如何让你的UWP应用程序无缝调用几何作图

有时候需要编辑一些几何图形，如三角形，圆锥曲线等，在UWP应用中加入这些几何作图功能是件费时间又很难做好的事。其实Windows 10 应用商店中已有一些专业的几何作图工具了，那么能借来一用吗？答案是肯定的。

UWP中，微软为Windows.System.Launcher启动器新增了很多的功能，以前只能启动App，打开指定扩展名文件，对uri协议的解析，以及当启动的应用没有安装时则会提示前往商店下载等。

如今，微软丰富了Launcher的功能，通过新增的LaunchUriForResultsAsync API，Windows应用程序可以相互启动并交换数据和文件。利用这个新的API，使得以前需要多个App才能完成的复杂任务现在可以无缝的进行处理，使用户根本无法感觉到应用之间的切换。比如我们可以构想这么一个场景：在一个文本编辑APP中打开一个几何作图APP，完成几何作图后返回几何图片及数据到文本编辑APP。然后点击该图片即可以再次启动几何作图APP编辑几何图形，编辑图形完成后，传递新的图片返回原APP。

首先我们需要从Windows 10 应用商店中安装一个几何作图APP。这里以“活动几何”APP为例，选择它的原因是：1.免费；2.有中文界面；3功能足够。

然后我们就可以上代码了：

Xaml 代码：

    <Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
        <StackPanel Margin="20">
            <Button x:Name="DoTest" Content="Do test" Click="DoTest_Click" />
            <CheckBox x:Name="IsIncludeProcess" Content="IncludeProcess" IsChecked="True" />
            <TextBlock x:Name="ShowMessage" Foreground="Red" />
            <Button x:Name="DoEdit" Content="Edit the Geometry" Click="DoEdit_Click" Visibility="Collapsed" />

            <ScrollViewer Height="600" Width="800" >
                <Image x:Name="ShowImage" />
            </ScrollViewer>
        </StackPanel>
    </Grid>

我们的Sample App界面是这样的（为突出重点，省去文本编辑功能代码）：

在“Do test”按钮点击事件函数中：

定义一个LauncherOptions变量，设置属性TargetApplicationPackageFamilyName 为该几何作图APP的PackageFamilyName，这里为62301LeonLi.ActiveGeometry_496e9sjp76zt6 :

var options = new LauncherOptions();
            options.TargetApplicationPackageFamilyName = "62301LeonLi.ActiveGeometry_496e9sjp76zt6";

定义一个启动Uri变量:

Uri uri = new Uri("ag.editgeometry:?");

还需要一个传入参数的ValueSet变量 inputData：

   ValueSet inputData = new ValueSet();

这样就可以调用LaunchUriForResultsAsync函数启动几何作图APP并将返回结果赋值给LaunchUriResult变量：

LaunchUriResult resultData = await Launcher.LaunchUriForResultsAsync(uri, options, inputData);

启动该几何作图APP后是这样的：

在几何作图完成后，点击返回按钮：

resultData的属性Status 为 LaunchUriStatus.Success 的话，就表示成功了。下面的代码是对返回的结果进行处理:

ValueSet theValues = resultData.Result;
                    var resultState = theValues["ReturnedState"] as string;
                    switch (resultState)
                    {
                        case "Success":
                            if (theValues.ContainsKey("ImgFileToken"))
                            {
                                var tokenObject = theValues["ImgFileToken"];
                                if (tokenObject != null)
                                {
                                    var token = tokenObject.ToString();
                                    var imgFile = await SharedStorageAccessManager.RedeemTokenForFileAsync(token);
                                    if (imgFile != null)
                                    {
                                        try
                                        {
                                            IRandomAccessStream imageStream = await imgFile.OpenReadAsync();
                                            BitmapImage bitmapImage = new BitmapImage();
                                            bitmapImage.SetSource(imageStream);
                                            ShowImage.Source = bitmapImage;
                                        }
                                        finally { }
                                    }
                                }
                            }

                            if (theValues.ContainsKey("DataFileToken"))
                            {
                                var tokenObject = theValues["DataFileToken"];
                                if (tokenObject != null)
                                {
                                    var token = tokenObject.ToString();
                                    var dataFile = await SharedStorageAccessManager.RedeemTokenForFileAsync(token);
                                    if (dataFile != null)
                                    {
                                        var localFolder = Windows.Storage.ApplicationData.Current.LocalFolder;
                                        file_demonstration = await dataFile.CopyAsync(localFolder);
                                        DoEdit.Visibility = Visibility.Visible;
                                    }
                                }
                            }
                            ShowMessage.Text = "Success";
                            break;                    }
                }

