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annotate docs/man3/SDL_SetColorKey.3 @ 2042:3908e1f808e1

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Fixed bug #292 I might be on crack here. It looks like SDL_ConvertMono() in src/audio/SDL_audiocvt.c adds the left and right channels of a stereo stream together, and clamps the new mono channel if it would overflow. Shouldn't it be dividing by 2 to average the two sample points instead of clamping? Otherwise the mono sample point's volume doubles in the conversion. This would also make the conversion faster, as it replaces two branches per sample frame with a bitwise shift. --ryan.
author Sam Lantinga <slouken@libsdl.org>
date Sun, 24 Sep 2006 15:56:36 +0000
parents e5bc29de3f0a
children 546f7c1eb755
rev   line source
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e5bc29de3f0a Updated from the SDL Documentation Project
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1 .TH "SDL_SetColorKey" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference"
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2 .SH "NAME"
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3 SDL_SetColorKey\- Sets the color key (transparent pixel) in a blittable surface and RLE acceleration\&.
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4 .SH "SYNOPSIS"
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5 .PP
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6 \fB#include "SDL\&.h"
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7 .sp
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8 \fBint \fBSDL_SetColorKey\fP\fR(\fBSDL_Surface *surface, Uint32 flag, Uint32 key\fR);
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9 .SH "DESCRIPTION"
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10 .PP
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11 Sets the color key (transparent pixel) in a blittable surface and enables or disables RLE blit acceleration\&.
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12 .PP
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13 RLE acceleration can substantially speed up blitting of images with large horizontal runs of transparent pixels (i\&.e\&., pixels that match the \fBkey\fR value)\&. The \fBkey\fR must be of the same pixel format as the \fBsurface\fR, \fI\fBSDL_MapRGB\fP\fR is often useful for obtaining an acceptable value\&.
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14 .PP
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15 If \fBflag\fR is \fBSDL_SRCCOLORKEY\fP then \fBkey\fR is the transparent pixel value in the source image of a blit\&.
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16 .PP
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17 If \fBflag\fR is OR\&'d with \fBSDL_RLEACCEL\fP then the surface will be draw using RLE acceleration when drawn with \fISDL_BlitSurface\fR\&. The surface will actually be encoded for RLE acceleration the first time \fISDL_BlitSurface\fR or \fISDL_DisplayFormat\fR is called on the surface\&.
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18 .PP
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19 If \fBflag\fR is 0, this function clears any current color key\&.
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20 .SH "RETURN VALUE"
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21 .PP
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22 This function returns \fB0\fR, or \fB-1\fR if there was an error\&.
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23 .SH "SEE ALSO"
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24 .PP
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25 \fI\fBSDL_BlitSurface\fP\fR, \fI\fBSDL_DisplayFormat\fP\fR, \fI\fBSDL_MapRGB\fP\fR, \fI\fBSDL_SetAlpha\fP\fR
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26 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01