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Hi,
I have the below code which runs after choosing an item from the listbox (choose the first one). Goes to the below item after 5 seconds and then goes to another after 5 sec again... So here is my question: I have a func which I named as process() I want to run this func only once when each item is selected in the listbox? So how can I do that???
Thank you,
Cem Louis
<br />
<br />
using System;<br />
using System.Drawing;<br />
using System.Collections;<br />
using System.ComponentModel;<br />
using System.Windows.Forms;<br />
using System.Data;<br />
using System.Timers;<br />
using System.Threading;<br />
<br />
namespace WindowsApplication14<br />
{<br />
public class Form1 : System.Windows.Forms.Form<br />
{<br />
private System.Windows.Forms.ListBox listBox1;<br />
private System.Windows.Forms.Button button1;<br />
private System.Timers.Timer timerClock = new System.Timers.Timer();<br />
private System.ComponentModel.Container components = null;<br />
<br />
public Form1()<br />
{<br />
InitializeComponent();<br />
InitializeTimer();<br />
<br />
}<br />
<br />
public void InitializeTimer()<br />
{<br />
this.timerClock.Elapsed += new ElapsedEventHandler(OnTimer);<br />
this.timerClock.Interval = 5000;<br />
}<br />
<br />
protected override void Dispose( bool disposing )<br />
{<br />
if( disposing )<br />
{<br />
if (components != null) <br />
{<br />
components.Dispose();<br />
}<br />
}<br />
base.Dispose( disposing );<br />
}<br />
<br />
#region Windows Form Designer generated code<br />
private void InitializeComponent()<br />
{<br />
this.listBox1 = new System.Windows.Forms.ListBox();<br />
this.button1 = new System.Windows.Forms.Button();<br />
this.SuspendLayout();<br />
this.listBox1.Location = new System.Drawing.Point(8, 8);<br />
this.listBox1.Name = "listBox1";<br />
this.listBox1.Size = new System.Drawing.Size(120, 95);<br />
this.listBox1.TabIndex = 0;<br />
this.button1.Location = new System.Drawing.Point(8, 112);<br />
this.button1.Name = "button1";<br />
this.button1.Size = new System.Drawing.Size(120, 23);<br />
this.button1.TabIndex = 1;<br />
this.button1.Text = "Run";<br />
this.button1.Click += new System.EventHandler(this.button1_Click);<br />
this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);<br />
this.ClientSize = new System.Drawing.Size(136, 142);<br />
this.Controls.Add(this.button1);<br />
this.Controls.Add(this.listBox1);<br />
this.Name = "Form1";<br />
this.Text = "Form1";<br />
this.Load += new System.EventHandler(this.Form1_Load);<br />
this.ResumeLayout(false);<br />
<br />
}<br />
#endregion<br />
<br />
[STAThread]<br />
static void Main() <br />
{<br />
Application.Run(new Form1());<br />
}<br />
<br />
private void Form1_Load(object sender, System.EventArgs e)<br />
{<br />
listBox1.Items.Add("Arthur");<br />
listBox1.Items.Add("Alex");<br />
listBox1.Items.Add("Amie");<br />
listBox1.Update();<br />
}<br />
<br />
private void OnTimer(object source, ElapsedEventArgs e)<br />
{<br />
this.nextvalue(this.listBox1.SelectedIndex);<br />
}<br />
<br />
private void button1_Click(object sender, System.EventArgs e)<br />
{<br />
if(this.listBox1.SelectedItem!=null)<br />
{<br />
this.timerClock.Start();<br />
}<br />
else<br />
{<br />
MessageBox.Show("Select an Item");<br />
}<br />
}<br />
<br />
private void nextvalue(int currentPosition)<br />
{<br />
if(currentPosition+1<=this.listBox1.Items.Count-1)<br />
{<br />
this.listBox1.SetSelected(currentPosition+1,true);<br />
}<br />
else<br />
{<br />
this.timerClock.Stop();<br />
}<br />
}<br />
<br />
private void process()<br />
{<br />
}<br />
}<br />
}<br />
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Add a boolean class member that starts out as false. Whenever the timer event is triggered, check if it's false. If so, set it to true. In the ListBox SelectedIndexChanged event handler (or whatever the event is called that gets called whenever you select a different item from the listbox), set the boolean to false again, thus resetting it and allowing the timer event to run again.
