public static CAGradientLayer BuildShimmeringGradient(
CGRect bounds,
int repeatCount = 3)
{
CAGradientLayer gradient = new CAGradientLayer();
CABasicAnimation animation = new CABasicAnimation()
{
KeyPath = "locations"
};
gradient.Colors = new CGColor[]
{
ShimmerAnimationConfig.DarkColor,
ShimmerAnimationConfig.LightColor,
ShimmerAnimationConfig.DarkColor
};
gradient.Frame = new CGRect(-2 * bounds.Size.Width, 0, 4 * bounds.Size.Width, bounds.Size.Height);
gradient.StartPoint = new CGPoint(0, 0.5);
gradient.EndPoint = new CGPoint(1, 0.5);
gradient.Locations = new Foundation.NSNumber[] { 0.4, 0.5, 0.6 };
animation.Duration = ShimmerAnimationConfig.Duration;
animation.RepeatCount = repeatCount;
animation.SetTo(NSArray.FromObjects(0.0, 0.12, 0.13));
animation.SetFrom(NSArray.FromObjects(0.6, 0.86, 1.0));
gradient.AddAnimation(animation, shimmerKey);
return(gradient);
}
/// <summary>
/// Adds a gradient layer as a background layer to a view.
/// </summary>
/// <param name="view">The view to add the gradient to.</param>
/// <param name="gradient">A gradient layer.</param>
/// <param name="index">The index to insert the gradient layer (default=0)</param>
public static void AddGradientBackground(this UIView view, CAGradientLayer gradient, int index = 0, bool animate = false)
{
gradient.Frame = view.Bounds;
gradient.MasksToBounds = true;
CAGradientLayer existingGradient = null;
if (view.Layer.Sublayers != null)
{
foreach (var l in view.Layer.Sublayers)
{
if (l.GetType() == typeof(CAGradientLayer))
{
existingGradient = (CAGradientLayer)l;
break;
}
}
}
view.Layer.InsertSublayer(gradient, index);
gradient.Opacity = animate ? 0 : 1;
if (existingGradient != null)
{
existingGradient.Opacity = 1;
view.Layer.InsertSublayer(gradient, index + 1);
if (animate)
{
// Create fade in animation for the new gradient
var fadein = CABasicAnimation.FromKeyPath("opacity");
fadein.SetTo(NSNumber.FromFloat(1));
fadein.Duration = .5;
fadein.AutoReverses = false;
fadein.RemovedOnCompletion = false;
fadein.FillMode = CAFillMode.Forwards;
// Create fade out animation for the existing gradient
var fadeout = CABasicAnimation.FromKeyPath("opacity");
fadeout.SetTo(NSNumber.FromFloat(0));
fadeout.Duration = .5;
fadeout.AutoReverses = false;
fadeout.RemovedOnCompletion = false;
fadeout.FillMode = CAFillMode.Forwards;
fadeout.AnimationStopped += (sender, e) =>
{
existingGradient.RemoveFromSuperLayer();
};
// Execute the animations.
gradient.AddAnimation(fadein, "opacityIN");
existingGradient.AddAnimation(fadeout, "opacityOUT");
}
else
{
existingGradient.RemoveFromSuperLayer();
}
}
}
public void AnimateGradient()
{
_currentGradient += 1;
var animation = CABasicAnimation.FromKeyPath(KeyPath);
animation.Duration = AnimationDuration;
var nsArray = NSArray.FromObjects(CurrentGradientSet());
animation.To = nsArray;
animation.RemovedOnCompletion = false;
animation.AnimationStopped += (sender, e) => {
_gradient.Colors = CurrentGradientSet();
AnimateGradient();
};
animation.FillMode = CAFillMode.Forwards;
_gradient.AddAnimation(animation, Key);
}
public static void ApplyShimmer(UIView viewToApplyShimmer)
{
var gradientLayer = new CAGradientLayer
{
Colors = new CGColor[] { UIColor.White.ColorWithAlpha(0f).CGColor, UIColor.White.ColorWithAlpha(1f).CGColor, UIColor.White.ColorWithAlpha(0f).CGColor },
StartPoint = new CGPoint(0.7, 1.0),
EndPoint = new CGPoint(0, 0.8),
Frame = viewToApplyShimmer.Bounds
};
viewToApplyShimmer.Layer.InsertSublayer(gradientLayer, 0);
var animation = new CABasicAnimation();
animation.KeyPath = "transform.translation.x";
animation.Duration = 1;
animation.From = NSNumber.FromNFloat(-viewToApplyShimmer.Frame.Size.Width);
animation.To = NSNumber.FromNFloat(viewToApplyShimmer.Frame.Size.Width);
animation.RepeatCount = float.PositiveInfinity;
gradientLayer.AddAnimation(animation, "");
}