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C# WinForms - Cannot access a control in a handler method

I have a form containing two flow layout panels (FLP), which dynamically have buttons added to them. These buttons are actually a class called tagButton which inherits from Button and I have added a handler in the constructor for the click() method. On click, I want to remove the button from the FLP it is currently in then add it to the other FLP.
Below is a trimmed down version of my code for the tagButton class. Note that the tagButton class is defined inside the of the form class both FLPs are in:
class tagButton : Button
{
public string tag = "";
public bool useTag = false; //tells you which FLP the button is in
public tagButton(String tag, Boolean useTag)
{
this.tag = tag;
this.Text = tag;
this.useTag = useTag;
this.Click += TagButton_Click;
}
private void TagButton_Click(object sender, EventArgs e)
{
tagButton tagButton = (tagButton)sender;
tagButton.useTag = !tagButton.useTag;
if (tagButton.useTag)
{
flowLayoutPanel.Controls.Remove(tagButton);
}
}
}
I'm having problems with the last line:
flowLayoutPanel.Controls.Remove(tagButton);
I can switch it to the following and it works, however there is no way for me to add it to the other FLP. Or at least, not without doing Parent.Parent.Parent.Controls[1]... etc which is clearly a bad idea.
tagButton.Parent.Controls.Remove(tagButton);
I've tried switching different classes and methods to static but nothing I tried worked, the this keyword doesn't seem to work either.

I would recommend having a separate class overriding a parent control that's aware of both FlowLayoutPanels. Then, when your button wants to switch, it can find that custom control in its parents and invoke a custom "switch" function that would move the invoking button from the list it's in to the list it wasn't in.

One of many ways to achieve this outcome is to have MainForm expose a static array of the FlowLayoutPanel candidates as Panels property:
public partial class MainForm : Form
{
public static Control[] Panels { get; private set; }
char _id = (char)64;
public MainForm()
{
InitializeComponent();
Panels = new Control[]{ flowLayoutPanelLeft, flowLayoutPanelRight, };
buttonAddLeft.Click += (sender, e) =>
{
flowLayoutPanelLeft.Controls.Add(new tagButton
{
Height= 50, Width=150,
Name = $"tagButton{++_id}",
Text = $"Button {_id}",
});
};
buttonAddRight.Click += (sender, e) =>
{
flowLayoutPanelRight.Controls.Add(new tagButton
{
Height= 50, Width=150,
Name = $"tagButton{++_id}",
Text = $"Button {_id}",
});
};
}
}
Then, suppose you want to swap between panels when a tagButton gets a right-click (for example).
class tagButton : Button
{
protected override void OnMouseDown(MouseEventArgs e)
{
base.OnMouseDown(e);
if (MouseButtons.Equals(MouseButtons.Right))
{
Control dest;
if(Parent.Name.Contains("Left"))
{
dest = MainForm.Panels.First(_=>_.Name.Contains("Right"));
}
else
{
dest = MainForm.Panels.First(_ => _.Name.Contains("Left"));
}
Parent.Controls.Remove(this);
dest.Controls.Add(this);
}
}
}

