c#: winform drags an icon from a toolstriptool into a custom usercontrol.

Effect:

In a winform project, add a ToolStrip and then add a ToolStripButton to it (tsbStart, which is the icon circled by the red box)

this.toolStripTools = new System.Windows.Forms.ToolStrip();
this.tsbStart = new System.Windows.Forms.ToolStripButton();

, when tsbStart is clicked and dragged to the workspace (the blank area in the lower part of the figure, it is a panel, and a usercontrol is dynamically added to the panel), the event WorkPlace_DragEnter(object sender, DragEventArgs e) is triggered when dragging into the workspace (usercontrol), put the mouse e.Effect = DragDropEffects.Copy;. When the drag is ended, when WorkPlace_DragDrop(object sender, DragEventArgs e) is monitored within the scope of the workspace (usercontroll), a control is dynamically added to the workspace to complete the drag effect.

Implementation code:

main form code:

 　　　　public Main()
        {
            InitializeComponent();
        }

        private void Main_Load(object sender, EventArgs e)
        {
            if (this.wpClient != null)
                wpClient.CloseFlow();

            // When the form is reloaded, clear the controls in the form. 
            this .plClient.Controls.Clear();

            wpClient = new WorkPlace("1", UserId, UserName);
            wpClient.WorkFlowCaption = "Hello WorkFlow Designer...";
            wpClient.CanEdit = true;
            wpClient.State = " Modify " ;

            // Add the wpClient object to the plClient control area. 
            this .plClient.Controls.Add( this .wpClient);

            // The toolbar icon of the Main form takes effect and is available. 
            this .toolStripTools.Enabled = true ;
        }

        private void tsbStart_MouseDown(object sender, MouseEventArgs e)
        {
            // If the left button is left, the flag is true (indicating that dragging starts) 
            if ((e.Button == System.Windows.Forms.MouseButtons.Left))
            {
                // Form a drag effect, a combined effect of move + copy 
                Button button = new Button();
                button.SetBounds(0, 0, 100, 20);
                button.Text = "button ";
                button.DoDragDrop(button, (DragDropEffects.Copy | DragDropEffects.Move)); // Form a drag effect, a combined effect of move + copy 
            }
        }

workspace custom control code:

        public WorkPlace()
        {
            InitializeComponent();
            // If the structure drag event is allowed, it must be set to true, otherwise the drag event cannot be ended.
            // The custom control itself supports dragged controls 
            this .AllowDrop = true ;
             this .DragEnter += new DragEventHandler(WorkPlace_DragEnter);
             this .DragDrop += new DragEventHandler(WorkPlace_DragDrop);
        }
        
        public WorkPlace(string workFlowId, string userId, string userName)
            : this()
        {
            this.WorkFlowId = workFlowId;
            this.UserId = userId;
            this.UserName = userName;
        }

        ///  <summary> 
        /// Close the form. When closing the form, you need to determine whether the current work content has been saved, otherwise a confirmation message will be prompted.
        ///  </summary> 
        public  void CloseFlow()
        {

        }
        
        void WorkPlace_DragEnter(object sender, DragEventArgs e)
        {
            // When the Button is dragged onto the WinForm, the mouse effect appears 
            if ((e.Data.GetDataPresent( typeof (Button))))
            {
                e.Effect = DragDropEffects.Copy;
            }
        }

        int count = 0;
        void WorkPlace_DragDrop(object sender, DragEventArgs e)
        {
            if ((e.Data.GetDataPresent(typeof(Button))))
            {
                // After dragging and dropping, a new control 
                Button is automatically generated btn = new Button();
                btn.SetBounds(e.X, e.Y, 100, 50);
                btn.Location = this .PointToClient( new Point(eX, eY));
                 // Use this method to calculate the X, Y coordinates of the client container interface. Otherwise use X directly, Y is the screen coordinate 
                this .Controls.Add(btn);
                btn.Text = " Button " + count.ToString();
                count = count + 1;
            }
        }

Precautions:

The property AllowDrop must be set to true inside the workplace custom control, otherwise the DragDown and DargDrop events will not be triggered.

this.AllowDrop = true;