C# pictureBox里拖动图片后，然后我在画直线，图片又回到拖动前的地方

Question

C# pictureBox里拖动图片后，然后我在画直线，图片又回到拖动前的地方
我在画直线的代码里，使用了
this.pictureBox1.Invalidata();我知道是这个原因造成的，但这个又不能去掉，
请问怎么办？

Answer 1

下面是我拖动图片用到的代码：
 private void MyReDrawTest(Point offset)
        {
            Image srcBitmap = this.pictureBox1.Image;
            if (srcBitmap == null)
                return;            BufferedGraphicsContext currentContext = BufferedGraphicsManager.Current;            BufferedGraphics myBuffer = currentContext.Allocate(this.pictureBox1.CreateGraphics(), this.pictureBox1.DisplayRectangle);            myBuffer.Graphics.Clear(this.pictureBox1.BackColor);            myBuffer.Graphics.DrawImage(srcBitmap, offset);            myBuffer.Render(this.pictureBox1.CreateGraphics());            myBuffer.Dispose();
        }

Answer 2

1、将BufferedGraphicsContext 、BufferedGraphics 为全局变量,在构造时赋值
2、绑定pictureBox重绘事件
3、在重绘时将图像缓存区图像写入Graphics
Code        BufferedGraphicsContext currentContext;
        BufferedGraphics myBuffer;
        Graphics g;
        bool userPaint;        public Form1()
        {
            InitializeComponent();
            currentContext = BufferedGraphicsManager.Current;
            g = pictureBox1.CreateGraphics();
            myBuffer = currentContext.Allocate(g, this.pictureBox1.DisplayRectangle);
            userPaint = false;
            pictureBox1.Paint += new PaintEventHandler(pictureBox1_Paint);
        } private void pictureBox1_Paint(object sender, PaintEventArgs e)
        {
            if (userPaint)
                myBuffer.Render(e.Graphics);
        }        private void MyReDrawTest(Point offset)
        {            Image srcBitmap = this.pictureBox1.Image;
            if (srcBitmap == null)
                return;            myBuffer.Graphics.Clear(this.pictureBox1.BackColor);            myBuffer.Graphics.DrawImage(srcBitmap, offset);            myBuffer.Render(this.pictureBox1.CreateGraphics());            if (!userPaint)
                userPaint = true;
        }