Winforms Control

Question

I have a button which I use all the time as a little pick button next to a combobox. When I click the button I open a larger full list. This side of things work well and I do not have a problem with this..

My problem lies when someone said to me can you change that ugly icon you picked to my nice icon.

I went crap, I have hundreds of these buttons on many forms. So I thought I will create a custom control called PickButton (which is a standard button and heap of default proeprties set) and drop these on the form everywhere instead. In the code of the PickButton custom control I set some properties and the image to the customers nice icon.

So I drop the PickButton from my toolbox onto the form, so far things are looking pretty good and I am feeling a bit clever. Now I think to myself I will change back to my nice icon not the crappy one the customer picked and change the code in the PickButton custom control. But I cannot get rid of that customers icon, because the code when the PickButton run happens before the code in the designer file which has the customers icon.

So my aim was to have a PickButton control and be able to change the icon and other properties in one place and all the properties would be set when an instance of the control is created and displayed on the form.

Was I not so clever and went about achieving the task the wrong way???

This is my PickButton custom control class

public class PickButton : Button
{

    public PickButton()
    {
        InitialiseButton();
    }

    internal void InitialiseButton()
    {
        this.ImageAlign = ContentAlignment.MiddleCenter;
        this.Image = WindowsFormsApplication1.Properties.Resources.Cancel.ToBitmap();
        this.Size = new Size( 28, 28 );
        this.Dock = DockStyle.Fill;
        this.Margin = new Padding( 0, 2, 2, 0 );
        this.Text = string.Empty;
    }
}

Now I drop one onto my form and the code in the designer is as follows

 // 
        // pickButton1
        // 
        this.pickButton1.Dock = System.Windows.Forms.DockStyle.Fill;
        this.pickButton1.Image = ((System.Drawing.Image)(resources.GetObject("pickButton1.Image")));
        this.pickButton1.Location = new System.Drawing.Point(0, 0);
        this.pickButton1.Margin = new System.Windows.Forms.Padding(0, 2, 2, 0);
        this.pickButton1.Name = "pickButton1";
        this.pickButton1.Size = new System.Drawing.Size(284, 262);
        this.pickButton1.TabIndex = 0;
        this.pickButton1.Text = "pickButton1";
        this.pickButton1.UseVisualStyleBackColor = true;

Now I want to change the image so I change my PickButton code to use a different icon

this.Image = WindowsFormsApplication1.Properties.Resources.Browse.ToBitmap();

Run the application andd the first icon is still the one being displayed because of this line of code in the designer file

        this.pickButton1.Image = ((System.Drawing.Image)(resources.GetObject("pickButton1.Image")));

Answer 1

The concept of setting all the properties in one place was a good idea, it just wasn't implemented quite right. I would make this class inherit from UserControl instead of from Button. By making it a UserControl, you can use the designer to set all the properties you want, like the default Image for the button. Set that in the designer, then just drag and drop your UserControl from the toolbox onto your forms. If you are only using your "PickButton" control with comboboxes, I would put the combobox on the UserControl as well. If you ever want to change your button image in the future (or any other property for that matter), you will be able to change it in ctlPickButton and that will propogate the changes to all the instances used throughout your project(s).

ctlPickButton:

public partial class ctlPickButton : UserControl
{
    public event EventHandler pickButtonClicked;

    public ctlPickButton()
    {
        InitializeComponent();
    }

    //Allows buttons image to be set in code if necessary
    public Image Image
    {
        get
        {
            return button1.Image;
        }
        set
        {
            if (Image != null)
            {
                button1.Image = value;
            }
        }
    }

    private void button1_Click(object sender, EventArgs e)
    {
        if (pickButtonClicked != null)
        {
            pickButtonClicked(sender, e);
        }
    }
}

---

Demo Form:

    public Form1()
    {
        InitializeComponent();

        ctlPickButton1.pickButtonClicked += new EventHandler(ctlPickButton1_pickButtonClicked);
        ctlPickButton2.pickButtonClicked += new EventHandler(ctlPickButton2_pickButtonClicked);
    }

    void ctlPickButton2_pickButtonClicked(object sender, EventArgs e)
    {
        if (comboBox2.SelectedItem != null)
        {
            MessageBox.Show(comboBox2.SelectedItem.ToString());
        }
    }

    void ctlPickButton1_pickButtonClicked(object sender, EventArgs e)
    {
        if (comboBox1.SelectedItem != null)
        {
            MessageBox.Show(comboBox1.SelectedItem.ToString());
        }
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        comboBox1.Items.Add("French");
        comboBox1.Items.Add("Spanish");
        comboBox1.Items.Add("English");
        comboBox1.Items.Add("German");

        comboBox2.Items.Add("Pizza");
        comboBox2.Items.Add("Hamburger");
        comboBox2.Items.Add("Potato");
        comboBox2.Items.Add("Chicken");

        //Shows how the default image set in the designer can be overwritten for a 
        //specific instance using the "Image" property
        ctlPickButton2.Image = Testbed.Properties.Resources.searchIcon2;
    }
}

---

Image of ctlPickButton in designer

Answer 2

I think I've found a simple, clean solution:

In the CustomButton class (which inherits from System.Windows.Forms.Button), override the Refresh() method, and set the image of the button to the one you want to see:

public class CustomButton : Button
{
  public override void Refresh()
  {
    Image = MyResources.HappyFace;
  }
}

In the form that will hold an instance of your CustomButton, simply call customButton.Refresh() in the constructor, after InitializeComponent():

public partial class MainForm : Form
{
  public MainForm()
  {
    InitializeComponent();

    customButton.Refresh();
  }
}

I've put a demo application up on Github.