声明:由于.net下没有IconBitmapEncoder类.其实还是用GDI+来做的.只不过是在Wpf环境下.

首先上图:

另附代码：

代码 
 <Canvas Margin="0,0,0,0">
        <Image x:Name="imgJpeg" Canvas.Left="90" Canvas.Top="62" Height="150" Stretch="Fill" Width="200" />
        <TextBlock Text="原始图像:" Height="16" Canvas.Left="65" Canvas.Top="231" Width="51"></TextBlock>
        <TextBox x:Name="txtImage" Width="138" Height="21.837" Canvas.Left="127" Canvas.Top="228" IsReadOnly="True"></TextBox>
        <Button x:Name="btnOk" Content="浏览" Width="50" Height="21.837" Canvas.Left="283" Canvas.Top="228" Click="btnOk_Click"></Button>
        <TextBlock Text="目标尺寸:" Height="16" Canvas.Left="65.11" Canvas.Top="267" Width="50.89"></TextBlock>
        <ComboBox x:Name="cmbSize" Height="22" Canvas.Left="127" Canvas.Top="265" Width="138" SelectionChanged="cmbSize_SelectionChanged">
            <ComboBoxItem DataContext="1" Selector.IsSelected="True">16*16</ComboBoxItem>
            <ComboBoxItem DataContext="2">32*32</ComboBoxItem>
            <ComboBoxItem DataContext="3">64*64</ComboBoxItem>
        </ComboBox>
        <Button x:Name="btnMake" Content="生成ico图标" Height="22" Canvas.Left="283" Canvas.Top="265" Width="70.84" Click="btnMake_Click"></Button>
    </Canvas>

 

后台代码:

代码 
 public partial class IconMake : Window
    {
        Bitmap srcBitmap = null;//用于保存原图
        System.Drawing.Size size;//用于保存目标图标的大小

        public IconMake()
        {
            InitializeComponent();
        }

        private void cmbSize_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            if (cmbSize.SelectedIndex == 0)
                size = new System.Drawing.Size(16, 16);
            else if (cmbSize.SelectedIndex == 1)
                size = new System.Drawing.Size(32, 32);
            else if (cmbSize.SelectedIndex == 2)
                size = new System.Drawing.Size(64, 64);
        }

        private void btnOk_Click(object sender, RoutedEventArgs e)
        {
            //弹出对话框
            OpenFileDialog dlg = new OpenFileDialog();
            dlg.InitialDirectory = "F:\\";
            dlg.Filter = "图片(*.jpg,*.png,*.bmp)|*.jpg;*.png;*.bmp";
            dlg.ValidateNames = true;
            dlg.CheckFileExists = true;
            dlg.CheckPathExists = true;
            //Nullable<bool> result = dlg.ShowDialog();
            if (dlg.ShowDialog() == System.Windows.Forms.DialogResult.OK)
            {
                txtImage.Text = dlg.FileName;
                srcBitmap = new Bitmap(dlg.FileName);
                imgJpeg.Source = new BitmapImage(new Uri(txtImage.Text, UriKind.RelativeOrAbsolute));
            }
        }

        private void btnMake_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                if (txtImage.Text != "" && cmbSize.Text != "")
                {
                    SaveFileDialog dlg = new SaveFileDialog();
                    dlg.Filter = "图标(*.ico)|*.ico";
                    dlg.CheckPathExists = true;
                    if (dlg.ShowDialog() == System.Windows.Forms.DialogResult.OK)
                    {
                        FileStream fs = new FileStream(dlg.FileName, FileMode.Create);
                        System.Drawing.Icon icon = ConvertBitmap2Ico(srcBitmap);
                        //将Icon保存的指定的输出
                        icon.Save(fs);
                        fs.Close();
                    }
                }
            }
            catch (Exception err)
            {
                System.Windows.MessageBox.Show(err.ToString());
            }
        }

         /// <summary>
        /// 实现bitmap到ico的转换
        /// </summary>
        /// <param name="bitmap">原图</param>
        /// <returns>转换后的指定大小的图标</returns>
        private Icon ConvertBitmap2Ico(Bitmap bitmap)
        {
            Bitmap icoBitmap = new Bitmap(bitmap, size);
            //获得原位图的图标句柄
            var a = icoBitmap.GetHicon();
            //从图标的指定WINDOWS句柄创建Icon
            System.Drawing.Icon icon = System.Drawing.Icon.FromHandle(a);
            return icon;
        }
    }

 

好了.有几点需要注意的地方.

1.首先我这里的对话框使用的winform下的.所以首先要引用System.Windows.Forms;另外还需引用using System.Drawing;

顺便说一下.wpf下貌似可以用两种类型的对话框.一种是System.Win32下,一种是System.Windows.Forms.有点小区别.win32的对话框边框是旧的样式.windows.forms下的对话框是win7主题样式.还有一个区别,DialogResult返回的结果不同.具体的大家可以自己测试下.

2.由于这里采用的是获取句柄方式转换的.所以图片会失真..