Hi I have a code to be written while window(WPF window) activate like clicking on the window or using alt/tab. The window is the child of a main form (windows app). I have used ToolWindow as the windowstyle.
It has a xamdatagrid which has to updated on activation
Problem is it fires multiple times. It should be fired once. I don not want my code to run multiple times
How to make it work. please help
From the Window.Activated Event page on MSDN:
Occurs when a window becomes the foreground window.
The Window.Activated Event is supposed to be called multiple times, so perhaps it is not the best event for you to handle. Alternatively, you could add a bool isFirstTime variable and use it to restrict your code to only being called once. Take this example:
private bool isFirstTime = true;
...
private void WindowActivated(object sender, EventArgs e)
{
if (isFirstTime)
{
isFirstTime = false;
// do something here just once
}
}
However, as (from the linked page)...
A window is activated (becomes the foreground window) when:
• The window is first opened.
• A user switches to a window by selecting it with the mouse, pressing ALT+TAB, or from Task Manager.
• A user clicks the window's taskbar button.
... you may find that this will not work for you.
I got it done.
I was using the below code
private void OnAttributeHistoryWindowActivated(object sender, EventArgs e)
{
var win = ((RoutedEventArgs)(e)).Source as AttributeHistoryWindow;
//My Code
}
The first line of code was firing back the Activated event. And it never goes to the next line of my code.
Now I used below code and it works.
private void OnAttributeHistoryWindowActivated(object sender, EventArgs e)
{
var win = sender as AttributeHistoryWindow;
//My Code
}
Now it fires once.
Related
I have a Windows form that has a validation event on a textBox so that if the value of that TextBox is a value that already exists it triggers a validation error.
private void txtUsername_Validating(object sender, CancelEventArgs e)
{
var alreadyExists = _logic.UserIdExists(txtUsername.Text.Trim());
if(alreadyExists)
{
errorProvider1.SetError(txtUsername, "This Userid already exists, please choose an alternative");
e.Cancel = true;
}
}
private void txtUsername_Validated(object sender, EventArgs e)
{
errorProvider1.SetError(txtUsername, "");
}
this.txtUsername.Validating += new System.ComponentModel.CancelEventHandler(this.txtUsername_Validating);
this.txtUsername.Validated += new System.EventHandler(this.txtUsername_Validated);
This results in an error image appearing next to that textBox along with a tooltip error message.
If I try and close the application, using the Close button at the top of the window, at this time I cannot as the above Event keeps firing even when I try and close the window (due to me taking focus away from the Text box).
Is there a way of closing the window, without resorting to creating an additional Close button on the form?
Based on your description, you want to maintain the default auto-validation behavior yet allow the Form to be closed using the title bar close button. I have observed that the Form.Closing event is raised in such a circumstance, however its argument Cancel property is preset to true. A simple solution is to handle this event and set e.Cancel = false. Implement any logic in the handler that you deem necessary.
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
if (e.CloseReason == CloseReason.UserClosing) e.Cancel = false;
}
Hi I've come across either a weird bug or I'm not understanding something.
To cut a long story short I've had everything I'm wanting to work on my form working fine, I then decided to turn the form into an options menu so it was no longer the first form that appears when the application is launched and is shown after I click a button on a different form with the code
private void ShowOptionsButton_Click(object sender, EventArgs e)
{
formHomePage.Show();
}
And for some reason a timer if statement is no longer working:
private void StartSubCheckT_Tick(object sender, EventArgs e)
{
if (subliminalMessages.Count > 0)
{
MessageBox.Show("list greater than 0 if");
StartSubB.Enabled = true;
}
there are other if statements below but are irrelevant and the point of this is to make a button usable once a list is greater than 0. I've created another test button to display the value and it shows that the sublminalMessages list is greater than 0
private void testbutton3_Click(object sender, EventArgs e)
{
MessageBox.Show(subliminalMessages.Count.ToString());
}
Which outputs at 1 which it should be from some other code that adds a value in at the beginning. But for some reason even with the subliminalmessages.count being greater than 0 the if statement is no longer being called ever since I'm making the form appear being called from another form from the button code above.
The subliminalMessages list is being populated and created on the same form
public List<string> subliminalMessages = new List<string>();
private void Form1_Load(object sender, EventArgs e)
{
if (!String.IsNullOrEmpty(Settings.Default["Subliminal1"].ToString()))
{
subliminalMessages.Add(Settings.Default["Subliminal1"].ToString());
MessageBox.Show("If worked");
}
}
There is a value in the Setting.Default that is being added
The button and timer are on the same form and the timer in question is enabled.
