主题：课上练习代码——按钮单击效果

#include "graphics.h"

main()
{
    int driver=VGA,model=VGAHI;
    initgraph(&driver,&model,"");
    setbkcolor(RGB(100,100,100));
    setlinestyle(SOLID_LINE,0,3);
    setcolor(WHITE);
    line(100,100,300,100);
    line(100,100,100,150);
    setcolor(BLACK);
    line(300,100,300,150);
    line(100,150,300,150);
    for ( ; is_run(); delay_fps(120))
    {
        while (mousemsg())
        {
            mouse_msg m = getmouse();
            if(m.x>=100 && m.x<=300 && m.y>=100 && m.y<=150)
            {
                if (m.msg == mouse_msg_down)
                {
                    setcolor(BLACK);
                    line(100,100,300,100);
                    line(100,100,100,150);
                    setcolor(WHITE);
                    line(300,100,300,150);
                    line(100,150,300,150);
                }
                if (m.msg == mouse_msg_up)
                {
                    setcolor(WHITE);
                    line(100,100,300,100);
                    line(100,100,100,150);
                    setcolor(BLACK);
                    line(300,100,300,150);
                    line(100,150,300,150);
                }
            }

        }
    }
}