After a button is clicked in a Windows form application written in C#, how to wait for another button to be clicked? Meanwhile I am updating a datagridview dynamically by current information.
EDIT
After button1 is clicked, I want to repeatedly update a dataGridView with current information and when button2 is clicked I want to stop updating the dataGridView.
Use Timer Class.
public partial class Form1 : Form
{
System.Windows.Forms.Timer timer;
public Form1()
{
InitializeComponent();
//create it
timer = new Timer();
// set the interval, so it'll fire every 1 sec. (1000 ms)
timer.Interval = 1000;
// bind an event handler
timer.Tick += new EventHandler(timer_Tick);
//...
}
void timer_Tick(object sender, EventArgs e)
{
//do what you need
}
private void button1_Click(object sender, EventArgs e)
{
timer.Start(); //start the timer
// switch buttons
button1.Enabled = false;
button2.Enabled = true;
}
private void button2_Click(object sender, EventArgs e)
{
timer.Stop(); //stop the timer
// switch buttons back
button1.Enabled = true;
button2.Enabled = false;
}
From MSDN:
A Timer is used to raise an event at user-defined intervals. This
Windows timer is designed for a single-threaded environment where UI
threads are used to perform processing. It requires that the user code
have a UI message pump available and always operate from the same
thread, or marshal the call onto another thread.
When you use this timer, use the Tick event to perform a polling
operation or to display a splash screen for a specified period of
time. Whenever the Enabled property is set to true and the Interval
property is greater than zero, the Tick event is raised at intervals
based on the Interval property setting.
So you have button A and button B. When button A is pressed you want to wait for button B to be pressed, then do something special? Without more information the simplest way is something like this:
private void OnButtonAClicked(object sender, EventArgs e)
{
ButtonA.Enabled = false;
ButtonA.Click -= OnButtonAClicked;
ButtonB.Click += OnButtonBClicked;
ButtonB.Enabled = true;
}
private void OnButtonBClicked(object sender, EventArgs e)
{
ButtonB.Enabled = false;
ButtonB.Click -= OnButtonBClicked;
// Do something truly special here
ButtonA.Click += OnButtonAClicked;
ButtonA.Enabled = true;
}
This code will toggle(initial state; button A is enabled, button B is disabled), when button A is pressed, button B becomes enabled and processes events, etc.
Use the BackgroundWorker http://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.aspx
It doesn't freeze the UI, support ProgressBar, also it can be async. At the link you will see a good example with same functional that you want (start some task by click on one button and cancel it by click on another button).
Related
I believe I have a misunderstanding about either how a lock works or how the System.Windows.Forms.Timer works in C#.
So I made a simple Windows Forms Application (.NET Framework) and I added a Timer and a Button to the Form from the Toolbox. The Button starts the Timer when clicked, and the Timer enters a lock on a dummy object and blocks it on the Tick event. For the Button's Click event I have the following method:
private void button1_Click(object sender, EventArgs e)
{
timer1.Enabled = true;
}
And for the Timer's Tick event I have this method:
readonly object lockObj = new object();
private void timer1_Tick(object sender, EventArgs e)
{
lock (lockObj)
{
MessageBox.Show("Entered the lock!");
MessageBox.Show("Exiting the lock...");
}
}
Everything else is left to default and there is no additional code.
I expected this program to show a single MessageBox with the text "Entered the lock!", then after I close it and also the following one with the message "Exiting the lock..." I thought the lock would be released and a queued up Tick event if any would acquire the lock, the process reapeating. Instead, the "Entered the lock!" MessageBox keeps opening multiple times without having to close it, as if every Tick event call enters the lock even if nobody releases it.
I tried to replicate this in a Console Application but with no luck. I'd appreciate a hint about what causes this problem so I know where to look into it.
Alternative code you can test in a Windows Forms Application:
using System;
using System.Drawing;
using System.Windows.Forms;
namespace Lock_Test_2
{
public partial class Form1 : Form
{
Timer timer1;
readonly object lockObj = new object();
public Form1()
{
InitializeComponent();
Button button1 = new Button();
button1.Location = new Point(100, 100);
button1.Size = new Size(187, 67);
button1.Text = "button1";
button1.Click += button1_Click;
Controls.Add(button1);
timer1 = new Timer();
timer1.Tick += timer1_Tick;
}
private void button1_Click(object sender, EventArgs e)
{
timer1.Enabled = true;
}
private void timer1_Tick(object sender, EventArgs e)
{
lock (lockObj)
{
MessageBox.Show("Entered the lock!");
MessageBox.Show("Exiting the lock...");
}
}
}
}
System.Windows.Forms.Timer dispatches its events via a windows message loop.
MessageBox.Show shows a messagebox and then pumps the windows message loop as a nested loop. This can include dispatching more events for a timer.
Since only a single thread (the UI thread) is involved, and lock is reentrant, that's why you get multiple message boxes shown.
