Forms :: Updating Large List Instantly - Datagridview Vs. Listview ?
Nov 1, 2011
What I am trying to do is to instantly apply a filter to a large list of data such that the list is updated almost immediately regardless of the number of items in the list. I have this working using a listview right now but it is far from instant, a list of 5000 items takes over a minute to get through. What I do currently is to maintain a cache of my data that my listview entries are based on. When the user selects a filter I parse this data one item at a time and determine if each item should still be displayed in the listview, if not I remove it. The complexity of determining whether or not a data entry meets the filter requirements is O(1), but just getting through each element in a loop takes significant time, and so does updating the list view graphically at the end of the process.
I have considered using a datagridview instead, using a database connection. I have never done this before and my main question here is whether this would allow me to do what I have described. With the database I could form an SQL query to return only the items that meet the new filter requirements... but would the data in the form update immediately, or would there still be significant delay?
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Dec 18, 2009
I need to constantly display large amounts of colored text in WPF or Silverlight, and I need the user to percieve it as showing up instantly.
Currently I'm doing this using a canvas and textblocks, one textblock per 80-character line, with multiple runs to a textblock to handle the different colors. There can often be 20+ runs to a line.
In a 45x80 grid of text, this gets a framerate of about 12 in Silverlight, which is sluggish. Oddly enough, it's even slower in WPF... I can only speculate that this has something to do with my dev machine's lousy video card. Maybe it's trying to hardware accelerate and actually slowing down because of it?
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May 25, 2011
i need to do quick selection and adding of large list in listview vb.net 2005, say 100,000. most people have suggested virtualmode, but i will be removing and adding items in these at different times. i thought of using api, as it is somtime faster,
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Jun 16, 2012
I have designed a form which contains a listview(to see the list records) and textboxes (used for adding or updating).an already save record into table using this
cmd.Connection = con
cmd.CommandText = "INSERT INTO student_info_tbl VALUES('" & txtUserId.Text & "','" & txtFirstName.Text & "','" & txtMiddleName.Text & "','" & txtLastName.Text _
[code].....
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Feb 6, 2009
I am relatively new to C# and winforms, although I have been using Java for years, so forgive me if im asking something relatively straightforward!I have a DataGridView, it needs to update regularly so I wish to provide a Collection of objects as its DataSource and NOT a database table.So far I have a List<MyObject> which will be constantly updated via a BackgroundWorker thread. I want my DataGridView to update when a change has been made to the List i.e. if the objects are resorted, added to or deleted from etc.Currently my DataGridView only displays the first object I add to the List, if I add more the DataGridView doesn't update to display the new objects added.This is a basic overview of how im coding it:
private List<MyObject> myList= new List<MyObject>();
myDataGridView.DataSource = myList;
Then my BackgroundWorker thread updates the list, e.g.
[code].....
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Nov 2, 2011
I am using a DataGridView bound to a BindingSource which is itself bound to a List of objects. This all works well until I remove objects from the list. If I am scrolled down to the bottom of the DataGridView and then remove a bunch of items from the list it is bound to it generates a DataError exception because the length changed and the rows I am looking at no longer exist... I changed my code to handle that error, but now instead of popping up a message it SLOWLY erases the data in each of the newly invalid rows at the end of the table (I think each time it does one it generates a new DataError, which is why it is so slow).
How do I prevent this? I want to be able to dynamically (and programmatically) add and remove items from the table without the possibility of this error... I assumed this would be handled automatically as part of the data binding process but I guess not.
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Nov 26, 2008
I use a List(Of T) (where each T is a custom type with a few members) to keep track of about 500 items that change all the time. The list can be changed from different locations within the program (uses background workers that monitor the list).
Question: Is there some built-in way to prevent the List from being updated from different locations or from different threads at the same time? For example, one thread may remove an item from the list while another location changes one of the members of an item, causing conflict, wrong data and errors. Perhaps there is a standard way in VB.Net (framework) to solve this type of problem?
I use VB2008 (VS2008 Pro) and WinXP SP2.
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Mar 2, 2010
I have a listview control in my form which contains 44 columns. When user clicks on particular node in the 'tree view' it loads corresponding records to the listview. If the number of records is less then it works fine, but if there is more number of records then it takes more time to load(very slow).
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Sep 21, 2010
I'm working on a website where we'll be getting a lot of videos to be uploaded. To keep things simple and secure, I'm just writing VB.net windows app to suck all the files in a directory in, allow you to set some options, and start the encode by spawning a new FFMpeg process.
[Code]...
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Dec 29, 2010
If I have a large number of classes, each similar to the other in certain aspects (they all share a common base class, but each does things differently), and I need to create Windows forms for each to allow easy changing of their values through a GUI? Create one matching form for each object in VS' forms designer, Or Use code to create the forms dynamically at runtime.
