(+) create mode 100644 distrib/sdl-1.2.15/docs/html/sdlevent.html (limited to 'distrib/sdl-1.2.15/docs/html/sdlevent.html') diff --git a/distrib/sdl-1.2.15/docs/html/sdlevent.html b/distrib/sdl-1.2.15/docs/html/sdlevent.html new file mode 100644 index 0000000..dfd21b7 --- /dev/null +++ b/distrib/sdl-1.2.15/docs/html/sdlevent.html @@ -0,0 +1,994 @@ +SDL_Event
SDL Library Documentation
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SDL_Event

Name

SDL_Event -- General event structure

Structure Definition

typedef union{
+  Uint8 type;
+  SDL_ActiveEvent active;
+  SDL_KeyboardEvent key;
+  SDL_MouseMotionEvent motion;
+  SDL_MouseButtonEvent button;
+  SDL_JoyAxisEvent jaxis;
+  SDL_JoyBallEvent jball;
+  SDL_JoyHatEvent jhat;
+  SDL_JoyButtonEvent jbutton;
+  SDL_ResizeEvent resize;
+  SDL_ExposeEvent expose;
+  SDL_QuitEvent quit;
+  SDL_UserEvent user;
+  SDL_SysWMEvent syswm;
+} SDL_Event;

Structure Data

typeThe type of event
activeActivation event
keyKeyboard event
motionMouse motion event
buttonMouse button event
jaxisJoystick axis motion event
jballJoystick trackball motion event
jhatJoystick hat motion event
jbuttonJoystick button event
resizeApplication window resize event
exposeApplication window expose event
quitApplication quit request event
userUser defined event
syswmUndefined window manager event

Description

The SDL_Event union is the core to all event handling is SDL, its probably the most important structure after SDL_Surface. SDL_Event 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 type.

Event typeEvent Structure
SDL_ACTIVEEVENTSDL_ActiveEvent
SDL_KEYDOWN/UPSDL_KeyboardEvent
SDL_MOUSEMOTIONSDL_MouseMotionEvent
SDL_MOUSEBUTTONDOWN/UPSDL_MouseButtonEvent
SDL_JOYAXISMOTIONSDL_JoyAxisEvent
SDL_JOYBALLMOTIONSDL_JoyBallEvent
SDL_JOYHATMOTIONSDL_JoyHatEvent
SDL_JOYBUTTONDOWN/UPSDL_JoyButtonEvent
SDL_QUITSDL_QuitEvent
SDL_SYSWMEVENTSDL_SysWMEvent
SDL_VIDEORESIZESDL_ResizeEvent
SDL_VIDEOEXPOSESDL_ExposeEvent
SDL_USEREVENTSDL_UserEvent

Use

The SDL_Event structure has two uses

Reading events from the event queue is done with either SDL_PollEvent or SDL_PeepEvents. We'll use SDL_PollEvent and step through an example.

First off, we create an empty SDL_Event structure. +

SDL_Event test_event;
+SDL_PollEvent removes the next event from the event queue, if there are no events on the queue it returns 0 otherwise it returns 1. We use a while loop to process each event in turn. +
while(SDL_PollEvent(&test_event)) {
+The SDL_PollEvent function take a pointer to an SDL_Event structure that is to be filled with event information. We know that if SDL_PollEvent removes an event from the queue then the event information will be placed in our test_event structure, but we also know that the type of event will be placed in the type member of test_event. So to handle each event type seperately we use a switch statement. +
  switch(test_event.type) {
+We need to know what kind of events we're looking for and the event type'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 SDL_MOUSEMOTION is, more than likely, the event we're looking for. A little more research tells use that SDL_MOUSEMOTION events are handled within the SDL_MouseMotionEvent structure which is the motion member of SDL_Event. We can check for the SDL_MOUSEMOTION event type within our switch statement like so: +
    case SDL_MOUSEMOTION:
+All we need do now is read the information out of the motion member of test_event. +
      printf("We got a motion event.\n");
+      printf("Current mouse position is: (%d, %d)\n", test_event.motion.x, test_event.motion.y);
+      break;
+    default:
+      printf("Unhandled Event!\n");
+      break;
+  }
+}
+printf("Event queue empty.\n");

It is also possible to push events onto the event queue and so use it as a two-way communication path. Both SDL_PushEvent and SDL_PeepEvents allow you to place events onto the event queue. This is usually used to place a SDL_USEREVENT 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 type member and filling the appropriate member structure with information. +

SDL_Event user_event;
+
+user_event.type=SDL_USEREVENT;
+user_event.user.code=2;
+user_event.user.data1=NULL;
+user_event.user.data2=NULL;
+SDL_PushEvent(&user_event);

See Also

SDL_PollEvent, +SDL_PushEvent, +SDL_PeepEvents

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