I am working on a large application and am adding some drag/drop functionality to it. Specifically, I am allowing the user to drag and drop a file into the main window to open the file.
The problem is that the drag/drop operation is still allowed to happen when the main window is displaying a dialog box (for example, a properties window for an item in the currently-open file). I would rather not allow this to happen if the main window is displaying a modal dialog box. This is because loading the new file in the application while the dialog box is open would probably crash the program: the code calling the dialog box does not expect the open file to be changed while the dialog box is open (that is why the dialog box was modal...).
The main application is written in C++, but I am posting a C# sample. The symptom/behavior is the same on both platforms, but I can demonstrate it in much less code with C#. I am very familiar with both languages/platforms so I can translate any answers to the appropriate language as needed.
To demonstrate the problem with my sample code, compile and run the following C# code. It will create a "main window" that is a valid drop target. Drag and drop a file from Windows Explorer onto the main window: you should see a "dropped" message box. Now, click the button on the form to pop up a dialog box. Again, attempt to drag and drop a file onto the main window while the dialog box is open. Notice that the drop is allowed even though a modal dialog box is open. How can I prevent this from happening when the dialog is open?
The obvious answer is to temporarily set AllowDrop to false while opening the dialog box. The problem is that the main application is very large and so there are numerous places that open dialog boxes. It will be difficult to find every single place that opens a dialog and add this code. Plus, every developer here would need to know to perform this action every time they open a modal window; it is unlikely that everyone will remember. I am worried that this is not a very good solution.
Surely there is a more maintainable method of doing this that doesn't require adding code in every place that a dialog is opened?
using System;
using System.Windows.Forms;
using System.Drawing;
public class MyDialog : Form {
public MyDialog() {
Text = "MyDialog";
}
}
public class MainForm : Form {
public MainForm() {
Button btn = new Button();
btn.Location = new Point(0, 0);
btn.Text = "ShowDialog";
btn.Size = new Size(75, 23);
btn.Click += new EventHandler(GoToDialog);
this.AllowDrop = true;
this.Controls.Add(btn);
this.Text = "Drop Target";
this.DragDrop += new DragEventHandler(this.MyDragDrop);
this.DragEnter += new DragEventHandler(this.MyDragEnter);
}
private void MyDragDrop(object sender, DragEventArgs e) {
MessageBox.Show("dropped");
}
private void MyDragEnter(object sender, DragEventArgs e) {
e.Effect = DragDropEffects.Copy;
}
private void GoToDialog(object sender, EventArgs e) {
using (MyDialog ab = new MyDialog()) {
ab.ShowDialog(this);
}
}
}
static class Program {
[STAThread]
static void Main() {
Application.Run(new MainForm());
}
}
I'm not sure how things work in C#, so let me know if this answer is incorrect. In C++ MFC, the main window is disabled when a dialog is displayed. You can test to see if the main window is disabled and ignore the drop if so.
private void MyDragDrop(object sender, DragEventArgs e) {
if (CanFocus)
MessageBox.Show("dropped");
}
private void MyDragEnter(object sender, DragEventArgs e) {
if (CanFocus)
e.Effect = DragDropEffects.Copy;
else
e.Effect = DragDropEffects.None;
}
Related
So, I'm making a payroll management system as a hobby project to help my resume and general knowledge of c#. So, I'm making a UI and I can open a new window just fine with this code:
private void button1_Click(object sender, EventArgs e)
{
CreateAdminAcct createAcct = new CreateAdminAcct();
createAcct.StartPosition = FormStartPosition.CenterScreen;
createAcct.Show();
this.Hide();
}
however, I don't know the event to check when the little red "x" button is clicked, because when that button is clicked, I want to go back to the main screen because I hide the main screen when that button is clicked, and when i click the red "x" on the screen that just opened, it closes, but the application continues to run in the background.
If there is some better way to manage multiple menus, I'm open to suggestions, however, this is what I've found easiest.
