04、Quick Start for Windows
创建一个新工程
1、在 VS 上,选择 File > New > Project..
2、在新工程窗口,选择 Visual C# > Windows Store > Blank App(XAML)
3、点击 OK.
向工程中添加类库
在使用 Nokia Imaging SDK 类库中的功能时,首先需要添加相应类库,请参考
Adding libraries to the project.
移除 Any CPU platform 选项
Nokia Imaging SDK 支持 ARM 和 X86 平台,不支持 Any CPU 。在编译引用了 Nokia Imaging SDK
的工程前,你必须移除 Any CPU 选项。
1、在 VS 工具栏,选择 Solution Configuration
2、选择 Configuration Manager...
3、从 Platform 中选择 <Edit...> 然后点击 Any CPU
4、点击 Remove
定义你的 XAML UI
这里定义的 UI 很简单,只有两个 XAML image 控件和两个 按钮。一个 Image 控件显示
原图,另一个显示经过滤镜处理的 Image。另外,一个按钮用来选择图片,另一个保存图片。
实现步骤
用下面的 XAML 替换 MainPage.xaml 中的 Grid:
<Grid Background="Transparent"> <Grid.RowDefinitions> <RowDefinition Height="Auto"/> <RowDefinition Height="*"/> <RowDefinition Height="Auto"/> </Grid.RowDefinitions> <Image x:Name="CartoonImage" Stretch="UniformToFill" Grid.RowSpan="3" /> <Image x:Name="OriginalImage" Width="334" Height="200" Stretch="UniformToFill" Grid.Row="1" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="12,12,0,0" /> <TextBlock Text="Nokia Imaging SDK" Grid.Row="0" Style="{StaticResource TitleTextBlockStyle}" /> <Button Content="Pick an image" Click="PickImage_Click" HorizontalAlignment="Left" Grid.Row="2" /> <Button Content="Save the image" Click="SaveImage_Click" x:Name="SaveButton" HorizontalAlignment="Right"
Grid.Row="2" IsEnabled="False" /> </Grid>
从 Camera Roll 中选择图片
接下来在 MainPage.xaml.cs 中使用 Win RT 库中提供的 FileOpenPicker 选择图片:
private async void PickImage_Click(object sender, RoutedEventArgs e) { SaveButton.IsEnabled = false; var openPicker = new FileOpenPicker { SuggestedStartLocation = PickerLocationId.PicturesLibrary, ViewMode = PickerViewMode.Thumbnail }; // Filter to include a sample subset of file types. openPicker.FileTypeFilter.Clear(); openPicker.FileTypeFilter.Add(".bmp"); openPicker.FileTypeFilter.Add(".png"); openPicker.FileTypeFilter.Add(".jpeg"); openPicker.FileTypeFilter.Add(".jpg"); // Open the file picker. StorageFile file = await openPicker.PickSingleFileAsync(); // file is null if user cancels the file picker. if (file != null) { if (await ApplyFilter(file)) return; SaveButton.IsEnabled = true; } } private async Task<bool> ApplyFilter(StorageFile file) { IRandomAccessStream fileStream = await file.OpenAsync(FileAccessMode.Read); return false; }
当用户选择了图片,我们通过 IRandomAccessStream 来打开文件。
使用 FilterEffect 来为图片添加一个 effect
1、添加下面的命名空间,来自 SDK
using Nokia.Graphics.Imaging; using Windows.UI.Xaml.Media.Imaging;
2、下面的命名空间用来 “选择” 和 “保存” 图片
using Windows.Storage.Streams; using Windows.Storage.Pickers; using Windows.Storage;
3、在 MainPage.xaml.cs 中,定义以下成员变量:
public sealed partial class MainPage : Page { // FilterEffect instance is used to apply different // filters to an image. // Here we will apply Cartoon filter to an image. private FilterEffect _cartoonEffect; // The following WriteableBitmap contains // The filtered and thumbnail image. private WriteableBitmap _cartoonImageBitmap; private WriteableBitmap _thumbnailImageBitmap;
4、然后在构造函数中,初始化这些变量:
public MainPage() { InitializeComponent(); Rect bounds = Window.Current.Bounds; _cartoonImageBitmap = new WriteableBitmap((int)bounds.Width, (int)bounds.Height); _thumbnailImageBitmap = new WriteableBitmap((int)OriginalImage.Width, (int)OriginalImage.Height); }
5、当用户选择完图片,我们就为图片添加滤镜。在这里我们添加 Cartoon 滤镜,然后把结果显示到 XAML
上的 Image 控件(CartoonImage):
private async Task<bool> ApplyFilter(StorageFile file) { // Open a stream for the selected file. IRandomAccessStream fileStream = await file.OpenAsync(FileAccessMode.Read); try { // Show thumbnail of original image. _thumbnailImageBitmap.SetSource(fileStream); OriginalImage.Source = _thumbnailImageBitmap; // Rewind stream to start. fileStream.Seek(0); // A cartoon effect is initialized with selected image stream as source. var imageStream = new RandomAccessStreamImageSource(fileStream); _cartoonEffect = new FilterEffect(imageStream); // Add the cartoon filter as the only filter for the effect. var cartoonFilter = new CartoonFilter(); _cartoonEffect.Filters = new[] {cartoonFilter}; // Render the image to a WriteableBitmap. var renderer = new WriteableBitmapRenderer(_cartoonEffect, _cartoonImageBitmap); _cartoonImageBitmap = await renderer.RenderAsync(); // Set the rendered image as source for the cartoon image control. CartoonImage.Source = _cartoonImageBitmap; } catch (Exception exception) { var dia = new MessageDialog(exception.Message); dia.ShowAsync(); return true; } return false; }
添加相应的权限
因为应用程序需要从 Pictures 文件夹读取数据,所以需要添加相应的权限:
1、在 VS 解决方案中,打开package.appxmanifest
2、选择 Capabilities 选项卡,然后选择Pictures Library,如下图:
生成和编码全尺寸 JPEG 图片
使用 FilterEffect 类的对象来输出全尺寸 JPEG 图片是很简单的。原图的每一个像素都会被
处理并且输出 JPEG 格式。
下面的示例演示如何把滤镜处理后的全尺寸图片保存到文件:
private async void SaveImage_Click(object sender, RoutedEventArgs e) { SaveButton.IsEnabled = false; if (_cartoonEffect == null) { return; } var jpegRenderer = new JpegRenderer(_cartoonEffect); // Jpeg renderer gives the raw buffer for the filtered image. IBuffer jpegOutput = await jpegRenderer.RenderAsync(); var picker = new FileSavePicker(); picker.FileTypeChoices.Add("JPG File", new List<string> { ".jpg" }); picker.SuggestedFileName = string.Format("CartoonImage_{0:G}", DateTime.Now); StorageFile file = await picker.PickSaveFileAsync(); if (file != null) { using (IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.ReadWrite)) { await stream.WriteAsync(jpegOutput); await stream.FlushAsync(); } } SaveButton.IsEnabled = true; }
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