How to add functions and properties to multiple controls in C #

I have classes called ButtonDesign, TextBoxDesign, and a few more. Everyone’s realization is exactly the same. I add a number of properties and functions to each control, the question is how can this be achieved without duplicate code, i.e .: is there a way to create only one class with the same attributes - and these attributes will be added to all the controls I want? .
If I create a primary class that inherits from the Control class - then these attributes will only be in the Control class and not in all the controls I want.
This is the code I'm trying to:
class ButtonDesign : Button
{
private Control save_properties = new Control();
public Color OnMouseHoverColor { get; set; }
public ButtonDesign()
{
this.MouseEnter += ButtonDesign_MouseEnter;
this.MouseLeave += ButtonDesign_MouseLeave;
}
private void ButtonDesign_MouseEnter(object sender, EventArgs e)
{
save_properties.BackColor = this.BackColor;
this.BackColor = this.OnMouseHvetColor;
}
private void ButtonDesign_MouseLeave(object sender, EventArgs e)
{
this.BackColor = save_properties.BackColor;
}
}
class TextBoxDesign : TextBox
{
private Control save_properties = new Control();
public Color OnMouseHoverColor { get; set; }
public TextBoxDesign()
{
this.MouseEnter += ButtonDesign_MouseEnter;
this.MouseLeave += ButtonDesign_MouseLeave;
}
private void TextBoxDesign_MouseEnter(object sender, EventArgs e)
{
save_properties.BackColor = this.BackColor;
this.BackColor = this.OnMouseHvetColor;
}
private void TextBoxDesign_MouseLeave(object sender, EventArgs e)
{
this.BackColor = save_properties.BackColor;
}
}

Congratulations, you've encountered the diamond inheritance problem. C# doesn't support this scenario, so what you're attempting to do is unfortunately not possible.
Your only options are:
Create a subclass of Control and make your custom controls inherit from it. This means you have to recreate the behaviour of the standard WinForms controls in your subclasses, which is painful at best.
public class MyControl : Control {}
public class MyButton : MyControl {}
Create an interface that your common controls implement. Have the interface implementations delegate to a shared library that does what needs to be done:
public interface IMyControl
{
void MySharedOperation();
}
public class MyButton : Button, IMyControl
{
public void MySharedOperation()
=> MySharedOperationHandler.MySharedOperation(this);
}
public static class MySharedOperationHandler
{
public static void MySharedOperation(Control control) {}
}
You'll end up with a fair amount of method implementations that do nothing more than delegate, but IMO this is far better than reinventing the control wheel as in the previous option.

If you want this, your class ButtonDesign is not a Button, it has a Button and a Layout. Similarly your class TextBoxDesign has a TextBox and a Layout.
In other words: don't use inheritance, use aggregation!
Every property that are both in Buttons, TextBoxes, and other Controls that have the properties that you want to change for all items in one statement, create a class that contains all these properties, with the proper events.
For every property you need a private member, a public get/set property and an event that will be raised when the property changes. Something like this:
class Layout
{
private Color backColor; // TODO: give proper initial values
private Color foreColor;
... // other properties that you want to change for all Controls
// Events:
public event EventHander BackColorChanged;
public event EventHandler ForeColorChanged;
... // etc
// Event raisers:
protected virtual void OnBackColorChanged()
{
this.BackColorChanged?.Invoke(this, EventArgs.Empty);
}
protected virtual void OnForColorChanged()
{
this.ForeColorChanged?.Invoke(this, EventArgs.Empty);
}
...
// Properties:
public Color BackColor
{
get => this.backColor;
set => if (this.BackColor != value) this.OnBackColorChanged();
}
public Color ForeColor ...
public Size Size ...
}
Your DesignButton will be a UserControl that has a Docked Button and a Layout. The constructor subscribes to the events. When raise the corresponding property on the button is set.
Use the visual studio designer to create the UserControl. Code will be similar to the following:
class MyButton : UserControl
{
private Button button; // visual studio designer will create this
private Layout layout;
public Layout Layout
{
get => this.layout;
set => if (this.Layout != value) this.ChangeLayout;
}
// you can't set the design properties. Only get.
protected Button Button => this.button;
Color BackColor
{
public get => this.Button.BackColor;
private set => this.Button.BackColor = value;
}
// etc for ForeColor, Text, ...
protected virtual void ChangeLayout(Layout newLayout)
{
// TODO: if there is an old Layout: desubscribe from all events from old Layout
this.layout = newLayout;
// subscribe to all events:
this.layout.BackColorChanged += this.BackColor_Changed;
this.layout.forColorChanged += this.ForColor_Changed;
...
this.BackColor = this.BackColor;
// TODO: if desired, for completeness add an event: LayoutChanged
}
Now whenever Layout raises event BackColorChanged you handle this event and assign the value to the Button. You'll get the gist.
Do something similar for TextBoxes, ComboBoxes, etc
Usage:
Layout commonLayout = new Layout
{
BackColor = Color.Yellow,
ForeColor = color.Black,
...
};
MyButton button1 = new MyButton
{
Layout = commonLayout,
};
MyTextBox textBox1 = new MyTextBox
{
Layout = commonLayout,
}
MyComboBox comboBox1 = ...
// Change the backgroundColor for all items:
commonLayout.BackColor = Color.Red;
If you have a lot of properties, consider to use generic classes
class LayoutProperty<T>
{
private T propertyValue;
public event eventHandler PropertyValueChanged
protected void OnPropertyValueChanged()
{
this.PropertyValueChanged?.Invoke(this, EventArgs.Empty);
}
public T PropertyValue
{
get => this.propertyValue;
set => if (this.PropertyValue != value) this.OnPropertyValueChanged();
}
}
class Layout
{
private PropertyValue<Color> backColor;
private PropertyValue<Color> foreColor;
// etc, see above for subscribtion and raising events.
And for all Controls:
public MyControl
{
private Control control;
private Layout layout;
// etc, see above for the event handling.
}
public MyButton : MyControl {Control = new Button()}
public MyTextBox : MyControl {Control = new Textbox()}

