Develop Reference

How to prevent user from dragging a control added to a user control container at design time

We want to create a usercontrol as container for maintain button status and arrange button location called ucSwitchButtonList.
This usercontrol added only one FlowLayoutControl.
After compiling, you can add ucSwitchButtonList on the form and successfully add buttons from CollectionEditor.
We can modify button objects added in ucSwitchButtonList and set properties at design time.
But, when we drag any button at design time, Visual Studio throws a NullReferenceException exception.
How to prevent user from dragging buttons in ucSwitchButtonList at design time? Or how to handle drag event at design time?
I want to achieve the effect of TabPage in TabControl, which can be selected but not dragged at design time.
ucSwitchButtonList.Designer.cs:
partial class ucSwitchButtonList
{
private System.ComponentModel.IContainer components = null;
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
private void InitializeComponent()
{
this.flpBtnContainer = new System.Windows.Forms.FlowLayoutPanel();
this.SuspendLayout();
//
// flpBtnContainer
//
this.flpBtnContainer.AutoScroll = true;
this.flpBtnContainer.AutoSizeMode = System.Windows.Forms.AutoSizeMode.GrowAndShrink;
this.flpBtnContainer.Location = new System.Drawing.Point(1, 1);
this.flpBtnContainer.Margin = new System.Windows.Forms.Padding(0);
this.flpBtnContainer.Name = "flpBtnContainer";
this.flpBtnContainer.Size = new System.Drawing.Size(116, 91);
this.flpBtnContainer.TabIndex = 0;
//
// ucSwitchButtonList
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.AutoSizeMode = System.Windows.Forms.AutoSizeMode.GrowAndShrink;
this.Controls.Add(this.flpBtnContainer);
this.DoubleBuffered = true;
this.Font = new System.Drawing.Font("新細明體", 9F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(136)));
this.Name = "ucSwitchButtonList";
this.Padding = new System.Windows.Forms.Padding(1);
this.Size = new System.Drawing.Size(209, 202);
this.Load += new System.EventHandler(this.ucSwitchButtonList_Load);
this.ResumeLayout(false);
}
private System.Windows.Forms.Panel flpBtnContainer;
}
ucSwitchButtonList.cs:
public partial class ucSwitchButtonList : UserControl
{
ObservableCollection<Button> _ButtonList = new System.Collections.ObjectModel.ObservableCollection<Button>();
[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
[Browsable(true), EditorBrowsable(EditorBrowsableState.Always),
Editor(typeof(CollectionEditor), typeof(UITypeEditor))
]
public ObservableCollection<Button> ButtonList
{
get => _ButtonList;
}
public ucSwitchButtonList()
{
InitializeComponent();
flpBtnContainer.Padding = new Padding(0);
flpBtnContainer.Size = this.Size;
flpBtnContainer.Dock = DockStyle.Fill;
_ButtonList.CollectionChanged += ButtonList_CollectionChanged;
Size = new Size(80, 160);
}
private void ucSwitchButtonList_Load(object sender, EventArgs e)
{
}
private void ButtonList_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
{
flpBtnContainer.SuspendLayout();
flpBtnContainer.Controls.Clear();
flpBtnContainer.Controls.AddRange(_ButtonList.ToArray());
flpBtnContainer.ResumeLayout();
foreach (Control ctl in flpBtnContainer.Controls)
{
if (ctl is Button btn)
{
btn.Click += Btn_Click;
if (e.NewItems.Contains(btn))
{
btn.BackColor = Color.White;
}
}
}
Invalidate(true);
}
private void Btn_Click(object sender, EventArgs e)
{
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
if (DesignMode && BorderStyle == BorderStyle.None)
{
var rect = Rectangle.Inflate(ClientRectangle, 0, 0);
rect.Width--;
rect.Height--;
Color lc = ControlPaint.Dark(Parent.BackColor);
if (lc == Parent.BackColor) lc = ControlPaint.LightLight(Parent.BackColor);
using (Pen lp = new Pen(lc))
{
lp.DashStyle = System.Drawing.Drawing2D.DashStyle.Dash;
lp.Alignment = System.Drawing.Drawing2D.PenAlignment.Center;
e.Graphics.DrawRectangle(lp, rect);
}
}
}
}