Thanks in advance
I second Robert Harvey's suggestion; this gives the user the reassurance tha tht emain window is still open/ nothing got lost, but it's unreachably "behind" the CreateAdminAcct form while the CreateAdminAcct form is open
private void button1_Click(object sender, EventArgs e)
{
CreateAdminAcct createAcct = new CreateAdminAcct();
createAcct.StartPosition = FormStartPosition.CenterScreen;
createAcct.ShowDialog();
//do any code here that needs to access createAcct before it's lost
MessageBox.Show(createAcct.NewAdmin.Name);
}
If you really do want to hide your main form, pass the main form itself to createAcct, and make it createAcct's job to re-open the main form when it is closing
private void button1_Click(object sender, EventArgs e)
{
CreateAdminAcct createAcct = new CreateAdminAcct(this); //note passing this form to constructor
createAcct.StartPosition = FormStartPosition.CenterScreen;
createAcct.Show();
}
class CreateAcctForm : Form{
private Form _showWhenClosing;
CreateAcctForm(Form revertTo){
InitializeComponent();
_showWhenClosing = revertTo;
}
}
void Form_Closing(object sender, ...){ //event
_showWhenClosing.Show();
}
Side note: please rename your controls after you drop them ona form. code that's stuffed with label57, textbox25 is effectively obfuscated and really wearisome to follow
I am working on a WinForms Desktop application in C# .NET. The target framework is .NET Framework 4.8. When the application is started, the main form is displayed with several buttons. Each button hides the main form when clicked and opens another form that displays data with which the user interacts. The main form is the owner of the new form.One button opens a form that presents a list of files from a network share folder in a data grid view. The user selects a row in the data grid and clicks a button to import the information in the file to various tables in a SQL Server database. When the import is complete, the selected row is removed from the data grid. When the user closes this form, there is code in the Form Closed event to show the owner. This all works well.My problem is that when the main form is unhidden, I need to disable the button that opens the form to list files to import if there are not any files in the network share folder to be imported. There is also a line of code to change the button's text property informing the user there are not any files to import.I realize I can place the code to disable the button and change button text in the VisibleChanged event. But, I only want the code to run after the owned form's closed event shows the owner form. How do I enclose the code in the main form's VisibleChanged event to disable the file import button only after the owned form is closed. Or, is it possible to edit the properties of the button on the owner form in the Form Closed event prior to the Owner.Show();I found a similar question WinForm Form Closed Event. But when I follow the suggestion
private void LoadChildForm_Click(object sender, EventArgs e)
{
ChildForm form = new ChildForm();
form.FormClosed += new FormClosedEventHandler(ChildFormClosed);
form.Show();
}
substituting my names
private void btnImportHFR_Click(object sender, EventArgs e)
{
Form form = new frmHFRFiles();
form.FormClosed += new FormClosedEventHandler(frmHFRFiles_FormClosed);
form.Show(this);
Hide();
}
Visual Studio flags frmHFRFiles_FormClosed as an error for the name does not exist in the current context.
ChildForm form = new ChildForm(this);
Then in ChildForm constructor:
MainForm m_MainForm;
Public ChildForm (MainForm mainForm)
{
m_MainForm = mainForm;
}
Then in closing event:
m_MainForm.button1.Enabled = false;
Ensure button1 is public
Here is what I did. I created a boolean variable in the main form and set the initial value to false.
private bool updateButtons = false;
The main form's constructor executes the search for files in the network folder.
public frmMainMenu()
{
InitializeComponent();
Shared.FilesForImport = GetHFRFiles();
}
The form's load event calls the EnableButtons() method
public void EnableButtons()
{
btnImportHFR.Enabled = Convert.ToBoolean(Shared.FilesForImport.Count);
btnImportHFR.Text = btnImportHFR.Enabled ? "Find Available HFR" : "No HFR For Import";
btnGetFacilityStatus.Enabled = Shared.sqlWrap.GetDataForFacStat(Shared.DsFacStat);
updateButtons = false;
}
The main form's visible changed event fires after the form load event. The network folder is not searched again because the updateButtons value is set to false.
private void frmMainMenu_VisibleChanged(object sender, EventArgs e)
{
if(updateButtons)
{
EnableButtons();
}
}
In the button click event, the updateButtons value is set to true after the main form is hidden.
private void btnImportHFR_Click(object sender, EventArgs e)
{
frmHFRFiles form = new frmHFRFiles();
form.Show(this);
Hide();
updateButtons = true;
}
The child form's closed event calls the Owner.Show() method
private void frmHFRFiles_FormClosed(object sender, FormClosedEventArgs e)
{
Owner.Show();
}
This causes the main form's visible changed event to fire. Only this time the EnableButtons() method will run because the updateButtons value is true.
