Windows 8學習筆記(十一)—圖片的顯示與儲存

圖片顯示

圖片的顯示應該都非常熟悉，情境很多，我先把我想的三個列舉一下：

情境一：

從本地圖片庫選擇圖片進行顯示：

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;        }

 

情境二：

直接請求網路URL

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

方法一：

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

方法二：

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;        }

若是簡單的顯示圖片，用方法一就足夠了，若需要儲存圖片，還是用方法二，因為方法一我目前還沒有辦法截取到它的流，除非再用HttpRequest請求一次;用方法二相對而言，就方便多了。

 

情境三：

顯示項目檔案中的圖片

string url = "ms-appx:///images/flower.jpg";

方法一：

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

方法二：

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;        }

原理與情境二是類似的

 

儲存圖片

儲存圖片也分兩種情況

直接儲存到圖片庫

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

RandomAccessStreamToBuffer是自定的轉換方法,在前面流的轉換中也已寫了,這裡再寫一下吧..

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();            }        }

 

顯示儲存檔案對話方塊，可以自行選擇儲存路徑，這時需用到FileSavePicker

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();

 

可能我上面的方法不是很簡單方便，希望有更簡捷的同胞可以共同分享下哈~