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Open a File by dropping it onto Form (C# example)

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kyrathaba:
Since I researched and implemented this for a recent short project, I thought I'd make it available in case it might benefit any other C# developers:

Sample Code for Opening a File Dropped onto Form.

f0dder:
In case you're going to semi-regularly post code snippets, you should check out SyntaxHighlighter - it's nice :)

kyrathaba:
Thanks for the link.  I also like Veign's Code Highlighter.

Of course, I can also just use the site's code tags:


--- Code: C# ---using System;using System.Windows.Forms;using System.Diagnostics;using System.IO; namespace BryanWinForms1 {    public partial class Form1 : Form {         private delegate void DelegateOpenFile(String s); //define delegate type        DelegateOpenFile _openFileDelegate; //declares a delegate instance         public Form1() {            InitializeComponent();            this.AllowDrop = true; //must set this to true, for dragDrop to work                        //delegate needed so Form1_DragDrop() can asynchronously                        //invoke our program's OpenFile() method            _openFileDelegate = new DelegateOpenFile(this.OpenFile); //instantiates delegate        }         private void openToolStripMenuItem_Click(object sender, EventArgs e) {            OpenFileDialog openDlg = new OpenFileDialog();            openDlg.Filter = "Any File (*.*)|*.*";            openDlg.FileName = "";            openDlg.CheckFileExists = true;            openDlg.CheckPathExists = true;             if (openDlg.ShowDialog() != DialogResult.OK)                return;             OpenFile(openDlg.FileName);        }         private void OpenFile(string sFile) {            //insert appropriate file-opening code here...            MessageBox.Show("\"" + sFile + "\" will be opened.");        }         private void Form1_DragEnter(object sender, DragEventArgs e) {                        //we're only interested if a FILE was dropped on the form            if (e.Data.GetDataPresent(DataFormats.FileDrop))                e.Effect = DragDropEffects.Copy;            else                e.Effect = DragDropEffects.None;        }         private void Form1_DragDrop(object sender, DragEventArgs e) {                        //good idea to use try-catch block, in case something goes wrong                        try {                Array a = (Array)e.Data.GetData(DataFormats.FileDrop);                if (a != null) {                    // Extract string from first array element                    // (ignore all files except first if number of files are dropped).                    string s = a.GetValue(0).ToString();                    // Call OpenFile asynchronously.                    // Explorer instance from which file is dropped is not responding                    // the entire time that the DragDrop handler is active, so we need to return                    // immidiately (especially if OpenFile shows MessageBox).                    this.BeginInvoke(_openFileDelegate, new Object[] { s });                    this.Activate();        // in the case Explorer overlaps this form                }            }            catch (Exception ex) {                Trace.WriteLine("Error in DragDrop function: " + ex.Message);                // don't show MessageBox here - Explorer is waiting !            }        }                                //next right-brace ends Form1 class    }        //next right-brace ends namespace}

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