0

我在多列列表框中查看所有接收到的数据。当我单击打印按钮时，它将打印出列表框中的所有数据审查。

这是我的代码：

1.首先，用户会根据ID搜索关键词。然后它将出现在多列列表视图中。此数据在 xml 文件中搜索。

XmlDocument xml = new XmlDocument();
xml.Load("C:\\Users\\HDAdmin\\Documents\\Fatty\\SliceEngine\\SliceEngine\\bin\\Debug\\patient.xml");
XmlNodeList xnList = xml.SelectNodes("/main/patient");
foreach (XmlNode xn in xnList)
{
    string date = xn.OfType<XmlNode>().FirstOrDefault(n => n.Name == "Date").FirstChild.Value;
    string id = xn.OfType<XmlNode>().FirstOrDefault(n => n.Name == "ID").FirstChild.Value;
    if (date == cari)
    {
       listviewitem = new ListViewItem(date);
       listviewitem.SubItems.Add("Smith");
       this.listView1.Items.Add(listviewitem);
    }
       if (id == cari)
       {                    
           listviewitem = new ListViewItem(date);

           id = xn.OfType<XmlNode>().FirstOrDefault(n => n.Name == "ID").FirstChild.Value;
           listviewitem.SubItems.Add(id);

           string level = xn.OfType<XmlNode>().FirstOrDefault(n => n.Name == "Level").FirstChild.Value;
           listviewitem.SubItems.Add(level);

           string name = xn.OfType<XmlNode>().FirstOrDefault(n => n.Name == "Name").FirstChild.Value;                    
           listviewitem.SubItems.Add(name);

2.用同样的方法，我添加了打印事件按钮

    this.components = new System.ComponentModel.Container();
    this.printBut = new System.Windows.Forms.Button();
    this.ClientSize = new System.Drawing.Size(504, 381);
    this.Text = "Print Example";

    printBut.ImageAlign = System.Drawing.ContentAlignment.MiddleLeft;               
    printBut.Location = new System.Drawing.Point(32, 110);
    printBut.FlatStyle = System.Windows.Forms.FlatStyle.Flat;
    printBut.TabIndex = 0;
    printBut.Text = "Print the file.";
    printBut.Size = new System.Drawing.Size(136, 40);
    printBut.Click += new System.EventHandler(printBut_Click);

    this.Controls.Add(printBut);
    //-------------print-----------------

3.这是 printBut_click。

private void printBut_Click(object sender, EventArgs e)
    {
        try
        {
            StreamReader streamToPrint = new StreamReader("C:\\Users\\HDAdmin\\Documents\\Fatty\\SliceEngine\\SliceEngine\\bin\\Debug\\aboutREPCS.txt");

            try
            {
                printFont = new Font("Arial", 10);
                pd = new PrintDocument();
                pd.PrintPage += new PrintPageEventHandler(this.pd_PrintPage);                       
                pd.Print();
            }
            finally
            {
                streamToPrint.Close();
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }

4.这是 printPage 事件

// The PrintPage event is raised for each page to be printed.
private void pd_PrintPage(object sender, PrintPageEventArgs ev)
    {
        float linesPerPage = 0;
        float yPos = 0;
        int count = 0;
        float leftMargin = ev.MarginBounds.Left;
        float topMargin = ev.MarginBounds.Top;
        string line = null;

        // Calculate the number of lines per page.
        linesPerPage = ev.MarginBounds.Height /
           printFont.GetHeight(ev.Graphics);

        // Print each line of the file.
        while (count < linesPerPage &&
           ((line = streamToPrint.ReadLine()) != null))
        {
            yPos = topMargin + (count *
               printFont.GetHeight(ev.Graphics));
            ev.Graphics.DrawString(line, printFont, Brushes.Black,
               leftMargin, yPos, new StringFormat());
            count++;
        }

        // If more lines exist, print another page.
        if (line != null)
            ev.HasMorePages = true;
        else
            ev.HasMorePages = false;
    }

当我运行此代码时，它会出现object reference not set to an instance of an object。 在此处输入图像描述

所以，让我重复一下这个应用程序的流程。

User insert keyword.
If keyword match, view data from xml file into multicolumn listview.
printBut will print all the data view in listview.
4

0 回答 0