Xamarion.IOS UIImage圖片的裁剪縮放等__IOS

應用中需要提取圖片的一部分來進行顯示，研究了一晚上也沒搞清楚雜整的，只有求助於google了，xamain的forum中找有人把辦法貼出來了。

Mark 一下。

參考：http://forums.xamarin.com/discussion/4170/resize-images-and-save-thumbnails

// resize the image to be contained within a maximum width and height, keeping aspect ratiopublic UIImage MaxResizeImage(UIImage sourceImage, float maxWidth, float maxHeight){    var sourceSize = sourceImage.Size;    var maxResizeFactor = Math.Max(maxWidth / sourceSize.Width, maxHeight / sourceSize.Height);    if (maxResizeFactor > 1) return sourceImage;    var width = maxResizeFactor * sourceSize.Width;    var height = maxResizeFactor * sourceSize.Height;    UIGraphics.BeginImageContext(new SizeF(width, height));    sourceImage.Draw(new RectangleF(0, 0, width, height));    var resultImage = UIGraphics.GetImageFromCurrentImageContext();    UIGraphics.EndImageContext();    return resultImage;}// resize the image (without trying to maintain aspect ratio)public UIImage ResizeImage(UIImage sourceImage, float width, float height){    UIGraphics.BeginImageContext(new SizeF(width, height));    sourceImage.Draw(new RectangleF(0, 0,