C# UIView.ResizableSnapshotView方法代码示例

        public override void AnimateTransition(IUIViewControllerContextTransitioning transitionContext, 
		                                        UIViewController fromViewController, UIViewController toViewController, 
		                                        UIView fromView, UIView toView)
        {
            UIView containerView = transitionContext.ContainerView;
            containerView.AddSubview (toView);
            containerView.SendSubviewToBack (toView);

            var size = toView.Frame.Size;
            var snapshots = new List<UIView> ();

            float xFactor = 10f;
            float yFactor = xFactor * size.Height / size.Width;

            for (float x = 0; x < size.Width; x += size.Width / xFactor) {
                for (float y = 0; y < size.Height; y += size.Height / yFactor) {
                    var snapshotRegion = new RectangleF (x, y, size.Width / xFactor, size.Height / yFactor);
                    UIView snapshot = fromView.ResizableSnapshotView (snapshotRegion, false, UIEdgeInsets.Zero);

                    snapshot.Frame = snapshotRegion;
                    containerView.AddSubview (snapshot);
                    snapshots.Add (snapshot);
                }
            }

            containerView.SendSubviewToBack (fromView);

            var rnd = new Random ();
            double duration = TransitionDuration (transitionContext);
            NSAction action = () => {
                foreach (UIView view in snapshots) {
                    float xOffset = rnd.Next (-100, 100);
                    float yOffset = rnd.Next (-100, 100);
                    view.Frame = new RectangleF (view.Frame.X + xOffset, view.Frame.Y + yOffset, view.Frame.Width, view.Frame.Height);
                    view.Alpha = 0f;
                    var transition = CGAffineTransform.MakeRotation (rnd.Next (-10, 10));
                    transition.Scale (0f, 0f);
                    view.Transform = transition;
                }
            };

            UIView.Animate (duration, action, () => {
                foreach (UIView view in snapshots)
                    view.RemoveFromSuperview ();

                transitionContext.CompleteTransition (!transitionContext.TransitionWasCancelled);
            });
        }

		private List<UIView> CreateSnapshots (UIView view, bool afterScreenUpdates)
		{
			UIView containerView = view.Superview;
			var snapshotRegion = new CGRect (0, 0, view.Frame.Size.Width / 2, view.Frame.Size.Height);
			UIView leftHandView = view.ResizableSnapshotView (snapshotRegion, afterScreenUpdates, UIEdgeInsets.Zero);
			leftHandView.Frame = snapshotRegion;
			containerView.AddSubview (leftHandView);

			snapshotRegion = new CGRect (view.Frame.Size.Width / 2, 0, view.Frame.Size.Width / 2, view.Frame.Size.Height);
			UIView rightHandView = view.ResizableSnapshotView (snapshotRegion, afterScreenUpdates, UIEdgeInsets.Zero);
			rightHandView.Frame = snapshotRegion;
			containerView.AddSubview (rightHandView);

			containerView.SendSubviewToBack (view);

			return new List<UIView> () { leftHandView, rightHandView };
		}

        private UIView CreateSnapshot(UIView view, bool afterUpdates, float offset, bool left)
        {
            CGSize size = view.Frame.Size;
            UIView containerView = view.Superview;
            float foldWidth = (float)(size.Width * 0.5f / Folds);

            UIView snapshotView;

            if (!afterUpdates) {
                // create a regular snapshot
                var snapshotRegion = new CGRect (offset, 0f, foldWidth, size.Height);
                snapshotView = view.ResizableSnapshotView (snapshotRegion, afterUpdates, UIEdgeInsets.Zero);
            } else {
                // for the to- view for some reason the snapshot takes a while to create. Here we place the snapshot within
                // another view, with the same bckground color, so that it is less noticeable when the snapshot initially renders
                snapshotView = new UIView (new CGRect (0f, 0f, foldWidth, size.Height));
                snapshotView.BackgroundColor = view.BackgroundColor;
                var snapshotRegion = new CGRect (offset, 0f, foldWidth, size.Height);
                UIView snapshotView2 = view.ResizableSnapshotView (snapshotRegion, afterUpdates, UIEdgeInsets.Zero);
                snapshotView.AddSubview (snapshotView2);
            }

            // create a shadow
            UIView snapshotWithShadowView = AddShadowToView (snapshotView, left);

            // add to the container
            containerView.AddSubview (snapshotWithShadowView);

            // set the anchor to the left or right edge of the view
            snapshotWithShadowView.Layer.AnchorPoint = new CGPoint (left ? 0f : 1f, 0.5f);

            return snapshotWithShadowView;
        }