How to implement drag-and-drop operations between controls in WinForms?

6 months ago

2 minutes

The drag-and-drop operation between controls in WinForms can be achieved by following these steps:

Set the AllowDrop property of the control that is going to be dragged to true in order to allow drag and drop operations.
Add a MouseDown event handler to the control you want to drag in order to initiate the dragging operation. Call the control’s DoDragDrop method within the event handler to start the dragging operation and pass the data to be dragged.
Add DragEnter and DragDrop event handlers to the controls that are meant to receive drag-and-drop interactions. In the DragEnter event handler, check if the data type being dragged is compatible with the requirements for dropping, and set the AllowDrop property to true. In the DragDrop event handler, retrieve and process the dragged data.

Below is a simple example code demonstrating how to implement drag and drop operation between controls in WinForms.

// 开始拖动操作
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
    pictureBox1.DoDragDrop(pictureBox1.Image, DragDropEffects.Copy);
}

// 拖动进入目标控件
private void pictureBox2_DragEnter(object sender, DragEventArgs e)
{
    if (e.Data.GetDataPresent(DataFormats.Bitmap))
    {
        e.Effect = DragDropEffects.Copy;
    }
}

// 放置操作
private void pictureBox2_DragDrop(object sender, DragEventArgs e)
{
    pictureBox2.Image = (Image)e.Data.GetData(DataFormats.Bitmap);
}

In this example, when the user clicks on the pictureBox1 control, they can drag the image within the control. When the drag enters the pictureBox2 control, it checks if the dragged data type is a Bitmap and allows the drop operation. When the drop occurs, the dragged image is set as the Image property of pictureBox2.