CODEWITHSUNDEEP
c#.netgdi+winforms
Joan Venge
Joan Venge

Reputation: 331112

How to set the default value of Colors in a custom control in Winforms?

I got the value to show up correctly using:

    [DefaultValue ( typeof ( Color ), "255, 0, 0" )]
    public Color LineColor
    {
        get { return lineColor; }
        set { lineColor = value; Invalidate ( ); }
    }

But after I reload the project the control is used, this value is set to White, which I can invoke Reset to get back to Red again, but I don't understand the problem.

How are you supposed to set the default value and make sure it's preserved unless I change the value manually from the default?

Actually I am also doing this, which sets Back and ForeColor to these values and the VS property editor shows them as if they are changed from the default value.

Is this wrong?

    public CoolGroupBox ( )
    {
        InitializeComponent ( );
        base.BackColor = Color.FromArgb ( 5, 5, 5 );
        base.ForeColor = Color.FromArgb ( 0, 0, 0 );
    }

Upvotes: 22

Views: 28688

Answers (8)

daniyal_1363
daniyal_1363

Reputation: 1

I used this code and it worked perfectly

Private _BackColorSelect As Color = Color.FromArgb(214, 234, 248)

<DefaultValue(GetType(Color), "214, 234, 248")>
Public Property BackColorSelect As Color
    Get
        Return _BackColorSelect
    End Get
    Set(value As Color)
        _BackColorSelect = value
    End Set
End Property

Upvotes: 0

Eych
Eych

Reputation: 323

You can set specific Attribute in the component.designer.cs in the Initializecomponent Method:

  private void InitializeComponent()
    {
        components = new System.ComponentModel.Container();
        this.LineColor= System.Drawing.Color.FromArgb(255, 0, 0);
    }

Rebuild the project and everything should also show up in the

Upvotes: 0

Kerran
Kerran

Reputation: 1

I didn't have any luck using the DefaultValue attribute with properties of type Color or of type Font, but I did succeed with these methods described in the msdn documentation:

"Defining Default Values with the ShouldSerialize and Reset Methods" http://msdn.microsoft.com/en-us/library/53b8022e(v=vs.90).aspx

I used Color.Empty and null, respectively, as the values for my private backing fields and had the public properties always return something useful.

Upvotes: 0

Michal Plško
Michal Plško

Reputation: 1

In DependencyProperty use a UIPropertyMetadata

like:

public static DependencyProperty TrueColorProperty = DependencyProperty.Register(
        "TrueColor", typeof (Color), typeof (LedControl), new UIPropertyMetadata(Colors.Red));

Upvotes: -2

Serge Wautier
Serge Wautier

Reputation: 21878

The [DefaultValue(...)] attribute is a hint to designers and code generators. It is NOT an instruction to the compiler.

More info in this KB article.

Upvotes: 4

marchewek
marchewek

Reputation: 561

There is quite an article about defaultvalue property initialization on CodeProject

Upvotes: -1

scottm
scottm

Reputation: 28699

What about just setting the private member variable to the default color you want?

private Color lineColor = Color.Red;

public Color LineColor
{
        get { return lineColor; }
        set { lineColor = value; Invalidate ( ); }
}

If you want it preserved, just take out the set accessor.

Edit

I see, you want the property list in the designer to show the default color.

You have to override the BackColor property of the base control, add a new DefaultValueAttribute for your new property, and then actually set the default color in the constructor or in the InitializeComponent() method (in the designer.cs file), which is probably better since this is for the designer.

public partial class RedBackgroundControl : UserControl
{
    public RedBackgroundControl()
    {
        InitializeComponent();
        base.BackColor = Color.Red;
    }

    [DefaultValue(typeof(Color), "Red")]
    new public Color BackColor
    {
        get
        {
            return base.BackColor;
        }
        set
        {
            base.BackColor = value;
        }
    }
}

Upvotes: 11

JDunkerley
JDunkerley

Reputation: 12505

The trick is to use the Hex code of the color:

    [DefaultValue(typeof(Color), "0xFF0000")]
    public Color LineColor
    {
            get { return lineColor; }
            set { lineColor = value; Invalidate ( ); }
    }

I think you can also use "255, 0, 0" but am not sure and have normally used either the named colors or the hex code.

Upvotes: 27

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