Showing and disposing tooltip .NET

I am working with yFiles.Net component which I use for representing dependencies between objects in some SQL database (graph representation).
I need to create tooltip which will appear when I point cursors on some object. That tooltip not contains just text, it contains images also. I know how to make custom class which extends default Tooltip class and then to override methods for drawing custom tooltips.
What i do not know is how to show tooltip when I point on some object on graph, and how to dispose it when I move cursor from object on graph? Can someone help me with this please?

If I understand you correctly, you want to intercept the
ItemHoverInputMode.HoveredItemChanged Event.
I have not tested this nor worked with yFiles before, but according to documentation this should work:
// 'gc' is of type yWorks.yFiles.UI.GraphControl.
var ihim = new ItemHoverInputMode();
ihim.HoveredItemChanged += YourEvenHandler;
gc.InputModes.Add(ihim);
Then check the element in the event handler and display or hide the tooltip.

private CustomTooltip m_tooltip;
private MouseHoverInputMode m_mouseHoverMode;
private void SetupToolTips(GraphEditorInputMode mode)
{
m_tooltip = new CustomTooltip(m_model.TooltipImages);
ItemHoverInputMode itemHoverMode = new ItemHoverInputMode();
itemHoverMode.HoverItems = GraphItemTypes.Node | GraphItemTypes.Edge;
mode.ItemHoverInputMode = itemHoverMode;
m_mouseHoverMode = new MouseHoverInputMode(m_tooltip, textProvider);
mode.MouseHoverInputMode = m_mouseHoverMode;
mode.ItemHoverInputMode.HoveredItemChanged += new EventHandler<HoveredItemChangedEventArgs>(ToolTipEvent);
}
private void ToolTipEvent(object sender, HoveredItemChangedEventArgs e)
{
m_tooltip.Item = e.Item;
}
private void textProvider(object sender, ToolTipQueryEventArgs e)
{
if (m_tooltip.Item is INode || m_tooltip.Item is IEdge)
{
e.ToolTip = " ";
}
}
public class CustomTooltip : ToolTip
{
private void OnPopup(object sender, PopupEventArgs e)
{
}
private void OnDraw(object sender, DrawToolTipEventArgs e)
{
}
}