I am working on antivirus program and on real-time protection panel I want checkbox when for example "Malware protection" checkbox is unchecked to make it not enable for like 15 minutes and after that time it is enabled again so it prevents spam.
If somebody can help me it would be great
I tried with Thread.Sleep() but it stops whole application, and I tried with timer but I think I did it wrong.
This is code for timer
private void checkBox1_CheckStateChanged(object sender, EventArgs e)
{
if (this.checkBox1.Checked)
{
this.checkBox1.Text = "On";
// these two pictureboxes are for "You are (not) protected"
// picture
picturebox1.Show();
pictureBox5.Hide();
timer1.Stop();
}
else
{
this.checkBox1.Text = "Off";
// this is the problem
timer1.Start();
this.checkBox1.Enabled = true;
pictureBox1.Hide();
pictureBox5.Show();
}
}
private void timer1_Tick(object sender, EventArgs e)
{
this.checkBox1.Enabled = false;
}
Short Answer
From the code you posted, it really only appears that you need to change the code to disable the checkbox in the CheckChanged event and enable it in the timer1_Tick event (and also Stop the timer in the Tick event).
Full Answer
Winforms has a Timer control that you can use for this. After you drop a Timer onto the designer, set the Interval property to the number of milliseconds you want to wait before enabling the checkbox (1 second is 1000 milliseconds, so 15 minutes is 15min * 60sec/min * 1000ms/sec, or 900,000 ms). Then double-click it to create the Tick event handler (or add one in your Form_Load event as I've done below).
Next, in the CheckChanged event, if the checkbox is not checked, disable the checkbox and start the timer.
Then, in the Tick event, simply enable the checkbox (remember, this event is triggered after Interval milliseconds have passed) and stop the timer.
For example:
private void Form1_Load(object sender, EventArgs e)
{
// These could also be done in through designer & property window instead
timer1.Tick += timer1_Tick; // Hook up the Tick event
timer1.Interval = (int) TimeSpan.FromMinutes(15).TotalMilliseconds; // Set the Interval
}
private void timer1_Tick(object sender, EventArgs e)
{
// When the Interval amount of time has elapsed, enable the checkbox and stop the timer
checkBox1.Enabled = true;
timer1.Stop();
}
private void checkBox1_CheckedChanged(object sender, EventArgs e)
{
if (!checkBox1.Checked)
{
// When the checkbox is unchecked, disable it and start the timer
checkBox1.Enabled = false;
timer1.Start();
}
}
This can be done without using Timer explicitly. Instead use asynchronous Task.Delay, which will simplify the code and make it easy to understand actual/domain intentions.
// Create extension method for better readability
public class ControlExtensions
{
public static Task DisableForSeconds(int seconds)
{
control.Enabled = false;
await Task.Delay(seconds * 1000);
control.Enabled = true;
}
}
private void checkBox1_CheckStateChanged(object sender, EventArgs e)
{
var checkbox = (CheckBox)sender;
if (checkbox.Checked)
{
checkbox.Text = "On";
picturebox1.Show();
pictureBox5.Hide();
}
else
{
checkbox.Text = "Off";
checkbox.DisableForSeconds(15 * 60);
pictureBox1.Hide();
pictureBox5.Show();
}
}
You could diseable and enable it with task.Delay(). ContinueWith(). This creates a new thread that fires after the delay is done. You need to make it thread safe, winforms isnt thread safe on its own
You should use Timer.SynchronizationObject
I have a NotifyIcon and I set balloon text with MouseMove event. The balloon text comes from a database. This results continuous database query.
private void notifyIcon1_MouseMove(object sender, MouseEventArgs e)
{
//database operations.......
}
How can I prevent this? I want to set balloon text once when mouse on NotifyIcon.
Use the BalloonTipShown event (https://msdn.microsoft.com/en-us/library/system.windows.forms.notifyicon.balloontipshown(v=vs.110).aspx)
The behaviour you are looking for matched that event alot better then the MouseMove event
Another approach would be to add a Timer to your Form and set its Interval to a delay like 1 second. This delay would be how often the user could hit the database. Setup a Flag that gets reset by the Timer and check it in your NotifyIcon event. Something like:
private bool AllowUpdate = true;
private void notifyIcon1_MouseMove(object sender, MouseEventArgs e)
{
if (AllowUpdate)
{
AllowUpdate = false; // don't allow updates until after delay
// ... hit the database ...
// ... update your text ...
timer1.Start(); // don't allow updates until after delay
}
}
private void timer1_Tick(object sender, EventArgs e)
{
// reset so it can be updated again
AllowUpdate = true;
timer1.Stop();
}
I am developing an application where i need the following requirement:
Suppose i have a button and a label (initially visibility set to false) in my form, and user clicks on the button, then the label should be displayed with some text that i assign to the label in the button click. But this label should be displayed only for some time, say some 3 secs and then it should automatically go invisible. For this if i gave:
private void button1_Click(object sender, EventArgs e)
{
label1.Visible=true;
label1.Text= "Magic";
Thread.Sleep(3000);
label1.Visible=false;
}
This code does not help the purpose. What is the approach to do it?
