Develop Reference

ASP.NET C# Adding LinkButtons to a List

I'm building an ASPX web page where some links will be visible or invisible depending on the user's access level. My thought was rather than create multiple functions and turn each link on or off, I could keep things neat and tidy by making List<LinkButton> members, like:
private List<LinkButton> adminButtons = new List<LinkButton>();
private List<LinkButton> guestButtons = new List<LinkButton>();
private List<LinkButton> userButtons = new List<LinkButton>();
Then I'd call one function to make them all visible or invisible.
private void DisplayButtons(List<LinkButton> linkButtons, bool displayButtons) {
for (int i = 0; i < linkButtons.Count; i++) {
linkButtons[i].Visible = displayButtons;
}
}
But I hit two snags. Firstly, I couldn't figure out how to initialize the lists with the links. For example, I've got asp:LinkButtons with IDs like ID='Link_UserManagement', ID='Link_InventoryManagement', et cetera. I can do this in the ASPX.CS file, and it works:
Link_UserManagement.Visible = false;
Link_InventoryManagement.Visble = true;
But this doesn't work:
private List<LinkButton> adminButtons = new List<LinkButton>() { Link_UserManagement }
And then if I try adding them this way, then the List count increases, but the values are null:
adminButtons.Add(Link_UserManagement);
So obviously I don't understand something about how these links work. My question is, why isn't this working the way I thought it would?
Secondly, if there's a better way to go about hiding and showing content based on a user's access level, I'm open to suggestions.

Organizing inventory by alphabetical order

So I created a method to populate the inventory system I have created in Unity, however I can't seem to figure out a way to order them in alphabetical order. Each button is created as a child of the button holder panel which is a game object variable. This method is called whenever the player picks something up.
private void Populate_Inventory ( )
{
Button btn_CurrentItem;
int int_Count;
for ( int_Count = int_PreviousCount; int_Count < strList_Inventory.Count; int_Count++ )
{
btn_CurrentItem = Instantiate ( btn_Item, pnl_ButtonHolder.transform );
btn_CurrentItem.name = strList_Inventory [ int_Count ];
btn_CurrentItem.GetComponentInChildren<Text> ( ).text = strList_Inventory [ int_Count ];
btn_CurrentItem.gameObject.AddComponent<Inventory_Item> ( );
btn_CurrentItem.GetComponent<Inventory_Item> ( ).str_Name = cls_Pickup.str_PickupName;
btn_CurrentItem.GetComponent<Inventory_Item> ( ).str_Information = cls_Pickup.str_PickupInformation;
int_PreviousCount = int_Count;
}
int_PreviousCount++;
}
If anyone can help it would be very appreciated.
Jonathan Palmer

The primary issue with this approach is that you're adding single buttons at a time whenever you pick up an item, and those buttons are created as children of the pnl_ButtonHolder object, but your method has no knowledge of previous buttons that have been created.
Option 1 (Bad)
You can use the GetComponentsInChildren<Button>() method on the pnl_ButtonHolder object to get all of the button components that have been previously created once you've added a new button, and then sort your buttons according to their name.
This isn't ideal as GetComponentsInChildren<>() is an expensive method, and doesn't make use of the idea of an Inventory very well.
Option 2 (Good)
Create an Inventory class that manages your actual inventory, including sorting items. It might look something like this:
public class Inventory_Button : MonoBehaviour
{
public Button button = default;
public void Initialize(Intenvory_Item item)
{
button.name = item.name;
// Other work here.
}
}
public class Inventory : MonoBehaviour
{
public GameObject inventoryItemPrefab = default;
public Transform inventoryParent = default;
private List<Inventory_Item> _inventory = new List<Inventory_Item>();
private List<Inventory_Button> _inventoryButtons = new List<Inventory_Button>();
public void AddItem(Intenvory_Item item)
{
_inventory.Add(item);
Inventory_Button button = GameObject.Instantiate(inventoryItemPrefab, inventoryParent).GetComponent<Inventory_Button>();
button.Initialize(item);
_inventoryButtons.Add(button);
_inventoryButtons.Sort((x, y) => x.name.CompareTo(y.name));
}
public void RemoveItem(Inventory_Item item)
{
// Do work to remove the item.
}
}
This kind of setup is useful for several reasons:
Your inventory management is now handled by a single class rather than a collection of objects. This makes it easy to interact with.
It will make removing items much easier in the future. With your current implementation, it looks like you'd have a difficult time removing an item from the player's inventory.
It separates responsibility between an Inventory class, an Inventory_Item class, and an Inventory_Button class, each of which stands on its own and works together.
A few final notes:
I've left out some details in the two classes above. You should fill them in to fit the needs of your game.
You can be more efficient with sorting by using something like Insertion Sort. This solution will get the job done.
Using prefixes for naming your variables can be quite confusing to people trying to read your code. I recommend you check out a style guide. There's a great one here.

