I set two events in my code, Drag_Drop and Drag_Event, and everytime I try to drag something into the form, the 'circle with a line through it' symbol appears. Funny thing is, I used the same exact code in another project, and it worked perfectly. I registered the events and everything. Here is my code:
private void Form1_DragEnter(object sender, DragEventArgs e)
{
if (toSaveIcon)
{
if (e.Data.GetDataPresent(DataFormats.FileDrop))
{
e.Effect = DragDropEffects.Copy;
}
}
}
private void Form1_DragDrop(object sender, DragEventArgs e)
{
if (toSaveIcon)
{
string[] filePath = (string[])e.Data.GetData(DataFormats.FileDrop);
foreach (string path in filePath)
{
icon = Icon.ExtractAssociatedIcon(path);
Debug.WriteLine("Icon saved successfully");
}
}
}
Funny thing is, I used the same exact code in another project, and it worked perfectly.
I had this issue before, I fixed it by running Visual Studio as a normal user. Make sure it is not running as an Administrator if you are running from visual studio.
You can also run the app directly from the bin folder , you will have a better idea.
Related
I've seen this done in Borland's Turbo C++ environment, but I'm not sure how to go about it for a C# application I'm working on. Are there best practices or gotchas to look out for?
Some sample code:
public partial class Form1 : Form {
public Form1() {
InitializeComponent();
this.AllowDrop = true;
this.DragEnter += new DragEventHandler(Form1_DragEnter);
this.DragDrop += new DragEventHandler(Form1_DragDrop);
}
void Form1_DragEnter(object sender, DragEventArgs e) {
if (e.Data.GetDataPresent(DataFormats.FileDrop)) e.Effect = DragDropEffects.Copy;
}
void Form1_DragDrop(object sender, DragEventArgs e) {
string[] files = (string[])e.Data.GetData(DataFormats.FileDrop);
foreach (string file in files) Console.WriteLine(file);
}
}
Be aware of windows vista/windows 7 security rights - if you are running Visual Studio as administrator, you will not be able to drag files from a non-administrator explorer window into your program when you run it from within visual studio. The drag related events will not even fire!
In Windows Forms, set the control's AllowDrop property, then listen for DragEnter event and DragDrop event.
When the DragEnter event fires, set the argument's AllowedEffect to something other than none (e.g. e.Effect = DragDropEffects.Move).
When the DragDrop event fires, you'll get a list of strings. Each string is the full path to the file being dropped.
You need to be aware of a gotcha. Any class that you pass around as the DataObject in the drag/drop operation has to be Serializable. So if you try and pass an object, and it is not working, ensure it can be serialized as that is almost certainly the problem. This has caught me out a couple of times!
Yet another gotcha:
The framework code that calls the Drag-events swallow all exceptions. You might think your event code is running smoothly, while it is gushing exceptions all over the place. You can't see them because the framework steals them.
That's why I always put a try/catch in these event handlers, just so I know if they throw any exceptions. I usually put a Debugger.Break(); in the catch part.
Before release, after testing, if everything seems to behave, I remove or replace these with real exception handling.
Here is something I used to drop files and/or folders full of files. In my case I was filtering for *.dwg files only and chose to include all subfolders.
fileList is an IEnumerable or similar In my case was bound to a WPF control...
var fileList = (IList)FileList.ItemsSource;
See https://stackoverflow.com/a/19954958/492 for details of that trick.
The drop Handler ...
private void FileList_OnDrop(object sender, DragEventArgs e)
{
var dropped = ((string[])e.Data.GetData(DataFormats.FileDrop));
var files = dropped.ToList();
if (!files.Any())
return;
foreach (string drop in dropped)
if (Directory.Exists(drop))
files.AddRange(Directory.GetFiles(drop, "*.dwg", SearchOption.AllDirectories));
foreach (string file in files)
{
if (!fileList.Contains(file) && file.ToLower().EndsWith(".dwg"))
fileList.Add(file);
}
}
Another common gotcha is thinking you can ignore the Form DragOver (or DragEnter) events. I typically use the Form's DragOver event to set the AllowedEffect, and then a specific control's DragDrop event to handle the dropped data.
The solution of Judah Himango and Hans Passant is available in the Designer (I am currently using VS2015):
You can implement Drag&Drop in WinForms and WPF.
WinForm (Drag from app window)
You should add mousemove event:
private void YourElementControl_MouseMove(object sender, MouseEventArgs e)
{
...
if (e.Button == MouseButtons.Left)
{
DoDragDrop(new DataObject(DataFormats.FileDrop, new string[] { PathToFirstFile,PathToTheNextOne }), DragDropEffects.Move);
}
...
