C# - How To Correctly Implement A Custom Timer In .Net
Sep 8, 2011
I have a requirement for a timer that has the following behaviour:
Millisecond accuracy I want the tick event handler to only be called once the current tick handler has completed (much like the winforms timer)I want exceptions on the main UI thread not to be swallowed up by the thread timer so this requires Invoke/Send instead of BeginInvoke/PostI've played around with CreateTimerQueueTimer and had some success but at the same time had problems with code reentrance and/or locks when deleting the timer.
I decided to create my own timer so that I could get a better idea of what is going on under the hood so that I can fix the locking and reentrance problems. My code seems to work fine leading me to believe that I may as well use it. Does it look sound? I've put in a check if the timer is deleted to make sure that the deletion is complete before the timer can be created again. Does that look ok?
Note: I should say that I call timeBeginPeriod(1) and timeEndPeriod(1) inorder to achieve the millisecond accuracy.(The following code is converted from vb.net to c#, so apologies for any missed mess-ups}
ETA: I've found a problem with it. If the timer is running at an interval of 1 millisecond, and I call, say, Change(300), it locks up @ while (this.DeleteRequest). This must be because the TimerLoop is in the this.CallbackDelegate.Invoke(null) call.
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Jul 29, 2009
I decided to get my head back into VB. My question is ; how to I correctly implement a Call procedure? I cannot seem to find a simple example through google.
for instance :
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim selectString As String = Nothing
[Code].....
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Jul 5, 2011
Suppose I have the following construct:
Public Sub SomeMethod()
Try
doSomething()
Catch ex as Exception
[code]...
And I would like to write handleException(ex). Suppose my class has different options of handling events:
Public Enum ExceptionHandlingType
DisplayInMessageBox 'Display in msgbox
ThrowToCaller 'Raise the error to the caller routine
[code]...
Below is my attempt at writing "handleException". It seems no matter what I do, if the object was set with Exception mode of "ThrowToCaller" then the stack trace gets all messed up when I use handleException(). How can I just have a clean stack trace generated when the option is "ThrowToCaller" (every other option seems like it is working fine)
Public Sub handleException(ex as Exception)
Select Case mExceptionHandling
Case ExceptionHandlingType.DisplayInMessageBox
MsgBox(ex.Message)
[code]...
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Oct 31, 2011
I have a linq query which loads approx. 1000 lines into a variable, during that process I want to display a progressbar, not necessarily stating the percentage, can be marquee style, doesnt matter.
This progressbar is on a modal form to precent the user from interacting with the app for the time the query's running.
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May 17, 2012
Ok so on my project it seems the timer is not working correctly, the interval is set to 5000 (which is 5 seconds... right?) so every 5 seconds it would display a MsgBox telling me the current date/time and then a time in a list.
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Nov 7, 2009
I have an object, - all done programmatically like:[code]I cannot figure out, how to add the times, so I can use it (Tics, Fire event, start/stop etc).I cannot add the timer to a panel via drag/drop as the class is made purely programmatically.MyTimer above seems not to have any "timer-related" properties/methods available. The docu suggest to add the timer to the panel, but how to do that in my case ? There seems to be several changes from VB Express 2005 to the 2008-version, that I'm using. Documentation contains only little info in this area.
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Aug 21, 2009
I am trying to implement a timer in my program and i am unable to do so till now.
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Static intCount As Integer
intCount = 10
While intCount <> 0
Dim fileReader As String
[Code] .....
How do I implement a timer that will close the IE after every 5 seconds till the count runs out?
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Apr 8, 2012
I'm trying to implement a timer into my program, because I want to take a capture from a webcamdevice every x seconds.I've wandered around google all day and tried to implement all kind of timer classes (with system.threading because I can't use system.windows.forms.timer) but I won't figure it out!
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Oct 1, 2010
I am trying to implement a progress bar into my code but it seems to not run when another section of code is running. I set a timer to run when the ok button is clicked and it should then start the progress bar but also when clicking the ok button whatever radio button is selected also runs. I am trying to do this in Visual Basic 2008. I will post my current code below and I will say I am a complete novice at this so I apologize if the code looks weird:
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May 26, 2010
I have a semi-transparent custom control in vb2005 - works fine, except I can't get it to update/refresh correctly. If I update the custom parameter _backgroundColor, the control appears to be overpainted - e.g. each attempt to update the colour of the control overpaints the existing colour - until it becomes a solid block of colour. However, forcing a refresh of the form makes the control display the correct colour. Any ideas? I don't want to have to repaint the form just to get this control to render correctly. Code for the custom control is below.