how to call Resize Event in C#

I'm trying to create new Button with custom event. It's new for me. I'm trying to call "Resize". I wanna create "switch" like in android.
I'm trying to do this like other existing controls. I've been doing this for 2 days and i still have nothing. I belive that you will able to help me :)
Here is my code:
public abstract class SwitchBase : Control
{
private Button first;
private Button second;
public SwitchBase()
{
InitializeMySwitch();
}
private void InitializeMySwitch()
{
Controls.Add(first = new Button());
Controls.Add(second = new Button());
//first
first.Text = "first";
//second
second.Text = "second";
second.Location = new System.Drawing.Point(first.Location.X + first.Width, first.Location.Y);
}
public delegate void ChangedEventHandler(object source, EventArgs args);
public event ChangedEventHandler Changed;
protected virtual void OnSwitchChanged()
{
if (Changed != null)
Changed(this, EventArgs.Empty);
}
public delegate void ResizeEventHandler(object source, EventArgs args);
public event ResizeEventHandler Resize;
protected virtual void OnResize()
{
Resize(this, EventArgs.Empty);
}
}
public class Switch : SwitchBase
{
public Switch()
{
}
protected override void OnSwitchChanged()
{
base.OnSwitchChanged();
}
protected override void OnResize()
{
base.OnResize();
}
}
In another button I change the size of my switch

From reading your code, I gather that by "call Resize" you mean to raise the event. What you are doing is correct... although it should be noted that by the default event implementation, it will be null if there are no subscribers...
In fact, another thread could be unsubscribing behind your back. Because of that the advice is to take a copy.
You can do that as follows:
var resize = Resize;
if (resize != null)
{
resize(this, EventArgs.Empty)
}
It should be noted that the above code will call the subscribers to the event, but will not cause the cotrol to resize. If what you want is to change the size of your control, then do that:
this.Size = new Size(400, 200);
Or:
this.Width = 400;
this.Height = 200;
Note: I don't know what Control class you are using. In particular, if it were System.Windows.Forms.Control it already has a Resize event, and thus you won't be defining your own. Chances are you are using a Control class that doesn't even have Size or Width and Height.
Edit: System.Web.UI.Control doesn't have Resize, nor Size or Width and Height. But System.Windows.Controls.Control has Width and Height even thought it doesn't have Resize.

.NET Collections and Accessing Object Methods

I'm completely new to GUI programming and need a little help with a list of pictureboxes.
The idea is that I have a list of pictureboxes. When a user clicks on one I want to (for example) change the BorderStyle property of the one selected to be Fixed3D, but change the remaining collection borders to FixedSingle (or something like that). What's the proper way to do something like this? I guess the bigger picture is how do I get a method of one class to call a method of another without having any information about it?
class myPicture
{
private int _pictureNumber;
private PictureBox _box;
public myPicture(int order)
{
_box = new List<PictureBox>();
_box.Click += new System.EventHandler(box_click);
_pictureNumber = order;
}
public void setBorderStyle(BorderStyle bs)
{
_box.BorderStyle = bs;
}
public void box_click(object sender, EventArgs e)
{
//here I'd like to call the set_borders from myPicturesContainer, but I don't know or have any knowledge of the instantiation
}
}
class myPicturesContainer
{
private List<myPicture> _myPictures;
//constructor and other code omitted, not really needed...
public void set_borders(int i)
{
foreach(myPicture mp in _MyPictures)
mp.setBorderStyle(BorderStyle.FixedSingle);
if(i>0 && _MyPictures.Count>=i)
_MyPictures[i].setBorderStyle(BorderStyle.Fixed3d);
}
}

You will need to create a Clicked event in your myPicture class and raise that event when it is clicked. Then you will need to attach to this event in your myPicturesContainer for each instance of myPicture that you have.
Here is a very simple example of what I mean:
class myPicture
{
public event Action<Int32> Clicked = delegate { };
private int _pictureNumber;
public void box_click(object sender, EventArgs e)
{
this.Clicked(this._pictureNumber);
}
}
class myPicturesContainer
{
private List<myPicture> _myPictures;
public void set_borders(int i)
{
foreach (myPicture mp in _myPictures)
{
mp.Clicked += pictureClick;
}
}
void pictureClick(Int32 pictureId)
{
// This method will be called and the pictureId
// of the clicked picture will be passed in
}
}