一个BMP图形调用问题。
大家看看以下这个显示BMP图片的程序有什么问题，编译时无错误,亦无警告，但一运行就自动退出（调试时需要一个320*200的BMP图，因不能附上图片，请自己动手画一幅以供调试）。
#include <io.h>
#include <stdio.h>
#include <dos.h>
#include <string.h>
#include <math.h>
#include <stdio.h>
#include <bios.h>
#include <mem.h>
#include <fcntl.h>
#include <stdlib.h>
#include <conio.h>
#define SCREEN_HEIGHT 200
#define SCREEN_WIDTH 320
#define PALETTE_MASK 0x3c6
#define PALETTE_REGISTER_RD 0x3c7
#define PALETTE_REGISTER_WR 0x3c8
#define PALETTE_DATA 0x3c9
#define VGA256 0x13
#define TEXT_MODE 0x03
unsigned char far *video_buffer=(char far *)0xA0000000L;
typedef struct BMP_file
{
unsigned int bfType;
unsigned long bfSize;
unsigned int Reserved1;
unsigned int reserved2;
unsigned long bfOffset;
}
bitmapfile;
typedef struct BMP_info
{
unsigned long biSize;
unsigned long biWidth;
unsigned long biHeight;
unsigned int biPlanes;
unsigned int biBitCount;
unsigned long biCompression;
unsigned long biSizeImage;
unsigned long biXpolsPerMeter;
unsigned long biYpelsPerMeter;
unsigned long biClrUsed;
unsigned long biClrImportant;
}
bitmapinfo;
typedef struct RGB_BMP_typ
{
unsigned char blue;
unsigned char green;
unsigned char red;
unsigned char reserved;
}RGB_BMP,*RGB_BMP_ptr;
typedef struct bmp_picture_typ
{
bitmapfile file;
bitmapinfo info;
RGB_BMP palette[256];
char far *buffer;
} bmp_picture, *bmp_picture_ptr;
void Set_BMP_Palette_Register(int index,RGB_BMP_ptr color)
{
outp(PALETTE_MASK,0xff);
outp(PALETTE_REGISTER_WR,index);
outp(PALETTE_DATA,color-> red);
outp(PALETTE_DATA,color-> green);
outp(PALETTE_DATA,color-> blue);
}
void Check_Bmp(bmp_picture_ptr bmp_ptr)
{
if(bmp_ptr-> file.bfType!=0x4d42)
{
printf( "Not a BMP file!\n ");
exit(1);
}
if(bmp_ptr-> info.biCompression!=0)
{
printf( "Can not display a compressed BMP file!\n ");
exit(1);
}
if(bmp_ptr-> info.biBitCount!=8)
{
printf( "Not a index 16color BMP file!\n ");
exit(1);
}
}
void BMP_Load_Screen(char *bmp)
{
int i,fp;
bmp_picture bmp256;
char *file_name;
if ((fp=open(bmp,O_RDONLY))==-1)
return;
read(fp,&bmp256.file,sizeof(bitmapfile));
read(fp,&bmp256.info,sizeof(bitmapinfo));
Check_Bmp((bmp_picture_ptr)&bmp256);
lseek(fp,54,0);
for (i=0;i <256;i++)
{
read(fp,&bmp256.palette[i].blue,1);
read(fp,&bmp256.palette[i].green,1);
read(fp,&bmp256.palette[i].red,1);
read(fp,&bmp256.palette[i].reserved,1);
bmp256.palette[i].blue=bmp256.palette[i].blue> > 2;
bmp256.palette[i].green=bmp256.palette[i].green> > 2;
bmp256.palette[i].red=bmp256.palette[i].red> > 2;
}
for (i=0;i <256;i++)
Set_BMP_Palette_Register(i,(RGB_BMP_ptr)&bmp256.palette[i]);
for(i=SCREEN_HEIGHT-1;i> =0;i--)
{
lseek(fp,1078+(long)(SCREEN_HEIGHT-i-1)*SCREEN_WIDTH,0);
read(fp,(void*)(&video_buffer[i*SCREEN_WIDTH]),SCREEN_WIDTH);
}
close(fp);
}
void Set_Video_Mode(int mode)
{
union REGS inregs,outregs;
inregs.h.ah=0;
inregs.h.al=(unsigned char)mode;
int86(0x10,&inregs,&outregs);
}
int main()
{
Set_Video_Mode(VGA256);
BMP_Load_Screen( "256.bmp ");
getch();
Set_Video_Mode(TEXT_MODE);
}
[解决办法]
if ((fp=open(bmp,O_RDONLY))==-1)
＝＝》
if ((fp=open(bmp,O_RDONLY|O_BINARY))==-1) //二进制方式读文件
[解决办法]
即使将if ((fp=open(bmp,O_RDONLY))==-1)改为if ((fp=open(bmp,O_RDONLY|O_BINARY))==-1)也不行，何况为什么一定要用二进制读取呢。
--------------------------------------
说的对极了！
关键是这里：
unsigned char far *video_buffer=(char far *)0xA0000000L;
老大，你确定这个地方你能用吗？除非纯DOS下，在WINDOWS下，很多地方你是不能访问的，虽然不禁止！
