Mercurial > sdl-ios-xcode
diff docs/html/guidevideoexamples.html @ 0:74212992fb08
Initial revision
| author | Sam Lantinga <slouken@lokigames.com> |
|---|---|
| date | Thu, 26 Apr 2001 16:45:43 +0000 |
| parents | |
| children | 55f1f1b3e27d |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/docs/html/guidevideoexamples.html Thu Apr 26 16:45:43 2001 +0000 @@ -0,0 +1,473 @@ +<HTML +><HEAD +><TITLE +>Video Examples</TITLE +><META +NAME="GENERATOR" +CONTENT="Modular DocBook HTML Stylesheet Version 1.61 +"><LINK +REL="HOME" +TITLE="SDL Library Documentation" +HREF="index.html"><LINK +REL="UP" +TITLE="Examples" +HREF="guideexamples.html"><LINK +REL="PREVIOUS" +TITLE="Examples" +HREF="guideexamples.html"><LINK +REL="NEXT" +TITLE="Event Examples" +HREF="guideeventexamples.html"></HEAD +><BODY +CLASS="SECT1" +BGCOLOR="#FFF8DC" +TEXT="#000000" +LINK="#0000ee" +VLINK="#551a8b" +ALINK="#ff0000" +><DIV +CLASS="NAVHEADER" +><TABLE +WIDTH="100%" +BORDER="0" +CELLPADDING="0" +CELLSPACING="0" +><TR +><TH +COLSPAN="3" +ALIGN="center" +>SDL Library Documentation</TH +></TR +><TR +><TD +WIDTH="10%" +ALIGN="left" +VALIGN="bottom" +><A +HREF="guideexamples.html" +>Prev</A +></TD +><TD +WIDTH="80%" +ALIGN="center" +VALIGN="bottom" +>Chapter 4. Examples</TD +><TD +WIDTH="10%" +ALIGN="right" +VALIGN="bottom" +><A +HREF="guideeventexamples.html" +>Next</A +></TD +></TR +></TABLE +><HR +ALIGN="LEFT" +WIDTH="100%"></DIV +><DIV +CLASS="SECT1" +><H1 +CLASS="SECT1" +><A +NAME="GUIDEVIDEOEXAMPLES" +>Video Examples</A +></H1 +><P +></P +><DIV +CLASS="SECT2" +><H2 +CLASS="SECT2" +><A +NAME="AEN303" +>Initializing the video display</A +></H2 +><P +><PRE +CLASS="PROGRAMLISTING" +> SDL_Surface *screen; + + /* Initialize the SDL library */ + if( SDL_Init(SDL_INIT_VIDEO) < 0 ) { + fprintf(stderr, + "Couldn't initialize SDL: %s\n", SDL_GetError()); + exit(1); + } + + /* Clean up on exit */ + atexit(SDL_Quit); + + /* Initialize the display in a 640x480 8-bit palettized mode */ + screen = SDL_SetVideoMode(640, 480, 8, SDL_SWSURFACE); + if ( screen == NULL ) { + fprintf(stderr, "Couldn't set 640x480x8 video mode: %s\n", + SDL_GetError()); + exit(1); + }</PRE +></P +></DIV +><DIV +CLASS="SECT2" +><H2 +CLASS="SECT2" +><A +NAME="AEN307" +>Initializing the best video mode</A +></H2 +><P +><PRE +CLASS="PROGRAMLISTING" +> /* Have a preference for 8-bit, but accept any depth */ + screen = SDL_SetVideoMode(640, 480, 8, SDL_SWSURFACE|SDL_ANYFORMAT); + if ( screen == NULL ) { + fprintf(stderr, "Couldn't set 640x480x8 video mode: %s\n", + SDL_GetError()); + exit(1); + } + printf("Set 640x480 at %d bits-per-pixel mode\n", + screen->format->BitsPerPixel);</PRE +></P +></DIV +><DIV +CLASS="SECT2" +><H2 +CLASS="SECT2" +><A +NAME="AEN311" +>Loading and displaying a BMP file</A +></H2 +><P +><PRE +CLASS="PROGRAMLISTING" +> SDL_Surface *image; + SDL_Rect dest; + int ncolors, i; + SDL_Color *colors; + + /* Load the BMP file into a surface */ + image = SDL_LoadBMP("sample.bmp"); + if ( image == NULL ) { + fprintf(stderr, "Couldn't load sample.bmp: %s\n", + SDL_GetError()); + return; + } + + /* Set the display colors -- SDL_SetColors() only does something on + palettized displays, but it doesn't