Not sure if my title makes much sense, so I will try to explain my question here. So basically I am expanding my program by allowing things to be customized within it.
Say for example I do this: I click on File -> Options, and a new form is opened with tabs. I have different settings that you can toggle via dropdown box and checkboxes. Now once a user sets the settings they want, or don't want, they click on a button that says either "OK" or "Cancel".
What is the method to saving these settings, or reverting back to the original settings? Do you save via txt file, or is this a default function within a certain line of code?
UPDATE:
So I fixed my previous issue. Now I am having another with the saves. The saves are working good, but I want to use them in selecting my CheckListBox Collection range and also have that range load on start as well. so these are the 2 things that I have been using to do so, that results in adding to the previous, set, collection.
Working for RNG:
Dim rand As New Random()
Dim winners = Enumerable.Range(1, My.Settings.numberSetting).OrderBy(Function(r) rand.Next()).Take(5).ToArray()
Not working for Onload CheckListBox:
Me.LotteryNumbers.Items.Add(1, My.Settings.numberSetting)
If I remove the 1 from Me.LotteryNumbers.Items.Add, the result is this:
This ought not compile:
LotteryNumbers.Items.Add(1, My.Settings.numberSetting)
The overload which takes a second argument expect a Boolean to set the item added to Checked or not. One way is to add items in a loop:
Dim maxNums = My.Settings.numberSetting
' make sure it is empty
clb.Items.Clear()
For n As Int32 = 1 To maxNums
clb.Items.Add(n.ToString)
Next
I don't like using items in Settings as variables, so it grabs the current value to use. Another way uses AddRange:
clb.Items.AddRange(Enumerable.Range(1, maxNums).Select(Function(s) s.ToString()).ToArray())
Items is an collection of Object, so the Select converts to string to add them.
NEVER ORDER BY RANDOM.NEXT()
Mostly you get lucky, but it's not guaranteed. It's only a matter of time before that code blows up on you at run time. The longer the sequence to be sorted, the more likely you are to get an exception.
What you should do instead is implement a Fisher-Yates sort method:
Private rand As New Random()
Public Function Shuffle(Of T)(ByVal items As IList(Of T)) As IList(Of T)
For i As Integer = items.Count - 1 To 1 Step -1
Dim j As Integer = rand.Next(i + 1)
Dim temp As T= items(i)
items(i) = items(j)
items(j) = temp
Next
Return items
End Function
Solution for the working code to update and save checklistbox box count.
Private Sub OptionOkButton_Click(sender As Object, e As EventArgs) Handles OptionOkButton.Click
Main.LotteryNumbers.Items.Clear()
My.Settings.numberSetting = CInt(NumberCombo.Text)
Dim maxNum = My.Settings.numberSetting
Main.LotteryNumbers.Items.AddRange(Enumerable.Range(1, maxNum).Select(Function(s) s.ToString()).ToArray())
My.Settings.Save()
Me.Close()
End Sub
Related
This is a school project for Programming (not an assessment or assignment, so I'm not cheating) where I have to make a 7-segment displaySource 1. I decided instead of going the traditional way and manually setting each RectangeShape to visible on each button pressed to display a number; store the corresponding number and which RectangleShape(s) to turn on as a key-value pair in a dictionary. I have some knowledge of Python, so this is where I got the idea from. My formSource 2 has 7 RectangleShape(s) and 10 Button(s). Just as an experiment since it's my first time working with Dictionaries and Lists in VB.net, I decided to only try it out for the number 1 for now (shp4 and shp5 should be visible). Here is the dictionary I made:
Dim Numbers As New Dictionary(Of Integer, List(Of PowerPacks.Shape)) From {{1, New List(Of PowerPacks.Shape) From {shp4, shp5}}, {2, New List(Of PowerPacks.Shape) From {shp2, shp3}}}
Here is the code for the button (btn1):
Private Sub btn1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn1.Click
Dim Thing As PowerPacks.Shape = Numbers(1)(0)
Thing.Visible = True
End Sub
When the program gets to the line that says Thing.Visible = True, it throws an error. It's a NullReferenceException that states Object reference not set to an instance of an object. Any ideas on how to fix this?