#2 makes the most sense to me, because a lot of these objects will share very common features of the form, notably "Ok" and "Cancel" buttons. But one object might need to draw a textbox on the form while another might need to draw a combobox. Not to mention, if I want to put icons on the "Ok" and "Cancel" buttons, I'd have to do this for each copy of the form in designer, and that sounds like it could get out of hand quickly.But is drawing forms through code sane? VS' forms designer is pretty sophisticated and designed to make life easier. Am I wise to consider ignoring its functionality and diving into the trench warfare of forms design through code? Or are there examples of automating form creation based on an existing object's properties?
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Aug 9, 2011
I have a large list of keyword and I want include this list in a listbox .How can I do it?
I tried by paste the list in the collection control but by this way the listbox allow only a small amount of keywords.
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Feb 12, 2010
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]...
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Aug 4, 2009
I'm trying to have it so theres a big list of items for example:
item1
item2
item3
[Code]....
I was thinking a list box? but I'm not all too sure on how to use one. I'd like the user to be able to scroll down through the list OR use a search. How could I search the list?(Id use a textbox as what to search for and a button to search the list.)
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Apr 12, 2011
I have a very simple class that crashes the VB.NET IDE when I added this list. Granted this is a list with 10,000 items but it crashes when I added it to the project. When I delete it with a text editor outside the project does not crash. I have not installed SP1 based on the comments not sure if this is a know problem or not. I can post the project its fairly small as its just text.
Private Shared ReadOnly _mdmCodes As List(Of [String]) = New List(Of String)() From { _
"AAAE-24422", _
"AAFP-02872", _
"AAGG-25572", _
"AAGN-16807", _..........
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Mar 17, 2009
I have a large financial application which I am migrating to VB.NETIt has two main components: charting and financial statements.I want to know if it is possible (and how) to create a main exe, and then two separate projects for the two components (as dll's?).
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Dec 27, 2009
I am currently helping to write a Visual Basics program that was originally writing with access.The Original Access program has been used and modified over the past 5 years, During that time the database has gotten pretty big.The problem I am having is If I add the entire database to my data sources it creates data tables for every Table and Stored procedure even when they are not currently used in the program resulting in a 20+ minute build time just to debug.I am currently only adding Tables and Stored Procedures as i need them, so its not that much of a problem now, but as I continue to work and add tables the build time is going to go back up, and Id hate to have to wait 20+ minutes to test a small tweak I made.
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Apr 12, 2010
I have the following code to generate combinations of string for a small list and would like to adapt this for a large list of over 300 string words.Can anyone suggest how to alter this code or to use a different method
[Code]...
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Feb 7, 2011
I am currently trying to create a program to list a large group of numbers for me. My final goal is to have every 2, 3, 4, ..., and 9 digit number containing only "1" "2" and "3". I thought I would go about this by using the following VB.NET program and then copying it into a text editor, and using find & replace to eliminate all other numbers.
Public Class Form1
Dim Start As Integer = 333333333
Dim Counter As Integer = 333333333
[Code].....
it fails due to the massive amount of processing that needs to take place. However, adding the intervals requires a great deal of time for each number to be displayed without any crashes.
Is there some way (in VB.NEt or another language) to get the number list I want in a short (an hour or less) amount of time?
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Aug 5, 2010
I am writing a basic application to provide remote support to multiple computers over a TCP Stream. For example, if my brother/dad has an issue with their computer, rather than going over to help them I can just use remote support (Yes, I know Windows has Remove Desktop, and their is TeamViewer, ect. But where is the fun in using those =P)Anyway, it basically works by taking a PrintScreen of their computer, sending it to mine and displaying it in a PictureBox, then when I click the image, it records the coordinates of my mouse, sends it to theirs (Little Maths for resolutions and positions ofc) and clicks, then sends a new image.
My problem is, I want a ListView displaying the PC Info, like:
PCName - RAM - Free HDD Space - 32/64Bit - Processor Speed
Now, my problem is, I have a Class which does the TCP Server, and in that class when it Receives a Message, it calls the Sub "RunCommand(ByVal Command As String)", which then splits the String and works with it.So, for example, their PC would send the String "Info|DadPC|2GB|235GB|32Bit|2.2GhZ|" And mine would split it, and add that data accordingly.However, what happens is, nothing. If I put in "MsgBox()" anywhere in the Code, it shows it is all Split, and received correctly and everything is fine, but no matter what happens, it wont add to the ListView (Or anywhere else on the form, for example "GUI.Text = Info(1)" Wont work either)?
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Oct 12, 2011
I'm working on a project that involves localizing a large number of Windows Forms. We're dealing with layout using the TableLayoutPanel control, which works nicely. One area we're striking problems with is when we set the Form.Localizable property to True, we then end up having to manage one .resx file per form per language.