This way, Process() can only run when a different item has been selected. And since the Process() then sets the boolean flag to true, it will only run once.
<br />
bool itemIsInTimer = false;<br />
<br />
private void listbox1_SelectedIndexChanged(object sender, System.EventArgs e)<br />
{<br />
this.itemIsInTimer = false;<br />
}<br />
<br />
private void process()<br />
{<br />
if(!this.itemIsInTimer)<br />
{<br />
this.itemIsInTimer = true;<br />
}<br />
}<br />
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I have the following:
To read an image from the northwing db im doing the following (im using 78 as the current images in the northwind db have 78 bytes of header information):
<br />
ms.Write(img, 78, img.Length-78);<br />
<br />
bmp = null;<br />
bmp = new Bitmap(ms);<br />
Then to write the image to the db:
<br />
FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);<br />
<br />
BinaryReader br = new BinaryReader(fs);<br />
<br />
byte[] photo = br.ReadBytes((int)fs.Length);<br />
The problem is I need to add 78 bytes when writing a new image to the db, so that when I read the image its like the others that already exist in the db. Anybody know how to do this?
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You will just have to create a new byte array with the 78 bytes in place, then copy the bytes from the read buffer to the other array.
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I realize that I can override the PaintMethod of the DataGridTextBoxColumn class in order to change the color of cells within a DataGrid.
I'd like to change the colors of individual columns headers also. Does anyone know if that is possible?
How might I do that?
Thanks!
Mark Mokris
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Will you check my article on DatagridFormattings. It may help you out.
Sreejith Nair
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 Hello
Basically iam vb programmer,i was declare global variable in module level.
where can i declare the global varibles in c# ,how can i access that
varible
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C# does not support global variables per se, it isn't good a object oriented design to have lots of global variables floating around. However, you can create static variables on a class which are accessible globally. For example:
public class GlobalConfiguration
{
private static int _sqlServerTimeout = 60;
public static int SqlServerTimeout
{
get
{
return _sqlServerTimeout;
}
set
{
_sqlServerTimeout = value;
}
}
}
Of course, you don't NEED to wrap the variable in a property, but it is good practice to do so. You can add extra validation in the setter, and the getter can internally operate a lazy lookup if the variable is not often required, but getting the value takes time (Once you have generated the value the first time you can store it, so that the next time you need the value it can be returned quickly).
Do you want to know more?
Vogon Building and Loan advise that your planet is at risk if you do not keep up repayments on any mortgage secured upon it. Please remember that the force of gravity can go up as well as down.
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First check out the tutorials at http://www.csharp-station.com/
I don't fully understand you question but it seems to me that you are trying to declare a public variable in a namespace ? Like that ?
namespace Something
{
public int myvariable = 0;
}
That's not possible. All members in C# must be inside objects (classes, structs). So what you must do is:
namespace Something
{
public class MyClass
{
public static int myvariable = 0;
}
}
The static modifier ensures you can access the variable without creating a new instance of the class.
P.S. You should however avoid using this tehnique as global variables are rarely needed and they're rally not usefull usually.
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hi,
This question is regards to code optimization.I have near to 100-150 labels and same number of textboxes in a my main form.And this form also contain few other controls. Say panel, combo box etc.
The data fetching is also dynamic based on users requirement. I check the maximum time with possible chances for data request(range).Performance is good. So i am not worried about data fetching.
My problems is with this much controls and their dynamic sub instances.I found my application becoming too very slow when this much control are drawn in the main form(I mean when form is loaded on the first time).I already told that, the above mentioned number of control is only an example. Some time it may decrease or increase. If i go for some optimization here in my design part then it won't serve users purpose. Clearly i am into trouble. What i can optimise is my code not design.
Is there any way to hadle this situation.
Sreejith Nair
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sreejith ss nair wrote:
I have near to 100-150 labels and same number of textboxes in a my main form.And this form also contain few other controls. Say panel, combo box etc.