Sources
Source 1:
Source 2:
Programming is not magic. It works pretty much as you'd expect. If you are getting Nothing out of your List within a Dictionary then you must be putting Nothing in. Did you use the debugger before posting? Did you actually look at the value of shp2, etc, when this line is executed:
Dim Numbers As New Dictionary(Of Integer, List(Of PowerPacks.Shape)) From {{1, New List(Of PowerPacks.Shape) From {shp4, shp5}}, {2, New List(Of PowerPacks.Shape) From {shp2, shp3}}}
Based on your use of that Numbers variable in the second code snippet, it must be a member variable, which means that that first code snippet is outside any method, which means that it is executed before the class constructor, which means that no controls have been created at that time, which means that any fields that refer to controls can't be anything but Nothing. If you had put a breakpoint on that line and used the debugger, as you should have, then you'd have seen that.
The solution is not actually add the Shapes to the collection until they are created. That means after the call to InitializeComponent. That means that you can create your own constructor and do it there if you want, but that you should probably just do it in the Load event handler. Just declare the Dictionary variable without creating an object:
Private numbers As Dictionary(Of Integer, PowerPacks.Shape())
Note that I have provide an explicit access modifier, which you should ALWAYS do for all members, and also started the name with a lower-case letter, which you probably ought to do for all private fields. You then create the object in the load event handler:
numbers As New Dictionary(Of Integer, PowerPacks.Shape()) From {{1, {shp4, shp5}},
{2, {shp2, shp3}}}
I've taken the liberty of simplifying that by using arrays rather than Lists that add no value.
On your 7-Segment Display Form, I would use a List (of String) containing which rectangles are turned on for each dictionary key (number). This would require first programatically adding the 7 shapes onto the form (looks like you already coded that), and then in each button (for numbers) just pick off which rectangles are turned on and change their background color. "Front loading" all the Shapes (rectangles) into the Dictionary is probably unnecessary, since they are already manually fixed on the Form. If they are not, then pull out the code that places them on the form and run that first, one time, when the form loads. Using this approach, you don't have to worry about Shapes any more.
In Form 1, add:
Dim dicRSBackColor As New Dictionary(Of Integer, List(Of String))
Dim SC As New ShapeContainer
In Form1_Load, add the following:
'define each of the 7 rectangles using, e.g.:
Dim myrec4 As New RectangleShape
myrec4.Name = "shp4"
myrec4.Visible = True
myrec4.BringToFront()
'add locations and size to myrec4
myrec4.Top=100
myrec4.Left=100
myrec4.Width=10
myrec4.Height=100
'then add myrec4 to Shape container
SC.Shapes.Add(myrec4)
'add myrec4 to Form1
Me.Controls.Add(myrec4)
'do the above for all 7 rectangleshapes
'For the dictionary, add number 1's rectangleshape (turned on)
Dim mylist As List(Of String)
mylist.Add("shp4")
mylist.Add("shp5")
dicRSBackColor.Add(1, mylist)
'add number 2 rectangles (turned on)
mylist.Clear()
mylist.Add("shp1")
mylist.Add("shp3")
mylist.Add("shp4")
mylist.Add("shp6")
mylist.Add("shp7")
dicRSBackColor.Add(2, mylist)
'continue until all 7 rec's added
Last, in the button _Click for number 1, use the following:
'First change background color of all rectangleshapes to Form1's back color
For Each rs As RectangleShape In Me.SC.Shapes
rs.BackColor = Me.BackColor
Next
'Now pull the list of shapes that are turned on for number 1 using the dictionary
Dim mylist1 As List(Of String)
mylist1 = dicRSBackColor(1) 'you're pulling the value for key=1, which is a list of strings
'use a double loop and find out when the list value is the same as the name of the rectangleshape, and then set the back color to orange
For Each item In mylist1
For Each rs As RectangleShape In Me.SC.Shapes
If item = rs.Name Then rs.BackColor = Color.Orange
Next
Next
I'm running the following loop successfully when the number of items is low. However, when run against a larger list on the ListView, it seems to be taking way too long. I tested it with a list of 8,700 files and it took about two hours to complete. Is there something I can do to speed this up? I guess that removing the check for the Cancel button would help but I would like to keep that there for usability. As I've mentioned in earlier posts, I'm pretty new to Visual Basic so please provide lots of explanation with your suggestions. Thanks. Here's the code:
For i As Integer = 0 To m_CountTo
' Has the background worker be told to stop?
