Mercurial > sdl-ios-xcode
view docs/man3/SDL_SetEventFilter.3 @ 1544:ab1e4c41ab71
Fixed bug #33
Mike Frysinger wrote:
> with libsdl-1.2.9, some games (like bomberclone) started
> segfaulting in Gentoo
[...snip...]
> the last change in the last hunk:
[...snip...]
> if i change the statement to read:
> (table[which].blit_features & GetBlitFeatures()) == GetBlitFeatures()
> bomberclone no longer segfaults on my box
Alex Volkov wrote:
> The test "(table[which].blit_features & GetBlitFeatures()) ==
> table[which].blit_features)" is correct, and the previous
> "(table[which].cpu_mmx == SDL_HasMMX())" was actually broken.
I think there is potentially a slightly different cause of the above problem.
During the introduction of the Altivec code, the blit_table struct field
'alpha' got changed from a straightforward enum to a bitmask, which makes
perfect sense by itself. However, now the table driven blitter selection code
in SDL_CalculateBlitN() can choose the wrong blitters when searching for a
NO_ALPHA blitter because of the following code:
int a_need = 0;
...
(a_need & table[which].alpha) == a_need &&
When searching through the normal_blit_2[] table, a SET_ALPHA blitter (like
Blit_RGB565_ARGB8888) can now be selected instead of a NO_ALPHA one, causing
alpha channel bits to appear in a non-alpha destination surface. I suppose this
could theoretically be an indirect cause of the segfault mentioned above.
I *think* this can be fixed by changing to
int a_need = NO_ALPHA;
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Wed, 15 Mar 2006 15:47:49 +0000 |
| parents | e5bc29de3f0a |
| children | 546f7c1eb755 |
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.TH "SDL_SetEventFilter" "3" "Tue 11 Sep 2001, 22:59" "SDL" "SDL API Reference" .SH "NAME" SDL_SetEventFilter\- Sets up a filter to process all events before they are posted to the event queue\&. .SH "SYNOPSIS" .PP \fB#include "SDL\&.h" .sp \fBvoid \fBSDL_SetEventFilter\fP\fR(\fBSDL_EventFilter filter\fR); .SH "DESCRIPTION" .PP This function sets up a filter to process all events before they are posted to the event queue\&. This is a very powerful and flexible feature\&. The filter is prototyped as: .PP .nf \f(CWtypedef int (*SDL_EventFilter)(const SDL_Event *event);\fR .fi .PP If the filter returns \fB1\fR, then the event will be added to the internal queue\&. If it returns \fB0\fR, then the event will be dropped from the queue\&. This allows selective filtering of dynamically\&. .PP There is one caveat when dealing with the \fBSDL_QUITEVENT\fP 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\&. .PP .RS \fBNote: .PP Events pushed onto the queue with \fI\fBSDL_PushEvent\fP\fR or \fI\fBSDL_PeepEvents\fP\fR do not get passed through the event filter\&. .RE .PP .RS \fBNote: .PP \fIBe Careful!\fP The event filter function may run in a different thread so be careful what you do within it\&. .RE .SH "SEE ALSO" .PP \fI\fBSDL_Event\fR\fR, \fI\fBSDL_GetEventFilter\fP\fR, \fI\fBSDL_PushEvent\fP\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:59