CODEWITHSUNDEEP
c#winforms
hjf
hjf

Reputation: 463

Custom WinForms button does not change image?

I created a custom Button, called AcceptButton, inheriting from System.Windows.Forms.Button

On the constructor I set a few properties, but most important, an image (A green checkmark), like this:

this.Image = Proyecto.Controls.Bases.Properties.Resources.ok_16;

When I add this control using VS2013 form designer, in another project that references the DLL I just created, the image is displayed correctly. But if I go into my control, and change the image in code, for example, to:

this.Image = Proyecto.Controls.Bases.Properties.Resources.ok_32;

The image is not changed in the projects that use this control (even if the solution is cleaned and regenerated). I followed the code generated by VS2013 and I found that the designer adds this line:

this.botonAceptar1.Image = ((System.Drawing.Image)(resources.GetObject("botonAceptar1.Image")));

For some reason, this resource is "hardcoded" in a resource file generated by VS, but it's not updated when I regenerate the solution.

Removing this line makes it work as expected (I can change the image in the "upstream" class and it'll be updated when the solution is regenerated).

Why is this happening? How can I avoid this?

Upvotes: 3

Views: 1501

Answers (1)

Jens
Jens

Reputation: 6375

This happens due to the DesignerSerializationVisibility (MSDN) attribute. Try adding this property and these methods (MSDN) to your class:

public class MyButton : System.Windows.Forms.Button
{
    public bool ShouldSerializeImage()
    {
        return !object.ReferenceEquals(this.Image, _BaseImage);
    }

    public void ResetImage()
    {
        this.Image = _BaseImage;
    }

    [System.ComponentModel.DesignerSerializationVisibility(System.ComponentModel.DesignerSerializationVisibility.Visible)]
    public new Image Image
    {
        get { return base.Image; }
        set { base.Image = value; }
    }
    private Bitmap _BaseImage;
    public MyButton()
    {
        _BaseImage = Proyecto.Controls.Bases.Properties.Resources.ok_16;
        this.Image = _BaseImage;
    }
}

This replaces the default Image property and prevents the serialization you encountered. Furthermore it allows the designer to check if the property has it's default value and if it needs to be serialized. The default value is stored in a private field in the button class. This should correctly serialize (or not serialize) the properties.

Remove all buttons you have, recompile, readd the buttons to make sure.

Upvotes: 4

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