C#Forms - 使用Paint方法？

Question

在c#表单中,我创建了一个新的绘制方法:

private void thisPolygon(PaintEventArgs e)
{
    Pen clrBlue = new Pen(Color.Blue, 3);
    Point[] Wst = new Point[5];
    Wst[0] = new Point(20, 350);
    Wst[1] = new Point(110, 200);
    Wst[2] = new Point(200, 190);
    Wst[3] = new Point(210, 275);
    Wst[4] = new Point(190, 400);
    Wst[5] = new Point(50, 390);
    e.Graphics.DrawPolygon(clrBlue, Wst);
}

现在,我该怎么称呼它？我不能让它工作,这不起作用:

private void Form1_Load(object sender, EventArgs e)
{
    thisPolygon(); ///I've tried adding some stuff in brackets area, failed.
}

Answer 1

你有一些不同的问题.

(1)阵列容量.您的阵列初始化为5个存储位置,但您尝试设置第六个值.

Point[] Wst = new Point[5]; // 5 indexes
...
Wst[5] = new Point(50, 390); // Tries to access a sixth, but is out of bounds

将此更改为.

Point[] Wst = new Point[6];

请记住,数组是从零开始索引的.

(2)不使用OnPaint.你正在调用thisPolygon这个OnLoad方法,它不会持久你的绘图.将您的调用移动到OnPaint表单的方法.

protected override void OnPaint(PaintEventArgs e) {
    base.OnPaint(e);
    thisPolygon();
}

(3)没有传递PaintEventArgs.你没有向你的thisPolygon方法传递任何事件参数,它甚至不会按原样编译.传入方法中的paint参数OnPaint.

protected override void OnPaint(PaintEventArgs e) {
    base.OnPaint(e); // Pass in e
    thisPolygon();
}