When ListView is not in Virtual mode the following method seems to be the fast method to load a large list into ListView:
Dim items As New List(Of ListViewItem)
Dim alllines as String()=System.IO.File.ReadAllLines("FilePath")
For each line as string in alllines
Dim item As New ListViewItem
item.Text = line
items.Add(item)
Next
ListView1.Items.AddRange(items.ToArray())
I have a pixel I want to monitor for change. For example, first it is white, and suddenly it is black, and then changes back to white. My method is not fast enough to get this change.any changes I call the function below to get the original color of the pixel. Then I have a timer that runs every 1 ms to take the color of the pixel, and if it's not equal to original color; do something. For example counts the time the pixel has changed. However, this function does not run fast enough. Is there any faster methods to check the pixel? The function returns an ARGB code of the pixel color.[code]....
View 3 RepliesMy current project is to process several files. The files come from a Unix server and have been SFTP'd to the Windows XP machine. (That's fixed protocol, I don't have control over it.) My problem now is that the Unix new line characters and Windows characters don't match. The solution is to read the file line by line and replace 0x0A with 0x0D + 0x0A, or Asc 10 with Asc 13 + Asc 10, or vbLf with vbCrLf, however you like to say it.Well I have a working function to do this, but any extra speed I could squeeze out of it would be fantastic. The text files I'm working with can reach sizes of about 100MB. So to the question:
Q: What is the fastest way to read a file in, change characters as necessary and then write the file out?Here is my current working code.
Private Sub FormatCharacters(ByVal files As String())
Try
For Each fileName As String In files
FileSystem.Rename(fileName, fileName & ".old")
[code]....
what I am trying to do is, when a ListView loads, for the code to check the entry in column one, and then return a message box if the column contains a specific date.
I am using:
SUB I DONT KNOW THE METHOD TO INSERT THIS INTO. I NEED IT CHECKED WHEN THE LISTVIEW CHANGES
If lvuPreviousJobs.SelectedItems(0).SubItems(2).Text = "31/12/9999" Then
{
MsgBox("TEST")
[code]....
1) a text document which has content like :
uber|uber|ultra
taxi|taxi|taxi cab|cab|minicab|airport taxi|airport transfer
genitalia|genitalia|genitals
[code].....
so the way I have this working now I'M using System.Collections.Generic.List(Of T) for holding 100's of a structure.Dim Users as New List(Of User)
I was wondering if there was any better way or faster list container or something like this in the .net framework?
[code]I load a text file to a list box and if I try to modify or save over that same text file I get an access violation error. How can I load a text file and release all permissions/holds on that file?
View 4 RepliesHow can to make control arrays in vb.net ? there is no INDEX property or Load method like VB6. so how i can do it ?
View 5 RepliesI'm trying to code a class of RandomNumber. One of the class methods needs to populate a "List (Of RandomNumber)" ... which was passed as a parameter to the method ... with 10 random numbers between 1 and 50. DEAD SIMPLE :)
View 6 RepliesI am trying to make a listview custom control based on the standard listview control that will allow me to drag a column header outside the standard listview control and drop it on a panel. I plan to use the drop event to determine which column I should group by view on.
View 2 RepliesPublic Class notifierMain
Public Class Contacts
Inherits List(Of row)
Public Sub New()
[code]....
When I debug this winforms application I get curType = "notifier.notifierMain+Contacts+row" I want to the Validate function to know it is in MyContacts. How do I do this?
I have implemented inheritance for two parent classes called Table and Field. Each parent class has several child classes. In the Table parent class, I created a method that expects parameter List(Of Field).
I get an error when trying to pass in parameter List(Of ChildField) to the method that expects a parameter of List(Of Field). The error message is as below:
Value of type
'System.Collections.Generic.List(Of
com.hlb.icisbatch.data.ChildField)'
[Code]....
I have a media browser program I am building. I am trying to use drag/drop so a user can drag media tracks from one listview to another listview and then use the second list view as a playlist in windows media player com object. Reading at MSDN I have found out that there is no built in support for item re-ordering with the listview control. I have listview1 working correctly but when I try to reorder items in listview2, the dragged item ends up at the end of the list. So basically I need to get the item insertion index corrected. I have tried more than 10 times to get this code right.
Here is my code which includes a form with two listview's.
