Introduction
The FlowLayoutPanel
control is actually pretty handy from time to time. In this article, I will explain how to enable drag and drop on two controls. I am using a custom progressbar with drag and drop enabled, so this will only show how to drop and reorder controls. As always, there is probably more than one way to solve this, but this is how I did.
Background
Recently, I had to create a custom drawn progressbar and somehow create a list of those with drag and drop functions. After searching the Internet for a while without luck, I decided to write a little helper here once I finished.
Using the Code
To be able to drag controls to the panel, we first have to add the DragEnter
event, either by code or in the Designer.
this.flowLayoutPanel1.DragEnter += new DragEventHandler(flowLayoutPanel_DragEnter);
void flowLayoutPanel_DragEnter(object sender, DragEventArgs e)
{
e.Effect = DragDropEffects.All;
}
Then, we add the actual drop event and write the code for it. First, I check if I have dragged the control to the same FlowLayoutPanel
. If that's the case, I reorder; if not, then I first add the control and then reorder. The reordering is based on which child control I "drop" the new control on.
this.flowLayoutPanel1.DragDrop += new DragEventHandler(flowLayoutPanel_DragDrop);
void flowLayoutPanel1_DragDrop(object sender, DragEventArgs e)
{
HarrProgressBar data = (HarrProgressBar)e.Data.GetData(typeof(HarrProgressBar));
FlowLayoutPanel _destination = (FlowLayoutPanel)sender;
FlowLayoutPanel _source = (FlowLayoutPanel)data.Parent;
if (_source != _destination)
{
_destination.Controls.Add(data);
data.Size = new Size(_destination.Width, 50);
Point p = _destination.PointToClient(new Point(e.X, e.Y));
var item = _destination.GetChildAtPoint(p);
int index = _destination.Controls.GetChildIndex(item, false);
_destination.Controls.SetChildIndex(data, index);
_destination.Invalidate();
_source.Invalidate();
}
else
{
Point p = _destination.PointToClient(new Point(e.X, e.Y));
var item = _destination.GetChildAtPoint(p);
int index = _destination.Controls.GetChildIndex(item, false);
_destination.Controls.SetChildIndex(data, index);
_destination.Invalidate();
}
}
This will move the control from one panel to another. This code will probably need some tuning if you want to drag from a normal Panel
to a FlowLayoutPanel
.
Points of Interest
I've put DoDragDrop();
in the HarrProgressBar
to be able to drag it onto other controls and to minimize code outside the class.
History
- 2009-12-21 - v1.0 - Article added.
I have been working with .NET development since 2003, working with backend systems, and both web and desktop applications. I have experience of integrating software with ERP-systems, connecting production environment, and publishing information to various platforms. With this comes very extensive knowledge about windows OS administration, both server and client. I have worked with almost every OS from Microsoft, and a few linux dists in mixed environment, along with several mobile and "Thin client"-solutions. I have experience in configuring and managing webservers, ftpservers, domains and mailservers in a mixed OS environment.
I'm always looking forward to learning and mastering new technologies.
Specialties: .NET development, PLC integration, ERP integration
Development -> C#, ASP.NET MVC, HTML, WCF, WinForms, Silverlight, PHP, VB6
Database -> MSSQL, MySQL, MsAccess
ERP -> Jeeves, JSB, Jeeves eSales
Automation integration -> TwinCAT, Siemens S7
Automation HMI -> Iconics, Beijer, Indusoft
Microsoft products -> Sharepoint, Microsoft Office
OS -> Windows Guru (Server & Client), Linux (Debian/Ubuntu)