Try replacing the last two lines of your method with this:
System.Windows.Forms.Timer timer = new System.Windows.Forms.Timer();
timer.Interval = 3000;
timer.Tick += (source, e) => {label1.Visible = false; timer.Stop();};
timer.Start();
Using Thread.Sleep() is never a good idea in WinForms; use timers instead.
Create a timer with 3s as Interval, start it, and set Visible to false in your timer Tick event. Also don't forget to stop the timer.
Never call Thread.Sleep in your UI thread: the application will be blocked as the UI thread won't accept messages (user click...) while sleeping.
// create a global _timer object
static Timer _timer; // From System.Timers
private void button1_Click(object sender, EventArgs e)
{
label1.Text = "Magic";
// Thread.Sleep(3000); // don't do Thread.Sleep()!
label1.Visible = false;
Start();
}
static void Start()
{
label1.Visible = true;
_timer = new Timer(3000); // Set up the timer for 3 seconds
_timer.Elapsed += new ElapsedEventHandler(_timer_Elapsed);
_timer.Enabled = true; // Enable it
}
static void _timer_Elapsed(object sender, ElapsedEventArgs e)
{
label1.Visible = false;
_timer.Stop();
}
Use Timer, perhaps Windows.Forms.Timer. You may have to play with enabling and disabling it when needed and not needed. Your current way does not help, coz your making the main UI thread to sleep. No use.
I was wondering if anyone knows how to use a dialog box to create a hold down button event. Here is the scenerio:
a user would like to shutdown their system, but because it is critical that they confirm, that user must hold the button for 5 seconds before the action can be done.
I am trying to do it in a yes no scenario ie.
To confirm shutdown please hold "Yes" for 5 seconds.
Anyone done this before able to offer a little help/insight?
Try using a button's Mouse_Down & Mouse_Up event, and a timer (this assumes you're using WinForms).
private void button1_MouseDown(object sender, MouseEventArgs e)
{
if (this.timer1.Enabled == false)
{
this.timer1.Interval = 5000;
this.timer1.Enabled = true;
}
}
private void timer1_Tick(object sender, EventArgs e)
{
this.timer1.Enabled = false;
MessageBox.Show("Shutdown!");
}
private void button1_MouseUp(object sender, MouseEventArgs e)
{
timer1.Enabled = false;
}
You could capture the button press on 'mousedown', and start a 5-second timer. Once the timer completes, shutdown is initiated. If a 'mouseup' event happens, it could stop and reset the timer.
Sure, handle BOTH the mousedown event and the mouseup event. Start a timer on the mousedown and see how long it has run on the mouseup. Done!
You could do this any number of ways. The first that comes to my mind would be to spin off a thread that waits 5 seconds and is simply aborted if the user's mouse comes back up.
Thread shutdown;
private void button1_MouseDown(object sender, MouseEventArgs e)
{
shutdown = new Thread(()=>ShutDown());
shutdown.Start();
}
private void ShutDown()
{
Thread.Sleep(5000);
Console.Write("5 seconds has elapsed");
// Do something.
}
private void button1_MouseUp(object sender, MouseEventArgs e)
{
if (shutdown != null)
{
shutdown.Abort();
shutdown = null;
}
}
Low overhead and you're not adding additional supporting controls for something this simple.
Why bother when you can just use getAsyncKeyState()? Tell them to hold down 'y' for 5 seconds. You can find a reference here: http://www.pinvoke.net/default.aspx/user32.getasynckeystate
Or you can do it your way and start a timer on MouseDown, then on MouseUp, end the timer and then see if it's more or less than 5 seconds. http://msdn.microsoft.com/en-us/library/system.windows.forms.control.mousedown%28VS.71%29.aspx
You can use the Form.MouseDown events do detect that the user has pressed the mouse button. In the event handler, check to see if cursor is over the button or not (the event is passed in the coordinates of the cursor). You can then enable a timer which will tick in 5 seconds, and perform the shutdown when the timer ticks.
When the user first clicks YES, start a timer that repeatedly checks if the mouse location is inside of the button. After 5 seconds has elapsed, proceed with the shutdown. If the user moves the mouse out of the button, stop the timer.
private DateTime mouseDownTime;
private void Button_MouseDown(object sender, MouseButtonEventArgs e)
{
mouseDownTime = DateTime.Now;
}
private void Button_MouseUp(object sender, MouseButtonEventArgs e)
{
if (mouseDownTime.AddSeconds(5) < DateTime.Now)
MessageBox.Show("You held it for 5 seconds!");
}
You can set up a timer on the MouseDown event, and if the mouse capture changes (check the MouseCaptureChanged event) to false before the timer event fires, cancel the timer.