CODEWITHSUNDEEP
c#winformsdrag-and-drop
MC9000
MC9000

Reputation: 2403

Drag and drop from windows explorer to custom C# app that actually works with Windows 7

I've attempted (using dozens of examples) to create a simple WinForms app that will allow me to drag-and-drop a simple text file into an input box on a custom DotNet program. Unfortunately, there appears to be no examples that actually work in Windows 7.

Here's a simple example (from another post that's been referenced all over the place) but it does not work at all.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO;


namespace DragAndDropTestCSharp
{
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        this.AllowDrop = true;
        this.DragEnter += Form1_DragEnter;
        this.DragDrop += Form1_DragDrop;
    }
    private void Form1_DragEnter(object sender, DragEventArgs e)
    {
        if (e.Data.GetDataPresent(DataFormats.FileDrop))
        {
            e.Effect = DragDropEffects.Copy;
        }
        else
        {
            e.Effect = DragDropEffects.None;
        }
    }

    private void Form1_DragDrop(object sender, DragEventArgs e)
    {
        if (e.Data.GetDataPresent(DataFormats.FileDrop))
        {
            string[] filePaths = (string[])(e.Data.GetData(DataFormats.FileDrop));
            foreach (string fileLoc in filePaths)
            {
                // Code to read the contents of the text file
                if (File.Exists(fileLoc))
                {
                    using (TextReader tr = new StreamReader(fileLoc))
                    {
                        MessageBox.Show(tr.ReadToEnd());
                    }
                }

            }
        }
    }
}
}

Could this be a UAC issue? If so, why does every other app in the world seem to do this simple, yet elusive feat of drag and drop with UAC on?

Does someone have a real, working example of getting this to work in Windows 7?

Upvotes: 0

Views: 2051

Answers (2)

Rui Ribeiro
Rui Ribeiro

Reputation: 36

I've tried your sample and it works fine. Check if you have hook the Load event to the form object to the Form1_Load handler and your namespace is the same.

this.Load += new System.EventHandler(this.Form1_Load);

or via properties editor:

Properties Load Handler

Upvotes: 1

MC9000
MC9000

Reputation: 2403

Ok, I discovered that running VS under Administrator (which I had to do for another project) was the culprit. Loading VS in normal user mode, it works fine with UAC on. Thanks all for your input!

Upvotes: 1

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