Mercurial > sdl-ios-xcode
annotate docs/man3/SDL_SetAlpha.3 @ 1584:b786d9c15e42
Fixed bug #61
Date: Mon, 24 Feb 2003 13:35:11 +0800
From: "Leonidas"
Subject: [SDL] Re: Trigger mouse wheel event -- not in X-environment
I have looked into the codes for the IMPS/2 mouse wheel mode of fbcon driver.
But I found something weird.
Here's the original codes to set a mouse device into IMPS/2 mode in libSDL.
In the file src/video/fbcon/SDL_fbevents.c
In function static int set_imps2_mode(int fd)
...
Uint8 set_imps2[] = {0xf3, 200, 0xf3, 100, 0xf3, 80};
Uint8 reset = 0xff;
fd_set fdset;
struct timeval tv;
int retval = 0;
// Set mouse device fd into IMPS/2 mode
if ( write(fd, &set_imps2, sizeof(set_imps2)) == sizeof(set_imps2) ) {
// ??? then RESET it..???
if (write(fd, &reset, sizeof (reset)) == sizeof (reset) ) {
retval = 1;
}
}
...........
Since it sets IMPS/2 mode then reset it, so you will never get a mouse into
IMPS/2 mode to use its wheel.
What I did to make the wheel usable is remove the RESET codes.
....
if ( write(fd, &set_imps2, sizeof(set_imps2)) == sizeof(set_imps2) ) {
/*
if (write(fd, &reset, sizeof (reset)) == sizeof (reset) ) {
}
*/
retval = 1;
}
....
And in FB_OpenMouse(_THIS)
Make the device /dev/psaux to be setted into imps2 mode such that it can be
detected its a imps/2 mouse or not.
(my mouse device is on ps2, but the codes only set /dev/input/mice device
originally)
Then I have done, I can use the mouse wheel when SDL uses frame buff driver.
I dont exactly know I did right or wrong, I just change it for my usuage.
Correct me please, if I did something wrong.
Best regards,
Li Tsung Lin
IAP Product Dept. Engineer
EeRise Corp. (Image Processing System, Computer Vision System)
Hsin Tien, Taipei Hsien, Taiwan, R.O.C.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Wed, 22 Mar 2006 07:22:40 +0000 |
| parents | e5bc29de3f0a |
| children | 546f7c1eb755 |
| rev | line source |
|---|---|
|
181
e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
|
1 .TH "SDL_SetAlpha" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" |
| 0 | 2 .SH "NAME" |
| 3 SDL_SetAlpha\- Adjust the alpha properties of a surface | |
| 4 .SH "SYNOPSIS" | |
| 5 .PP | |
| 6 \fB#include "SDL\&.h" | |
| 7 .sp | |
| 8 \fBint \fBSDL_SetAlpha\fP\fR(\fBSDL_Surface *surface, Uint32 flag, Uint8 alpha\fR); | |
| 9 .SH "DESCRIPTION" | |
| 10 .PP | |
| 11 .RS | |
| 12 \fBNote: | |
| 13 .PP | |
| 14 This function and the semantics of SDL alpha blending have changed since version 1\&.1\&.4\&. Up until version 1\&.1\&.5, an alpha value of 0 was considered opaque and a value of 255 was considered transparent\&. This has now been inverted: 0 (\fBSDL_ALPHA_TRANSPARENT\fP) is now considered transparent and 255 (\fBSDL_ALPHA_OPAQUE\fP) is now considered opaque\&. | |
| 15 .RE | |
| 16 .PP | |
|
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17 \fBSDL_SetAlpha\fP is used for setting the per-surface alpha value and/or enabling and disabling alpha blending\&. |
| 0 | 18 .PP |
|
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19 The\fBsurface\fR parameter specifies which surface whose alpha attributes you wish to adjust\&. \fBflags\fR is used to specify whether alpha blending should be used (\fBSDL_SRCALPHA\fP) and whether the surface should use RLE acceleration for blitting (\fBSDL_RLEACCEL\fP)\&. \fBflags\fR can be an OR\&'d combination of these two options, one of these options or 0\&. If \fBSDL_SRCALPHA\fP is not passed as a flag then all alpha information is ignored when blitting the surface\&. The \fBalpha\fR parameter is the per-surface alpha value; a surface need not have an alpha channel to use per-surface alpha and blitting can still be accelerated with \fBSDL_RLEACCEL\fP\&. |
| 0 | 20 .PP |
| 21 .RS | |
| 22 \fBNote: | |
| 23 .PP | |
| 24 The per-surface alpha value of 128 is considered a special case and is optimised, so it\&'s much faster than other per-surface values\&. | |
| 25 .RE | |
| 26 .PP | |
| 27 Alpha effects surface blitting in the following ways: | |
| 28 .TP 20 | |
| 29 RGBA->RGB with \fBSDL_SRCALPHA\fP | |
| 30 The source is alpha-blended with the destination, using the alpha channel\&. \fBSDL_SRCCOLORKEY\fP and the per-surface alpha are ignored\&. | |
| 31 .TP 20 | |
| 32 RGBA->RGB without \fBSDL_SRCALPHA\fP | |