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Jul 19, 2011
Here are my interface and it's implementation class file. While implenting service function there is a chance to get 3 exceptions.
I need to handle these using a custom fault contract. how to implement 3 exceptions under one fault contract.
Interface:
Function GetEntities() As String
Class file that use the service Interface:
Public Function GetEntities() As String
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May 9, 2012
With String.Format() it is possible to format for example DateTime objects in many different ways. Every time I am looking for a desired format I need to search around on Internet. Almost always I find an example I can use. For example:
String.Format("{0:MM/dd/yyyy}", DateTime.Now); // "09/05/2012"
But I don't have any clue how it works and which classes support these 'magic' additional strings.So my questions are:How does String.Format map the additional information MM/dd/yyyy to a string result?Do all Microsoft objects support this feature?Is this documented somewhere?Is it possible to do something like this:String.Format("{0:MyCustomFormat}", new MyOwnClass())
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Sep 30, 2009
I have been developing in VB.net for a cople of years now. I really miss the increment and decrement operators for integers that I grew attached to while using Java and C#. I have seen posts explaining how to implement a custom operator for a class that I have written, but I have not seen any examples of how to do it for a basic type like Integer.[code]....
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Feb 20, 2012
I was wondering how to implement a custom character set for use by an application, i.e. hex bytes that are read by the program then converted and displayed in the window. If this requires first converting the bytes in a file to an already implemented character set, I'm cool with it - I'll go with whatever works or works best. I'm writing with VB.NET 2010, and running Windows 7 Home Premium x64, by the way.
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Apr 21, 2010
I am looking for ways to implement custom user-roles in windows application with vb.net. I got a database table called Roles with Administrator and User entries. User cannot see some of the form data. In ASP.NET MVC we can do like.
[Authorize(Roles = "Administrator")]
public function GetAccount() as Array
End Function
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Feb 22, 2011
i'm trying to implement my own custom titlebar using a picturebox. can anyone tell me why my right click won't open the system menu?here's my code:
Imports System.Runtime.InteropServices
Public Class Form2
<DllImport("user32.dll")> _
Public Shared Function ReleaseCapture() As Boolean[code]......
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Aug 6, 2009
Im looking for code that will take a screen shot of the screen every X amount of seconds and save it with a filename of like "SSLaptop Todays Date & Time"
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Oct 1, 2010
I have a custom timer that acts like a Wait for some number of milliseconds and then execute a function. It looks like this:
Public Class MyTimer
Inherits Timers.Timer
Public Event Done()
[code]....
(So, every one second, Timer checks if TextBox1 is empty. If it isn't, it displays a message box and stops checking.)I get a warning that Timer is used before it has been assigned a value, but it is used in the statement that assigns its value. The timer's interval is required to be greater than zero.
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Aug 2, 2010
What I need to do to make this code work for hours as well?[code]...
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Jan 15, 2009
I need an accurate timer to interface a Windows application to a piece of lab equipment.I used System.Timers.Timer() to create a timer that ticks every 10 msec, but this clock runs slow. For example 1000 ticks with an interval of 10 msec should take 10 wall-clock seconds, but it actually takes more like 20 wall-clock sec (on my PC). I am guessing this is because System.Timers.Timer() is an interval timer that is reset every time it elapses. Since it will always take some time between when the timer elapses and when it is reset (to another 10msec) the clock will run slow. This probably fine if the interval is large (seconds or minutes) but unacceptable for very short intervals.Is there a function on Windows that will trigger a procedure every time the system clock crosses a 10 msec (or whatever) boundary?
UPDATE: System.Timers.Timer() is extremely inaccurate for small intervals.I wrote a simple program that counted 10 seconds several ways:
Interval=1, Count=10000, Run time = 160 sec, msec per interval=16
Interval=10, Count=1000, Run time = 16 sec, msec per interval=15
Interval=100, Count=100, Run time = 11 sec, msec per interval=110
Interval=1000, Count=10, Run time = 10 sec, msec per interval=1000
It seems like System.Timers.Timer() cannot tick faster that about 15 msec, regardless of the interval setting.Note that none of these tests seemed to use any measurable CPU time, so the limit is not the CPU, just a .net limitation (bug?)For now I think I can live with an inaccurate timer that triggers a routine every 15 msec or so and the routine gets an accurate system time. Kinda strange, but...I also found a shareware product ZylTimer.NET that claims to be a much more accurate .net timer (resolution of 1-2 msec). This may be what I need. If there is one product there are likely others.