}
WinForm (Drag to app window)
You should add DragDrop event:
private void YourElementControl_DragDrop(object sender, DragEventArgs e)
{
...
foreach (string path in (string[])e.Data.GetData(DataFormats.FileDrop))
{
File.Copy(path, DirPath + Path.GetFileName(path));
}
...
}
Source with full code.
Note that for this to work, you also need to set the dragDropEffect within _drawEnter...
private void Form1_DragEnter(object sender, DragEventArgs e)
{
Console.WriteLine("DragEnter!");
e.Effect = DragDropEffects.Copy;
}
Source: Drag and Drop not working in C# Winforms Application
I've seen this done in Borland's Turbo C++ environment, but I'm not sure how to go about it for a C# application I'm working on. Are there best practices or gotchas to look out for?
Some sample code:
public partial class Form1 : Form {
public Form1() {
InitializeComponent();
this.AllowDrop = true;
this.DragEnter += new DragEventHandler(Form1_DragEnter);
this.DragDrop += new DragEventHandler(Form1_DragDrop);
}
void Form1_DragEnter(object sender, DragEventArgs e) {
if (e.Data.GetDataPresent(DataFormats.FileDrop)) e.Effect = DragDropEffects.Copy;
}
void Form1_DragDrop(object sender, DragEventArgs e) {
string[] files = (string[])e.Data.GetData(DataFormats.FileDrop);
foreach (string file in files) Console.WriteLine(file);
}
}
Be aware of windows vista/windows 7 security rights - if you are running Visual Studio as administrator, you will not be able to drag files from a non-administrator explorer window into your program when you run it from within visual studio. The drag related events will not even fire!
In Windows Forms, set the control's AllowDrop property, then listen for DragEnter event and DragDrop event.
When the DragEnter event fires, set the argument's AllowedEffect to something other than none (e.g. e.Effect = DragDropEffects.Move).
When the DragDrop event fires, you'll get a list of strings. Each string is the full path to the file being dropped.
You need to be aware of a gotcha. Any class that you pass around as the DataObject in the drag/drop operation has to be Serializable. So if you try and pass an object, and it is not working, ensure it can be serialized as that is almost certainly the problem. This has caught me out a couple of times!
Yet another gotcha:
The framework code that calls the Drag-events swallow all exceptions. You might think your event code is running smoothly, while it is gushing exceptions all over the place. You can't see them because the framework steals them.
That's why I always put a try/catch in these event handlers, just so I know if they throw any exceptions. I usually put a Debugger.Break(); in the catch part.
Before release, after testing, if everything seems to behave, I remove or replace these with real exception handling.
Here is something I used to drop files and/or folders full of files. In my case I was filtering for *.dwg files only and chose to include all subfolders.
fileList is an IEnumerable or similar In my case was bound to a WPF control...
var fileList = (IList)FileList.ItemsSource;
See https://stackoverflow.com/a/19954958/492 for details of that trick.
The drop Handler ...
private void FileList_OnDrop(object sender, DragEventArgs e)
{
var dropped = ((string[])e.Data.GetData(DataFormats.FileDrop));
var files = dropped.ToList();
if (!files.Any())
return;
foreach (string drop in dropped)
if (Directory.Exists(drop))
files.AddRange(Directory.GetFiles(drop, "*.dwg", SearchOption.AllDirectories));
foreach (string file in files)
{
if (!fileList.Contains(file) && file.ToLower().EndsWith(".dwg"))
fileList.Add(file);
}
}
Another common gotcha is thinking you can ignore the Form DragOver (or DragEnter) events. I typically use the Form's DragOver event to set the AllowedEffect, and then a specific control's DragDrop event to handle the dropped data.
The solution of Judah Himango and Hans Passant is available in the Designer (I am currently using VS2015):
You can implement Drag&Drop in WinForms and WPF.
WinForm (Drag from app window)
You should add mousemove event:
private void YourElementControl_MouseMove(object sender, MouseEventArgs e)
{
...
if (e.Button == MouseButtons.Left)
{
DoDragDrop(new DataObject(DataFormats.FileDrop, new string[] { PathToFirstFile,PathToTheNextOne }), DragDropEffects.Move);
}
...
}
WinForm (Drag to app window)
You should add DragDrop event:
private void YourElementControl_DragDrop(object sender, DragEventArgs e)
{
...
foreach (string path in (string[])e.Data.GetData(DataFormats.FileDrop))
{
File.Copy(path, DirPath + Path.GetFileName(path));
}
...
}
Source with full code.
