通过创建一个button按钮对控件进行截图操作

按一个button实现截图

先看XAML:`

Window x:Class="BMPGenerator.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525" >
    <Grid>
        <StackPanel HorizontalAlignment="Left" Height="319" VerticalAlignment="Top" Width="517" >
            <Canvas x:Name="MainCanvas" Height="270" >
                <Canvas.Background>
                    <ImageBrush ImageSource="C:\Users\pandong\Documents\Visual Studio 2012\Projects\BMPGenerator\BMPGenerator\Resources\aaa.jpg" Stretch="Fill" TileMode="FlipXY"/>
                </Canvas.Background>   //这里是导入背景图片
            </Canvas>
            <Button x:Name="Button" Content="PicGenerate" Click="Button_Click" >
                <Button.Background>
                    <ImageBrush ImageSource="C:\Users\pandong\Documents\Visual Studio 2012\Projects\BMPGenerator\BMPGenerator\Resources\aaa.jpg" Stretch="Fill"/>
                </Button.Background>
            </Button>

        </StackPanel>

    </Grid>
</Window>

效果如下

主代码如下：
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;
using System.Windows.Forms;

namespace BMPGenerator
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {


        public MainWindow()
        {
            InitializeComponent();
        }
           //保存图片处理事件
        private void Button_Click(object sender, RoutedEventArgs e)
        {
            string outputfile = "";
            System.Windows.Forms.SaveFileDialog saveFileDialog1 = new System.Windows.Forms.SaveFileDialog();
            saveFileDialog1.Filter = "Png Files|*.png|Jpeg Image|*.jpg|Gif Image|*.gif";        //文件保存的格式

            if (saveFileDialog1.ShowDialog() == System.Windows.Forms.DialogResult.OK)
                outputfile = saveFileDialog1.FileName;                                      //获取的名字里面包含路径
            if (outputfile != "")
            {
                GetPicFromControl(MainCanvas, "BMP", @outputfile);   //MainCanvas是要截图的控件                  
            }



        }

        //FrameworkElement  为wpf元素提供wpf框架级的属性、事件和方法集
        //截图
        private void GetPicFromControl(FrameworkElement element, String type, String outputPath)
        {
            var bitmapRender = new RenderTargetBitmap((int)element.ActualWidth, (int)element.ActualHeight, 96, 96, PixelFormats.Pbgra32);//初始化一个系统windows媒体成像渲染目标位图类的新实例，它具有指定的参数

            bitmapRender.Render(element);
            BitmapEncoder encoder = null;                                                                                          //将XX对象的集合编码到图像流中

            switch (type.ToUpper() ) 
            {                  
                case "BMP":
                    encoder = new BmpBitmapEncoder();               
                    break;
                case "GIF":
                    encoder = new GifBitmapEncoder();
                    break;
                case "JPEG":
                    encoder = new JpegBitmapEncoder();
                    break;
                case "PNG":
                    encoder = new PngBitmapEncoder();
                    break;
                case "TIFF":
                    encoder = new TiffBitmapEncoder();
                    break;
                default:
                    break;
            }

            encoder.Frames.Add(BitmapFrame.Create(bitmapRender));        //根据提供的参数创建一个新的位图
            using (var file = File.Create(outputPath))               //在指定的路径outputPath中创建或覆盖文件
            encoder.Save(file);

        }

    }
}