1 // 边缘填充算法.cpp : 定义控制台应用程序的入口点。
 2 //
 3 
 4 #include "stdafx.h"
 5 #include<stdio.h>
 6 #include"graphics.h"
 7 #include<stdlib.h>
 8 
 9 //函数声明
10 int  maxX(int a[], int n);//求取最大值
11 void Edgefilling(int a[], int n);
12 int putcolor(int x, int y);//颜色填充
13 
14 int main()
15 {
16     int gdriver = DETECT, gmode,n,i;
17     
18     printf("please input the nymber of point:\n");
19     scanf_s("%d", &n);
20 
21     int *a = (int *)malloc(n*sizeof(int));//动态分配内存
22     
23     printf("input the point:\n");
24     for (i = 0; i < n; i++)
25         scanf_s("%d",&a[i]);
26 
27     initgraph(&gdriver, &gmode, "");
28 
29     setcolor(YELLOW);
30     setbkcolor(BLACK);
31 
32     drawpoly(n / 2, a);//画出多边形
33 
34     Edgefilling(a, n);
35 
36     system("pause");
37     closegraph();
38     
39     return 0;
40 }
41 
42 //边缘填充算法实现
43 void Edgefilling(int a[],int n)
44 {
45     int i,x,y,Ymax,Ymin;
46 
47     for (i = 0; i < n - 2; i = i + 2)
48     {
49         //判断纵坐标大小
50         Ymax = (a[i + 1] > a[i + 3]) ? a[i + 1] : a[i + 3];
51         Ymin = (a[i + 1] <= a[i + 3]) ? a[i + 1] : a[i + 3];
52 
53         for (y = Ymin; y < Ymax; y++)
54         {
55             x = (y - a[i + 1])*(a[i + 2] - a[i]) / (a[i + 3] - a[i + 1]) + a[i];
56 
57             while (x <= maxX(a, n))
58             {
59                 putpixel(x, y, putcolor(x, y));
60                 x++;
61             }
62         }
63     }
64     
65 }
66 
67 //求取最大值
68 int  maxX(int a[],int n)
69 {
70     int i,max=a[0];
71 
72     for (i = 0; i < n; i += 2)
73     {
74         if (a[i] > max)
75             max = a[i];
76     }
77 
78     return max;
79 }
80 
81 //颜色填充
82 int putcolor(int x, int y)
83 {
84     if (getpixel(x, y) == BLACK)
85         return BLUE;
86     else if (getpixel(x, y) == BLUE)
87         return BLACK;
88     else
89         return YELLOW;
90 }