例子2-1.起始Video Display
var screen_ : PSDL_Surface; begin //起始SDL程式庫 if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) then begin
MessageBox(0, PChar(Format('Couldn''t initialize SDL : %s',
[SDL_GetError])), 'Error', MB_OK or MB_ICONHAND);
//在離開前清除 SDL_Quit;exit;
(*
*預置在一640x480 8位palettized方式中展示
*請求一軟體表面
*)
screen_:=SDL_SetVideoMode((640,480,8,SDL_SWSURFACE);
if(screen_=nil)then
begin
MessageBox(0, PChar(Format('Couldn''t set 840x480x8 video mode : %s',
[SDL_GetError])), 'Error', MB_OK or MB_ICONHAND);
SDL_Quit;
exit;
例子2-2.最好的影像方式
//偏愛8位但是接受任何深度 screen_ := SDL_SetVideoMode(640, 480, 8, SDL_SWSURFACE or SDL_ANYFORMAT); if ( screen_ = nil ) then begin
MessageBox(0, PChar(Format('Couldn''t set 640x480x8 video mode : %s',
[SDL_GetError])), 'Error', MB_OK or MB_ICONHAND);
SDL_Quit;halt(1);
MessageBox(0, PChar(Format('Set 640x480 at %d bits-per-pixel mode',
[screen_.format.BitsPerPixel])), 'Error', MB_OK or MB_ICONHAND);
例子2-3.裝載和展示一BMP檔案
procedure display_bmp( file_name : PChar ); var image : PSDL_Surface; begin //把BMP檔案裝入一表面 image := SDL_LoadBMP(file_name); if ( image = nil ) then begin
MessageBox(0, PChar(Format('Couldn''t load %s : %s',
[file_name, SDL_GetError])), 'Error', MB_OK or MB_ICONHAND);
exit;
(*
*Palettized銀幕方式將有一塊預設的調色盤(一個標準
*8*8*4彩色的方塊),但是如果影像也是palettized,我們可以
*為一更好的彩色使用那塊調色盤相配
*)
if (image.format.palette and screen_.format.palette)
then
begin
SDL_SetColors(screen_, @image.format.palette.colors[0], 0, image.format.palette.ncolors);
end;
//Blit 到銀幕表面上面
if (SDL_BlitSurface(image, nil, screen_, nil)
< 0) then
MessageBox(0, PChar(Format('BlitSurface error : %s', [SDL_GetError])),
'Error', MB_OK or MB_ICONHAND);
SDL_UpdateRect(screen_, 0, 0, image.w, image.h);
//釋放分配到的BMP影像表面
SDL_FreeSurface(image);
end;
在轉變映像點數值和他們的紅色,綠色,blue成分時，請用SDL_GetRGB(和SDL_MapRGB).
例子2-4.getpixel()
(* *取回映像點數值在(x,y) *筆記:在呼叫這個之前,影像表面一定要鎖住! *) function getpixel( surface : PSDL_Surface; x : integer; y : integer ) : Uint32; type TByteArray = array[0..2] of Byte; PByteArray = ^TByteArray; var bpp : integer; p : PInteger; begin bpp := surface.format.BytesPerPixel; //這裡p向我們想要找回的映像點是地址 p := Pointer(Uint32(surface_.pixels) + y * surface_.pitch + x * bpp); case bpp of 1: result := LongWord(p^); 2: result := PUint16(p)^; 3: if (SDL_BYTEORDER = SDL_BIG_ENDIAN) then result := PByteArray(p)[0] shl 16 or PByteArray(p)[1] shl 8 or PByteArray(p)[2] else result := PByteArray(p)[0] or PByteArray(p)[1] shl 8 or PByteArray(p)[2] shl 16; 4: result := PUint32(p)^; else result := 0; // shouldn't happen, but avoids warnings end; end;
例子2-5.putpixel
(* *設定映像點（x，y）成一特定的數值
*筆記:在呼叫這個之前,影像表面一定要鎖住! *) function getpixel( surface : PSDL_Surface; x : integer; y : integer ) : Uint32; type TByteArray = array[0..2] of Byte; PByteArray = ^TByteArray; var bpp : integer; p : PInteger; begin bpp := surface.format.BytesPerPixel; //這裡p是我們想要設定的映像點的地址 p := Pointer(Uint32(surface_.pixels) + y * surface_.pitch + x * bpp); case bpp of 1: result := LongWord(p^); 2: result := PUint16(p)^; 3: if (SDL_BYTEORDER = SDL_BIG_ENDIAN) then result := PByteArray(p)[0] shl 16 or PByteArray(p)[1] shl 8 or PByteArray(p)[2] else result := PByteArray(p)[0] or PByteArray(p)[1] shl 8 or PByteArray(p)[2] shl 16; 4: result := PUint32(p)^; else result := 0; // shouldn't happen, but avoids warnings end; end;
例子2-6.使用putpixel
//程式在銀幕的中心部署一黃色映像點 var x, y : integer; yellow : Uint32; begin (*把彩色的黃色映射到這展示(R:=$ff,G:=$FF,B:=$00) 筆記:如果展示是palettized,你必須首先設定調色盤. *) yellow := SDL_MapRGB(screen_.format, $ff, $ff, $00); x := screen_.w div 2; y := screen_.h div 2; //使銀幕鎖上，以直接傳取映像點 if ( SDL_MustLock(screen_) ) then begin if ( SDL_LockSurface(screen_) < 0 ) then begin
MessageBox(0, PChar(Format('Can''t lock screen : %s', [SDL_GetError])), 'Error', MB_OK or MB_ICONHAND);
exit;
putpixel(screen_, x, y, yellow);
if ( SDL_MustLock(screen_) > 0 ) then
begin
SDL_UnlockSurface(screen_);
end;
//更新我們已經改變的部份
SDL_UpdateRect(screen_, x, y, 1, 1);
end;