private void frmMainMenu_VisibleChanged(object sender, EventArgs e)
{
if(updateButtons)
{
EnableButtons();
}
}
public void EnableButtons()
{
btnImportHFR.Enabled = Convert.ToBoolean(Shared.FilesForImport.Count);
btnImportHFR.Text = btnImportHFR.Enabled ? "Find Available HFR" : "No HFR For Import";
btnGetFacilityStatus.Enabled = Shared.sqlWrap.GetDataForFacStat(Shared.DsFacStat);
updateButtons = false;
}
Finally, the EnableButtons() method sets the updateButtons value to false.
It seems rudimentary to me, but it works. Thank you everyone for your feedback.
My problem is that when the main form is unhidden, I need to disable the button that opens the form to list files to import if there are not any files in the network share folder to be imported. There is also a line of code to change the button's text property informing the user there are not any files to import.
So your main form has a button X. If this button is clicked a method is called. This method will first hide the form, then show the subform until the subform is closed. The method should disable button X, change the button's text and unhide the form.
To make this flexible, we won't do everything in one procedure, we make several procedures with the intention of the procedure: "Inform operator there are no files to import" "Disable opening the subform", and of course their counterparts "Enable opening the subform", "Inform operator there are files to import"
TODO: invent proper method names
private void ShowNoFilesToImport()
{
this.buttonX.Text = ...;
}
private void DisableOpeningSubForm()
{
this.buttonX.Text.Enabled = false;
}
The advantage of this, is that if you later want to change the way that you want to inform the operator, for instance if you want to use an information field at the bottom of you screen, you will only have to change this in one place.
Furthermore, you can reuse the procedures, for instance you can add a menu item that will do the same as button X, this menu item can call the same methods
private void PerformActionsButtonX() // TODO: invent proper name
{
// Hide this form, and show the Subform until it is closed
this.Visible = false;
using (var dlg = new SubForm())
{
// if needed, set properties of the subForm:
dlg.Text = ...
dlg.Position = ...
// show the form until it is closed
var dlgResult = dlg.ShowDialog();
this.ProcessDlgResult(dlgResult, dlg);
}
// Show that there are no files to Import and disable OpeningSubform
this.ShowNoFilesToImport();
this.DisableOpeningSubform();
// Finally: show this form:
this.Visible = true;
}
And of course call this method when ButtonX or menu item Y are clicked:
private void OnButtonX_Clicked(object sender, ...)
{
this.PerformActionsButtonX();
}
private void OnMenyItemYClicked(object sender, ...)
{
this.PerformActionsButtonX();
}
I need to be alerted before my entire form loses focus. The Deactivate event only triggers after it loses focus. LostFocus and Leave are only for controls.
I have also tried overriding WndProc but this only triggers after the message has been processed.
overriding PreProcessMessage only can be used for keyboard stuff, not form deactivation.
Dodgy Method
Even though this is a quick and hacky way of doing it, changing Input Language is unnatural to start with..
private void Form1_Deactivate(object sender, EventArgs e)
{
((Form)sender).Activate();
System.Diagnostics.Debug.WriteLine(this.ActiveControl.Name);
//Change Input Language here..
//Alt TAB to set focus to the application selected 5 milliseconds ago
SendKeys.SendWait("%{TAB");
}
Correct and orthadox method
How to monitor focus changes? and C#: Detecting which application has focus
Its using the Automation framework, Add references to UIAutomationClient and UIAutomationTypes and use Automation.AddAutomationFocusChangedEventHandler, e.g.:
public class FocusMonitor
{
public FocusMonitor()
{
AutomationFocusChangedEventHandler focusHandler = OnFocusChanged;
Automation.AddAutomationFocusChangedEventHandler(focusHandler);
}
private void OnFocusChanged(object sender, AutomationFocusChangedEventArgs e)
{
AutomationElement focusedElement = sender as AutomationElement;
if (focusedElement != null)
{
int processId = focusedElement.Current.ProcessId;
using (Process process = Process.GetProcessById(processId))
{
Debug.WriteLine(process.ProcessName);
}
}
}
}
Got it, this hack works perfectly.
private void MyForm_Deactivate(object sender, EventArgs e)
{
Thread.Sleep(200); //delay to allow external tab time to open
Form f1 = new Form(); //create a new form that will take focus, switch input, then terminate itself
f1.Shown += new EventHandler((s, e1) => { f1.Activate(); InputLanguage.CurrentInputLanguage = InputLanguage.DefaultInputLanguage; f1.Close(); });
f1.Show();
}
EDIT: upon further testing I have found this to be equally unreliable. It doesn't seem like there is a good way to do this at all.
