- C# code
using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Windows.Forms;using System.Drawing.Drawing2D;namespace WindowsFormsApplication3{ public partial class Form1 : Form { private PointF current; private PointF movepf; public Form1() { InitializeComponent(); } private void pictureBox1_MouseClick(object sender, MouseEventArgs e) { current = e.Location; } private void pictureBox1_MouseMove(object sender, MouseEventArgs e) { movepf = e.Location; Invalidate(); } protected override void OnPaint(PaintEventArgs e) { Bitmap mp = new Bitmap(pictureBox1.Width, pictureBox1.Height); Pen pen = new Pen(Color.Blue); SolidBrush drawBrush = new SolidBrush(Color.Black); using (Graphics g = Graphics.FromImage(mp)) { g.DrawImage(mp, pictureBox1.ClientRectangle.X, pictureBox1.ClientRectangle.Y); g.DrawLine(pen, current, movepf); PointF pt1 = new PointF(); pt1.X = (current.X + movepf.X) / 2; pt1.Y = (current.Y + movepf.Y) / 2; g.DrawString("12345", this.Font, drawBrush, pt1); using (Graphics gg = this.CreateGraphics()) { gg.DrawImage(mp, pictureBox1.ClientRectangle.X, pictureBox1.ClientRectangle.Y); } } base.OnPaint(e); } }}就是想知道 我这样画线， 就一个窗体一个picturebox ，我想在picturebox里面画线,可是线条老出在form上面 怎么办呢
------解决方案--------------------------------------------------------
protected override void OnPaint(PaintEventArgs e)
这句是Form的Paint事件，你不觉得理所当然是画在窗体上吗。
你应该自己写个方法
private void pictureBoxPaint(object sender, PaintEventArgs e)
然后关联给你的pictureBox1.Paint事件
------解决方案--------------------------------------------------------
问题出在你用的Graphics是Form的（this.CreateGraphics()），用PictureBox的就可以画到PictureBox中了。不过效果估计不是你想要的。
代码改成如下的样子就可以了：
- C# code
using (Graphics gg = Graphics.FromHwnd(pictureBox1.Handle)) //this.CreateGraphics())