Fade a color to white (increasing brightness)

Question

I want to make a text box in .NET \"glow\" yellow, and then \"fade\" to white (basically, by incrementally increasing the brightness). I think Stackoverflow does this after you\

Answer 1

This may be more than you need, here's the code for the class I use:

public class ControlColorAnimator
{
    private const int INTERVAL = 100;

    private readonly decimal _alphaIncrement;
    private readonly decimal _blueIncrement;
    private readonly Color _endColor;
    private readonly decimal _greenIncrement;
    private readonly int _iterations;
    private readonly decimal _redIncrement;
    private readonly Color _startColor;

    private decimal _currentAlpha;
    private decimal _currentBlueValue;
    private decimal _currentGreenValue;
    private decimal _currentRedValue;

    private Timer _timer;

    public ControlColorAnimator(TimeSpan duration, Color startColor, Color endColor)
    {
        _startColor = startColor;
        _endColor = endColor;
        resetColor();

        _iterations = duration.Milliseconds / INTERVAL;
        _alphaIncrement = ((decimal) startColor.A - endColor.A) / _iterations;
        _redIncrement = ((decimal) startColor.R - endColor.R) / _iterations;
        _greenIncrement = ((decimal) startColor.G - endColor.G) / _iterations;
        _blueIncrement = ((decimal) startColor.B - endColor.B) / _iterations;
    }

    public Color CurrentColor
    {
        get
        {
            int alpha = Convert.ToInt32(_currentAlpha);
            int red = Convert.ToInt32(_currentRedValue);
            int green = Convert.ToInt32(_currentGreenValue);
            int blue = Convert.ToInt32(_currentBlueValue);

            return Color.FromArgb(alpha, red, green, blue);
        }
    }

    public event EventHandler> ColorChanged;

    public void Go()
    {
        disposeOfTheTimer();
        OnColorChanged(_startColor);

        resetColor();

        int currentIteration = 0;
        _timer = new Timer(delegate
            {
                if (currentIteration++ >= _iterations)
                {
                    Stop();
                    return;
                }
                _currentAlpha -= _alphaIncrement;
                _currentRedValue -= _redIncrement;
                _currentGreenValue -= _greenIncrement;
                _currentBlueValue -= _blueIncrement;
                OnColorChanged(CurrentColor);
            }, null, TimeSpan.FromMilliseconds(INTERVAL), TimeSpan.FromMilliseconds(INTERVAL));
    }

    public void Stop()
    {
        disposeOfTheTimer();
        OnColorChanged(_endColor);
    }

    protected virtual void OnColorChanged(Color color)
    {
        if (ColorChanged == null) return;
        ColorChanged(this, color);
    }

    private void disposeOfTheTimer()
    {
        Timer timer = _timer;
        _timer = null;

        if (timer != null) timer.Dispose();
    }

    private void resetColor()
    {
        _currentAlpha = _startColor.A;
        _currentRedValue = _startColor.R;
        _currentGreenValue = _startColor.G;
        _currentBlueValue = _startColor.B;
    }
}

This uses DataEventArgs (shown below)

/// 

/// Generic implementation of  that allows for a data element to be passed.
/// 
/// The type of data to contain.
[DebuggerDisplay("{Data}")]
public class DataEventArgs : EventArgs
{
    private T _data;

    /// 

    /// Constructs a .
    /// 
    /// The data to contain in the 
    [DebuggerHidden]
    public DataEventArgs(T data)
    {
        _data = data;
    }

    /// 

    /// Gets the data for this .
    /// 
    public virtual T Data
    {
        [DebuggerHidden]
        get { return _data; }
        [DebuggerHidden]
        protected set { _data = value; }
    }

    [DebuggerHidden]
    public static implicit operator DataEventArgs(T data)
    {
        return new DataEventArgs(data);
    }

    [DebuggerHidden]
    public static implicit operator T(DataEventArgs e)
    {
        return e.Data;
    }
}

Use in your form like this:

private ControlColorAnimator _animator;

private void runColorLoop()
{
    endCurrentAnimation();
    startNewAnimation();
}

private void endCurrentAnimation()
{
    ControlColorAnimator animator = _animator;
    _animator = null;
    if (animator != null)
    {
        animator.ColorChanged -= _animator_ColorChanged;
        animator.Stop();
    }
}

private void startNewAnimation()
{
    _animator = new ControlColorAnimator(TimeSpan.FromSeconds(.6), Color.Yellow, BackColor);
    _animator.ColorChanged += _animator_ColorChanged;
    _animator.Go();
}

private void _animator_ColorChanged(object sender, DataEventArgs e)
{
    invokeOnFormThread(delegate { setColor(e); });
}

private void setColor(Color color)
{
    // code to set color of the controls goes here
}

private void invokeOnFormThread(MethodInvoker method)
{
    if (IsHandleCreated)
        Invoke(method);
    else
        method();
}