Mercurial > sdl-ios-xcode
view docs/man3/SDL_JoyButtonEvent.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> |
---|---|
date | Sat, 03 Oct 2009 16:23:16 +0000 |
parents | 546f7c1eb755 |
children | 1238da4a7112 |
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.TH "SDL_JoyButtonEvent" "3" "Tue 11 Sep 2001, 22:59" "SDL" "SDL API Reference" .SH "NAME" SDL_JoyButtonEvent \- Joystick button event structure .SH "STRUCTURE DEFINITION" .PP .nf \f(CWtypedef struct{ Uint8 type; Uint8 which; Uint8 button; Uint8 state; } SDL_JoyButtonEvent;\fR .fi .PP .SH "STRUCTURE DATA" .TP 20 \fBtype\fR \fBSDL_JOYBUTTONDOWN\fP or \fBSDL_JOYBUTTONUP\fP .TP 20 \fBwhich\fR Joystick device index .TP 20 \fBbutton\fR Joystick button index .TP 20 \fBstate\fR \fBSDL_PRESSED\fP or \fBSDL_RELEASED\fP .SH "DESCRIPTION" .PP \fBSDL_JoyButtonEvent\fR is a member of the \fI\fBSDL_Event\fR\fR union and is used when an event of type \fBSDL_JOYBUTTONDOWN\fP or \fBSDL_JOYBUTTONUP\fP is reported\&. .PP A \fBSDL_JOYBUTTONDOWN\fP or \fBSDL_JOYBUTTONUP\fP event occurs when ever a user presses or releases a button on a joystick\&. The field \fBwhich\fR is the index of the joystick that reported the event and \fBbutton\fR is the index of the button (for a more detailed explaination see the \fIJoystick section\fR)\&. \fBstate\fR is the current state or the button which is either \fBSDL_PRESSED\fP or \fBSDL_RELEASED\fP\&. .SH "SEE ALSO" .PP \fI\fBSDL_Event\fR\fR, \fIJoystick Functions\fR, \fI\fBSDL_JoystickEventState\fP\fR, \fI\fBSDL_JoystickGetButton\fP\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:59