c#编程之文件IO 自动滚动至底部（补充）

　　这里对上一文章做一个补充，因为很多时候，我们需要分步计算多个文件的crc值，而往往最后显示的值都需要在第一时间内进入眼帘。所以我们需要确保最后文件的计算结果必须显示到UI的最前端。

同样，我们依然使用格式：控件名称+ScrollToEnd()函数实现：

代码如下：

                UserInput.ScrollToEnd();
                if(UserInput.IsFocused==true)
                {
                    UserInput.SelectionStart = UserInput.Text.Length;
                }

最后整理代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.IO;

namespace FileSample
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        UInt16 [] crc_table=new UInt16[256]{
        0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7, 
        0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef, 
        0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6, 
        0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de, 
        0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485, 
        0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d, 
        0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4, 
        0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc, 
        0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823, 
        0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b, 
        0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12, 
        0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a, 
        0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41, 
        0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49, 
        0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70, 
        0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78, 
        0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f, 
        0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067, 
        0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e, 
        0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256, 
        0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d, 
        0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405, 
        0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c, 
        0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634, 
        0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab, 
        0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3, 
        0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a, 
        0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92, 
        0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9, 
        0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1, 
        0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8, 
        0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0}; 
        public MainWindow()
        {
            InitializeComponent();
        }
        public UInt16 crc_16(UInt16 crc, byte data)
        {
            byte da;

            da = (byte)(crc / 256);
            crc <<= 8;              //crc=crc*256
            crc ^= crc_table[da ^ data];
            return crc;
        }
        private void open_Click(object sender, RoutedEventArgs e)
        {
            System.Windows.Forms.OpenFileDialog openfile = new System.Windows.Forms.OpenFileDialog();
            UInt16 crc;
            openfile.InitialDirectory = "D:\";
            openfile.Filter = "txt files |*.txt|All files |*.*";
            openfile.FilterIndex = 1;
            openfile.RestoreDirectory = true;
            if(openfile.ShowDialog()==System.Windows.Forms.DialogResult.OK)
            {
                UserInput.Text += openfile.FileName + "
";
                StreamReader sr = new System.IO.StreamReader(openfile.FileName, Encoding.Default);
                crc = 0xffff;
                while(sr.Peek() > 0)
                {
                    //UserInput.Text += (char)sr.Read();
                    crc = crc_16(crc, (byte)sr.Read());
                }
                UserInput.Text += "crc=" + crc.ToString() + "(Int), " + crc.ToString("X2") + "(Hex)" + "
";
                UserInput.ScrollToEnd();
                if(UserInput.IsFocused==true)
                {
                    UserInput.SelectionStart = UserInput.Text.Length;
                }
            }
        }

        private void TextBox_PreviewDrop(object sender, DragEventArgs e)
        {
            UInt16 crc;
            //get files counter
            Array fileArray = (System.Array)e.Data.GetData(DataFormats.FileDrop);
            string filePath;
            for (int i=0; i < fileArray.Length; i++)
            {
                filePath = ((System.Array)e.Data.GetData(DataFormats.FileDrop)).GetValue(i).ToString();
                UserInput.Text += filePath + "
";
                StreamReader sr=new System.IO.StreamReader(filePath,Encoding.Default);
                crc = 0xffff;
                while(sr.Peek()>0)
                {
                    crc = crc_16(crc, (byte)sr.Read());
                }
                UserInput.Text += "crc=" + crc.ToString() + "(Int), " + crc.ToString("X2") + "(Hex)" + "
";
                UserInput.ScrollToEnd();
                if(UserInput.IsFocused==true)
                {
                    UserInput.SelectionStart = UserInput.Text.Length;
                }
            }
        }

        private void TextBox_PreviewDragOver(object sender, DragEventArgs e)
        {
            if (e.Data.GetDataPresent(DataFormats.FileDrop))
            {
                e.Effects = DragDropEffects.Link;
                e.Handled = true;
            }
            else
                e.Effects = DragDropEffects.None;
        }
    }
}

End.谢谢.