Mercurial > sdl-ios-xcode
annotate docs/man3/SDL_PixelFormat.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_PixelFormat" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" |
| 0 | 2 .SH "NAME" |
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3 SDL_PixelFormat \- Stores surface format information |
| 0 | 4 .SH "STRUCTURE DEFINITION" |
| 5 .PP | |
| 6 .nf | |
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7 \f(CWtypedef struct SDL_PixelFormat { |
| 0 | 8 SDL_Palette *palette; |
| 9 Uint8 BitsPerPixel; | |
| 10 Uint8 BytesPerPixel; | |
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11 Uint8 Rloss, Gloss, Bloss, Aloss; |
| 0 | 12 Uint8 Rshift, Gshift, Bshift, Ashift; |
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13 Uint32 Rmask, Gmask, Bmask, Amask; |
| 0 | 14 Uint32 colorkey; |
| 15 Uint8 alpha; | |
| 16 } SDL_PixelFormat;\fR | |
| 17 .fi | |
| 18 .PP | |
| 19 .SH "STRUCTURE DATA" | |
| 20 .TP 20 | |
| 21 \fBpalette\fR | |
| 22 Pointer to the \fIpalette\fR, or \fBNULL\fP if the \fBBitsPerPixel\fR>8 | |
| 23 .TP 20 | |
| 24 \fBBitsPerPixel\fR | |
| 25 The number of bits used to represent each pixel in a surface\&. Usually 8, 16, 24 or 32\&. | |
| 26 .TP 20 | |
| 27 \fBBytesPerPixel\fR | |
| 28 The number of bytes used to represent each pixel in a surface\&. Usually one to four\&. | |
| 29 .TP 20 | |
| 30 \fB[RGBA]mask\fR | |
| 31 Binary mask used to retrieve individual color values | |
| 32 .TP 20 | |
| 33 \fB[RGBA]loss\fR | |
| 34 Precision loss of each color component (2^[RGBA]loss) | |
| 35 .TP 20 | |
| 36 \fB[RGBA]shift\fR | |
| 37 Binary left shift of each color component in the pixel value | |
| 38 .TP 20 | |
| 39 \fBcolorkey\fR | |
| 40 Pixel value of transparent pixels | |
| 41 .TP 20 | |
| 42 \fBalpha\fR | |
| 43 Overall surface alpha value | |
| 44 .SH "DESCRIPTION" | |
| 45 .PP | |
| 46 A \fBSDL_PixelFormat\fR describes the format of the pixel data stored at the \fBpixels\fR field of a \fI\fBSDL_Surface\fR\fR\&. Every surface stores a \fBSDL_PixelFormat\fR in the \fBformat\fR field\&. | |
| 47 .PP | |
| 48 If you wish to do pixel level modifications on a surface, then understanding how SDL stores its color information is essential\&. | |
| 49 .PP | |
| 50 8-bit pixel formats are the easiest to understand\&. Since its an 8-bit format, we have 8 \fBBitsPerPixel\fR and 1 \fBBytesPerPixel\fR\&. Since \fBBytesPerPixel\fR is 1, all pixels are represented by a Uint8 which contains an index into \fBpalette\fR->\fBcolors\fR\&. So, to determine the color of a pixel in a 8-bit surface: we read the color index from \fBsurface\fR->\fBpixels\fR and we use that index to read the \fI\fBSDL_Color\fR\fR structure from \fBsurface\fR->\fBformat\fR->\fBpalette\fR->\fBcolors\fR\&. Like so: | |
| 51 .PP | |
| 52 .nf | |
| 53 \f(CWSDL_Surface *surface; | |
| 54 SDL_PixelFormat *fmt; | |
| 55 SDL_Color *color; | |
| 56 Uint8 index; | |
| 57 | |
| 58 \&. | |
| 59 \&. | |
| 60 | |
| 61 /* Create surface */ | |
| 62 \&. | |
| 63 \&. | |
| 64 fmt=surface->format; | |
| 65 | |
| 66 /* Check the bitdepth of the surface */ | |
| 67 if(fmt->BitsPerPixel!=8){ | |
