橡皮筋画线法

在这里我用STRUCT和指向函数的指针定义结合实现了模拟鼠标类,并用它来写了橡皮筋画线法

#include <stdio.h>
#include <graphics.h>
#include <dos.h>
typedef struct
{
 void (*Inits)();/*初始化鼠标驱动*/ 
 int  (*MButton)();/*按键位置与按键状态*/
 void (*MouseIco)();/*画鼠标光标*/
 int  x;/*横向坐标*/
 int  y;/*竖向坐标*/
 int  ox;
 int  oy;
 int  button;/*按键标志*/
}MOUSE;/*鼠标类*/
void mInits();
int  mMButton();
void mMouseIco();
union REGS rg;
int main()
{
 MOUSE *pM,mouse;
 int graphdrive=0,graphmode=0;
 int tracking=0,x1,y1,ox1,oy1;
 pM=&mouse;
 pM->Inits=mInits;
 pM->MButton=mMButton;
 pM->MouseIco=mMouseIco;
 initgraph(&graphdrive,&graphmode,"");
 setbkcolor(1);
 setwritemode(1);/*画线模式*/
 pM->Inits(&pM->x,&pM->y);
 pM->ox=pM->x;
 pM->oy=pM->y;
 do
 {
  pM->button=pM->MButton(&pM->x,&pM->y);
  pM->MouseIco(&pM->x,&pM->y,&pM->ox,&pM->oy);
  if(pM->button==1)
  {
    if(!tracking)/*捕捉开关*/
       {
  ox1=x1=pM->x;
  oy1=y1=pM->y;
  tracking=1;
       }
    if(pM->x!=ox1||pM->y!=oy1)
     {
      line(x1,y1,ox1,oy1);
      ox1=pM->x;
      oy1=pM->y;
      line(x1,y1,pM->x,pM->y);
     }
  }
  else tracking=0;
 }while(pM->button!=3);
}
void mInits(int *mx,int *my)
{
 rg.x.ax=0;
 int86(0x33,&rg,&rg);
 if(rg.x.ax==0)
    exit(1);
 rg.x.ax=7;
 rg.x.cx=2;
 rg.x.dx=640;
 int86(0x33,&rg,&rg);
 rg.x.ax=8;
 rg.x.cx=2;
 rg.x.dx=480;
 int86(0x33,&rg,&rg);
 rg.x.ax=4;
 *mx=rg.x.cx=640/2;
 *my=rg.x.dx=480/2;
 int86(0x33,&rg,&rg);
 rectangle(rg.x.cx-2,rg.x.dx-2,rg.x.cx+2,rg.x.dx+2);
}
int mMButton(int *lx,int *ly)
{
 rg.x.ax=3;
 int86(0x33,&rg,&rg);
 *lx=rg.x.cx;
 *ly=rg.x.dx;
 return rg.x.bx;
}
void mMouseIco(int *x,int *y,int *oldx,int *oldy)
{
 if(*x!=*oldx||*y!=*oldy)
 {
  rectangle(*oldx-2,*oldy-2,*oldx+2,*oldy+2);
  *oldx=*x;
  *oldy=*y;
  rectangle(*x-2,*y-2,*x+2,*y+2);
 }
}