| 33 The RGB data is copied from the source\&. The source alpha channel and the per-surface alpha value are ignored\&. | |
| 34 .TP 20 | |
| 35 RGB->RGBA with \fBSDL_SRCALPHA\fP | |
|
55
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
36 The source is alpha-blended with the destination using the per-surface alpha value\&. If \fBSDL_SRCCOLORKEY\fP is set, only the pixels not matching the colorkey value are copied\&. The alpha channel of the copied pixels is set to opaque\&. |
| 0 | 37 .TP 20 |
| 38 RGB->RGBA without \fBSDL_SRCALPHA\fP | |
|
55
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
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39 The RGB data is copied from the source and the alpha value of the copied pixels is set to opaque\&. If \fBSDL_SRCCOLORKEY\fP is set, only the pixels not matching the colorkey value are copied\&. |
| 0 | 40 .TP 20 |
| 41 RGBA->RGBA with \fBSDL_SRCALPHA\fP | |
| 42 The source is alpha-blended with the destination using the source alpha channel\&. The alpha channel in the destination surface is left untouched\&. \fBSDL_SRCCOLORKEY\fP is ignored\&. | |
| 43 .TP 20 | |
| 44 RGBA->RGBA without \fBSDL_SRCALPHA\fP | |
| 45 The RGBA data is copied to the destination surface\&. If \fBSDL_SRCCOLORKEY\fP is set, only the pixels not matching the colorkey value are copied\&. | |
| 46 .TP 20 | |
| 47 RGB->RGB with \fBSDL_SRCALPHA\fP | |
| 48 The source is alpha-blended with the destination using the per-surface alpha value\&. If \fBSDL_SRCCOLORKEY\fP is set, only the pixels not matching the colorkey value are copied\&. | |
| 49 .TP 20 | |
| 50 RGB->RGB without \fBSDL_SRCALPHA\fP | |
| 51 The RGB data is copied from the source\&. If \fBSDL_SRCCOLORKEY\fP is set, only the pixels not matching the colorkey value are copied\&. | |
|
55
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
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52 .PP |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
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diff
changeset
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53 .RS |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
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diff
changeset
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54 \fBNote: |
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55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
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55 .PP |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
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56 Note that RGBA->RGBA blits (with SDL_SRCALPHA set) keep the alpha of the destination surface\&. This means that you cannot compose two arbitrary RGBA surfaces this way and get the result you would expect from "overlaying" them; the destination alpha will work as a mask\&. |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
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57 .PP |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
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58 Also note that per-pixel and per-surface alpha cannot be combined; the per-pixel alpha is always used if available |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
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59 .RE |
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55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
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60 .SH "RETURN VALUE" |
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55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
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diff
changeset
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61 .PP |
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55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
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diff
changeset
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62 This function returns \fB0\fR, or \fB-1\fR if there was an error\&. |
| 0 | 63 .SH "SEE ALSO" |
| 64 .PP | |
| 65 \fI\fBSDL_MapRGBA\fP\fR, \fI\fBSDL_GetRGBA\fP\fR, \fI\fBSDL_DisplayFormatAlpha\fP\fR, \fI\fBSDL_BlitSurface\fP\fR | |
|
181
e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
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66 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01 |