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Jul 9, 2009
I have a timer on a page in ASP.NET.
After a certain period of time elapses, I want to disable the timer.
I want to put a static variable in the timers tick event that will track how many seconds have elapsed.
My question is, will this work?
If user X and Y are viewing the page will they both have separate local static variables?
What is the best method of shutting down an ASP.NET timer after a certain elapsed time?
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Apr 23, 2009
I have a windows application that need to process som quite time consuming jobs. In my first try i did all processing under
the form thread. The result was bad response and update of the form due to the heavy jobs.To get around the problem with bad response from the form i created a new class "processing" where i put all the data processing. Then i instanciated a background worker where i in the "doWork" sub created a new instance of "processing".The "processing" class creates a timer from system.timer, and the timer drives the processing.On the Timer event Elapsed the timer starts a new thread from the thread pool.
My problem is now when i want to asynchronously close the background worker (with the corresponding function call what ever it is called ...) there is still a timer thread out there that causes exceptions for me.
1. How can i close my background worker and at the same time have the timer to be stopped?
2. Is there a way to synchronize the timer event so that the timer executes from the background worker thread?
3. Is there a better approach for me to adapt?
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Jan 11, 2011
I want to create an array of timer in vb.net. My problem is that how will i raise the tick event for a particular timer, say mytimer(x).tick and inside the tick event there is also a button, say mybutton(x) which changes location every interval. for example:
public class blah
dim mybuttons(20) as button
dim mytimer(20) as timer
private sub form_load(....) handles me.load
for x as integer = 0 to 20
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i dont know what to do next, all i want is to pass the button mybuttons(x) to mytimer(x) tick event, in which their index number are the same. i want to create one timer per button. how to do that? please help me and post example codes. i've researched the net but i cant understand passing variables, addhandlers, etc. i'm just new to programming object oriented.
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Jul 4, 2011
How can I incorporate the timer so once a page loads the timer activates, waits a few seconds then I tell my program what to do next.I tried this code but it didnt work:
Timer1.Interval = 5000
Timer1.Enabled = True
Timer1.Start()
[code]....
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Sep 30, 2010
Everything is nice and dandy on my pc, then I compile, move it to its final destination and I doesn't work! At first I thought it was a OS problem, but both machines has win7, I then thought it was a compilation problem, installed visual studio on the other pc, recompiled still with no luck, then it dawned on me, may it be a problem of 32bit vs 64bit?The piece of code is this:[code]....
By the way is not a problem of mouse_event, is the timer that doesn't work
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Mar 24, 2009
I have a timer in vb.net and it's interval is 1000ms ,. i have placed in it's timer_tick event a code that will print screen the screen and save it to a database.The problem is when i click outside of the form, or loosing the focus of the mouse to the form containing that timer/printscreen, the timer stops. As a result the printscreen also stops.here are it's properties:
generate member = true
interval = 1000
modifiers = friend
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Jul 14, 2011
I recently switched my code from using the windows.forms.timer to the systems.timer.timer and it has resulted in a multithreading error. I'm using the timer to trigger just one event so multithreading shouldn't be an issue. To give more detail I have implemented the timer at follows:
At the top of the class I have: Private Shared timr1sec As System.Timers.Timer
When the program loads (Private Sub Test_load):
timr1sec = New System.Timers.Timer(1000)
AddHandler timr1sec.Elapsed, AddressOf OnTimedEvent
In OnTimedEvent I call several subroutines, and write some data to the screen using a ListView object.VisualExpress throws the multithreading error on the last line of this code, which is in OnTimedEvent
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Aug 13, 2010
I have a routine which is controlled by a timer. It works perfectly. The problem is that now, I need to run this routine several times, so I need to start differents threads so that my program doesn't get hung up. I've been trying to start my timer inside a thread, but it doesn't work!
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Nov 6, 2009
VB6 create object of timer instead of timer control
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Apr 6, 2009
Is it possible to use a timer to delay code? For example:
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