If BackgroundWorker1.CancellationPending Then
' Set Cancel to True
e.Cancel = True
Exit For
End If
'Select the row from the LVFiles ListView, then move the first column (0) into strSourceFilePath and the last
' column (3) into strDestFilePath. Execute the CopyFile method to copy the file.
LVFiles.Items(i).Selected = True
strSourceFilePath = LVFiles.SelectedItems(i).SubItems(0).Text
strDestFilePath = LVFiles.SelectedItems(i).SubItems(3).Text
My.Computer.FileSystem.CopyFile(strSourceFilePath, strDestFilePath, overwrite:=False)
' Report The progress of the Background Worker.
BackgroundWorker1.ReportProgress(CInt((i / m_CountTo) * 100))
' Me.LabelStatus.Text = FormatPercent((i + 1) / (intLVIndex + 1), 2) ' Show Percentage in Label
SetLabelText_ThreadSafe(Me.LabelStatus, FormatPercent(i / m_CountTo, 2))
Next
The Backgroundworker encapsulates a new thread. You cannot directly access controls that are created in another thread. If you do you will get an InvalidOperationException because of a cross-thread operation. The Backgroundworker however offers some functionality to share data (or access to controls) between threads. You should use them.
Private Sub StartBGW_Click(sender As Object, e As EventArgs) Handles StartBGW.Click
Dim dict As New Dictionary(Of String, String)
For i As Integer = 0 To m_CountTo
dict.Add(Me.LVFiles.Items(i).SubItems(0).Text,
Me.LVFiles.Items(i).SubItems(3).Text)
Next
Me.BackgroundWorker1.RunWorkerAsync(dict)
End Sub
First we prepare a dictionary that contains the source as Key and the target as Value. This object is given to the BackgroundWorker as a parameter.
Now comes the essential part:
Private Sub BackgroundWorker1_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
Dim counter As Integer = -1
Dim dict = DirectCast(e.Argument, Dictionary(Of String, String))
For Each kvp In dict
counter += 1
' Has the background worker be told to stop?
If Me.BackgroundWorker1.CancellationPending Then
' Set Cancel to True
e.Cancel = True
Exit For
End If
'Select the row from the LVFiles ListView, then move the first column (0) into strSourceFilePath and the last
' column (3) into strDestFilePath. Execute the CopyFile method to copy the file.
My.Computer.FileSystem.CopyFile(kvp.Key, kvp.Value, overwrite:=False)
' Report The progress of the Background Worker.
Me.BackgroundWorker1.ReportProgress(CInt((counter / m_CountTo) * 100), counter)
Next
End Sub
We don't access the ListView anymore. Instead we use the dictionary that is given to us as a parameter through e.Argument. Theres also a slight difference in the BackgroundWorker1.ReportsProgress line. There's a second parameter I have used to pass the current index to the ProgressChanged event which can be obtained via e.UserState.
Private Sub BackgroundWorker1_ProgressChanged(sender As Object, e As System.ComponentModel.ProgressChangedEventArgs) Handles BackgroundWorker1.ProgressChanged
Me.LVFiles.Items(Convert.ToInt32(e.UserState)).Selected = True
Me.LabelStatus.Text = e.ProgressPercentage.ToString
End Sub
This event is designed to be raised with a SynchronizationContext of the calling thread, in this case the UI thread. Here we can safely access any control and update them. The index is passed as e.UserState, so we can access the relevant item and set their Selected property to true.
The biggest improvement comes from the change of Me.LVFiles.SelectedItems(i).SubItems(0).Text to Me.LVFiles.Items(i).SubItems(0).Text. I'm not a professional, but it seems that SelectedItems isn't a real list. Instead it iterates through every item using the SendMessage API until the desired index is reached. This is why it takes longer the higher your index is. Everytime it starts with the first item and iterates through them. Lot of operations.