For now I am tracking the mouse and keyboard to detect when the user is about to deactivate it. Obviously a mouse and keyboard hook is a horrible solution but its the only reliable solution so far.
Is possible to show "page setup" and "printer setup" as modeless forms? I used code as follows, but that forms display as modal forms:
// page setup
private void btnPageSetup_Click(object sender, EventArgs e)
{
this.pageSetupDialog1.PageSettings = new PageSettings();
this.pageSetupDialog1.PrinterSettings = this.printDocument1.PrinterSettings;
this.pageSetupDialog1.ShowDialog();
if (this.pageSetupDialog1.PageSettings != null)
{
this.printDocument1.DefaultPageSettings = this.pageSetupDialog1.PageSettings;
}
}
// print setup
private void btnPrintSetup_Click(object sender, EventArgs e)
{
this.pageSetupDialog1.Document = this.printDocument1;
if (this.pageSetupDialog1.ShowDialog() == DialogResult.OK)
{
this.printDocument1.Print();
}
}
You can show a form as non-modal by calling Show rather than ShowDialog.
However, you'll also have to shuffle your code around, because your main form will no longer sit and wait for one of the subforms to close in order to check what the user did.
For example, you'll have to change the Print Setup code such that your PageSetupDialog prints the document itself when the user clicks OK, rather than relying on the main form to act when the user has clicked OK.
Similarly, you'll need to change the Page Setup code such that your PageSetupDialog sets Document.DefaultPageSettings itself, rather than "returning" settings in the PageSettings property and relying on the main form handling them.
I'm making a new WPF application and I need to be able to minimize the application and have nice and snug in the system tray, right beside the clock (or in that general area).
This has to work on Windows XP, Vista and 7. I don't have to support older versions of Windows.
What's the simplest way to achieve this if I'm using .NET 4?
Example in MSDN forum
Here's a quick example to show how to minimize to the notification area. You need to add references to the System.Window.Forms and System.Drawing assemblies.
public partial class Window1 : System.Windows.Window
{
public Window1()
{
InitializeComponent();
System.Windows.Forms.NotifyIcon ni = new System.Windows.Forms.NotifyIcon();
ni.Icon = new System.Drawing.Icon("Main.ico");
ni.Visible = true;
ni.DoubleClick +=
delegate(object sender, EventArgs args)
{
this.Show();
this.WindowState = WindowState.Normal;
};
}
protected override void OnStateChanged(EventArgs e)
{
if (WindowState == System.Windows.WindowState.Minimized)
this.Hide();
base.OnStateChanged(e);
}
}
I've had success using this free notify-icon implementation in WPF.
http://www.hardcodet.net/projects/wpf-notifyicon
It's pretty simple to setup and the source code is provided. It doesn't rely on Windows Forms, so it's 'pure' WPF and very customizable.
You can find a tutorial on how to use it on CodeProject.
And here is the Nuget Package
Add notifyIcon to your App from Toolbox.
Select your main form >> go to the Properties >> select Events icon >> under FromClosing event type MainForm_FormClosing >> hit enter.
In opened .cs file enter following event action:
private void MainForm_FormClosing(object sender, FormClosingEventArgs e)
{
this.Hide();
notifyIcon.Visible = true;
ShowInTaskbar = false;
e.Cancel = true;
}
Now your main FORM window will be minimized to the system tray when you click on X button. Next step is to get FORM back to normal state.
Go to the Properties of your notifyIcon >> find DoubleClick event >> type NotifyIcon_DoubleClick and hit enter to get event function created for you.
Put this code to your event:
private void NotifyIcon_DoubleClick(object sender, EventArgs e)
{
this.Show();
notifyIcon.Visible = false;
}
Now, if you want to make the notify icon in fancy style you can add context menu and link it to your notify icon, so you get something like that:
Here is where you link contextMenuStrip to NotifyIcon:
Good luck!