Question

GDI+ C# 绘图的基本过程以及问题

1.最近刚学GDI+ ，用GDI+绘图并保存图片的一些基本流程是什么？
2.单击按钮，在picturebox上画图，我之前写的一些简单代码如下：

Graphics g;
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
g=e.Graphics;
}
private void btnRandom_Click(object sender, EventArgs e)
{
TestCreatePoint createPoint = new TestCreatePoint(16, "time");
GDIShowData showData = new GDIShowData(); GDIDrawCoordinate showCoordinate = new GDIDrawCoordinate();
ArrayList randomList = createPoint.Randtimeseries(1, 10, this.pictureBox1.Height - 50);
showData.DrawPoint(g, randomList);
showData.DrawLine(new Pen(Color.Black, 1), g, randomList);
showCoordinate.GDIDrawAxis(g, new Pen(Color.Brown, 3));
showCoordinate.GDIDrawGrid(g, new Pen(Color.Gray, 1), new Point(30, this.pictureBox1.Height - 30), new Point(this.pictureBox1.Width - 10, 10), 20, 20);
...
}

目的是要在一个picturebox上画出一个坐标系和折线，如果将click事件处理函数里的语句放到picturebox的paint事件里，就可以成功的画出图片，但是如果放在click里，就不行了,是graphics对象的问题吗? 那应该如何获取picturebox的graphics

Answer 1

调用控件的CreateGraphics方法

Answer 2

picturebox.CreateGraphics().drawlines()