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annotate docs/man3/SDL_UserEvent.3 @ 3333:b334b4f7dfa0
[SDL] Bad math in SDL_RenderCopy
Mason Wheeler to sdl
When I tried to render an image using something other than NULL for srcrect, it got horribly distorted. I traced it down to the fact that the math in the rectangle adjustments performed just before the call to renderer->RenderCopy is written inside out. It should look like this:
if (dstrect->w != real_dstrect.w) {
int deltax = (dstrect->x - real_dstrect.x);
int deltaw = (dstrect->w - real_dstrect.w);
real_srcrect.x += (deltax * real_srcrect.w) / dstrect->w;
real_srcrect.w += (deltaw * real_srcrect.w) / dstrect->w;
}
if (dstrect->h != real_dstrect.h) {
int deltay = (dstrect->y - real_dstrect.y);
int deltah = (dstrect->h - real_dstrect.h);
real_srcrect.y += (deltay * real_srcrect.h) / dstrect->h;
real_srcrect.h += (deltah * real_srcrect.h) / dstrect->h;
author | Sam Lantinga <slouken@libsdl.org> |
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date | Sat, 03 Oct 2009 16:23:16 +0000 |
parents | 546f7c1eb755 |
children | 1238da4a7112 |
rev | line source |
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181
e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
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1 .TH "SDL_UserEvent" "3" "Tue 11 Sep 2001, 23:00" "SDL" "SDL API Reference" |
0 | 2 .SH "NAME" |
2283
546f7c1eb755
Merged revision 3472 from SDL 1.2, fixing bug #493
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
3 SDL_UserEvent \- A user-defined event type |
0 | 4 .SH "STRUCTURE DEFINITION" |
5 .PP | |
6 .nf | |
7 \f(CWtypedef struct{ | |
8 Uint8 type; | |
9 int code; | |
10 void *data1; | |
11 void *data2; | |
12 } SDL_UserEvent;\fR | |
13 .fi | |
14 .PP | |
15 .SH "STRUCTURE DATA" | |
16 .TP 20 | |
17 \fBtype\fR | |
18 \fBSDL_USEREVENT\fP through to \fBSDL_NUMEVENTS-1\fP | |
19 .TP 20 | |
20 \fBcode\fR | |
21 User defined event code | |
22 .TP 20 | |
23 \fBdata1\fR | |
24 User defined data pointer | |
25 .TP 20 | |
26 \fBdata2\fR | |
27 User defined data pointer | |
28 .SH "DESCRIPTION" | |
29 .PP | |
30 \fBSDL_UserEvent\fR is in the \fBuser\fR member of the structure \fI\fBSDL_Event\fR\fR\&. This event is unique, it is never created by SDL but only by the user\&. The event can be pushed onto the event queue using \fI\fBSDL_PushEvent\fP\fR\&. The contents of the structure members or completely up to the programmer, the only requirement is that \fBtype\fR is a value from \fBSDL_USEREVENT\fP to \fBSDL_NUMEVENTS-1\fP (inclusive)\&. | |
31 .SH "EXAMPLES" | |
32 .PP | |
33 .PP | |
34 .nf | |
35 \f(CWSDL_Event event; | |
36 | |
37 event\&.type = SDL_USEREVENT; | |
38 event\&.user\&.code = my_event_code; | |
39 event\&.user\&.data1 = significant_data; | |
40 event\&.user\&.data2 = 0; | |
41 SDL_PushEvent(&event);\fR | |
42 .fi | |
43 .PP | |
44 .SH "SEE ALSO" | |
45 .PP | |
46 \fI\fBSDL_Event\fR\fR, \fI\fBSDL_PushEvent\fP\fR | |
181
e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
|
47 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:00 |