That would be fine if the .resx files only contained the Localized text, but it also contains a vast amount of layout data for the form. Is there a way to separate the localizable text elements from the control layout information, that continues to work in the visual studio IDE? I've noticed that I can modify my the form's designer file to look at another resource file, but when I use the form designer, these changes are deleted:
'Label1
Me.Label1.AutoSize = True
Me.Label1.Dock = System.Windows.Forms.DockStyle.Top
Me.Label1.Location = New System.Drawing.Point(3, 0)
Me.Label1.Name = "Label1"
Me.Label1.Size = New System.Drawing.Size(61, 13)
Me.Label1.TabIndex = 1
Me.Label1.Text = My.Resources.ResourceManager.GetString("Form1_Label1_Text")
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Mar 11, 2012
I've got a collection of a type of form and multiple of these can be displayed on the screen independently at the same time and now I'm wanting to add the ability to cascade these forms, but these forms can all be re-sized so it'll be very rare when they are of the same or similar size. I would like to be able to cascade them based on their present size, so the largest for is in the back and the smallest is in front.
I also realize that a form could be wider than than another form but that other form is taller than the current one, in which case I would like the taller form to be considered the larger one (an arbitrary decision, I know). Here's the code I currently have that cascades them in the order they are in the collection, I just need to know how to re-order them based on their size.
[Code]...
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Nov 21, 2007
I just converted my project from VS 2005 to 2008 and started getting really bad lag only when intellisense iterates my dataset objects. The cpu maxes out one of my cores for about 2-3 seconds each time the intellisense list pops up. Is this a new feature of the 2008 ide?
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Sep 13, 2010
i want to display a large data in a cell of DataGridView as multiplelines to avoid the horizontalscroll.
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Apr 11, 2012
As quick solution to the user wanting to be able to open a particular form from any other form (in a large application with many forms, not an MDI app), I added KeyPreview to each form and corresponding KeyPress event so that said form will open (ShowDialog) upon pressing F12 from all these other forms.
Since this update has been in place, the user has been getting intermittent (maybe 2 or 3 within the course of a workday) but nasty errors such as "exception has been thrown by the target of an invocation" and the dreaded "out of memory". Is there reason to believe (off the top of your head) that the KeyPreview could be causing this?
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Oct 28, 2010
I need to load a large txt file that is in a fixed width format. There are over 45K lines, so speed is important.I need to load one of the fields into a dropdown box and have another field (label) display the text of another field in the related line.I could import the file to an access db if needed, but would rather not as i also want the txt file to update from a link on a regular bases. So having it in a DB would be more work to process that part.[code]
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Jan 21, 2012
The scenario is i get a string sent to me that i split by a space. Any thing under 60 count when the split occurs it's fine. After that i have a problem.Now there is a lot that needs to happen before we can add this newly split array to the listview.First we need to check what the name starts with. Then assign an icon to this nick.When my server class gets sent this string. Raw Numeric 353 channel names i then send it to my nicklist class.
vb
Private Sub InitiateThread(ByVal nicks As String) Handles _server.NameListEventArgs
Dim thread As New Thread(DirectCast(Sub() DoWorkChannelNicks(nicks), ThreadStart))
thread.Start()
End Sub
Then we split the string and loop each item
vb
Private Sub DoWorkChannelNicks(ByVal users As String)
Dim nicks() As String = users.Split(" "c)
[code]....
how to speed the process up?
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Sep 20, 2009
I'm using the following to check the state of checkboxes and then activate some public subs based on the checked state of the checkboxes:
vb.net
Public Sub TestSub() If Me.CheckBox1.InvokeRequired Then Me. CheckBox1.Invoke(New MethodInvoker(AddressOf TestSub)) Else Begin() End If End Sub
Within the Begin sub, I have code that performs specific actions and then updates a ListView with that information.As far as I can tell, the actions are being performed, but the ListView isn't being updated with the info.I'm calling the Test sub from a seperate form, within the BackGroundWorker's DoWork event.Would I have to check the InvokeRequired property of the ListView as well?I'm looking more into the documentation of the BackGroundWorker.
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Apr 21, 2009
I am having a problem regarding to pass all the data on the listview from one form to another and add another columns. The purpose of my columns is that I want to put text from there because I am sending a mail but I want to get the status of my message if it failed or send and write it at every end of the rows.
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Sep 7, 2011
I have a shopping cart ListView control backed by a custom object that has methods for selecting and deleting. In the ListView, one of the columns is an ImageButton that is essentially a delete icon, with the CommandName parameter set to CommandName="Delete".
My issue is related to updating the shopping cart ListView on delete; as the delete method is stored in the custom business entity object, I am having trouble in terms of updating the calculations made inside the cart (we have deleted an item, so I need to recalc shipping, taxes, etc).
[Code]...
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May 4, 2011
I've a datagridview with a multiline textboxcolum, if the cell content is small (one line) the scroll works fine and I can see the content of all rows. But, if a row cell content is very large (ten lines), only is visible the top of the cell and if I try scroll down, the scroll goes to the next row without can see the rest of the cell text, even using the arrows for move inside the cell, the bottom is not visible.I was searching in the web and the only solution is use panel and put inside the datagridview. It looks me a fix more than a solution.
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