Windows 8学习笔记(十一)图片的显示与保存

图片显示

图片的显示应该都非常熟悉，场景很多，我先把我想的三个列举一下：

场景一：

从本地图片库选择图片进行显示：

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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;

        }

场景二：

直接请求网络URL

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

方法一：

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BitmapImage bitmapImage = new BitmapImage(new Uri(url));

img.Source = bitmapImage;

方法二：

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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;

        }

若是简单的显示图片，用方法一就足够了，若需要保存图片，还是用方法二，因为方法一我目前还没有办法截取到它的流，除非再用HttpRequest请求一次;用方法二相对而言，就方便多了。

 

场景三：

显示项目文件中的图片

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

方法一：

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BitmapImage bitmapImage = new BitmapImage(new Uri(url));

img.Source = bitmapImage;

方法二：

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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;

        }

原理与场景二是类似的

 

保存图片

保存图片也分两种情况

直接保存到图片库

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StorageFolder folder = KnownFolders.PicturesLibrary;

storageFile = await folder.CreateFileAsync("sample.jpg", CreationCollisionOption.ReplaceExisting);

IBuffer buffer = RandomAccessStreamToBuffer(streamRandom);

await FileIO.WriteBufferAsync(storageFile, buffer);

RandomAccessStreamToBuffer是自定的转换方法,在前面流的转换中也已写了,这里再写一下吧..

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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();

            }

        }

显示保存文件对话框，可以自行选择保存路径，这时需用到FileSavePicker

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FileSavePicker fileSave = new FileSavePicker();

fileSave.SuggestedSaveFile = storageFile;

fileSave.SuggestedStartLocation = PickerLocationId.Desktop;

fileSave.SuggestedFileName = "test418";

fileSave.DefaultFileExtension = ".jpg";

fileSave.FileTypeChoices.Add("JPEG file", new List<string> { ".jpg" });

StorageFile file = await fileSave.PickSaveFileAsync();</string>

可能我上面的方法不是很简单方便，希望有更简捷的同胞可以共同分享下哈~

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