UIImageView-GeometryConvesion.swift

extension UIImageView {
	
	func convertPoint(fromImagePoint imagePoint: CGPoint) -> CGPoint {
		guard let imageSize = image?.size else { return CGPoint.zero }

		var viewPoint = imagePoint
		let viewSize = bounds.size
		
		let ratioX = viewSize.width / imageSize.width
		let ratioY = viewSize.height / imageSize.height
		
		switch contentMode {
		case .scaleAspectFit: fallthrough
		case .scaleAspectFill:
			var scale : CGFloat = 0
			
			if contentMode == .scaleAspectFit {
				scale = min(ratioX, ratioY)
			}
			else {
				scale = max(ratioX, ratioY)
			}
			
			viewPoint.x *= scale
			viewPoint.y *= scale
			
			viewPoint.x += (viewSize.width  - imageSize.width  * scale) / 2.0
			viewPoint.y += (viewSize.height - imageSize.height * scale) / 2.0
		
		case .scaleToFill: fallthrough
		case .redraw:
			viewPoint.x *= ratioX
			viewPoint.y *= ratioY
		case .center:
			viewPoint.x += viewSize.width / 2.0  - imageSize.width  / 2.0
			viewPoint.y += viewSize.height / 2.0 - imageSize.height / 2.0
		case .top:
			viewPoint.x += viewSize.width / 2.0 - imageSize.width / 2.0
		case .bottom:
			viewPoint.x += viewSize.width / 2.0 - imageSize.width / 2.0
			viewPoint.y += viewSize.height - imageSize.height
		case .left:
			viewPoint.y += viewSize.height / 2.0 - imageSize.height / 2.0
		case .right:
			viewPoint.x += viewSize.width - imageSize.width
			viewPoint.y += viewSize.height / 2.0 - imageSize.height / 2.0
		case .topRight:
			viewPoint.x += viewSize.width - imageSize.width
		case .bottomLeft:
			viewPoint.y += viewSize.height - imageSize.height
		case .bottomRight:
			viewPoint.x += viewSize.width  - imageSize.width
			viewPoint.y += viewSize.height - imageSize.height
		case.topLeft: fallthrough
		default:
			break
		}
		
		 return viewPoint
	}
	
	func convertRect(fromImageRect imageRect: CGRect) -> CGRect {
		let imageTopLeft = imageRect.origin
		let imageBottomRight = CGPoint(x: imageRect.maxX, y: imageRect.maxY)
		
		let viewTopLeft = convertPoint(fromImagePoint: imageTopLeft)
		let viewBottomRight = convertPoint(fromImagePoint: imageBottomRight)
		
		var viewRect : CGRect = .zero
		viewRect.origin = viewTopLeft
		viewRect.size = CGSize(width: abs(viewBottomRight.x - viewTopLeft.x), height: abs(viewBottomRight.y - viewTopLeft.y))
		return viewRect
	}
	
	func convertPoint(fromViewPoint viewPoint: CGPoint) -> CGPoint {
		guard let imageSize = image?.size else { return CGPoint.zero }
		
		var imagePoint = viewPoint
		let viewSize = bounds.size
		
		let ratioX = viewSize.width / imageSize.width
		let ratioY = viewSize.height / imageSize.height
		
		switch contentMode {
		case .scaleAspectFit: fallthrough
		case .scaleAspectFill:
			var scale : CGFloat = 0
			
			if contentMode == .scaleAspectFit {
				scale = min(ratioX, ratioY)
			}
			else {
				scale = max(ratioX, ratioY)
			}
			
			// Remove the x or y margin added in FitMode
			imagePoint.x -= (viewSize.width  - imageSize.width  * scale) / 2.0
			imagePoint.y -= (viewSize.height - imageSize.height * scale) / 2.0
			
			imagePoint.x /= scale;
			imagePoint.y /= scale;
			
		case .scaleToFill: fallthrough
		case .redraw:
			imagePoint.x /= ratioX
			imagePoint.y /= ratioY
		case .center:
			imagePoint.x -= (viewSize.width - imageSize.width)  / 2.0
			imagePoint.y -= (viewSize.height - imageSize.height) / 2.0
		case .top:
			imagePoint.x -= (viewSize.width - imageSize.width)  / 2.0
		case .bottom:
			imagePoint.x -= (viewSize.width - imageSize.width)  / 2.0
			imagePoint.y -= (viewSize.height - imageSize.height);
		case .left:
			imagePoint.y -= (viewSize.height - imageSize.height) / 2.0
		case .right:
			imagePoint.x -= (viewSize.width - imageSize.width);
			imagePoint.y -= (viewSize.height - imageSize.height) / 2.0
		case .topRight:
			imagePoint.x -= (viewSize.width - imageSize.width);
		case .bottomLeft:
			imagePoint.y -= (viewSize.height - imageSize.height);
		case .bottomRight:
			imagePoint.x -= (viewSize.width - imageSize.width)
			imagePoint.y -= (viewSize.height - imageSize.height)
		case.topLeft: fallthrough
		default:
			break
		}
		
		return imagePoint
	}
	
	func convertRect(fromViewRect viewRect : CGRect) -> CGRect {
		let viewTopLeft = viewRect.origin
		let viewBottomRight = CGPoint(x: viewRect.maxX, y: viewRect.maxY)
		
		let imageTopLeft = convertPoint(fromImagePoint: viewTopLeft)
		let imageBottomRight = convertPoint(fromImagePoint: viewBottomRight)
		
		var imageRect : CGRect = .zero
		imageRect.origin = imageTopLeft
		imageRect.size = CGSize(width: abs(imageBottomRight.x - imageTopLeft.x), height: abs(imageBottomRight.y - imageTopLeft.y))
		return imageRect
	}

}