| 68 fprintf(stderr, "Not an 8-bit surface\&. | |
| 69 "); | |
| 70 return(-1); | |
| 71 } | |
| 72 | |
| 73 /* Lock the surface */ | |
| 74 SDL_LockSurface(surface); | |
| 75 | |
| 76 /* Get the topleft pixel */ | |
| 77 index=*(Uint8 *)surface->pixels; | |
| 78 color=fmt->palette->colors[index]; | |
| 79 | |
| 80 /* Unlock the surface */ | |
| 81 SDL_UnlockSurface(surface); | |
| 82 printf("Pixel Color-> Red: %d, Green: %d, Blue: %d\&. Index: %d | |
| 83 ", | |
| 84 color->r, color->g, color->b, index); | |
| 85 \&. | |
| 86 \&.\fR | |
| 87 .fi | |
| 88 .PP | |
| 89 .PP | |
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90 Pixel formats above 8-bit are an entirely different experience\&. They are considered to be "TrueColor" formats and the color information is stored in the pixels themselves, not in a palette\&. The mask, shift and loss fields tell us how the color information is encoded\&. The mask fields allow us to isolate each color component, the shift fields tell us the number of bits to the right of each component in the pixel value and the loss fields tell us the number of bits lost from each component when packing 8-bit color component in a pixel\&. |
| 0 | 91 .PP |
| 92 .nf | |
| 93 \f(CW/* Extracting color components from a 32-bit color value */ | |
| 94 SDL_PixelFormat *fmt; | |
| 95 SDL_Surface *surface; | |
| 96 Uint32 temp, pixel; | |
| 97 Uint8 red, green, blue, alpha; | |
| 98 \&. | |
| 99 \&. | |
| 100 \&. | |
| 101 fmt=surface->format; | |
| 102 SDL_LockSurface(surface); | |
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103 pixel=*((Uint32*)surface->pixels); |
| 0 | 104 SDL_UnlockSurface(surface); |
| 105 | |
| 106 /* Get Red component */ | |
| 107 temp=pixel&fmt->Rmask; /* Isolate red component */ | |
| 108 temp=temp>>fmt->Rshift;/* Shift it down to 8-bit */ | |
| 109 temp=temp<<fmt->Rloss; /* Expand to a full 8-bit number */ | |
| 110 red=(Uint8)temp; | |
| 111 | |
| 112 /* Get Green component */ | |
| 113 temp=pixel&fmt->Gmask; /* Isolate green component */ | |
| 114 temp=temp>>fmt->Gshift;/* Shift it down to 8-bit */ | |
| 115 temp=temp<<fmt->Gloss; /* Expand to a full 8-bit number */ | |
| 116 green=(Uint8)temp; | |
| 117 | |
| 118 /* Get Blue component */ | |
| 119 temp=pixel&fmt->Bmask; /* Isolate blue component */ | |
| 120 temp=temp>>fmt->Bshift;/* Shift it down to 8-bit */ | |
| 121 temp=temp<<fmt->Bloss; /* Expand to a full 8-bit number */ | |
| 122 blue=(Uint8)temp; | |
| 123 | |
| 124 /* Get Alpha component */ | |
| 125 temp=pixel&fmt->Amask; /* Isolate alpha component */ | |
| 126 temp=temp>>fmt->Ashift;/* Shift it down to 8-bit */ | |
| 127 temp=temp<<fmt->Aloss; /* Expand to a full 8-bit number */ | |
| 128 alpha=(Uint8)temp; | |
| 129 | |
| 130 printf("Pixel Color -> R: %d, G: %d, B: %d, A: %d | |
| 131 ", red, green, blue, alpha); | |
| 132 \&. | |
| 133 \&. | |
| 134 \&.\fR | |
| 135 .fi | |
| 136 .PP | |
| 137 .SH "SEE ALSO" | |
| 138 .PP | |
| 139 \fI\fBSDL_Surface\fR\fR, \fI\fBSDL_MapRGB\fP\fR | |
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140 .\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01 |