Mercurial > sdl-ios-xcode
annotate docs/man3/SDL_DisplayFormatAlpha.3 @ 872:e7be95d758e8
Date: Fri, 05 Mar 2004 16:08:01 +0000
From: Alan Swanson
Subject: Re: [SDL] Fatal signal when initiaize with USB joystick on 2.6.2 kern
On Fri, 2004-03-05 at 15:09, Sam Lantinga wrote:
> > Fred, how does the attached patch work for you? Do all your axes work?
>
> I think you meant the two lines to be reversed.
> I checked a more robust version of this into CVS. Fred, can you see if
> it works?
You've misread the code. :-/
For coef[0] and coef[1], it is (values[2]+values[1]) / 2 and then add
or subtract values[4] to the answer.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sat, 06 Mar 2004 02:58:06 +0000 |
| parents | e5bc29de3f0a |
| children | 546f7c1eb755 |
| rev | line source |
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1 .TH "SDL_DisplayFormatAlpha" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" |
| 0 | 2 .SH "NAME" |
| 3 SDL_DisplayFormatAlpha\- Convert a surface to the display format | |
| 4 .SH "SYNOPSIS" | |
| 5 .PP | |
| 6 \fB#include "SDL\&.h" | |
| 7 .sp | |
| 8 \fBSDL_Surface *\fBSDL_DisplayFormatAlpha\fP\fR(\fBSDL_Surface *surface\fR); | |
| 9 .SH "DESCRIPTION" | |
| 10 .PP | |
| 11 This function takes a surface and copies it to a new surface of the pixel format and colors of the video framebuffer plus an alpha channel, suitable for fast blitting onto the display surface\&. It calls \fISDL_ConvertSurface\fR | |
| 12 .PP | |
| 13 If you want to take advantage of hardware colorkey or alpha blit acceleration, you should set the colorkey and alpha value before calling this function\&. | |
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14 .PP |
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15 This function can be used to convert a colourkey to an alpha channel, if the \fBSDL_SRCCOLORKEY\fP flag is set on the surface\&. The generated surface will then be transparent (alpha=0) where the pixels match the colourkey, and opaque (alpha=255) elsewhere\&. |
| 0 | 16 .SH "RETURN VALUE" |
| 17 .PP | |
| 18 If the conversion fails or runs out of memory, it returns \fBNULL\fR | |
| 19 .SH "SEE ALSO" | |
| 20 .PP | |
| 21 \fISDL_ConvertSurface\fR, \fISDL_SetAlpha\fR, \fISDL_SetColorKey\fR, \fISDL_DisplayFormat\fR, \fISDL_Surface\fR | |
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22 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01 |