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annotate docs/man3/SDL_GetRGBA.3 @ 1240:3b8a43c428bb

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From Bug #36: There are a couple of issues with the selection of Altivec alpha-blitting routines in CalculateAlphaBlit() in src/video/SDL_Blit_A.c. 1) There's no check for the presence of Altivec when checking if the Blit32to565PixelAlphaAltivec() routine can be selected. 2) Altivec cannot be used in video memory, and there's no check if the destination surface is a hardware surface. (Alpha-blitting to a hardware surface with GPU support is a bad idea, but somebody's bound to do it anyway.) Patch to fix these attached.
author Ryan C. Gordon <icculus@icculus.org>
date Sun, 08 Jan 2006 21:18:15 +0000
parents e5bc29de3f0a
children 546f7c1eb755
rev   line source
181
e5bc29de3f0a Updated from the SDL Documentation Project
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1 .TH "SDL_GetRGBA" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference"
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2 .SH "NAME"
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3 SDL_GetRGBA\- Get RGBA values from a pixel in the specified pixel format\&.
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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 \fBvoid \fBSDL_GetRGBA\fP\fR(\fBUint32 pixel, SDL_PixelFormat *fmt, Uint8 *r, Uint8 *g, Uint8 *b, Uint8 *a\fR);
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9 .SH "DESCRIPTION"
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10 .PP
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11 Get RGBA component values from a pixel stored in the specified pixel format\&.
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12 .PP
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13 This function uses the entire 8-bit [0\&.\&.255] range when converting color components from pixel formats with less than 8-bits per RGB component (e\&.g\&., a completely white pixel in 16-bit RGB565 format would return [0xff, 0xff, 0xff] not [0xf8, 0xfc, 0xf8])\&.
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14 .PP
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15 If the surface has no alpha component, the alpha will be returned as 0xff (100% opaque)\&.
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16 .SH "SEE ALSO"
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17 .PP
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18 \fISDL_GetRGB\fR, \fISDL_MapRGB\fR, \fISDL_MapRGBA\fR, \fISDL_PixelFormat\fR
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19 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01