async void OnTapGestureRecognizerTapped(object sender, EventArgs args)
{
if (_isInFront)
{
_contentHolder.RaiseChild(BackView);
FrontView.Opacity = 0.2f;
await Task.WhenAll(
FrontView.FadeTo(1, 500),
FrontView.TranslateTo(0, -translationPosition, 500),
BackView.TranslateTo(0, 0, 500),
BackView.ScaleTo(1, 500),
FrontView.ScaleTo(0.8f, 500)
);
}
else
{
_contentHolder.RaiseChild(FrontView);
BackView.Opacity = 0.2f;
await Task.WhenAll(
BackView.FadeTo(1, 500),
FrontView.TranslateTo(0, 0, 500),
BackView.TranslateTo(0, -translationPosition, 500),
FrontView.ScaleTo(1, 500),
BackView.ScaleTo(0.8f, 500)
);
}
_isInFront = !_isInFront;
}
public void Flip(FlipDirection direction, NSAction completion)
{
if (flippingInProgress || FrontView == null || BackView == null)
{
return;
}
flippingInProgress = true;
projectionLayer = CALayer.Create(); // this is to make the perspective and 2.5D effect
projectionLayer.Frame = this.Layer.Bounds;
var perspective = CATransform3D.Identity;
float zDistanse = 350f; // change this to the actual perspective and distance of the projection plane
perspective.m34 = 1f / -zDistanse;
projectionLayer.SublayerTransform = perspective;
this.Layer.AddSublayer(projectionLayer);
frontImage = FrontView.GetImage();
backImage = BackView.GetImage();
topFaceLayer = new GradientLayer(GradientLayerType.Face, GradientLayerAreaType.Top);
topFaceLayer.Frame = new RectangleF(0f, 0f, projectionLayer.Frame.Size.Width, (float)Math.Floor(projectionLayer.Frame.Size.Height / 2f));
bottomFaceLayer = new GradientLayer(GradientLayerType.Face, GradientLayerAreaType.Bottom);
bottomFaceLayer.Frame = new RectangleF(0f, (float)Math.Floor(projectionLayer.Frame.Size.Height / 2f), projectionLayer.Frame.Size.Width, (float)Math.Floor(projectionLayer.Frame.Size.Height / 2f));
mainFlipLayer = new DoubleSidedLayer();
mainFlipLayer.AnchorPoint = new PointF(1f, 1f);
mainFlipLayer.Frame = new RectangleF(0f, 0f, projectionLayer.Frame.Size.Width, (float)Math.Floor(projectionLayer.Frame.Size.Height / 2f));
mainFlipLayer.ZPosition = 1f;
mainFlipLayer.FrontLayer = new GradientLayer(GradientLayerType.Flip, GradientLayerAreaType.Top);
mainFlipLayer.BackLayer = new GradientLayer(GradientLayerType.Flip, GradientLayerAreaType.Bottom);
// offscreen rendering optimization to reuse the offscreen buffer
topFaceLayer.ShouldRasterize = true;
bottomFaceLayer.ShouldRasterize = true;
if (direction == FlipDirection.Down)
{
topFaceLayer.Contents = backImage.CGImage;
bottomFaceLayer.Contents = frontImage.CGImage;
mainFlipLayer.FrontLayer.Contents = frontImage.CGImage;
mainFlipLayer.BackLayer.Contents = backImage.CGImage;
topFaceLayer.GradientOpacity = 1f;
mainFlipLayer.Transform = CATransform3D.Identity;
}
else
{
topFaceLayer.Contents = frontImage.CGImage;
bottomFaceLayer.Contents = backImage.CGImage;
mainFlipLayer.FrontLayer.Contents = backImage.CGImage;
mainFlipLayer.BackLayer.Contents = frontImage.CGImage;
bottomFaceLayer.GradientOpacity = 1f;
mainFlipLayer.Transform = CATransform3D.MakeRotation((float)-Math.PI, 1f, 0f, 0f);
}
// Add layers to the projection layer, so we apply the projections to it
projectionLayer.AddSublayer(topFaceLayer);
projectionLayer.AddSublayer(bottomFaceLayer);
projectionLayer.AddSublayer(mainFlipLayer);
NSTimer.CreateScheduledTimer(0.01, delegate {
CATransaction.Begin();
CATransaction.AnimationDuration = Duration;
CATransaction.AnimationTimingFunction = CAMediaTimingFunction.FromName(CAMediaTimingFunction.EaseOut);
CATransaction.CompletionBlock = delegate {
fv = this.FrontView;
FrontView = BackView;
BackView = fv;
flippingInProgress = false;
if (completion != null)
{
completion.Invoke();
}
};
// this is the whole trick, change the angle in timing function
float angle = (float)Math.PI * (1f - (float)direction);
mainFlipLayer.Transform = CATransform3D.MakeRotation(angle, 1f, 0f, 0f);
topFaceLayer.GradientOpacity = (float)direction;
bottomFaceLayer.GradientOpacity = 1f - (float)direction;
mainFlipLayer.FrontLayer.GradientOpacity = 1f - (float)direction;
mainFlipLayer.BackLayer.GradientOpacity = (float)direction;
CATransaction.Commit();
});
}