Is there a simple method to get coordinates of a particular item in a checkedlistbox?

I am making a simple class extending CheckedListBox that just adds a small textbox to the right of an item when it is checked. My issue is finding a good way to place the box at the correct location.
I had initially though I could use the Controls.Find() along with the ItemCheckEventArgs index to get the coordinates of the checkbox in question, and move to the right edge of the column from there. However, that did not work, and a brief look through the CheckedListBox class seemed to show that it does not actually contain any CheckBox controls, but merely draws images of them.
I then came up with the following method:
void CreateAmountBox(int index)
{
int itemsPerCol = Height/ItemHeight;
int x = GetColumn(index, itemsPerCol)*ColumnWidth - boxWidth;
int y = (index % itemsPerCol)*ItemHeight - offset;
System.Windows.Forms.TextBox NewAmountTextBox = new System.Windows.Forms.TextBox();
NewAmountTextBox.Location = new System.Drawing.Point(x, y);
NewAmountTextBox.Name = Items[index] + "Amount";
NewAmountTextBox.Size = new System.Drawing.Size(20, boxWidth);
Controls.Add(NewAmountTextBox);
}
where GetColumn(...) returns the column of the given index (from the CheckEventArgs). This works, but it feels like a hack and is not very readable.
Two other ideas I thought of:
1) I could just create all the TextBoxes at the start, and simply hide them until they are needed. Controls like these are all created dynamically throughout the rest of the program however, and I don't want these ones to be the odd exception. It also means that some more functionality needs to be added for cases when an item is added or removed.
2) I could use mouse position, which of course won't work if the input is via keyboard. I don't anticipate it ever being so, but best not to leave that possibility.
With some googling, the only other way I found of possibly doing this was using the ListBoxItem and TranslatePoint method, but I haven't gotten that to work, and I'm unsure as to whether it even can with a CheckedListBox instead of a ListBox.
So, is there a simple way of finding the x and y of the checked item that I don't know of? Or am I limited to simply extracting the x and y declarations above into a method and leaving it there?

You can just use the GetItemRectangle function to accomplish that:
void checkedListBox1_ItemCheck(object sender, ItemCheckEventArgs e) {
Rectangle r = checkedListBox1.GetItemRectangle(e.Index);
TextBox newAmountTextBox = new TextBox();
newAmountTextBox.Location = new Point(r.Left, r.Top);
//...
}

c# store multiple splitter position in user.config

In my winform there are some Splitter to separate some datagridviews, is there a way to store (and recover) the splitter position into the user.config?
I wish avoid to add a setting with a different name for each splitter if it's possible.
thanks in advance

