C# UIImage.AsPNG方法代码示例

		public System.IO.Stream RenderToStream (byte[] documentData, int pageIndex)
		{
			using (MemoryStream ms = new MemoryStream (documentData))
			{
				// open document
				using (Document doc = new Document (ms)) 
				{
					// prepare for rendering
					int width = (int)doc.Pages [pageIndex].Width;
					int height = (int)doc.Pages [pageIndex].Height;
					// render the page to a raw bitmap data represented by byte array
					byte[] imageData = ConvertBGRAtoRGBA(doc.Pages [pageIndex].RenderAsBytes (width,height, new RenderingSettings (), null));

					// create CGDataProvider which will serve CGImage creation
					CGDataProvider dataProvider = new CGDataProvider (imageData, 0, imageData.Length);

					// create core graphics image using data provider created above, note that
					// we use CGImageAlphaInfo.Last(ARGB) pixel format
					CGImage cgImage = new CGImage(width,height,8,32,width*4,CGColorSpace.CreateDeviceRGB(),CGImageAlphaInfo.Last,dataProvider,null,false, CGColorRenderingIntent.Default);

					// create UIImage and save it to gallery
					UIImage finalImage = new UIImage (cgImage);
								
					return finalImage.AsPNG ().AsStream();
				}
			}						
		}

        public override void DidCropToImage(TOCropViewController cropViewController, 
            UIImage image, CoreGraphics.CGRect cropRect, nint angle)
        {
            var imageBytes = image.AsPNG().ToArray();
            _taskCompletionSource.SetResult(imageBytes);

            cropViewController.DismissViewController(true, null);
        }

 public void SaveTrasnformedImage(UIImage source)
 {
     byte[] myByteArray;
     using (var imageData = source.AsPNG())
     {
         myByteArray = new byte[imageData.Length];
         System.Runtime.InteropServices.Marshal.Copy(imageData.Bytes, myByteArray, 0, Convert.ToInt32(imageData.Length));
     }
     SaveImageLocally(myByteArray, 101);
 }

 private static NSData GetData(UIImage image, ImageType type, int quality)
 {
     var floatQuality = quality/100f;
     switch(type)
     {
         case ImageType.Jpg:
             return image.AsJPEG(floatQuality);
         case ImageType.Png:
             return image.AsPNG();
         default:
             return image.AsJPEG(floatQuality);
     }
 } 

		public ImageData (UIImage image, string filename)
		{
			if (image == null) {
				throw new ArgumentNullException ("image");
			}
			if (string.IsNullOrEmpty (filename)) {
				throw new ArgumentException ("filename");
			}

			Image = image;
			Filename = filename;

			MimeType = (filename.ToLowerInvariant ().EndsWith (".png")) ?
				"image/png" : "image/jpeg";

			if (MimeType == "image/png") {
				Data = new NSDataStream (image.AsPNG ());
			}
			else {
				Data = new NSDataStream (image.AsJPEG ());
			}
		}

		public override void DidCropToImage (TOCropViewController cropViewController, UIImage image, CoreGraphics.CGRect cropRect, nint angle)
		{
			DidCrop = true;

			try 
			{
				if (image != null)
					App.CroppedImage = image.AsPNG().ToArray();

			}
			catch (Exception ex) {
				Debug.WriteLine (ex.Message);
			}
			finally
			{
				if (image != null) {
					image.Dispose ();
					image = null;
				}
			}

			parent.DismissViewController (true, App.PopModal);
		}

        private static Stream GetImageStream(UIImage image, ImageFormatType formatType)
        {
            if (formatType == ImageFormatType.Jpg)
                return image.AsJPEG().AsStream();

            return image.AsPNG().AsStream();
        }

		// Parse UIImage to Byte[]
		public static byte[] UIImageToByteArray (UIImage _image)
		{ 
			Byte[] byteArray; 
			using (NSData nsImageData = _image.AsPNG ()) { 
				byteArray = new Byte[nsImageData.Length]; 
				System.Runtime.InteropServices.Marshal.Copy (nsImageData.Bytes, byteArray, 0, Convert.ToInt32 (nsImageData.Length)); 
			} 

			return byteArray; 
		}

		public async Task SetGeneratedImageAsync (string key, UIImage uiImage, bool saveToDisk = true)
		{
			if (uiImage == null) {
				RemoveImage (key);
				return;
			}

			//
			// Does it already exist in memory?
			//
			SetMemoryImage (key, uiImage, DateTime.UtcNow);

			//
			// If we added it to memory, then save it to disk
			//
			if (saveToDisk) {
				await Task.Run (() => {
					FileSystemManager.EnsureDirectoryExists (cacheDirectory);
					var cachePath = GetCachePath (key);
					NSError err;
					uiImage.AsPNG ().Save (cachePath, false, out err);
					if (err != null) {
						Debug.WriteLine (err);
					}
				});
			}
		}

 public override void DidOutputImage(BlinkID blinkid, UIImage image, string name)
 {
     MessagingCenter.Send (new Messages.BlinkIDImage {
         Image = ImageSource.FromStream (() => image.AsPNG ().AsStream ())
     }, Messages.BlinkIDImageMessage);
 }