|
Size: 2456
Comment: correct typo; camelcase
|
Size: 2468
Comment: update content for consistency - callback (rv indent)
|
| Deletions are marked like this. | Additions are marked like this. |
| Line 17: | Line 17: |
| ||'''filter'''||a function that gets called when an event happens; see [[#Remarks|Remarks]] for details|| ||'''userdata'''||^a pointer to the event queue to filter^|| |
||'''filter'''||the function to call when an event happens; see [[#Remarks|Remarks]] for details|| ||'''userdata'''||a pointer that is passed to '''filter'''|| |
| Line 28: | Line 28: |
| The '''filter''' function has the following form: | The function prototype for '''filter''' is: |
| Line 34: | Line 34: |
| where `YourEventFilter` is the name of your function, `userdata` is what was passed as '''userdata''' to [[SDL_SetEventFilter]](), and `event` is the event that triggered the callback. | . where `YourEventFilter` is the name of your function and its parameters are: ||`userdata`||what was passed as '''userdata''' to [[SDL_SetEventFilter]]()|| ||`event`||the event that triggered the callback|| |
| Line 36: | Line 38: |
If the '''filter''' returns 1, then the event will be added to the internal queue. If it returns 0, then the event will be dropped from the queue, but the internal state will still be updated. This allows selective filtering of dynamically arriving events. |
. If '''filter''' returns 1, then the event will be added to the internal queue. If it returns 0, then the event will be dropped from the queue, but the internal state will still be updated. This allows selective filtering of dynamically arriving events. |
DRAFT |
SDL_SetEventFilter
Use this function to set up a filter to process all events before they change internal state and are posted to the internal event queue.
Syntax
void SDL_SetEventFilter(SDL_EventFilter filter,
void* userdata)
Function Parameters
filter |
the function to call when an event happens; see Remarks for details |
userdata |
a pointer that is passed to filter |
Code Examples
You can add your code example here
Remarks
The function prototype for filter is:
int YourEventFilter(void* userdata, SDL_Event* event)
where YourEventFilter is the name of your function and its parameters are:
userdata
what was passed as userdata to SDL_SetEventFilter()
event
the event that triggered the callback
If filter returns 1, then the event will be added to the internal queue. If it returns 0, then the event will be dropped from the queue, but the internal state will still be updated. This allows selective filtering of dynamically arriving events.
![/!\](/moin_static198/fixedleft/img/alert.png "/!\"){kind=small}
Be very careful of what you do in the event filter function, as it may run in a different thread!
There is one caveat when dealing with the SDL_QUITEVENT 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.
green
*Note: Events pushed onto the queue with SDL_PushEvent() or SDL_PeepEvents() do not get passed through the event filter.*
Related Functions
SDL_PeepEvents *???
SDL_PushEvent *???
