annotate docs/man3/SDL_BlitSurface.3 @ 1982:3b4ce57c6215

First shot at new audio data types (int32 and float32). Notable changes: - Converters between types are autogenerated. Instead of making multiple passes over the data with seperate filters for endianess, size, signedness, etc, converting between data types is always one specialized filter. This simplifies SDL_BuildAudioCVT(), which otherwise had a million edge cases with the new types, and makes the actually conversions more CPU cache friendly. Left a stub for adding specific optimized versions of these routines (SSE/MMX/Altivec, assembler, etc) - Autogenerated converters are built by SDL/src/audio/sdlgenaudiocvt.pl. This does not need to be run unless tweaking the code, and thus doesn't need integration into the build system. - Went through all the drivers and tried to weed out all the "Uint16" references that are better specified with the new SDL_AudioFormat typedef. - Cleaned out a bunch of hardcoded bitwise magic numbers and replaced them with new SDL_AUDIO_* macros. - Added initial float32 and int32 support code. Theoretically, existing drivers will push these through converters to get the data they want to feed to the hardware. Still TODO: - Optimize and debug new converters. - Update the CoreAudio backend to accept float32 data directly. - Other backends, too? - SDL_LoadWAV() needs to be updated to support int32 and float32 .wav files (both of which exist and can be generated by 'sox' for testing purposes). - Update the mixer to handle new datatypes. - Optionally update SDL_sound and SDL_mixer, etc.
author Ryan C. Gordon <icculus@icculus.org>
date Thu, 24 Aug 2006 12:10:46 +0000
parents e5bc29de3f0a
children 546f7c1eb755
rev   line source
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1 .TH "SDL_BlitSurface" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference"
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2 .SH "NAME"
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3 SDL_BlitSurface\- This performs a fast blit from the source surface to the destination surface\&.
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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 \fBint \fBSDL_BlitSurface\fP\fR(\fBSDL_Surface *src, SDL_Rect *srcrect, SDL_Surface *dst, SDL_Rect *dstrect\fR);
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9 .SH "DESCRIPTION"
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10 .PP
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11 This performs a fast blit from the source surface to the destination surface\&.
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12 .PP
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13 Only the position is used in the \fBdstrect\fR (the width and height are ignored)\&.
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14 .PP
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15 If either \fBsrcrect\fR or \fBdstrect\fR are \fBNULL\fP, the entire surface (\fBsrc\fR or \fBdst\fR) is copied\&.
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16 .PP
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17 The final blit rectangle is saved in \fBdstrect\fR after all clipping is performed (\fBsrcrect\fR is not modified)\&.
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18 .PP
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19 The blit function should not be called on a locked surface\&.
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20 .PP
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21 The results of blitting operations vary greatly depending on whether \fBSDL_SRCAPLHA\fP is set or not\&. See \fISDL_SetAlpha\fR for an explaination of how this affects your results\&. Colorkeying and alpha attributes also interact with surface blitting, as the following pseudo-code should hopefully explain\&.
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22 .PP
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23 .nf
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24 \f(CWif (source surface has SDL_SRCALPHA set) {
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25 if (source surface has alpha channel (that is, format->Amask != 0))
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26 blit using per-pixel alpha, ignoring any colour key
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27 else {
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28 if (source surface has SDL_SRCCOLORKEY set)
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29 blit using the colour key AND the per-surface alpha value
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30 else
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31 blit using the per-surface alpha value
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32 }
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33 } else {
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34 if (source surface has SDL_SRCCOLORKEY set)
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35 blit using the colour key
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36 else
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37 ordinary opaque rectangular blit
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38 }\fR
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39 .fi
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40 .PP
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41 .SH "RETURN VALUE"
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42 .PP
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43 If the blit is successful, it returns \fB0\fR, otherwise it returns \fB-1\fR\&.
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44 .PP
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45 If either of the surfaces were in video memory, and the blit returns \fB-2\fR, the video memory was lost, so it should be reloaded with artwork and re-blitted:
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46 .PP
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47 .nf
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48 \f(CW while ( SDL_BlitSurface(image, imgrect, screen, dstrect) == -2 ) {
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49 while ( SDL_LockSurface(image)) < 0 )
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50 Sleep(10);
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51 -- Write image pixels to image->pixels --
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52 SDL_UnlockSurface(image);
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53 }\fR
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54 .fi
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55 .PP
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56 This happens under DirectX 5\&.0 when the system switches away from your fullscreen application\&. Locking the surface will also fail until you have access to the video memory again\&.
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57 .SH "SEE ALSO"
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58 .PP
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59 \fI\fBSDL_LockSurface\fP\fR, \fI\fBSDL_FillRect\fP\fR, \fI\fBSDL_Surface\fR\fR, \fI\fBSDL_Rect\fR\fR
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60 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01