Note that for this to work, you also need to set the dragDropEffect within _drawEnter...
private void Form1_DragEnter(object sender, DragEventArgs e)
{
Console.WriteLine("DragEnter!");
e.Effect = DragDropEffects.Copy;
}
Source: Drag and Drop not working in C# Winforms Application
I've seen this done in Borland's Turbo C++ environment, but I'm not sure how to go about it for a C# application I'm working on. Are there best practices or gotchas to look out for?
Some sample code:
public partial class Form1 : Form {
public Form1() {
InitializeComponent();
this.AllowDrop = true;
this.DragEnter += new DragEventHandler(Form1_DragEnter);
this.DragDrop += new DragEventHandler(Form1_DragDrop);
}
void Form1_DragEnter(object sender, DragEventArgs e) {
if (e.Data.GetDataPresent(DataFormats.FileDrop)) e.Effect = DragDropEffects.Copy;
}
void Form1_DragDrop(object sender, DragEventArgs e) {
string[] files = (string[])e.Data.GetData(DataFormats.FileDrop);
foreach (string file in files) Console.WriteLine(file);
}
}
Be aware of windows vista/windows 7 security rights - if you are running Visual Studio as administrator, you will not be able to drag files from a non-administrator explorer window into your program when you run it from within visual studio. The drag related events will not even fire!
In Windows Forms, set the control's AllowDrop property, then listen for DragEnter event and DragDrop event.
When the DragEnter event fires, set the argument's AllowedEffect to something other than none (e.g. e.Effect = DragDropEffects.Move).
When the DragDrop event fires, you'll get a list of strings. Each string is the full path to the file being dropped.
You need to be aware of a gotcha. Any class that you pass around as the DataObject in the drag/drop operation has to be Serializable. So if you try and pass an object, and it is not working, ensure it can be serialized as that is almost certainly the problem. This has caught me out a couple of times!
Yet another gotcha:
The framework code that calls the Drag-events swallow all exceptions. You might think your event code is running smoothly, while it is gushing exceptions all over the place. You can't see them because the framework steals them.
That's why I always put a try/catch in these event handlers, just so I know if they throw any exceptions. I usually put a Debugger.Break(); in the catch part.
Before release, after testing, if everything seems to behave, I remove or replace these with real exception handling.
Here is something I used to drop files and/or folders full of files. In my case I was filtering for *.dwg files only and chose to include all subfolders.
fileList is an IEnumerable or similar In my case was bound to a WPF control...
var fileList = (IList)FileList.ItemsSource;
See https://stackoverflow.com/a/19954958/492 for details of that trick.
The drop Handler ...
private void FileList_OnDrop(object sender, DragEventArgs e)
{
var dropped = ((string[])e.Data.GetData(DataFormats.FileDrop));
var files = dropped.ToList();
if (!files.Any())
return;
foreach (string drop in dropped)
if (Directory.Exists(drop))
files.AddRange(Directory.GetFiles(drop, "*.dwg", SearchOption.AllDirectories));
foreach (string file in files)
{
if (!fileList.Contains(file) && file.ToLower().EndsWith(".dwg"))
fileList.Add(file);
}
}
Another common gotcha is thinking you can ignore the Form DragOver (or DragEnter) events. I typically use the Form's DragOver event to set the AllowedEffect, and then a specific control's DragDrop event to handle the dropped data.
The solution of Judah Himango and Hans Passant is available in the Designer (I am currently using VS2015):
You can implement Drag&Drop in WinForms and WPF.
WinForm (Drag from app window)
You should add mousemove event:
private void YourElementControl_MouseMove(object sender, MouseEventArgs e)
{
...
if (e.Button == MouseButtons.Left)
{
DoDragDrop(new DataObject(DataFormats.FileDrop, new string[] { PathToFirstFile,PathToTheNextOne }), DragDropEffects.Move);
}
...
}
WinForm (Drag to app window)
You should add DragDrop event:
private void YourElementControl_DragDrop(object sender, DragEventArgs e)
{
...
foreach (string path in (string[])e.Data.GetData(DataFormats.FileDrop))
{
File.Copy(path, DirPath + Path.GetFileName(path));
}
...
}
Source with full code.
Note that for this to work, you also need to set the dragDropEffect within _drawEnter...
private void Form1_DragEnter(object sender, DragEventArgs e)
{
Console.WriteLine("DragEnter!");
e.Effect = DragDropEffects.Copy;
}
Source: Drag and Drop not working in C# Winforms Application
With winforms, when I right click on a folder or try to delete a folder within the FolderBrowserDialog the window becomes irresponsive and I've to force-close it.