hurt anything on HiColor or + TrueColor displays. + If the display colors have already been set, this step can be + skipped, and the library will automatically map the image to + the current display colors. + */ + if ( image->format->palette ) { + ncolors = image->format->palette->ncolors; + colors = (SDL_Color *)malloc(ncolors*sizeof(SDL_Color)); + memcpy(colors, image->format->palette->colors, ncolors); + } + else { + int r, g, b; + + /* Allocate 256 color palette */ + ncolors = 256; + colors = (SDL_Color *)malloc(ncolors*sizeof(SDL_Color)); + + /* Set a 3,3,2 color cube */ + for ( r=0; r<8; ++r ) { + for ( g=0; g<8; ++g ) { + for ( b=0; b<4; ++b ) { + i = ((r<<5)|(g<<2)|b); + colors[i].r = r<<5; + colors[i].g = g<<5; + colors[i].b = b<<6; + } + } + } + /* Note: A better way of allocating the palette might be + to calculate the frequency of colors in the image + and create a palette based on that information. + */ + } + /* Set colormap, try for all the colors, but don't worry about it */ + SDL_SetColors(screen, colors, 0, ncolors); + free(colors); + + /* Blit onto the screen surface */ + dest.x = 0; + dest.y = 0; + dest.w = image->w; + dest.h = image->h; + SDL_BlitSurface(image, NULL, screen, &dest); + + SDL_UpdateRects(screen, 1, &dest); + + /* Free the allocated BMP surface */ + SDL_FreeSurface(image); + return;</PRE +></P +></DIV +><DIV +CLASS="SECT2" +><H2 +CLASS="SECT2" +><A +NAME="AEN315" +>Drawing directly to the display</A +></H2 +><P +><PRE +CLASS="PROGRAMLISTING" +> /* Code to set a yellow pixel at the center of the screen */ + + Sint32 X, Y; + Uint32 pixel; + Uint8 *bits, bpp; + + /* Map the color yellow to this display (R=0xFF, G=0xFF, B=0x00) + Note: If the display is palettized, you must set the palette first. + */ + pixel = SDL_MapRGB(screen->format, 0xFF, 0xFF, 0x00); + + /* Calculate the framebuffer offset of the center of the screen */ + if ( SDL_MUSTLOCK(screen) ) { + if ( SDL_LockSurface(screen) < 0 ) + return; + } + bpp = screen->format->BytesPerPixel; + X = screen->w/2; + Y = screen->h/2; + bits = ((Uint8 *)screen->pixels)+Y*screen->pitch+X*bpp; + + /* Set the pixel */ + switch(bpp) { + case 1: + *((Uint8 *)(bits)) = (Uint8)pixel; + break; + case 2: + *((Uint16 *)(bits)) = (Uint16)pixel; + break; + case 3: { /* Format/endian independent */ + Uint8 r, g, b; + + r = (pixel>>screen->format->Rshift)&0xFF; + g = (pixel>>screen->format->Gshift)&0xFF; + b = (pixel>>screen->format->Bshift)&0xFF; + *((bits)+screen->format->Rshift/8) = r; + *((bits)+screen->format->Gshift/8) = g; + *((bits)+screen->format->Bshift/8) = b; + } + break; + case 4: + *((Uint32 *)(bits)) = (Uint32)pixel; + break; + } + + /* Update the display */ + if ( SDL_MUSTLOCK(screen) ) { + SDL_UnlockSurface(screen); + } + SDL_UpdateRect(screen, X, Y, 1, 1); + + return;</PRE +></P +></DIV +><DIV +CLASS="SECT2" +><H2 +CLASS="SECT2" +><A +NAME="AEN319" +>Fastest possible surface blit</A +></H2 +><P +>There are three different ways you can draw an image to the screen: +<P +></P +><TABLE +BORDER="0" +><TBODY +><TR +><TD +>1.Create a surface and use <A +HREF="sdlblitsurface.html" +><TT +CLASS="FUNCTION" +>SDL_BlitSurface</TT +></A +> to blit it to the screen</TD +></TR +><TR +><TD +>2.Create the video surface in system memory and call <A +HREF="sdlupdaterect.html" +><TT +CLASS="FUNCTION" +>SDL_UpdateRect</TT +></A +></TD +></TR +><TR +><TD +>3.Create the video surface in video memory and call <A +HREF="sdllocksurface.html" +><TT +CLASS="FUNCTION" +>SDL_LockSurface</TT +></A +></TD +></TR +></TBODY +></TABLE +><P +></P +> +The best way to do this is to combine methods: +<PRE +CLASS="PROGRAMLISTING" +>#include <stdio.h> +#include <stdlib.h> +#include "SDL.h" +#include "SDL_timer.h" + +void ComplainAndExit(void) +{ + fprintf(stderr, "Problem: %s\n", SDL_GetError()); + exit(1); +} + +int main(int argc, char *argv[]) +{ + SDL_PixelFormat fmt; + SDL_Surface *screen, *locked; + SDL_Surface *imagebmp, *image; + SDL_Rect dstrect; + int i; + Uint8 *buffer; + + /* Initialize SDL */ + if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) { + ComplainAndExit(); + } + atexit(SDL_Quit); + + /* Load a BMP image into a surface */ + imagebmp = SDL_LoadBMP("image.bmp"); + if ( imagebmp == NULL ) { + ComplainAndExit(); + } + + /* Set the video mode (640x480 at native depth) */ + screen = SDL_SetVideoMode(640, 480, 0, SDL_HWSURFACE|SDL_FULLSCREEN); + if ( screen == NULL ) { + ComplainAndExit(); + } + + /* Set the video colormap */ + if ( imagebmp->format->palette != NULL ) { + SDL_SetColors(screen, + imagebmp->format->palette->colors, 0, + imagebmp->format->palette->ncolors); + } + + /* Convert the image to the video format (maps colors) */ + image = SDL_DisplayFormat(imagebmp); + SDL_FreeSurface(imagebmp); + if ( image == NULL ) { + ComplainAndExit(); + } + + /* Draw bands of color on the raw surface */ + if ( SDL_MUSTLOCK(screen) ) { + if ( SDL_LockSurface(screen) < 0 ) + ComplainAndExit(); + } + buffer=(Uint8 *)screen->pixels; + for ( i=0; i<screen->h; ++i ) { + memset(buffer,(i*255)/screen->h, + screen->w*screen->format->BytesPerPixel); + buffer += screen->pitch; + } + if ( SDL_MUSTLOCK(screen) ) { + SDL_UnlockSurface(screen); + } + + /* Blit the image to the center of the screen */ + dstrect.x = (screen->w-image->w)/2; + dstrect.y = (screen->h-image->h)/2; + dstrect.w = image->w; + dstrect.h = image->h; + if ( SDL_BlitSurface(image, NULL, screen, &dstrect) < 0 ) { + SDL_FreeSurface(image); + ComplainAndExit(); + } + SDL_FreeSurface(image); + + /* Update the screen */ + SDL_UpdateRects(screen, 1, &dstrect); + + SDL_Delay(5000); /* Wait 5 seconds */ + exit(0); +}</PRE +></P +></DIV +></DIV +><DIV +CLASS="NAVFOOTER" +><HR +ALIGN="LEFT" +WIDTH="100%"><TABLE +WIDTH="100%" +BORDER="0" +CELLPADDING="0" +CELLSPACING="0" +><TR +><TD +WIDTH="33%" +ALIGN="left" +VALIGN="top" +><A +HREF="guideexamples.html" +>Prev</A +></TD +><TD +WIDTH="34%" +ALIGN="center" +VALIGN="top" +><A +HREF="index.html" +>Home</A +></TD +><TD +WIDTH="33%" +ALIGN="right" +VALIGN="top" +><A +HREF="guideeventexamples.html" +>Next</A +></TD +></TR +><TR +><TD +WIDTH="33%" +ALIGN="left" +VALIGN="top" +>Examples</TD +><TD +WIDTH="34%" +ALIGN="center" +VALIGN="top" +><A +HREF="guideexamples.html" +>Up</A +></TD +><TD +WIDTH="33%" +ALIGN="right" +VALIGN="top" +>Event Examples</TD +></TR +></TABLE +></DIV +></BODY +></HTML +> \ No newline at end of file