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.
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;
}
I have 2 forms and want to alternate back and forth between them on button click in each. This can be done by opening the new form and closing the current one. However, from experience, if the new one takes time to fully show there can be a gap where no form is shown. I'm trying to use the Form.Shown event to avoid this:
private void button1_Click(object sender, EventArgs e)
{
var form2 = new Form2();
var shown = new AutoResetEvent(false);
form2.Shown += (ta, tb) => { shown.Set(); };
form2.Show();
shown.WaitOne();
Close();
}
However, it deadlocks on the WaitOne statement. It appears the Shown event isn't thrown until after the click method is finished. How else might I do it?
I have multiple children of the same WinForms form, each with its own handler for a keyboard event. For a minimal example (C#):
public Form1() {
InitializeComponent();
c1 = new Control();
c2 = new Control();
c1.KeyPress += c1_KeyPress;
c2.KeyPress += c2_KeyPress;
Controls.Add(c1);
Controls.Add(c2);
}
void c1_KeyPress(object sender, KeyPressEventArgs e) {
Text += " c1";
e.Handled = true;
}
void c2_KeyPress(object sender, KeyPressEventArgs e) {
Text += " c2";
e.Handled = true;
}
When the event fires, it always gets handled by whichever child was originally added to the form first. Reordering the children with c2.BringToFront() or Controls.SetChildIndex(c2, 0) doesn't change the priority. Reordering the constructions or the delegate assignments doesn't change anything either. Calling c2.Focus() doesn't either. Changing the order of the Add calls is the only thing that seems to affect it.
(By contrast, for mouse events the priority gets resolved in an expected way: the topmost control under the pointer hotspot gets dibs on the event, and "topmost" is a clear concept I can control using BringToFront and friends.)
In my real case, c1 is a simple custom control derived from WinForms.UserControl, and c2 is a CefSharp.WinForms.ChromiumWebBrowser. There the keyboard events are caught by c2 no matter what I do.
What decides this priority of handlers? How can I change it?
There is no "priority", keyboard events are raised on the control that has the focus. Intuitively simple to understand, entering text in a TextBox requires selecting it first. A very significant flaw in the posted snippet is that you cannot tell which one has the focus. Although the Control class is usable as-is, in practice you almost always need to derive your own class from it to give it desirable behavior.
Add a new class to your project and paste the code shown below. Replace new Control() with new MyControl(). Now you can tell.
using System;
using System.Windows.Forms;
class MyControl : Control {
protected override void OnEnter(EventArgs e) {
this.Invalidate();
base.OnEnter(e);
}
protected override void OnLeave(EventArgs e) {
this.Invalidate();
base.OnLeave(e);
}
protected override void OnPaint(PaintEventArgs e) {
if (this.Focused) {
ControlPaint.DrawFocusRectangle(e.Graphics, this.DisplayRectangle);
}
base.OnPaint(e);
}
}
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.
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";
}
}