Here's the code:
private void btnOpenFileDialog_Click(object sender, EventArgs e)
{
folderBrowserDialog1.SelectedPath = txtBoxLog.Text;
folderBrowserDialog1.RootFolder = Environment.SpecialFolder.MyComputer;
if (folderBrowserDialog1.ShowDialog()==DialogResult.OK)
{
txtBoxLog.Text = folderBrowserDialog1.SelectedPath;
}
}
The problem was system wide, so the control was correctly behaving in an incorrect way (irony).
I've seen this done in Borland's Turbo C++ environment, but I'm not sure how to go about it for a C# application I'm working on. Are there best practices or gotchas to look out for?
Some sample code:
public partial class Form1 : Form {
public Form1() {
InitializeComponent();
this.AllowDrop = true;
this.DragEnter += new DragEventHandler(Form1_DragEnter);
this.DragDrop += new DragEventHandler(Form1_DragDrop);
}
void Form1_DragEnter(object sender, DragEventArgs e) {
if (e.Data.GetDataPresent(DataFormats.FileDrop)) e.Effect = DragDropEffects.Copy;
}
void Form1_DragDrop(object sender, DragEventArgs e) {
string[] files = (string[])e.Data.GetData(DataFormats.FileDrop);
foreach (string file in files) Console.WriteLine(file);
}
}
Be aware of windows vista/windows 7 security rights - if you are running Visual Studio as administrator, you will not be able to drag files from a non-administrator explorer window into your program when you run it from within visual studio. The drag related events will not even fire!
In Windows Forms, set the control's AllowDrop property, then listen for DragEnter event and DragDrop event.
When the DragEnter event fires, set the argument's AllowedEffect to something other than none (e.g. e.Effect = DragDropEffects.Move).
When the DragDrop event fires, you'll get a list of strings. Each string is the full path to the file being dropped.
You need to be aware of a gotcha. Any class that you pass around as the DataObject in the drag/drop operation has to be Serializable. So if you try and pass an object, and it is not working, ensure it can be serialized as that is almost certainly the problem. This has caught me out a couple of times!
Yet another gotcha:
The framework code that calls the Drag-events swallow all exceptions. You might think your event code is running smoothly, while it is gushing exceptions all over the place. You can't see them because the framework steals them.
That's why I always put a try/catch in these event handlers, just so I know if they throw any exceptions. I usually put a Debugger.Break(); in the catch part.
Before release, after testing, if everything seems to behave, I remove or replace these with real exception handling.
Here is something I used to drop files and/or folders full of files. In my case I was filtering for *.dwg files only and chose to include all subfolders.
fileList is an IEnumerable or similar In my case was bound to a WPF control...
var fileList = (IList)FileList.ItemsSource;
See https://stackoverflow.com/a/19954958/492 for details of that trick.
The drop Handler ...
private void FileList_OnDrop(object sender, DragEventArgs e)
{
var dropped = ((string[])e.Data.GetData(DataFormats.FileDrop));
var files = dropped.ToList();
if (!files.Any())
return;
foreach (string drop in dropped)
if (Directory.Exists(drop))
files.AddRange(Directory.GetFiles(drop, "*.dwg", SearchOption.AllDirectories));
foreach (string file in files)
{
if (!fileList.Contains(file) && file.ToLower().EndsWith(".dwg"))
fileList.Add(file);
}
}
Another common gotcha is thinking you can ignore the Form DragOver (or DragEnter) events. I typically use the Form's DragOver event to set the AllowedEffect, and then a specific control's DragDrop event to handle the dropped data.
The solution of Judah Himango and Hans Passant is available in the Designer (I am currently using VS2015):
You can implement Drag&Drop in WinForms and WPF.
WinForm (Drag from app window)
You should add mousemove event:
private void YourElementControl_MouseMove(object sender, MouseEventArgs e)
{
...
if (e.Button == MouseButtons.Left)
{
DoDragDrop(new DataObject(DataFormats.FileDrop, new string[] { PathToFirstFile,PathToTheNextOne }), DragDropEffects.Move);
}
...
}
WinForm (Drag to app window)
You should add DragDrop event:
private void YourElementControl_DragDrop(object sender, DragEventArgs e)
{
...
foreach (string path in (string[])e.Data.GetData(DataFormats.FileDrop))
{
File.Copy(path, DirPath + Path.GetFileName(path));
}
...
}
Source with full code.
Note that for this to work, you also need to set the dragDropEffect within _drawEnter...
private void Form1_DragEnter(object sender, DragEventArgs e)
{
Console.WriteLine("DragEnter!");
e.Effect = DragDropEffects.Copy;
}
Source: Drag and Drop not working in C# Winforms Application