Does anyone know why?
Thanks
I'll have a stab at giving you an answer. But it's a little swerve from what you're doing now.
From what I understand of your code you are using the timer to enable/disable the StartSubB button. Or maybe just enable it.
Instead of relying on the timer which appears to not work why not use a BindingList<string>. This has an event called ListChanged which you can handle and then enable/disable your button.
Here's a test form I created:
public partial class Form1 : Form
{
BindingList<string> items;
public Form1()
{
InitializeComponent();
button3.Enabled = false;
items = new BindingList<string>();
items.ListChanged += Items_ListChanged;
}
private void Items_ListChanged(object sender, ListChangedEventArgs e)
{
button3.Enabled = items.Count > 0;
}
private void btnAdd_Click(object sender, EventArgs e)
{
items.Add("a");
}
private void btnRemove_Click(object sender, EventArgs e)
{
if (items.Count > 0)
items.RemoveAt(items.Count - 1);
}
}
I have a BindingList<string> called items. This is analagous with your subliminalmessages list but it's a BindingList. This type of list has a ListChanged event that fires when items are added or removed from the list. In the constructor we new up the items list and subscribe to the ListChanged event.
When the Items_ListChanged event fires button3 is enabled or disabled based on whether items.Count > 0 or not.
In btnAdd_Click we just add an item to the list.
In btnRemove_Click we check that there are some items then remove the last one.
If you were to run this you'd see that when we click the Add button, button3 gets enabled. If we click the Remove button we'll see button3 get disabled.
The only limitation of BindingList is that you can't add a range by passing in another List.
If you implement this and your button still doesn't activate then you'll probably need to post some more code. Strip out all the irrelevant stuff and put it in a new project that demonstrates the failure of the condition and either copy the code here or provide a link to download the project. The only reason the if statement should fail is if the list is actually empty.
I have a simple WPF button and a textbox in my WPF application(not using MVC or binding at all). I like to be able to do the following upon clicking the button:
1) Clear the textbox
2) Create the result
3) assign the result to the textbox
I used Textbox.Clear, TextBox.Text= String.Empty, delegates and a dispatcher approach like
private void button_Click(object sender, RoutedEventArgs e)
{
Application.Current.Dispatcher.BeginInvoke(new Action (ClearReportTxtBox), DispatcherPriority.Send);
System.Threading.Thread.Sleep(5000);
runTest();
}
private void ClearReportTxtBox()
{
Report_textBox.Text = string.Empty;
}
None of them working correctly for me. The dispatcher method is somehow working but not as I wish. It seems that the Clear task will be queued and when the all actions in the button click handler are finished, it will come into play and delete the textbox, but this causes that the generated report and already assigned to the textbox (created by runtest in the code above) will be deleted as well. Hence it is too late delete action and eliminate the whole result.
Currently it seems to me that by clicking on the button the UIthread blocks and takes the control. The Dispatcher will queue the delete action as next action after finishing the button click.
Is it possible to force delete at the beginning and then do the rest? What I like to reach is that I pause the button activity and do delete at first action and then continue with the rest of actions in the button handler.
Am I doing something wrong?
Thank you for your help in advance.
The "Dispatcher.BeginInvoke" is kinda weird for what you want to do
All the UI update has to be done on main thread. Since the "Button_click" event is executing on main thread, the delegate you push into Dispatcher can only be executed AFTER the button_click handle is completed. That's why the execution sequence becomes
1. The GUI freeze because Thread.Sleep
2. RunTest
3. ClearReportTextBox
Guess you can try sth like the following instead.
private void ButtonBase_OnClick(object sender, RoutedEventArgs e)
{
ClearReportTxtBox();
Task.Factory.StartNew(RunTest);
}
private void ClearReportTxtBox()
{
MyTextBox.Text = string.Empty;
}
private void RunTest()
{
System.Threading.Thread.Sleep(5000);
if (dispatcher != null && !dispatcher.CheckAccess())
{
dispatcher.Invoke(priority, ()=> MyTextBox.Text = "123");
}
else
{
MyTextBox.Text = "123";
}
}
i will first explain the UI of my WPF App.
