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[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
line wrap: on
line source

.TH "SDL_Overlay" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" 
.SH "NAME"
SDL_Overlay \- YUV video overlay
.SH "STRUCTURE DEFINITION"
.PP
.nf
\f(CWtypedef struct{
  Uint32 format;
  int w, h;
  int planes;
  Uint16 *pitches;
  Uint8 **pixels;
  Uint32 hw_overlay:1;
} SDL_Overlay;\fR
.fi
.PP
.SH "STRUCTURE DATA"
.TP 20
\fBformat\fR
Overlay format (see below)
.TP 20
\fBw, h\fR
Width and height of overlay
.TP 20
\fBplanes\fR
Number of planes in the overlay\&. Usually either 1 or 3
.TP 20
\fBpitches\fR
An array of pitches, one for each plane\&. Pitch is the length of a row in bytes\&.
.TP 20
\fBpixels\fR
An array of pointers to teh data of each plane\&. The overlay should be locked before these pointers are used\&.
.TP 20
\fBhw_overlay\fR
This will be set to 1 if the overlay is hardware accelerated\&.
.SH "DESCRIPTION"
.PP
A \fBSDL_Overlay\fR is similar to a \fI\fBSDL_Surface\fR\fR except it stores a YUV overlay\&. All the fields are read only, except for \fBpixels\fR which should be \fIlocked\fR before use\&. The \fBformat\fR field stores the format of the overlay which is one of the following: 
.PP
.nf
\f(CW#define SDL_YV12_OVERLAY  0x32315659  /* Planar mode: Y + V + U */
#define SDL_IYUV_OVERLAY  0x56555949  /* Planar mode: Y + U + V */
#define SDL_YUY2_OVERLAY  0x32595559  /* Packed mode: Y0+U0+Y1+V0 */
#define SDL_UYVY_OVERLAY  0x59565955  /* Packed mode: U0+Y0+V0+Y1 */
#define SDL_YVYU_OVERLAY  0x55595659  /* Packed mode: Y0+V0+Y1+U0 */\fR
.fi
.PP
 More information on YUV formats can be found at \fIhttp://www\&.webartz\&.com/fourcc/indexyuv\&.htm (link to URL http://www.webartz.com/fourcc/indexyuv.htm) \fR\&.
.SH "SEE ALSO"
.PP
\fI\fBSDL_CreateYUVOverlay\fP\fR, \fI\fBSDL_LockYUVOverlay\fP\fR, \fI\fBSDL_UnlockYUVOverlay\fP\fR, \fI\fBSDL_FreeYUVOverlay\fP\fR
...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01