Public Class Form1
Private Sub ListView_ItemDrag(ByVal sender As Object, ByVal e As _
System.Windows.Forms.ItemDragEventArgs) Handles ListView1.ItemDrag, _
ListView2.ItemDrag
[CODE]...
I have 3 forms, one frmMain - main form, second is frmUserType- childform, and the last frmCreateUserType. In the main form I have a menu item to open my frmUserType, In this form I have a button to open another form which is my frmCreateUserType, In this form I have a button to add records then update the listview in frmUserType. The problem is the listview will not access with my add button control in frmCreateUserType. I tried not to used mdiparent declaration for my frmMain and frmUserType as children and it works, so meaning that the problem is showing my frmUserType as childform?I am using vb.net 2008
Code to open my second form (frmUserType)
[CODE]...........
Code for my add button to update the listview in frmUserType
[CODE]...........
I'm using ListView control, with SmallIcons style in VB.NET. Icons are loaded fine, but when I start to scroll ListView down or up from scrollbar (clicking from arrows), rowheight drops to about half from normal in next 20-30 rows below/above upper/bottom row (depends from the scrolling position). After 1-2 seconds, ListView is "refreshed" and scrolling continues normally. When focus in on the ListView and I'm moving up/down with arrow keys or PageUp/PageDown, everything is normal. Any suggestions, what is happening? SmallIcons size is 16 * 16. Is it compulsory to set "Blank icon" with SmallIcon size to all rows, when adding them or what? Wasn't like that in VB6, how is it in VB.NET?
View 4 RepliesI have a vb-2008 program that contains a (listview) control.
View = details
AllowColumnReorder = true
Lets say the table has 3 columns (a,b,c) and 1 row of data.
a b c
1 2 3
I want the user to be able to re-arrange the columns (by dragging the column headers) before printing the contents of the table.
c a b
3 1 2
Statements like:
.. ListViewX.Columns(2).Text
.. ListViewX.Columns.Item(2).Text
.. ListViewX.Items(0).SubItems(2).ToString
Give the column-name (c) and cell-contents (3) of the origional table .. not the (3rd) column (b) of the re-arranged table.
How can i get the column-name and cell-contents of the (3rd) column of the re-arranged table?
I am working in VB.NET Win forms and what I would like to do is create an object to use its properties.
The trick is that I want to create a reference to an existing class using a string variable that gets passed in to my method.
The project is a web app in ASP/VB.net. The issue is that some pages are mind-boggingly slow. After trying to track down the bottleneck, it was discovered to be the load method when filling a datatable with query results.
We are using an Oracle database and queries are executed in stored procedures. As an example, we have a relatively simple select statement within a procedure which returns 2 columns with 6 rows which was determined to take about 0.015 seconds to execute. However it takes on average 7 seconds to load the OracleDataReader into a datatable - a ridiculous amount of time for such a small record set. After messing around with the query, I found that a simple decode statement appeared to be causing the issue. The decode statement is used similar to as follows[code]...
The iBln variable is simply a number being passed in to act as a boolean variable for determining which column should be between two dates. If I comment this decode statement out and make it simply "column1 BETWEEN iDate1 and iDate2" then the load method takes no time at all as it should, signifying that it is indeed the decode statement causing issues.
I have working code to read an RSS feed that uses:
Dim doc As New XmlDocument
doc.Load("http://...")
Dim channel As XmlElement = doc("rss")("channel")
Dim items As XmlNodeList = channel.GetElementsByTagName("item")
Unfortunately the doc.Load call causes the rest of the program to become unresponsive until it finishes.What's the best way to perform the load asynchronously and have a callback function to process the data?Edit: Here's the code I've tried using WebClient - the Load method is still lagging:
Private Sub checkResults()
'request rss feed
Dim w As New System.Net.WebClient
[code]....
The rssReadCallback method is executed fairly quickly after calling checkResults, but then the UI freezes during the Load method.
when I add a Control to the List(Of Control) what gets added to the List? Is it the Control or reference to the Control.I have a collection of controls (picture boxes representing notes,comments, icons, etc.), which can be drag and drop into other picture boxes holding read only images. Those controls are never permamently added to those images, they can be move or dispose as needed. I need to save those controls to a file and retrieve it later, however when retrieved, they must be place onto the same location in the image. Saving just the image is not the option, I also need to save all the control attributes.