The second improvement is the separation of code that access UI controls. It's all done in one method now. More clear and readable.
Update: #Enigmativity mentioned that SelectedListViewItemCollection implements IList and therefore is a real list. Even though it has no underlying list containing all selected items like you have in ListViewItemCollection. My point was to say, that accessing a single element is more complicated.
I'm working on a project that requires I iterate through a list of controls on a tabpage to find all of the checkboxes. Then depending on the state of the box (checked or unchecked) select individual variables (filenames) to then perform either a batch rename or delete of files on the filesystem (cb.checked = perform action).
I have managed to create the "for each" for the iteration of the controls (thanks google) but I'm struggling to figure out how to pick the variables. They are all named differently, obviously, as are the checkboxes. Also the checkboxes are statically assigned to the form/tabpage. Here's what I have at the moment.
Public Sub delBut_code(ByRef fname As String)
If (Sanity = 1) Then
For Each cb As Control In Form1.Controls
If TypeOf cb Is CheckBox AndAlso DirectCast(cb,
CheckBox).Checked Then
If My.Computer.FileSystem.FileExists(fname) Then
My.Computer.FileSystem.DeleteFile(fname)
End If
End If
Next
MessageBox.Show("All Actions Completed Successfully")
Else
MessageBox.Show("Please select a File To Delete")
End If
End Sub
and here is an example of some of the variables:
Dim castle As String = selPath & "\zm_castle_loadingmovie.txt"
Dim factory As String = selPath &
"\zm_factory_load_factoryloadingmovie.txt"
Dim island As String = selPath & "\zm_island_loadingmovie.txt"
N.B selpath collects a user entered folder path and can be ignored here
I would really appreciate any pointers.
First, you can do much better with the loop:
Public Sub delBut_code(ByRef fname As String)
If Sanity <> 1 Then
MessageBox.Show("Please select a File To Delete")
Exit Sub
End If
Dim checked = Form1.Controls.OfType(Of CheckBox)().Where(Function(c) c.Checked)
For Each box As CheckBox in checked
Try
'A file not existing is only one reason among many this could fail,
' so it needs to be in a Try/Catch block.
' And once you're using a Try/Catch block anyway,
' the FileExists() check becomes a slow and unnecessary extra trip to the disk.
My.Computer.FileSystem.DeleteFile(fname)
Catch
'Do something here to let the user know it failed for this file
End Try
Next
MessageBox.Show("All Actions Completed")
End Sub
But now you need to know how have the right value in that fname variable. There's not enough information in the question for us to fully answer this, but we can give some suggestions. There a number of ways you could do this:
Set the Tag property in the Checkboxes when you build the string variables. Then fname becomes DirectCast(box.Tag, String).
Inherit a custom control from CheckBox to use instead of a normal Checkbox that has an additional String property for the file name. Set this property when you build the string variables.
Name your string variables in a way that you can derive the string variable name from the CheckBox variable name, and then use a Switch to pick the right string variable from each box.Name.
Keep a Dictionary(Of CheckBox, String) that maps the Checkboxes to the right string values.
But without knowing more context of the application, I hesitate to recommend any of these over the others as best for your situation.
Although I'm reasonable experienced VBA developer, I have not had the need to use class modules or collections but thought this may be my opportunity to extend my knowledge.
In an application I have a number of forms which all have the same functionality and I now need to increase that functionality. Towards that, I am trying to reorder a collection in a class module, but get an error 91 - object variable or with block not set. The collection is created when I assign events to controls. The original code I obtained from here (Many thanks mwolfe) VBA - getting name of the label in mousemove event
and has been adapted to Access. The assignments of events works well and all the events work providing I am only doing something with that control such as change a background color, change size or location on the form.
The problem comes when I want to reorder it in the collection - with a view to having an impact on location in the form. However I am unable to access the collection itself in the first place.
