C# Windows 窗体：将图片拖放到 WPF RichTextBox 中（在 ElementHost 中）答案

【问题标题】：C# Windows Forms: Drop a picture into a WPF RichTextBox (in ElementHost)C# Windows 窗体：将图片拖放到 WPF RichTextBox 中（在 ElementHost 中）
【发布时间】：2014-09-21 19:54:17
【问题描述】：

我有一个 c# Windows Forms 项目，表单上有一个 WPF RichTextBox（在 ElementHost 中），并希望将图片从资源管理器（Windows 7 x64）拖放到其中，但光标仅显示不允许的符号。这是我的代码：

    private void Form1_Load(object sender, EventArgs e)
    {
        this.AllowDrop = true;
        elementHost1.AllowDrop = true;
    }

    public UserControl1()
    {
        InitializeComponent();
        Background = System.Windows.Media.Brushes.Transparent;
        this.AllowDrop = true;
        richTextBox1.AllowDrop = true;
    }

使用设计器订阅事件。他们都没有被解雇：

    private void richTextBox1_DragEnter(object sender, DragEventArgs e)
    {
        MessageBox.Show("Test");
    }

    private void richTextBox1_DragLeave(object sender, DragEventArgs e)
    {
        MessageBox.Show("Test");
    }

    private void richTextBox1_DragOver(object sender, DragEventArgs e)
    {
        MessageBox.Show("Test");
    }

    private void richTextBox1_Drop(object sender, DragEventArgs e)
    {
        MessageBox.Show("Test");
    }

如果我使用 Windows 窗体 RichTextBox 是可行的，但我需要 WPF RichTextBox：

    private void Form1_Load(object sender, EventArgs e)
    {
        richTextBox1.AllowDrop = true;
        richTextBox1.DragDrop += new DragEventHandler(richTextBox1_DragDrop);
    }

    private void richTextBox1_DragDrop(object sender, EventArgs e)
    {
        MessageBox.Show("Test");
    }

【问题讨论】：

标签： c# image richtextbox drag elementhost

【解决方案1】：

您需要使用PreviewDragEnter、PreviewDragOver 和PreviewDrop 事件：

    public Window1()
    {
        InitializeComponent();

        // mainRTB is the name of my RichTextBox.

        mainRTB.PreviewDragEnter += new DragEventHandler(mainRTB_PreviewDragEnter);

        mainRTB.PreviewDragOver += new DragEventHandler(mainRTB_PreviewDragEnter);

        mainRTB.PreviewDrop += new DragEventHandler(mainRTB_PreviewDrop);

        mainRTB.AllowDrop = true;
    }

    static bool IsImageFile(string fileName)
    {
        return true;  // REPLACE THIS STUB WITH A REAL METHOD.
    }

    void mainRTB_PreviewDrop(object sender, DragEventArgs e)
    {
        if (e.Data.GetDataPresent(DataFormats.FileDrop))
        {
            // Note that you can have more than one file.
            string[] files = (string[])e.Data.GetData(DataFormats.FileDrop);
            if (files != null && files.Length > 0)
            {
                // Filter out non-image files
                if (mainRTB.Document.PasteImageFiles(mainRTB.Selection, files.Where(IsImageFile)))
                    e.Handled = true;
            }
        }
    }

    void mainRTB_PreviewDragEnter(object sender, DragEventArgs e)
    {
        string[] files = (string[])e.Data.GetData(DataFormats.FileDrop);
        // Filter out non-image files
        if (files != null && files.Length > 0 && files.Where(IsImageFile).Any())
        {
            // Consider using DragEventArgs.GetPosition() to reposition the caret.
            e.Handled = true;
        }
    }

然后下面的方法将图片粘贴到当前选择范围内：

    public static bool PasteImageFiles(this FlowDocument doc, TextRange selection, IEnumerable<string> files)
    {
        // Assuming you have one file that you care about, pass it off to whatever
        // handling code you have defined.
        FlowDocument tempDoc = new FlowDocument();
        Paragraph par = new Paragraph();
        tempDoc.Blocks.Add(par);

        foreach (var file in files)
        {
            try
            {
                BitmapImage bitmap = new BitmapImage(new Uri(file));
                Image image = new Image();
                image.Source = bitmap;
                image.Stretch = Stretch.None;

                InlineUIContainer container = new InlineUIContainer(image);
                par.Inlines.Add(container);
            }
            catch (Exception)
            {
                Debug.WriteLine("\"file\" was not an image");
            }
        }

        if (par.Inlines.Count < 1)
            return false;

        try
        {
            var imageRange = new TextRange(par.Inlines.FirstInline.ContentStart, par.Inlines.LastInline.ContentEnd);
            using (var ms = new MemoryStream())
            {
                string format = DataFormats.XamlPackage;

                imageRange.Save(ms, format, true);
                ms.Seek(0, SeekOrigin.Begin);
                selection.Load(ms, format);

                return true;
            }
        }
        catch (Exception)
        {
            Debug.WriteLine("Not an image");
            return false;
        }
    }
}

顺便说一句，这种方法避免了使用剪贴板将图像粘贴到RichTextBox —— 有时会看到这样做，但这并不理想。

您可能希望将图像拖放到当前放置位置，而不是粘贴当前选择。如果是这样，从这个开始：Get the mouse position during drag and drop 和这个：How can I insert an image into a WPF RichTextBox at runtime in between text so the text floats around the image

【讨论】：