Mercurial > sdl-ios-xcode
annotate docs/man3/SDL_SetAlpha.3 @ 4391:07b330419439 SDL-1.2
Fixed bug #849 some more:
Tim Angus 2009-11-26 14:41:04 PST
Fix to the cursor not being responsive when the app doesn't have
SDL_APPINPUTFOCUS
The problems with the directx driver are similar to the ones I introduced in
the windib driver with r4478. Basically if the application did not have focus,
the mouse position is not updated. It's not really that the mouse cursor was
invisible, it's that it is stuck underneath another window where you can't see
it. This behaviour predates my r4478 changes and is the reason I unwittingly
broke the windib driver as I had been replicating the way the directx driver
deals with focus. Prior to r4478 the directx driver could not be used in
windowed mode, so the broken focusing would not have actually been observable.
Anyway, the attached patch makes the directx driver behaves like the windib
driver in terms of focus.
Time for 1.2.15? ;)
I've added an additional change of moving the calls to WIN_GrabInput that are
made on WM_ACTIVATE messages so that they only occur when the state is
SDL_APPINPUTFOCUS. When a fullscreen application is minimised using alt-tab, it
still receives WM_ACTIVATE messages when other applications are selected. If
WIN_GrabInput is called when the SDL application doesn't have input focus, bad
things happen; it shouldn't be being called at all.
I've also added a line to make sure that SDL_APPMOUSEFOCUS state is dropped
when the application is minimised following an alt-tab.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Fri, 11 Dec 2009 15:24:53 +0000 |
| parents | 1238da4a7112 |
| children |
| rev | line source |
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Updated from the SDL Documentation Project
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1 .TH "SDL_SetAlpha" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" |
| 0 | 2 .SH "NAME" |
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3 SDL_SetAlpha \- Adjust the alpha properties of a surface |
| 0 | 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 | |
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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 | |
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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\&. | |
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52 .PP |
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53 .RS |
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54 \fBNote: |
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55 .PP |
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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\&. |
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57 .PP |
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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 |
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59 .RE |
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60 .SH "RETURN VALUE" |
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61 .PP |
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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 | |
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66 .\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01 |