View 2 RepliesI am stumped by being unable to cancel a list view insert operation following a method to validate a string. While the method validates the string and shows a modal popup when the string is not valid, then I want to stop the insert using e.cancel
Imports System.Data
'Imports System.Data.SqlClient
Public Class SecureOrderHCTPScan
[code].....
So in my window onLoad method I am pre-populating a grid with values retrieved from a database. Here is the method below for the window load:
Private Sub winMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
''#Load Grid
Dim dt As New DataTable
With dt
[code].....
What happens is, when I press F5 to debug, the program loads, and the grid is still empty, just as it is without a datasource. When I try to step through the code, it actually reaches down to the line that reads
Budgets = BudgetManager.Process.Budget.GetAllBudgets()
and then stepping over this line...the window loads and it doesn't go any further in the method. What the line of code above does is eventually make a execution call of some SQL to a SQLite database, and the code gets to the point at which it calls the execute method, but doesn't even make the query yet. All the objects up until that point in the code are set properly as well (found through debugging and checking locals.)Edit:Exception is this:
"Mixed mode assembly is built against version 'v2.0.50727' of the runtime and cannot be loaded in the 4.0 runtime without additional configuration information.
I'm trying to write a method that is called from a variety of forms at load. So with a Form1 load event I would call the following:
Dim testpoint As New Point(10, 20)
DrawVerticalStringFromBottomUp("Hello", testpoint, Me)
The DrawVerticalSTringFromBottomUp Method is as follows:
[Code]....
When I call the code at a form's load event, nothing happens. When I call it from a button click after the form has loaded it works! I know this should be called from the paint method, but that doesn't suit my purposes.
way to make this work from the form load event?
I am upgrading user control from vb6 to vb.net.In the vb6 application I am loading 3000 labels using a label control array.In vb.net I am doing same but it's taking too much time to load.In vb6 it's taking 1-2 seconds, but in vb.net it's taking 30-40 seconds for same work. Why does it take too much time in vb.net for same work?Code is given below, here Led is the label control array.
For l = 1 To 3000
Led.Load(ledCounter)
ColLed.Add(Led(ledCounter))
[code]....
I have a program that scrap websites and "puts" the information into a table.
My problem is that now and then i get values that i already have in the table. to avoid getting duplicates i search thru the table first to see if the value exist or if the record exist but might be in need of getting updated.
My table contains 60 000 records and is growing.
first i filtered a datagrid but it takes to long so i used the "select" method on the dataset table but it takes longer.
the program loops thru thousands of websites so it'll be doing a search for every website and the added time to collect the data just takes too long.
When I have many controls on a Form (i.e. Label, Button etc) that do almost the same thing, I often use one method to handle all the controls Click, MouseDown, MouseUp events.But to know which of the controls throwing the event and access the properties of that control I need to cast the "sender" object to the correct type.
The thing is that I always know which type it is, I don't really have to "TryCast", "DirectCast" and check if the operation returns true. I some times use CType as well.
[Code]...
epeat some instructions the fastest?i tried this:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
start()
[code]....
I save data from a ListView control to a xml file, and this works real great, but I can't figure out how to load the data again Private Sub ToolStripButton2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ToolStripButton2.Click
Dim x As New Xml.XmlTextWriter("C:Listviewout.xml", System.Text.Encoding.ASCII)
Dim i As Integer
x.WriteStartDocument()
x.WriteStartElement("ListViewItems")
i = lvFiles.Items.Count
[Code]...
rewriting the above so I can be able to load the same data again ?
I have a xml doc that i want to load into a listview with the code i included i also included the xml.But i cant get it working.i am new to xml and read and searched for days now in the web of vb.net xml pages.I am using vs2008.
Dim XMLReader As Xml.XmlReader
XMLReader = New Xml.XmlTextReader("c:ookmagxmldoc.xml")
'Dim sFile As String = String.Empty[code]......
I am trying to add a subitem to a listview in a threadsafe manner.In a single threaded application it works like so:
[Code]...
However if run in another thread it causes a cross threading error.I have looked at examples of delegate subs that use Invoke, but all examples i have seen involve updating the text property of an object, and i cant get my head round how to apply the concept to actually add a subitem to a listview.