Windows 8 learning notes (11)-display and save images

Image Display

Image display should be very familiar with many scenarios. Let me first list the three items I want:

Scenario 1:

Select an image from the local image library for display:

async private void LoadPictureByPicker()        {            FileOpenPicker fileOpen = new FileOpenPicker()            {                FileTypeFilter={ ".jpg", ".jpeg", ".png", ".bmp" },                ViewMode=PickerViewMode.Thumbnail,                SuggestedStartLocation=PickerLocationId.PicturesLibrary            };           bitmapImage = new BitmapImage();           storageFile = await fileOpen.PickSingleFileAsync();           if (storageFile != null)           {               using (IRandomAccessStream stream = await storageFile.OpenAsync(FileAccessMode.Read))               {                   bitmapImage.SetSource(stream);               }           }           img.Source = bitmapImage;        }

 

Scenario 2:

Directly request the network URL

String url = "http://ww4.sinaimg.cn/bmiddle/8193c63ajw1ds3o5e56jaj.jpg ";

Method 1:

BitmapImage bitmapImage = new BitmapImage(new Uri(url));img.Source = bitmapImage;

Method 2:

async private void LoadPictrueByUrl()        {            var  rass = RandomAccessStreamReference.CreateFromUri(new Uri(url));            streamRandom = await rass.OpenReadAsync();            var bitmapImage = new BitmapImage();            bitmapImage.SetSource(streamRandom);            img.Source = bitmapImage;        }

If you simply display an image, it is enough to use method 1. If you need to save the image, use method 2, because method 1 has no way to capture the stream, unless the httprequest request is used again, it is much more convenient to use method 2.

Scenario 3:

Show images in the project file

String url = "MS-appx: // images/flower.jpg ";

Method 1:

BitmapImage bitmapImage = new BitmapImage(new Uri(url));img.Source = bitmapImage;

Method 2:

async private void LoadPictureByNative()        {            var  rass = RandomAccessStreamReference.CreateFromUri(new Uri(url));            streamRandom = await rass.OpenReadAsync();            var bitmapImage = new BitmapImage();            bitmapImage.SetSource(streamRandom);            img.Source = bitmapImage;        }

The principle is similar to scenario 2.

Save image

There are two ways to save an image:

Save to image library directly

StorageFolder folder = KnownFolders.PicturesLibrary;storageFile = await folder.CreateFileAsync("sample.jpg", CreationCollisionOption.ReplaceExisting);IBuffer buffer = RandomAccessStreamToBuffer(streamRandom);await FileIO.WriteBufferAsync(storageFile, buffer);

Randomaccessstreamtobuffer is a custom conversion method. It has already been written in the previous Stream Conversion. Please write it again here ..

private IBuffer RandomAccessStreamToBuffer(IRandomAccessStream randomstream)        {            Stream stream = WindowsRuntimeStreamExtensions.AsStreamForRead(randomstream.GetInputStreamAt(0));            MemoryStream memoryStream = new MemoryStream();            if (stream != null)            {                byte[] bytes = ConvertStreamTobyte(stream);                if (bytes != null)                {                    var binaryWriter = new BinaryWriter(memoryStream);                    binaryWriter.Write(bytes);                }            }            IBuffer buffer = WindowsRuntimeBufferExtensions.GetWindowsRuntimeBuffer(memoryStream, 0, (int)memoryStream.Length);            return buffer;        }        public static byte[] ConvertStreamTobyte(Stream input)        {            byte[] buffer = new byte[16 * 1024];            using (MemoryStream ms = new MemoryStream())            {                int read;                while ((read = input.Read(buffer, 0, buffer.Length)) > 0)                {                    ms.Write(buffer, 0, read);                }                return ms.ToArray();            }        }

 

The Save file dialog box is displayed. You can select a save path.

FileSavePicker fileSave = new FileSavePicker();fileSave.SuggestedSaveFile = storageFile;fileSave.SuggestedStartLocation = PickerLocationId.Desktop;fileSave.SuggestedFileName = "test418";fileSave.DefaultFileExtension = ".jpg";fileSave.FileTypeChoices.Add("JPEG file", new List
 
   { ".jpg" });StorageFile file = await fileSave.PickSaveFileAsync();
 

 

Maybe the method above is not very simple and convenient. I hope more simple people can share it with me ~