Adding a user control to a TabPage

I create a TabPage and add on the TabPage a user control.
private void AddScriptTab(TabControl tab_contr, string tab_name, int idx)
{
TabPage tab_page = new TabPage();
UserControlScript user_contr = new UserControlScript(serial_port, ref tabs);
tab_contr.TabPages.Insert(idx, tab_page);
tab_page.Text = tab_name;
tab_page.Tag = "script";
user_contr.Dock = DockStyle.Fill;
user_contr.Tag = idx.ToString();
tab_page.Controls.Add(user_contr);
}
Now in the created TabPage I click on the button in my user control and check the tag I assigned
user_contr.Tag = idx.ToString();
private void buttonParamsLoad_Click(object sender, EventArgs e)
{
foreach (TabParams tab in tablist)
{
if (tab.Tag.ToString() == Tag.ToString())
tab.File = file_path;
}
}
But I getting an exception Tag is null.
Why?

OMG! I found the problem. I should add components in the right order.
private void AddScriptTab(TabControl tab_contr, string tab_name, int idx)
{
TabPage tab_page = new TabPage();
UserControlScript user_contr = new UserControlScript(serial_port);
tab_page.Text = tab_name;
tab_page.Tag = "script";
user_contr.Dock = DockStyle.Fill;
user_contr.Tag = idx.ToString();
tab_page.Controls.Add(user_contr);
tab_contr.TabPages.Insert(idx, tab_page);
}

FlowLayoutPanel inside a tabControl

I have a tabControl and a flowLayoutPanel inside each tab.. When I drag and drop a file onto a tab it creates a button with the icon of the file dropped. But i have the option to create more tabs and I want to be able to drag files into the selected tab.. but the problem is the flowLayoutPanel when adding the button..
My code so far:
public Process myProcess = new Process();
FlowLayoutPanel fl_panel = new FlowLayoutPanel();
string path_app;
public Form1()
{
InitializeComponent();
//add the flowLayoutPanel on the first tab
fl_panel.Dock = DockStyle.Fill;
fl_panel.BringToFront();
tabPage1.Controls.Add(fl_panel);
this.DragEnter += new DragEventHandler(Form1_DragEnter);
this.DragDrop += new DragEventHandler(Form1_DragDrop);
}
void Form1_DragEnter(object sender, DragEventArgs e)
{
if (e.Data.GetDataPresent(DataFormats.FileDrop, false))
e.Effect = DragDropEffects.All;
}
void Form1_DragDrop(object sender, DragEventArgs e)
{
string[] fileList = e.Data.GetData(DataFormats.FileDrop) as string[];
foreach (string s in fileList)
{
Button button = new Button();
button.Click += new EventHandler(this.button_Click);
fl_panel.Controls.Add(button);
path_app = String.Format("{0}", s);
button.Tag = path_app;
string filename = path_app;
Icon icon = System.Drawing.Icon.ExtractAssociatedIcon(filename);
Bitmap bmp = icon.ToBitmap();
button.BackgroundImage = bmp;
button.Width = 60;
button.Height = 75;
button.FlatStyle = FlatStyle.Flat;
button.BackgroundImageLayout = ImageLayout.Stretch;
}
}
private void button_Click(object sender, System.EventArgs e)
{
String path_app = ((sender as Button).Tag as String);
myProcess.StartInfo.FileName = path_app;
myProcess.Start();
}
private void add_tab_btn_Click(object sender, EventArgs e)
{
//Create new tab with FLP inside
string title = Convert.ToString(textBox1.Text);
TabPage new_TabPage = new TabPage(title);
fl_panel.Dock = DockStyle.Fill;
fl_panel.BringToFront();
new_TabPage.Controls.Add(fl_panel);
tabControl1.TabPages.Add(new_TabPage);
}
}
If I use fl_panel.Controls.Add(button); it adds the buttons fine, on the first tab, but if I create a new tab I don't know how to use tabControl.SelectedTab with the fl_panel.Controls.Add(button) to add the buttons correctly on the selected tab.

You have to create a new FlowLayoutPanel for every tab:
FlowLayoutPanel fl_panel = new FlowLayoutPanel();
...
new_TabPage.Controls.Add(fl_panel);
And then you can cast the first element of the TabPage to the FlowLayoutPanel and access the Controls from there:
FlowLayoutPanel selectedFLP = (FlowLayoutPanel)tabControl.SelectedTab.Controls[0];
...

