接受拖放时如何在文本框上移动插入插入符号

我在所有关于拖放的建议中遗漏的是使文本插入符号可见。最终,我发现您只需将焦点设置到控件中!因此textBox1.DragOver事件处理程序的最终代码如下所示。我已经包含了上一个答案中的GetCaretIndexFromPoint函数:

/// <summary>
/// Gives visual feedback where the dragged text will be dropped.
/// </summary>
private void textBox1_DragOver(Object sender, System.Windows.Forms.DragEventArgs e)
{
    // fake moving the text caret
    textBox1.SelectionStart = GetCaretIndexFromPoint(textBox1, e.X, e.Y);
    textBox1.SelectionLength = 0;
    // don't forget to set focus to the text box to make the caret visible!
    textBox1.Focus();
}

/// <remarks>
/// GetCharIndexFromPosition is missing one caret position, as there is one extra caret
/// position than there are characters (an extra one at the end).
/// </remarks>
private int GetCaretIndexFromPoint(System.Windows.Forms.TextBox box, int x, int y)
{
    Point realPoint = box.PointToClient(newPoint(x, y));
    int index = box.GetCharIndexFromPosition(realPoint);
    if (index == box.Text.Length - 1)
    {
        Point caretPoint = box.GetPositionFromCharIndex(index);
        if (realPoint.X > caretPoint.X)
        {
            index += 1;
        }
    }
    return index;
}

我想你应该看看如何处理textBox1_DragOver事件。将DragOver事件参数中包含的鼠标位置传递给“textBox1.GetCharIndexFromPosition()”

这是您的文档 GetCharIndexFromPosition

这实际上是非常令人恼火的,因为GetCharIndexFromPosition(显然)缺少一个插入符号位置,因为有一个额外的插入符号位置比有个字符多(末尾有一个额外的)。我用它在DragOver上设置SelectionStart,在DragDrop上设置Insert。

    private int GetCaretIndexFromPoint(TextBox tb, int x, int y)
    {
        Point p = tb.PointToClient(new Point(x, y));
        int i = tb.GetCharIndexFromPosition(p);
        if (i == tb.Text.Length - 1)
        {
            Point c = tb.GetPositionFromCharIndex(i);
            if (p.X > c.X)
                i++;
        }
        return i;
    }

    /// <summary>
    /// Handles the Preview DragOver event to set the textbox selection at the precise place where the user dropped the dragged text
    /// </summary>
    private static void element_PreviewDragOver(object sender, DragEventArgs dragEventArgs)
    {
        TextBox textBox = sender as TextBox;
        if (textBox != null && dragEventArgs != null)
        {
            // Set the caret at the position where user ended the drag-drop operation
            Point dropPosition = dragEventArgs.GetPosition(textBox);

            textBox.SelectionStart = GetCaretIndexFromPoint(textBox, dropPosition);
            textBox.SelectionLength = 0;

            // don't forget to set focus to the text box to make the caret visible!
            textBox.Focus();
            dragEventArgs.Handled = true;
        }
    }

    /// <summary>
    /// Gets the caret index of a given point in the given textbox
    /// </summary>
    /// <param name="textBox"></param>
    /// <param name="point"></param>
    /// <returns></returns>
    private static int GetCaretIndexFromPoint(TextBox textBox, Point point)
    {
        int index = textBox.GetCharacterIndexFromPoint(point, true);

        // GetCharacterIndexFromPoint is missing one caret position, as there is one extra caret position than there are characters (an extra one at the end).
        //  We have to add that caret index if the given point is at the end of the textbox
        if (index == textBox.Text.Length - 1)
        {
            // Get the position of the character index using the bounding rectangle
            Rect caretRect = textBox.GetRectFromCharacterIndex(index);
            Point caretPoint = new Point(caretRect.X, caretRect.Y);

            if (point.X > caretPoint.X)
            {
                index += 1;
            }
        }
        return index;
    }

    /// <summary>
    /// Handler for preview drag event in a textbox
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="dragEventArgs"></param>
    private static void element_PreviewDrop(object sender, DragEventArgs dragEventArgs)
    {
        TextBox textBox = sender as TextBox;
        if (textBox != null && dragEventArgs != null && dragEventArgs.Data != null && dragEventArgs.Data.GetDataPresent(DataFormats.StringFormat))
        {
            string newText = dragEventArgs.Data.GetData(DataFormats.StringFormat) as string;
            if (!string.IsNullOrEmpty(newText))
            {
                // do your custom logic here
                textBox.Focus();
            }
            dragEventArgs.Handled = true;
        }
    }

要模拟常用工具(如记事本)的行为,GetCaretIndexFromPoint()函数必须同时检查X和Y坐标。

/// <summary>
/// Gives visual feedback where the dragged text will be dropped.
/// </summary>
private void textBox1_DragOver(Object sender, System.Windows.Forms.DragEventArgs e)
{
    // fake moving the text caret
    textBox1.SelectionStart = GetCaretIndexFromPoint(textBox1, e.X, e.Y);
    textBox1.SelectionLength = 0;
    // don't forget to set focus to the text box to make the caret visible!
    textBox1.Focus();
}

/// <remarks>
/// GetCharIndexFromPosition is missing one caret position, as there is one extra caret
/// position than there are characters (an extra one at the end).
/// </remarks>
private int GetCaretIndexFromPoint(System.Windows.Forms.TextBox box, int x, int y)
{
    Point realPoint = box.PointToClient(new Point(x, y));
    int index = box.GetCharIndexFromPosition(realPoint);
    if (index == box.Text.Length - 1)
    {
        Point caretPoint = box.GetPositionFromCharIndex(index);
        if ((realPoint.X > caretPoint.X) || (realPoint.Y > caretPoint.y))
        {
            index += 1;
        }
    }
    return index;
}

感谢用户468106给出的精彩回答!