winForm 打印预览

自己很少写技术博客，虽然已经干程序员两年多了，winform开发，web开发都干过，不论项目大小对于.net的相关技术也是了解的，如mvc,wcf,wpf,silverlight,socekt通讯，nhibernate,spring.net wp手机开发等，但是最终发现还是软件架构比所谓的单一功能更为系统化。

下面是一个小的例子 Winfom打印预览

首先是基类DocumentBase继承系统的PrintDocument

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Drawing;
using System.Drawing.Printing;
using System.Windows.Forms;

namespace prientDemo
{
   public class DocumentBase:PrintDocument
    {
       public DialogResult ShowPrintPreviewDialog()
       {
           PrintPreviewDialog dialog = new PrintPreviewDialog();
           dialog.Document = this;
           return dialog.ShowDialog();

       }
    }
}

然后ImageDocument再继承ImageDocument

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace prientDemo
{
   public class ImageDocument:ImageDocument
    {
       private Image _image;
       public Image Image
       { get { return _image; } set { _image = value; } }
       public ImageDocument()
       { }
       public ImageDocument(Image image)
       { this.Image = image; }
       protected override void OnPrintPage(System.Drawing.Printing.PrintPageEventArgs e)
       {
          if(Image==null)
          {
              throw new InvalidOperationException();
          }
          e.Graphics.DrawImage(Image, e.MarginBounds);
       }
    }
}

以上是做打印功能时需要自己写的两个类，

下面是winform窗体的代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace prientDemo
{
    public partial class LoadPicture : Form
    {
        public LoadPicture()
        {
            InitializeComponent();
        }
        OpenFileDialog pfd = new OpenFileDialog();
        private DocumentBase _document;
        private void Load_Click(object sender, EventArgs e)
        {
            if(pfd.ShowDialog(this)==DialogResult.OK){
                try
                {
                    pictureImage.Image = Image.FromFile(pfd.FileName);
                    _document = new ImageDocument(pictureImage.Image);
                }
                catch (Exception ex)
                {
                    MessageBox.Show("This image could not be loaded."+ex.Message);
                }

            }

        }

        private void Preview_Click(object sender, EventArgs e)
        {
            if(_document==null)
            {
                MessageBox.Show("You must load an image first");
                return;
            }
            _document.ShowPrintPreviewDialog();
        }
    }
}

下面就完成了，运行效果：如下图