How to retrieve the name of a control created programmatically

in an app where it is possible to create a serie of buttons programmatically, how can I retrieve the name of one of these buttons once I click its context menu?
This is the piece of code:
private void addButton_Click(object sender, System.EventArgs e)
{
int y = (buttonIndex * 80) + 5;
btn.Name = "btn" + buttonIndex.ToString();
btn.Content = "button " + buttonIndex.ToString();
btn.Width = 440;
btn.Height = 100;
Thickness margin = new Thickness(0, y, 0, 0);
btn.Margin = margin;
// .. all other properties..
pivot1Grid.Children.Add(btn);
buttonIndex++;
AddContextMenuItems(btn);
}
private void AddContextMenuWithMenuItems(Button btn)
{
ContextMenu contextMenu = new ContextMenu();
MenuItem menuItem1 = new MenuItem() { Header = "Edit", Tag = "Edit" };
MenuItem menuItem2 = new MenuItem() { Header = "Remove", Tag = "Remove" };
menuItem1.Click += new RoutedEventHandler(menuItem1_Click);
menuItem2.Click += new RoutedEventHandler(menuItem2_Click);
contextMenu.Items.Add(menuItem1);
contextMenu.Items.Add(menuItem2);
ContextMenuService.SetContextMenu(btn, contextMenu);
}
Now in the click event I should be able to get the name of the button clicked (it works in case the context menu is created directly in XAML):
void menuItem1_Click(object sender, RoutedEventArgs e)
{
string btnName = ((sender as MenuItem).Parent as ContextMenu).Name;
..
}
but it gives always an empty string.
Could you please tell me where is the mistake?
Thanks

In your code, you're casting sender.Parent to ContextMenu. So you know you are manipulating the ContextMenu object. Then why are you expecting to magically get the name of the button by querying the name of the context menu?
The easiest way in your case is to store your information in the Tag property of the context menu:
private void AddContextMenuWithMenuItems(Button btn)
{
ContextMenu contextMenu = new ContextMenu();
MenuItem menuItem1 = new MenuItem() { Header = "Edit", Tag = "Edit" };
MenuItem menuItem2 = new MenuItem() { Header = "Remove", Tag = "Remove" };
menuItem1.Click += new RoutedEventHandler(menuItem1_Click);
menuItem2.Click += new RoutedEventHandler(menuItem2_Click);
contextMenu.Items.Add(menuItem1);
contextMenu.Items.Add(menuItem2);
// Store the name of the button in the Tag property of the context menu
contextMenu.Tag = btn.Name;
ContextMenuService.SetContextMenu(btn, contextMenu);
}
Then, in the event handler, you just have to retrieve the value you've set before:
void menuItem1_Click(object sender, RoutedEventArgs e)
{
var contextMenu = (ContextMenu)((MenuItem)sender).Parent;
string btnName = (string)contextMenu.Tag;
..
}

Combining several ContextMenu items into one

I am trying to combine several ContextMenu items into one. Currently, I am using separate MenuItem for it to work. Is there a way to combine all these MenuItems into one WHILE being able to control each of these event triggers when the users click on the different MenuItems?
NotifyIcon notifyIcon = new NotifyIcon();
System.Windows.Forms.ContextMenu contextMenu = new System.Windows.Forms.ContextMenu();
System.Windows.Forms.MenuItem ChangeDetailsMenu = new System.Windows.Forms.MenuItem();
ChangeDetailsMenu.Text = "Change Contact Details";
ChangeDetailsMenu.Click += ChangeContactDetails;
System.Windows.Forms.MenuItem ChangeKinectAngleMenu = new System.Windows.Forms.MenuItem();
ChangeKinectAngleMenu.Text = "Change Kinect Angle";
ChangeKinectAngleMenu.Click += ChangeKinectAngle;
System.Windows.Forms.MenuItem exitMenu = new System.Windows.Forms.MenuItem();
exitMenu.Text = "Exit";
exitMenu.Click += ExitHandler;
contextMenu.MenuItems.Add(exitMenu);
contextMenu.MenuItems.Add(ChangeDetailsMenu);
contextMenu.MenuItems.Add(ChangeKinectAngleMenu);
Icon icon = new Icon("kse.ico");
notifyIcon.ContextMenu = contextMenu;
notifyIcon.Icon = icon;
notifyIcon.Visible = true;
private void ExitHandler(object sender, EventArgs e)
{
notifyIcon.Visible = false;
System.Windows.Application.Current.Shutdown();
}
private void ChangeContactDetails(object sender, EventArgs e)
{
}
private void ChangeKinectAngle(object sender, EventArgs e)
{
}