I have created a window which contains many buttons which is always visible to the user(lets call it main window), each button will open a new window relevant to the task. what i want done is that whenever a button is clicked, the main window should be hidden(visibility : collapsed) and the new window should be shown. This second window will also contain a button which will hide the second window and show back the main window.
also the second window which will be opening will have different dimensions as per the command associated with it so i will be having different windows for eaach
TLDR i want to be able to switch between multiple windows such that only one window is visible at one time, how do i manage the switching between multiple windows ??
Note : I can show the second window from main window but what about showing main from the second window....can't get it....or if anyone can show me a different approach to implement this : other than multiple windows
Also, this is an extension to the UI, i want to show the buttons in this crystalised sort of look like on this page : http://postimage.org/image/4yibiulsh/
can anyone direct me to a proper implementation, i have been through many sites and also tried to create these through blend but i just am not a UI Person....pls need help on this
Thanks in advance.
I would create a "Window manager" which will subscribe to the changes of opening/closing.
In this case you don't have to overload Window classes.
Example (worked for me).
public class WindowsManager
{
static readonly List<Window> Windows=new List<Window>();
public static T CreateWindow<T>(T window) where T:Window
{
Windows.Add(window);
window.Closed += WindowClosed;
window.IsVisibleChanged += WindowIsVisibleChanged;
return window;
}
static void WindowIsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
{
var mainWindow = Application.Current.Windows.OfType<MainWindow>().Single();
mainWindow.Visibility = Equals(e.NewValue, true) ? Visibility.Hidden : Visibility.Visible;
}
static void WindowClosed(object sender, System.EventArgs e)
{
var window = (Window) sender;
window.Closed -= WindowClosed;
window.IsVisibleChanged -= WindowIsVisibleChanged;
Windows.Remove(window);
}
}
How to use:
private void button1_Click(object sender, RoutedEventArgs e)
{
WindowsManager.CreateWindow(new Child1()).Show();
}
private void button2_Click(object sender, RoutedEventArgs e)
{
WindowsManager.CreateWindow(new Child2()).Show();
}
So, when the child window will close, WindowsManager will be notified about this and will update visibility for the main window
UPD1.
added line to unscubscribe from VisibleChanged
You can use several approaches for that.
To easy switch back to main Window: inject a reference of your MainWindow to your SecondWindow (or any other Window you want to display) and in the Closing Event of that Window you set the Visibility of the MainWindow back to Visible.
Have you also considered keeping everything in the same Window but having different Panels that you set Visible and Invisible? That could have the same effect but it's less complicated...
Hope that helps...
I have a simple two forms, one that contains a grid and a button. When I click the button, my application starts doing a long operation. While it is working, I show another form that contains a progress bar
I open it like this:
_busyWindow.ShowDialog();
And defined
public partial class BusyWindow : DevExpress.XtraEditors.XtraForm
{
public BusyWindow()
{
InitializeComponent();
}
private void BusyWindow_FormClosing(object sender, FormClosingEventArgs e)
{
this.Hide();
e.Cancel = true; // this cancels the close event.
}
}
When the operation is finished, I hide the form like this
if (ended)
_busyWindow.Hide();
It works fine. The problem is that when I close the second form (same closing code), it also closes fine but my main GUI loses the focus. For example, if I have the Firefox opened behind the application, then the Firefox gets the focus.
This only happens when I close the second form when the busyWindow has been opened, and no when it hasn't (ie, if I open the form, I close it without clicking on the button, then the main GUI doesn't lose the focus).
Do you know what is happening or where could I try to search?
There could be two possible solutions to enable you to keep focus on your main window:
//Edited: Main Window in the below example would be the window with Grid and Button.
Since you are showing the busy window via ShowDialog() try setting the owner of the window by this: _busyWindow.ShowDialog(this);. I had earlier faced a similar problem and this worked for me. Since you specify the owner of the busyWindow, when it closes it would put the focus back on its owner,i.e. your main window
In case the above technique doesnt work (it should, as it worked for me), you could try to pass the reference of the main window to the busyWindow and then on its close set the focus of the main window. Sample:
_busyWindow.MyMainWindow = this; //MyMainWindow references mainWindow of your app
_busyWindow.ShowDialog();
And the following at the FormClosing of busyWindow:
private void BusyWindow_FormClosing(object sender, FormClosingEventArgs e)
{
this.Hide();
e.Cancel = true; // this cancels the close event.
MainWindow.Focus();
}
See if it works. The first solution should work.
Hope it helps.
Thanks & Happy Windowing!
Just set child's window Owner = null before closing it