C# CGRect.UnionWith方法代码示例

		public override bool FinishedLaunching (UIApplication application, NSDictionary launchOptions)
		{
			// Two disjoint rects
			var r1 = new CGRect (50, 50, 10, 10);
			var r2 = new CGRect (100, 100, 10, 10);

			// This condradicts with Apple's doc – https://developer.apple.com/reference/coregraphics/cgrectnull
			// The null rectangle. This is the rectangle returned when, for example, you intersect two disjoint rectangles.
			// Note that the null rectangle is not the same as the zero rectangle. 
			// For example, the union of a rectangle with the null rectangle is the original rectangle (that is, the null rectangle contributes nothing).
			var tmp = r1;
			tmp.Intersect (r2); // this is mutable method
			Console.WriteLine (tmp.IsNull ()); // Expected true, but result is false

			tmp = CGRectIntersection (r1, r2);
			Console.WriteLine (tmp.IsNull ()); // Expected true, actual true

			// This should be CGRectNull
			var rectNull = new CGRect (nfloat.PositiveInfinity, nfloat.PositiveInfinity, 0, 0);
			Console.WriteLine (rectNull.IsNull ());  // Expected true, actual true

			// CGRectEmpty and CGRectNull are different
			var union1 = r1.UnionWith (CGRect.Empty); // new rect {0, 0, 60, 60}
			Console.WriteLine (union1);
			var union2 = r1.UnionWith (rectNull);     // r1
			Console.WriteLine (union2);

			return true;
		}

        static CGRect UpdateRectForLinePoint(LinePoint point, LinePoint previousPoint)
        {
            var rect = new CGRect (point.Location, CGSize.Empty);
            var pointMagnitude = point.Magnitude;

            if (previousPoint != null) {
                pointMagnitude = NMath.Max (pointMagnitude, previousPoint.Magnitude);
                rect = rect.UnionWith (new CGRect (previousPoint.Location, CGSize.Empty));
            }

            // The negative magnitude ensures an outset rectangle.
            var magnitude = -3 * pointMagnitude - 2;
            rect = rect.Inset (magnitude, magnitude);

            return rect;
        }

		CGRect AddPointsOfType (PointType type, UITouch[] touches, Line line, CGRect rect)
		{
			var accumulatedRect = CGRect.Empty;

			for (int i = 0; i < touches.Length; i++) {
				var touch = touches [i];
				bool isStylus = touch.Type == UITouchType.Stylus;

				// The visualization displays non-`.Stylus` touches differently.
				if (!isStylus)
					type = type.Add (PointType.Finger);

				if (isTouchUpdatingEnabled && (touch.EstimatedProperties != 0))
					type = type.Add (PointType.NeedsUpdate);

				bool isLast = i == touches.Length - 1;
				if (type.Has (PointType.Coalesced) && isLast) {
					type = type.Remove (PointType.Coalesced);
					type = type.Add (PointType.Standard);
				}

				var touchRect = line.AddPointOfType (type, touch);
				accumulatedRect = accumulatedRect.UnionWith (touchRect);
				CommitLine (line);
			}

			return rect.UnionWith (accumulatedRect);
		}