看似简单的功能，实施起来却是有着一堆大坑。
按着基本功能来写吧
1.选择图片并显示到Image控件中
2.图片序列化为byte数组以及反序列化
3.本地存储与读取
1.选择图片：
逻辑就是使用FileOpenPicker选择一个图片文件后，将该文件从StorageFile对象转化成可以赋值给Image.Source的ImageSource类的对象。
（这里需要注意的是WriteableBitmap，BitmapImage，SoftwareBitmapSource都可以赋值给Image.Source，你赋值给Image.Source的是什么对象，你就只能用as符把Image.Source转化成什么对象。 比如：你使用WriteableBitmap赋值给Image.Source，那么你后面只能用 var t = imageSource as WriteableBitmap, 你如果使用var t = imageSource as BitmapImage的话编译器不会报错，但是t的值最后会是null）
1.1 选取图片文件并实例化为WriteableBitmap对象
private async void ChoosePhoto()
{
FileOpenPicker fileOpenPicker = new FileOpenPicker();
fileOpenPicker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
fileOpenPicker.FileTypeFilter.Add(".jpg");
fileOpenPicker.FileTypeFilter.Add(".png");
fileOpenPicker.ViewMode = PickerViewMode.Thumbnail;
StorageFile imgFile_tmp = await fileOpenPicker.PickSingleFileAsync();
if (imgFile_tmp == null)
{
return;
}
else
{
this.imgFile = imgFile_tmp;
using (IRandomAccessStream stream = await imgFile.OpenAsync(FileAccessMode.Read))
{
var srcImage = new WriteableBitmap(,);
await srcImage.SetSourceAsync(stream);
Image_Thumbnail.Source = srcImage;
}
}
}
1.2 选取图片文件并实例化为BitmapImage对象
private async void ChoosePhoto()
{
FileOpenPicker fileOpenPicker = new FileOpenPicker();
fileOpenPicker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
fileOpenPicker.FileTypeFilter.Add(".jpg");
fileOpenPicker.FileTypeFilter.Add(".png");
fileOpenPicker.ViewMode = PickerViewMode.Thumbnail;
StorageFile imgFile_tmp = await fileOpenPicker.PickSingleFileAsync();
if (imgFile_tmp == null)
{
return;
}
else
{
this.imgFile = imgFile_tmp;
using (IRandomAccessStream stream = await imgFile.OpenAsync(FileAccessMode.Read))
{
var srcImage = new BitmapImage();
await srcImage.SetSourceAsync(stream);
Image_Thumbnail.Source = srcImage;
}
}
}
1.3 选取图片实例化为SoftwareBitmapSource对象
private async void ChoosePhoto()
{
FileOpenPicker fileOpenPicker = new FileOpenPicker();
fileOpenPicker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
fileOpenPicker.FileTypeFilter.Add(".jpg");
fileOpenPicker.FileTypeFilter.Add(".png");
fileOpenPicker.ViewMode = PickerViewMode.Thumbnail;
StorageFile imgFile_tmp = await fileOpenPicker.PickSingleFileAsync();
if (imgFile_tmp == null)
{
return;
}
else
{
SoftwareBitmap softwareBitmap;
this.imgFile = imgFile_tmp;
using (IRandomAccessStream stream = await imgFile.OpenAsync(FileAccessMode.Read))
{
// Create the decoder from the stream
BitmapDecoder decoder = await BitmapDecoder.CreateAsync(stream);
// Get the SoftwareBitmap representation of the file
softwareBitmap = await decoder.GetSoftwareBitmapAsync();
}
if (softwareBitmap.BitmapPixelFormat != BitmapPixelFormat.Bgra8 || softwareBitmap.BitmapAlphaMode == BitmapAlphaMode.Straight)
{
softwareBitmap = SoftwareBitmap.Convert(softwareBitmap, BitmapPixelFormat.Bgra8, BitmapAlphaMode.Premultiplied);
}
var source = new SoftwareBitmapSource();
await source.SetBitmapAsync(softwareBitmap);
// Set the source of the Image control
Image_Thumbnail.Source = source;
}
}
2.图片序列化为byte数组以及反序列化
2.1 WriteableBitmap对象（Image.Source赋值的时候使用的是WriteableBitmap）序列化为byte数组
public static async Task<byte[]> SaveToBytesAsync(ImageSource imageSource)
{
byte[] imageBuffer;
var localFolder = ApplicationData.Current.TemporaryFolder;
var file = await localFolder.CreateFileAsync("temp.jpg", CreationCollisionOption.GenerateUniqueName);
using (var ras = await file.OpenAsync(FileAccessMode.ReadWrite, StorageOpenOptions.None))
{
WriteableBitmap bitmap = imageSource as WriteableBitmap;
var stream = bitmap.PixelBuffer.AsStream();
