.net - Animated Glow Effect for Button - C# Windows Forms

Question

I want to apply animation to my button when pressing button. In WPF I can use Storyboard with triggers to create animation. Here is an example:

<Storyboard x:Key="AniOpacityDelay">
  <DoubleAnimation
    Storyboard.TargetName="background"
    Storyboard.TargetProperty="Opacity"
    AutoReverse="True"
    To="0.65"
    Duration="0:0:0.2"/>
</Storyboard>

and:

<ColorAnimationUsingKeyFrames
  Storyboard.TargetName="Itemcont"
  Storyboard.TargetProperty="(TextElement.Foreground).(SolidColorBrush.Color)">

  <EasingColorKeyFrame KeyTime="0" Value="#EEEEEE"/>
</ColorAnimationUsingKeyFrames>

Windows Forms doesn't have Storyboard and triggers. How to make smooth animation in Windows Forms?

Here's my code for Windows Forms:

void DelayTime()
{
  timer = new Timer();
  timer.Interval = (int)System.TimeSpan.FromSeconds(this.DelayTime).TotalMilliseconds;
  timer.Tick += (s, es) =>
  {
    this.mouseover = false; 
    this.Cursor = Cursors.Hand;
    this.Enabled = true;
  };
  timer.Start();
}

protected override void OnMouseDown(MouseEventArgs mevent)
{
  base.OnMouseDown(mevent);
  mouseover = true;
  this.Enabled = false;
  DelayTime();
}

protected override void OnPaint(PaintEventArgs e)
{
  Color bg = this._Background;
  bg = mouseover ? this._HoverColor : this._Background;
  e.Graphics.FillRectangle(new SolidBrush(bg), this.ClientRectangle);
}

Answer 1

The basic idea is using a Timer and alpha-blending the glow color with original background color.

For example you can set FlatStyle of the button to Flat and override OnMouseEnter and OnMouseLeave. In OnMouseEnter start the timer and in and OnMouseLeave stop the timer. In timer Tick event you can set the MouseOverBackColor of FlatAppearance of button to a color which you increase it's alpha channel in Tick event.

Glow Button Code

using System;
using System.Drawing;
using System.Windows.Forms;
public class GlowButton : Button
{
    Timer timer;
    int alpha = 0;
    public Color GlowColor { get; set; }
    public GlowButton()
    {
        this.DoubleBuffered = true;
        timer = new Timer() { Interval = 50 };
        timer.Tick += timer_Tick;
        this.FlatStyle = System.Windows.Forms.FlatStyle.Flat;
        this.GlowColor = Color.Gold;
        this.FlatAppearance.MouseDownBackColor = Color.Gold;
    }
    protected override void OnMouseEnter(EventArgs e)
    {
        base.OnMouseEnter(e);
        this.FlatAppearance.MouseOverBackColor = CalculateColor();
        timer.Start();
    }
    protected override void OnMouseLeave(EventArgs e)
    {
        base.OnMouseLeave(e);
        timer.Stop();
        alpha = 0;
        this.FlatAppearance.MouseOverBackColor = CalculateColor();
    }
    void timer_Tick(object sender, EventArgs e)
    {
        int increament = 25;
        if (alpha + increament < 255) { alpha += increament; }
        else { timer.Stop(); alpha = 255; }
        this.FlatAppearance.MouseOverBackColor = CalculateColor();
    }
    protected override void Dispose(bool disposing)
    {
        if (disposing) timer.Dispose();
        base.Dispose(disposing);
    }
    private Color CalculateColor()
    {
        return AlphaBlend(Color.FromArgb(alpha, GlowColor), this.BackColor);
    }
    public Color AlphaBlend(Color A, Color B)
    {
        var r = (A.R * A.A / 255) + (B.R * B.A * (255 - A.A) / (255 * 255));
        var g = (A.G * A.A / 255) + (B.G * B.A * (255 - A.A) / (255 * 255));
        var b = (A.B * A.A / 255) + (B.B * B.A * (255 - A.A) / (255 * 255));
        var a = A.A + (B.A * (255 - A.A) / 255);
        return Color.FromArgb(a, r, g, b);
    }
}