The below is my latest attempt and the error occurs in the collcount Get indicated by asterisks (right at the bottom of the code block). I am using Count as a test. Once I understand what I am doing wrong I should be able to manipulate it as required.
mLabelColl returns a correct count before leaving the LabelsToTrack function, but is then not found in any other function.
As you will see from the commented out debug statements, I have tried making mLabelColl Private and Dim in the top declaration, using 'Debug.Print mLabelColl.Count' in the mousedown event and trying to create a different class to store the list of labels.
I feel I am missing something pretty simple but I'm at a loss as to what - can someone please put me out of my misery
Option Compare Database
Option Explicit
'weMouseMove class module:
Private WithEvents mLbl As Access.Label
Public mLabelColl As Collection
'Dim LblList as clLabels
Function LabelsToTrack(ParamArray labels() As Variant)
Set mLabelColl = New Collection 'assign a pointer
Dim i As Integer
For i = LBound(labels) To UBound(labels)
'Set mLabelColl = New Collection events not assigned if set here
Dim LblToTrack As weMouseMove 'needs to be declared here - why?
Set LblToTrack = New weMouseMove 'assign a pointer
Dim lbl As Access.Label
Set lbl = labels(i)
LblToTrack.TrackLabel lbl
mLabelColl.Add LblToTrack 'add to mlabelcoll collection
'Set LblList as New clLabels
'LblList.addLabel lbl
Next i
Debug.Print mLabelColl.Count 'returns correct number
Debug.Print dsform.countcoll '1 - incorrect
End Function
Sub TrackLabel(lbl As Access.Label)
Set mLbl = lbl
End Sub
Private Sub mLbl_MouseDown(Button As Integer, Shift As Integer, x As Single, Y As Single)
Dim tLbl As Access.Label
'Debug.Print LblList.Count 'Compile error - Expected function or variable (Despite Count being an option
'Debug.Print mLabelColl.Count 'error 91
'Debug.Print LblList.CountLbls 'error 91
Debug.Print collCount
End Sub
Property Get collCount() As Integer
*collCount = mLabelColl.Count* 'error 91
End Property
In order to have all the weMouseMove objects reference the same collection in their mLabelColl pointer, a single line can achieve it:
LblToTrack.TrackLabel lbl
mLabelColl.Add LblToTrack
Set LblToTrack.mLabelColl = mLabelColl ' <-- Add this line.
But please be aware that this leads to a circular reference between the collection and its contained objects, a problem that is known to be a source of memory leaks, but this should not be an important issue in this case.
Typically, when designing a DataGridView, I try to size the columns so that nothing will need to be resized by the user. This practice works most of the time, but I recently had a user change her Windows settings so that text would display larger than usual.
That single act broke all of the tedious sizing that I worked so hard on. I have looked into saving column width per user and allowing them to be saved to the registry. The issue I run into is having to create a field in the application settings for each and every value that I want to save to the registry.
When saving settings for a single form, that is not a problem, and I do use the application settings for this purpose to save the main window size/location so that users can determine the optimal view of the application.
My question is:
Is there a way to save an array to the registry, or perhaps otherwise save dynamic values into the registry, without adding these values to the application settings in advance? Ideally, I will just have a "ColumnWidths" application setting or something along those lines, and dynamically add column name/width for any column that is resized by the user.
I have the following code, which is fine if I add a new setting for each individual form that I want to save sizing for, but I'm hoping to achieve this with a single setting, that will save column sizing for multiple DataGridView/Forms.
Private Sub SaveColumnSettings()
If My.Settings.CustomColumnWidths Is Nothing Then
My.Settings.CustomColumnWidths = New StringCollection
End If
For Each dc As DataGridViewColumn In grdBackOrderedItems.Columns
My.Settings.CustomColumnWidths.Add(dc.Width.ToString())
Next
End Sub
Private Sub LoadColumnSettings()
For i As Integer = 0 To My.Settings.CustomColumnWidths.Count - 1
grdBackOrderedItems.Columns(i).Width = CInt(My.Settings.CustomColumnWidths(i))
Next
End Sub
Settings allows for a Collection type, however it is a string collection (initial post seemed not to know this).