byte[] buffer = new byte[stream.Length];
await stream.ReadAsync(buffer, , buffer.Length);
BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, ras);
encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Ignore, (uint)bitmap.PixelWidth, (uint)bitmap.PixelHeight, 96.0, 96.0, buffer);
await encoder.FlushAsync(); var imageStream = ras.AsStream();
imageStream.Seek(, SeekOrigin.Begin);
imageBuffer = new byte[imageStream.Length];
var re = await imageStream.ReadAsync(imageBuffer, , imageBuffer.Length);
}
await file.DeleteAsync(StorageDeleteOption.Default);
return imageBuffer;
}
2.2Byte数组反序列化为ImageSource（WriteableBitmap）
public static async Task<ImageSource> SaveToImageSource(byte[] imageBuffer)
{
ImageSource imageSource = null;
try
{
using (MemoryStream stream = new MemoryStream(imageBuffer))
{
var ras = stream.AsRandomAccessStream();
BitmapDecoder decoder = await BitmapDecoder.CreateAsync(BitmapDecoder.JpegDecoderId, ras);
var provider = await decoder.GetPixelDataAsync();
byte[] buffer = provider.DetachPixelData();
WriteableBitmap bitmap = new WriteableBitmap((int)decoder.PixelWidth, (int)decoder.PixelHeight);
await bitmap.PixelBuffer.AsStream().WriteAsync(buffer, , buffer.Length);
imageSource = bitmap;
}
}
catch (Exception ex)
{ }
return imageSource;
}
2.3 BitmapImage对象序列化为byte数组
需要注意的是这里所调用的BitmspImage对象，必须是使用BitmapImage(uri)方法实例化出来的BitmapImage对象，因此下列方法主要用于实现对网络图片的序列化与反序列化。
如果使用从FileOpenPicker选取出来图片文件实例化出来的BitmapImage对象的话，该对象的UriSource属性为空，故下列方法无法实现。
RandomAccessStreamReference random = RandomAccessStreamReference.CreateFromUri(himage.UriSource);
IRandomAccessStreamWithContentType streamWithContent = await random.OpenReadAsync();
byte[] buffer = new byte[streamWithContent.Size];
await streamWithContent.ReadAsync(buffer.AsBuffer(), (uint)streamWithContent.Size, InputStreamOptions.None);
2.4 byte数组反序列化为BitmapImage对象
BitmapImage image = new BitmapImage();
using (InMemoryRandomAccessStream stream = new InMemoryRandomAccessStream())
{
await stream.WriteAsync(obj.ImgArray.AsBuffer());
stream.Seek();
await image.SetSourceAsync(stream);
}
3.本地存储与读取
（需要注意的是：StorageFile这类的存储操作貌似只允许存一些简单的数据类型，所以我的解决方法就是把自定义的类的对象里的图片转化为byte数组，然后再将自定义类的对象的List转化成json字符串存进文件，读取文件的时候再读出这些Json字符串并反序列化为我需要的类型）
3.1 存储数据
public static async Task SaveData(string filename, T data)
{
try
{
StorageFile file = await ApplicationData.Current.LocalFolder.CreateFileAsync(filename, CreationCollisionOption.ReplaceExisting);
using (IRandomAccessStream raStream = await file.OpenAsync(FileAccessMode.ReadWrite))
{
using (IOutputStream outStream = raStream.GetOutputStreamAt())
{ var json = JsonConvert.SerializeObject(data);
DataContractSerializer serializer = new DataContractSerializer(typeof(string));
serializer.WriteObject(outStream.AsStreamForWrite(), json);
var t =JsonConvert.DeserializeObject<T>(json);
await outStream.FlushAsync();
}
}
}
catch (Exception exc)
{
throw exc;
}
}
3.2 加载数据
public static async System.Threading.Tasks.Task<List<ShowInfo>> LoadData(string filename)
{
try
{
if (ApplicationData.Current.LocalFolder.TryGetItemAsync(filename) != null)
{
StorageFile file = await ApplicationData.Current.LocalFolder.GetFileAsync(filename);
using (IInputStream inStream = await file.OpenSequentialReadAsync())
{
DataContractSerializer serializer = new DataContractSerializer(typeof(string));
var json = (string)serializer.ReadObject(inStream.AsStreamForRead());
var data = JsonConvert.DeserializeObject<List<ShowInfo>>(json);
return data;
}
}
else
{
return new List<ShowInfo>();
} }
catch (FileNotFoundException ex)
{
throw ex;
}
catch (Exception ex)
{
throw ex;
}
}