C图形库骨架代码的澄清

Question

我正在学习 C，并且得到了绘制单行像素的代码:

void draw_line(unsigned char x1, unsigned char y1, unsigned char x2, unsigned char y2) {
// Insert algorithm here.
if (x1 == x2) {
    //Draw Horizontal line
    unsigned char i;
    for (i = y1; i <= y2; i++){
        set_pixel(x1, i, 1);
    }           
} else if (y1 == y2){
    //Draw vertical line
    unsigned char i;
    for (i = x1; i <= x2; i++){
        set_pixel(i, y1, 1);
    }       

我了解它是如何工作的，但不知道如何实现它。有人可以提供如何使用它的示例吗？

Answer 1

希望这对您有帮助:

算法:
1)获取直线起点和终点的X、Y坐标。
2)求X和Y坐标值的差值dx和dy。
3)检查dx是否大于dy，并将较大的值赋给“steps”。
4)通过将相应轴差值除以步长，定期增加X和Y值。
5)使用“PUTPIXEL”语法绘制初始点。
6)重复步骤4‘steps’次数并使用“PUTPIXEL”语法标记终点。
7)结束程序。

Program:#include"graphics.h"
#include"stdio.h"
#include"conio.h"
#include"math.h"
void linedraw(int,int,int,int);
int main()
{
    int x1coeff,y1coeff,x2coeff,y2coeff;
    printf("\Enter the x and y value for starting point:");
    scanf("%d%d",&x1coeff,&y1coeff);
    printf("\Enter the x and y value for end point:");
    scanf("%d%d",&x2coeff,&y2coeff);
    linedraw(x1coeff,y1coeff,x2coeff,y2coeff);
    getch();
    return 0;
}
void linedraw(int xa,int ya,int xb,int yb)
{
    int dx,dy,steps,k;
    int gdriver=DETECT,gmode;
    float xinc,yinc,x,y;
    initgraph(&gdriver,&gmode,""); //initialise graphics
    dx=xb-xa;
    dy=yb-ya;
    x=xa;
    y=ya;
    if(abs(dx)>abs(dy))
    {
        steps=abs(dx);
    }
    else
    {
        steps=abs(dy);
    }
    xinc=dx/steps;
    yinc=dy/steps;
    putpixel(x,y,WHITE);
    for(k=0;k    {
        x+=xinc;
        y+=yinc;
        putpixel(x,y,WHITE);
    }}
Output:
 Enter the x and y value for starting point:100 100
 Enter the x and y value for end point:200 200
 The Line drawn is