am doing something very very simple.
I have a listbox whose events are set like this :
public Form1()
{
InitializeComponent();
this.listBox1.AllowDrop = true;
this.listBox1.DragEnter += new DragEventHandler(listBox1_DragEnter);
this.listBox1.DragDrop += new DragEventHandler(listBox1_DragDrop);
}
void listBox1_DragDrop(object sender, DragEventArgs e)
{
//code to add labelText to Items of ListBox
}
void listBox1_DragEnter(object sender, DragEventArgs e)
{
//set DragDropEffects;
}
now I have a label, code for which is as follows:
private void label1_MouseDown(object sender, MouseEventArgs e)
{
DoDragDrop((sender as Label).Text, DragDropEffects.Copy);
//this.label1.DoDragDrop((sender as Label).Text, DragDropEffects.Copy);
//used one of them at a time.
}
but nothing happens. listbox DragEnter event never fires up. in fact, drag never happens. whenever i try to drag label (text), not allowed windows cursor appears, instead of ' DragDropEffects.Copy
's cursor
Drag and Drop doesn't take place..
when I modify the listbox (and the associated code) to accept files to be dropped on it from any other window, that works perfectly.
so..am unable to perform drag from a control kept on the form to another control kept on the same form.
am I missing something? am running windows XP.
I went through this and through this
please help...
Your code does work actually. You just have to set the right drag effects in your event handlers.
void listBox1_DragDrop(object sender, DragEventArgs e)
{
e.Effect = DragDropEffects.Copy;
}
void listBox1_DragEnter(object sender, DragEventArgs e)
{
e.Effect = DragDropEffects.Copy;
}
检查ListBox.AllowDrop是否设置为TRUE
The following is an example of what you need, with all the code (adding it here for whoever finds this post).
#region Initial Values
//Constructor:
public Form1() {
InitializeComponent();
}
private void Form1_Load( object sender, EventArgs e ) {
InitialValues();
}
private void InitialValues() {
PrepareDragAndDrop();
}
#endregion Initial Values
#region Drag & Drop
private void PrepareDragAndDrop() {
//For the object that receives the other dragged element:
TheSamplListBox.AllowDrop = true;
TheSamplListBox.DragEnter += TheSamplListBox_DragEnter;
TheSamplListBox.DragLeave += TheSamplListBox_DragLeave;
TheSamplListBox.DragDrop += TheSamplListBox_DragDrop;
//For the object that will be dragged:
TheSampleLabel.MouseDown += ( sender, args ) => DoDragDrop( TheSampleLabel.Text, DragDropEffects.Copy );
}
private void TheSamplListBox_DragEnter( object theReceiver, DragEventArgs theEventData ) {
theEventData.Effect = DragDropEffects.Copy;
//Only the code above is strictly for the Drag & Drop. The following is for user feedback:
//You can use [TheSamplListBox] but this approach allows for multiple receivers of the same type:
var theReceiverListBox = (ListBox) theReceiver;
theReceiverListBox.BackColor = Color.LightSteelBlue;
}
private void TheSamplListBox_DragLeave( object theReceiver, EventArgs theEventData ) {
//No code here for the Drag & Drop. The following is for user feedback:
//You can use [TheSamplListBox] but this approach allows for multiple receivers of the same type:
var theReceiverListBox = (ListBox) theReceiver;
theReceiverListBox.BackColor = Color.White;
}
private void TheSamplListBox_DragDrop( object theReceiver, DragEventArgs theEventData ) {
//You can use [TheSamplListBox] but this approach allows for multiple receivers of the same type:
var theReceiverListBox = (ListBox) theReceiver;
//Get the data being dropped. In this case, a string:
var theStringBeingDropped = theEventData.Data.GetData( "System.String" );
//Add the string to the ListBox:
theReceiverListBox.Items.Add( theStringBeingDropped );
//Only the code above is strictly for the Drag & Drop. The following is for user feedback:
theReceiverListBox.BackColor = Color.White;
}
#endregion Drag & Drop
.
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