That sounds like a very cluttered form. It sounds to me like you should be thinking of redesigning that so that there are less controls, by moving some to subordinate forms of some kind.
sreejith ss nair wrote:
If i go for some optimization here in my design part then it won't serve users purpose. Clearly i am into trouble. What i can optimise is my code not design.
You should think very carefully about your user interface, because, even if you do improve the speed, your form, with that many controls, is likely to overwhelm your users.
Do you want to know more?
Vogon Building and Loan advise that your planet is at risk if you do not keep up repayments on any mortgage secured upon it. Please remember that the force of gravity can go up as well as down.
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All these controls are very urgent for me. Say these controls are small in size and they are used to show different date of year. So user want to see all date values at a time. So i can't go for control customization
Sreejith Nair
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If its just labels and text boxes, maybe you could use a grid control to display the information.
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All these controls are very urgent for me. Say these controls are small in size and they are used to show different date of year. So user want to see all date values at a time. So i can't go for control customization
Sreejith Nair
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1. Even if the controls are important you can create a wizard sort of User Interface by logically breaking up controls on several screens.
2. You can either create controls at runtime at some instance and then creating adding controls to your form dynamically. This will speed up your form initialization because you are not creating all 100-150 controls at form load.
hope it helps....
best regards,
Hatim Ali.
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hi,
Defanitly it won't help me. My interface, that is the interface that i am going to show is the final out for the user. I can't make any sort of updation or customiztion in my controls list or my interface. This is the way it is working.
I have a small doubt to ask you.
Suppose if you want to show few date values for two months. What you will do ?. Here you need to know one more thing that, you need to show all date value at a time.
anyhow thanks for sharing my this problem
Sreejith Nair
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You have a choice. Either redesign your interface so it is more organized, even if it means duplicating information on sub-forms, or leave it as is. There's nothing else you can do about this. You simply have way too many controls on a single form.
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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im trying to use the image.saveadd function to save a group of gif images in a single file, the problem is that this function has Encoderparameters parameter and i dont know how to use it, does anybody know how to use the saveadd function or anything about the encoderparameter class?
huda
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Hello,
how is it possible to rename an XmlNode in a DOM implementation like XmlDocument or XPathDocument?
XmlNode node;
node.Name = "abcdef";
This would be very simple but the Name property is Read-Only...
thanks
pete
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It's not allowed to change a node's name, although I'm not to sure why..... You can only add a new Node with, for example the old node's content and with the desired name, after which you delete the old node.
i.e.
<br />
System.Xml.XmlDocument doc = new System.Xml.XmlDocument();<br />
doc.LoadXml("<Test><Testing>content</Testing><Test>");<br />
<br />
System.Xml.XmlNode oldNode = doc.SelectSingleNode("/Test/Testing");<br />
<br />
System.Xml.XmlNode newNode = doc.CreateElement("NewTest");<br />
newNode.InnerXml = oldNode.InnerXml;<br />
oldNode.ParentNode.AppendChild(newNode);<br />
doc.RemoveChild(oldNode);<br />
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//I came across this trick by accident. works like a charm and ridiculously simple.
XmlDocument myXml;
myXml.Load(myXmlNode); //Not sure if this will work, but you get the idea
myXml.InnerXml = myXml.InnerXml.Replace("<OldName", "<NewName").Replace("</OldName>", "</NewName>");
//or if you know name is unique in the node
myXml.InnerXml = myXml.InnerXml.Replace("OldName", "NewName");
"I have found the paradox that if I code until it hurts, then there is no hurt, but only more code". Mother Teresa (if she were a coder)
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hi,
I need a global store for storing error messages. It could be done using singleton.
Now whats the difference between the following two.
1. Implement singleton pattern.
2. Creat a class. Make its contructor private. Expose the functionality using static functions.
In singleton pattern a single object is created but in 2nd approach no object is created. Which approach is better ??
Thanks...
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If there is no explicit need for an object instance, I find the use of all static members simpler. If you want to use it to persist data using the framework's builtin serialization, then you would need an object.
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how do you use system.xml to read and write xml files directly....not by loading them into a dataset.....
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You can either use XmlDocument Class or XmlTextReader / XmlTextWriter Classes for reading/writing XML other than dataset.
hope it helps
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