一、调用打开文件对话框

1.选用openfiledialog1对话框控件。

2.定义一个文件名称，例如： private string FileName;

3.代码调用

openFileDialog1.Filter = "所有图像文件（*.bmp;*.gif.;*.jpg）|*.bmp;*.gif;*.jpg";
                      openFileDialog1.Title = "打开文件";   //文件过滤；
            openFileDialog1.ShowDialog();                   //打开对话框；
            FileName = openFileDialog1.FileName;     //对fileName进行赋值；
            if (FileName != "")     //对filename进行判断，不为空的情况下在picturebox中打开图片    
            {

FileName = openFileDialog1.FileName;
                Bitmap pic = new Bitmap(FileName);
                pictureBox1.Image = pic;
            }

二、图片放大缩小时自动产生滚动条

1.选用Panel控件，调整控件大小位置合适，并将Autoscroll属性更改为TRUE。

2.将picturebox控件拖放到panel控件上，可根据自己的需要选择picturebox的AutoMode属性。

//图片放大代码

int x, y;
            x = pictureBox1.Location.X - 5;
            if (pictureBox1.Location.Y <= 0){y = 0;}
            else{y = pictureBox1.Location.Y - 4;}
            pictureBox1.Location = new Point(x, y);
            pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;
            pictureBox1.Size = new Size(pictureBox1.Width + 10, pictureBox1.Height + 14);

//图片缩小代码

int x, y;
            x = pictureBox1.Location.X + 5;
            if (pictureBox1.Location.X < 300){y = 0;}
            else{y = pictureBox1.Location.Y + 4;}
            pictureBox1.Location = new Point(x, y);
            pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;
            pictureBox1.Size = new Size(pictureBox1.Width - 10, pictureBox1.Height - 14);