.NET Windows窗体鼠标为所有现有的PictureBox控件输入效果

Question

I'm new here, and this is my first post here. My apologies if I don't follow the standards on creating a new question here on SO.

I've been racking my brains for the past couple of hours to try to program a custom class which would allow me to add a new property to existing PictureBox controls, allowing me to set a Color to my custom property, which would result in setting a border with the selected color as the user hovers the control.

Below is the code I've written so far:

[ProvideProperty("HoverColor", typeof(PictureBox))]
public class PictureBoxHover : Component, IExtenderProvider
{
    private readonly Dictionary<IntPtr, Color> _hoverColors;
    public PictureBoxHover()
    {
        _hoverColors = new Dictionary<IntPtr, Color>();
    }
    public bool CanExtend(object extendee)
    {
        return (extendee is PictureBox);
    }
    public Color GetHoverColor(PictureBox picb)
    {
        Color color;
        if (_hoverColors.TryGetValue(picb.Handle, out color))
            return color;
        return Color.Empty;
    }
    public void SetHoverColor(PictureBox picb, Color color)
    {
        Color hoverColor;
        _hoverColors[picb.Handle] = color;
    }
}

The above code adds the custom property "HoverColor" to all existing PictureBox controls in my solution - just as I need. All I need to do now is somehow have it draw a border around my PictureBoxes with the set color when the user hovers over the control.

I DON'T want my class to inherit the PictureBox or Control classes, as that would require having to change all my PictureBoxes from the ordinaly PictureBox to my custom PictureBox - which is why I instead want to 'append' this custom property and functionality to the ordinary PictureBox control.

Any help would be greatly appreciated =)

Answer 1

Maybe you could achieve your goal simpler by using custom user control instead of creating extended properties for picture box. Below is a simple sample:

public class FramedPictureBox : UserControl
{
    private readonly PictureBox _pictureBox;

    public FramedPictureBox()
    {
        const int FRAME_SIZE = 3;
        _pictureBox = new PictureBox
                          {
                              Left = FRAME_SIZE,
                              Top = FRAME_SIZE,
                              Width = Width - 2*FRAME_SIZE,
                              Height = Height - 2*FRAME_SIZE,
                              Anchor = AnchorStyles.Left | AnchorStyles.Bottom | AnchorStyles.Right | AnchorStyles.Top
                          };

        _pictureBox.MouseEnter += OnPictureBoxMouseEnter;
        _pictureBox.MouseLeave += OnPictureBoxMouseLeave;

        Controls.Add(_pictureBox);
    }

    protected override void OnLoad(EventArgs e)
    {
        var image = new Bitmap(_pictureBox.Width, _pictureBox.Height);
        var graphics = Graphics.FromImage(image);
        graphics.Clear(Color.White);

        _pictureBox.Image = image;

        base.OnLoad(e);
    }

    private void OnPictureBoxMouseEnter(object sender, EventArgs e)
    {
        BackColor = Color.Red;
    }

    private void OnPictureBoxMouseLeave(object sender, EventArgs e)
    {
        BackColor = SystemColors.Control;
    }
}