I came up with something you may be able to use. A few things about this example:
I used SplitContainer, but I'd imagine you could adapt this pretty easily.
I only scan the form's list of controls - this method won't pick up all SplitContainer (you'll probably need to do that recursively).
This assumes you have a user setting called SplitterPositions of type string.
This doesn't take into account future changes to the form (i.e. rearranging controls, adding new sections, removing existing sections, etc.), so it's a bit fragile in that regard.
I would personally recommend assigning names to your Splitters (or SplitContainers, depending on which type you're using) since that should shield you from the issues I mentioned.
In any event I hope this helps.
public Form1()
{
InitializeComponent();
Closing += Form1_Closing;
ApplySavedSplitterData();
}
void Form1_Closing(object sender, CancelEventArgs e)
{
SaveSplitterData();
}
private void SaveSplitterData()
{
Settings.Default.SplitterPositions = string.Join(";",
Controls.OfType<SplitContainer>()
.Select(s => s.SplitterDistance));
Settings.Default.Save();
}
private void ApplySavedSplitterData()
{
if (string.IsNullOrEmpty(Settings.Default.SplitterPositions))
{
return;
}
var positions = Settings.Default.SplitterPositions
.Split(';')
.Select(int.Parse).ToList();
var splitContainers = Controls.OfType<SplitContainer>().ToList();
for (var x = 0; x < positions.Count && x < splitContainers.Count; x++)
{
splitContainers[x].SplitterDistance = positions[x];
}
}

You can use the library from the article User Settings Applied to save the splitter position into the user settings.
Additionally you can persist the form size/location and any custom form setting.

Browsable(false) at run time?

I am using a datasource to populate my datagridview with the data. However, im trying to find a way for the user to be able to hide columns that he does not want to see.
I am able to hide and show columns before the program runs using:
[Browsable(false)]
public string URL
{
get
{
return this._URL;
}
set
{
this._URL = value;
this.RaisePropertyChnaged("URL");
}
}
I cannot seem to figure out how to change the [Browsable(false)] at run time.
Any ideas how I could accomplish this?
Basically, I want to bind an "on/off" to a menu.
Apologies if im not using the right terminology when explaining my problem, I am self taught and started a few weeks ago - so still very newbie :)
Edit:
Cant hide the column because when i run my update function all columns appear again. Here is my function for updating:
private void UpdateResults()
{
Invoke(new MethodInvoker(
delegate
{
this.dgvResults.SuspendLayout();
this.dgvResults.DataSource = null;
this.dgvResults.DataSource = this._mySource;
this.dgvResults.ResumeLayout();
this.dgvResults.Refresh();
}
));
}

At run time, you can just specify the column as being invisible:
dgv.Columns["ColumnName"].Visible = false;

The way to do this properly at runtime is to provide a custom ITypedList implementation on the collection, or provide a TypeDescriptionProvider for the type, or (for single-object bindings, not lists), to implement ICustomTypeDescriptor. Additionally, you would need to provide your own filtered PropertyDescriptor implementation. Is it really worth it? In most cases: no. It is much easier to configure the grid properly, showing (or not) the appropriate columns by simply choosing which to add.

Indeed, as others had mention the purpose of BrowsableAttribute is different, but I understand what you want to do:
Let's suppose that we want to create a UserControl than wraps a DataGridView and gives the user the ability to select which columns to display, allowing for complete runtime binding. A simple design would be like this (I'm using a ToolStrip, but you can always use a MenuStrip if that's what you want):
private void BindingSource_ListChanged(object sender, ListChangedEventArgs e) {
this.countLabel.Text = string.Format("Count={0}", this.bindingSource.Count);
this.columnsToolStripButton.DropDownItems.Clear();
this.columnsToolStripButton.DropDownItems.AddRange(
(from c in this.dataGrid.Columns.Cast<DataGridViewColumn>()
select new Func<ToolStripMenuItem, ToolStripMenuItem>(
i => {
i.CheckedChanged += (o1, e2) => this.dataGrid.Columns[i.Text].Visible = i.Checked;
return i;
})(
new ToolStripMenuItem {
Checked = true,
CheckOnClick = true,
Text = c.HeaderText
})).ToArray());
}
In this case, bindingSource is the intermediary DataSource of the dataGrid instance, and I'm responding to changes in bindingSource.ListChanged.