#define BMP_WINDOW_OPEN

#include <windows.h >
#include <stdio.h >
#include <malloc.h>

typedef struct
{
  unsigned char b;
  unsigned char g;
  unsigned char r;
}
rgb16M;

typedef struct {
    FILE *fp ;
    int WIDTH ;
    int HEIGHT ;
    long fix ;
    int outx ;
    int outy ;
    int file_x1 ;
    int file_y1 ;
    int file_x2 ;
    int file_y2 ;
    int lucency ;
}BmpFile ;

HDC SBmp_hdc ;


/***********************************函数目录***********************************/
int drawBmpPixel(HDC hdc, FILE *fp
                 , long jump
                 , int draw_x , int draw_y
                 , int width_x, int height_y
                 , int lucency) ;
int drawBmp(HDC hdc, char filename[], int x0, int y0, int lucency ) ;
int swap_6num(int *x1, int *x2
              , int *WIDTH
              , int *y1, int *y2
              , int *HEIGHT) ;
int drawPartBmp(HDC hdc, char filename[]
                , int x0, int y0, int x1, int y1, int x2, int y2
                , int lucency ) ;
int fopenBmpFile(char filename[]) ;
int getWidth(FILE *fp) ;
int getHeight( FILE *fp) ;
int noNameDraw(HDC hdc, BmpFile partview) ;
/******************************************************************************/


int drawBmpPixel(HDC hdc, FILE *fp
                 , long jump
                 , int draw_x , int draw_y
                 , int width_x, int height_y
                 , int lucency)
{
    int i, j ;
    rgb16M *buffer ;
    long color_rbg ;

    buffer  =  (rgb16M *)malloc(width_x*sizeof(rgb16M)) ;

    for(j = height_y ; j  >=  0 ; j--)
    {
        fread(buffer, 1, width_x*sizeof(rgb16M), fp) ;

        for(i  =  0 ; i < width_x ; i++)
        {
            color_rbg = RGB(buffer[i].r, buffer[i].g, buffer[i].b) ;
            if(color_rbg+lucency)
             SetPixel (hdc, draw_x + i,  draw_y + j,  color_rbg) ;
        }
        fseek(fp,  jump,  SEEK_CUR) ;
    }

    free(buffer) ;

    return 0 ;
}

int drawBmp(HDC hdc, char filename[20], int x0, int y0, int lucency )
{
    int WIDTH,  HEIGHT ;
    FILE *fp ;
    long fix ;

    if((fp  =  fopen(filename,  "rb"))  ==  NULL)
    {
        char str[20] ;
        
        exit(1) ;
    }

    WIDTH = getWidth(fp) ;
    HEIGHT = getHeight(fp) ;

    fix  = (long)WIDTH & 3 ;

    fseek(fp,  54l+fix,  SEEK_SET) ;

    drawBmpPixel(hdc, fp, fix, x0, y0, WIDTH, HEIGHT - 1, lucency) ;

    fclose(fp) ;

    return 0 ;
}

int swap_6num(int *x1, int *x2
              , int *WIDTH
              , int *y1, int *y2
              , int *HEIGHT)
{
    int *t ;

    if(*x1 > *x2)
    {
        *t = *x1 ;
        *x1 = *x2 ;
        *x2 = *t ;
    }
    if(*x1 > *WIDTH)
     *x1 = *WIDTH ;
    if(*x2 > *WIDTH)
     *x2 = *WIDTH ;
    if(*y1 > *y2)
    {
        *t = *y1 ;
        *y1 = *y2 ;
        *y2 = *t ;
    }
    if(*y1 > *HEIGHT)
     *y1 = *HEIGHT ;
    if(*y2 > *HEIGHT)
     *y2 = *HEIGHT ;
    
    return 0 ;
}

//x0,y0:图片的绘制位置，x1,y1--x2,y2图片文件剪切位置 lucency透明度
int drawPartBmp(HDC hdc, char filename[]
                , int x0, int y0, int x1, int y1, int x2, int y2
                , int lucency )
{
    int WIDTH,  HEIGHT ;
    FILE *fp ;
    long fix ;
    int t ;
   
    if((fp  =  fopen(filename,  "rb"))  ==  NULL)
    {
        char str[20] ;

        exit(1) ;
    }

    WIDTH = getWidth(fp) ;
    HEIGHT = getHeight(fp) ;

    fix  = (long) WIDTH & 3 ;

    swap_6num(&x1, &x2, &WIDTH, &y1, &y2, &HEIGHT) ;

    fseek(fp,  54l+(long)(HEIGHT-y2)*(WIDTH*3+fix)+x1*3,  SEEK_SET) ;

    drawBmpPixel(hdc, fp, (x1+WIDTH-x2)*3+fix, x0, y0, x2-x1, y2-y1, lucency) ;

    fclose(fp) ;
   
    return 0 ;
}

int fopenBmpFile(char filename[])
{
    FILE *fp ;

    if((fp  =  fopen(filename,  "rb"))  ==  NULL)
    {
        char str[20] ;
        

        exit(0) ;
    }
   
    return 0 ;
}

int getWidth(FILE *fp)
{
    int WIDTH ;

    fseek(fp,  18l,  SEEK_SET) ;
    fread(&WIDTH, 4,  1, fp ) ;

    return  WIDTH ;
}

int getHeight( FILE *fp)
{
    int HEIGHT ;

    fseek(fp,  22l,  SEEK_SET) ;
    fread(&HEIGHT, 4,  1, fp ) ;

    return  HEIGHT ;
}

这里面用到的是C的写法是么 我很多地方看不懂
基本我就不理解这个类是用来干吗的 不知怎么修改
求教int swap_6num之后的每部注解 谢谢