The current edit is dicey since it assumes one collection will fit all DGVs on all forms (that is, the same number of columns for all of them) and you are only adding to the Collection every time you save - making it larger. Since you want to save the users optimal view you should have one collection per DGV since they might well make col4 on DGVFoo wider than elsewhere.
Rather than adding a collection Setting for each DGV (ie "DGVFooColumns", "DGVBarColumns" etc), which requires each one be hard coded to map to the correct entry, I would use a custom class and serialize it.
Most everything regarding them can be internalized to the class. This is not a finished class, but a rough out of making one class service any and all DGVs (it should be very close):
' for the collection
Imports System.Collections.ObjectModel
Imports System.Runtime.Serialization.Formatters.Binary
<Serializable>
Public Class GridLayouts
<Serializable>
Friend Class GridLayout
Public Property GridName As String
Public Widths As New List(Of Integer)
' Some Serializers will require a simple ctor
Public Sub New()
Widths = New List(Of Integer)
End Sub
Public Sub SaveLayout(name As String, dgv As DataGridView)
' something the code uses to map them
' other than "DataGridView1" of which there may be several
GridName = name
' ToDo: loop thru DGV save widths to Widths
End Sub
End Class
Private mCol As Collection(Of GridLayout)
Private myFile As String
Public Sub New(filename As String)
myFile = filename
mCol = New Collection(Of GridLayout)
End Sub
Private Function IndexOf(grdName As String) As Integer
For n As Integer = 0 To mCol.Count - 1
If grdName = mCol(n).GridName Then
Return n
End If
Next
Return -1 ' not found
' alternatively find by name:
'Dim item = mCol.FirstOrDefault(Function(i) i.GridName = grdName)
'Return item
End Function
Public Sub StoreLayout(name As String, dgv As DataGridView)
Dim ndx As Integer = IndexOf(name)
If ndx <> -1 Then
mCol.RemoveAt(ndx) ' throw away old one
End If
Dim grd As New GridLayout
grd.SaveLayout(name, dgv)
mCol.Add(grd)
End Sub
Public Sub RestoreLayout(name As String, dgv As DataGridView)
Dim ndx As Integer = IndexOf(name)
If ndx = -1 Then
Exit Sub
End If
For n As Integer = 0 To mCol(ndx).Widths.Count - 1
' loop thru grid and set the columns
' maybe check that the col sizes are equal
dgv.Columns(n).Width = mCol(n).Widths(n)
Next n
End Sub
Public Sub Save()
' ToDo: Make a backup (?)
' Add a Try/Catch and convert to function
Dim bf As New BinaryFormatter
Using fs As New FileStream(myFile, FileMode.OpenOrCreate)
bf.Serialize(fs, mCol)
End Using
End Sub
Public Sub Load()
Dim bf As New BinaryFormatter
Using fs As New FileStream(myFile, FileMode.Open)
mCol = CType(bf.Deserialize(fs), Collection(Of GridLayout))
End Using
End Sub
End Class
Notes:
1) The Example has SaveLayout at the Class-Item level and RestoreLayout at the Collection Level. I would pick one way or the other not split it. This is was for illustrative purposes. I would generally favor the ClassItem Level for both.
2) Rather than the BinaryFormatter, you can use the XML Serializer. I personally loathe it.
3) Note that the collection class saves/loads its own data.
4) System.Collections.ObjectModel is required for Collection(of T) and prevent VB from wanting the use the vile VisualBasic Collection (which stores only Object).
5) Code elsewhere could be optimized so that you only store a layout if they actually change the widths and click something (or have an AutoSaveChanges option).
6) A fair amount is riding on the names being unique so that the layouts can be found.
Usage
Dim SaveFile As String = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
CompName,
ProgramName,
filename)
' e.g C:\Users\Ziggy\MyCompany\ThisProd\GridSettngs.bin
' application-wide collection of grid layouts for this user
Private myGrids As New GridLayouts(SaveFile)
...
myGrids.StoreLayout("Customers", datagridView12)
myGrids.RestoreLayout("Orders", datagridView34)