StorageFile file_demonstration;

imgFile是传回的图片文件，可以将该图片插入你想要的地方；dataFile是相应的数据文件，将该文件拷贝到你自己APP的目录下，用文件变量file_demonstration记住它，如果选择了“IsIncludeProcess”，则该文件中还包括了作图过程的数据。现在Sample App是这样的了:

可以看到在得到的几何图上新出现了一个“Edit the Geometry”按钮，这是用于再次编辑该几何图形的:

        private async void DoEdit_Click(object sender, RoutedEventArgs e)
        {
            if (file_demonstration == null)
                return;

            var token = SharedStorageAccessManager.AddFile(file_demonstration);
            ValueSet inputData = new ValueSet();
            inputData.Add("EditFileToken", token);
            await EditGeometry(true, inputData);
        }

完整的代码如下：

namespace CallEditGeometryAppSample
{
    /// <summary>
    /// An empty page that can be used on its own or navigated to within a Frame.
    /// </summary>
    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();
        }

        private async void DoTest_Click(object sender, RoutedEventArgs e)
        {
            EditGeometry(true);
        }

        public async void EditGeometry(bool needResult)
        {
            bool isNew = true;

            ValueSet inputData = new ValueSet();
            if (isNew)
            {
            }
            else
            {
                FileOpenPicker openPicker = new FileOpenPicker();
                openPicker.ViewMode = PickerViewMode.List;
                openPicker.FileTypeFilter.Add(".sam");
                openPicker.FileTypeFilter.Add(".sdz");
                var gpxFile = await openPicker.PickSingleFileAsync();
                if (gpxFile == null)
                {
                    return;
                }

                var token = SharedStorageAccessManager.AddFile(gpxFile);
                inputData.Add("EditFileToken", token);
            }

            await EditGeometry(needResult, inputData);

        }

        private async System.Threading.Tasks.Task EditGeometry(bool needResult, ValueSet inputData)
        {
            var options = new LauncherOptions();
            options.TargetApplicationPackageFamilyName = "62301LeonLi.ActiveGeometry_496e9sjp76zt6";

            Uri uri = new Uri("ag.editgeometry:?");

            if (!needResult)
            {
                await Launcher.LaunchUriAsync(uri, options, inputData);
                ShowMessage.Text = "No Reuslt Success";
            }
            else
            {
                if (!IsIncludeProcess.IsChecked.Value)
                {
                    inputData.Add("IncludeProcess", "N");
                }

                LaunchUriResult resultData = await Launcher.LaunchUriForResultsAsync(uri, options, inputData);
                ShowMessage.Text = resultData.Status.ToString();
                if (resultData.Status == LaunchUriStatus.Success &&
                    resultData.Result != null &&
                    resultData.Result.ContainsKey("ReturnedState"))
                {
                    ValueSet theValues = resultData.Result;
                    var resultState = theValues["ReturnedState"] as string;
                    switch (resultState)
                    {
                        case "Success":
                            if (theValues.ContainsKey("ImgFileToken"))
                            {
                                var tokenObject = theValues["ImgFileToken"];
                                if (tokenObject != null)
                                {
                                    var token = tokenObject.ToString();
                                    var imgFile = await SharedStorageAccessManager.RedeemTokenForFileAsync(token);
                                    if (imgFile != null)
                                    {
                                        try
                                        {
                                            IRandomAccessStream imageStream = await imgFile.OpenReadAsync();
                                            BitmapImage bitmapImage = new BitmapImage();
                                            bitmapImage.SetSource(imageStream);
                                            ShowImage.Source = bitmapImage;
                                        }
                                        finally { }
                                    }
                                }
                            }

                            if (theValues.ContainsKey("DataFileToken"))
                            {
                                var tokenObject = theValues["DataFileToken"];
                                if (tokenObject != null)
                                {
                                    var token = tokenObject.ToString();
                                    var dataFile = await SharedStorageAccessManager.RedeemTokenForFileAsync(token);
                                    if (dataFile != null)
                                    {
                                        var localFolder = Windows.Storage.ApplicationData.Current.LocalFolder;
                                        file_demonstration = await dataFile.CopyAsync(localFolder);
                                        DoEdit.Visibility = Visibility.Visible;
                                    }
                                }
                            }
                            ShowMessage.Text = "Success";
                            break;
                        case "Error":
                            var resultMessage = theValues["ReturnedMessage"] as string;
                            if (resultMessage == "Duplicate")
                            {
                                string mes = "Active Geometry has opened another windows. Please close it first.";
                                ShowMessage.Text = mes;
                            }

                            var isCloseByOther = theValues["ByOtherClosed"] as string;
                            if (isCloseByOther != "Y")
                            {
                                ShowMessage.Text += " ---   By Other Closed";
                            }
                            break;
                    }
                }
            }
        }

        StorageFile file_demonstration;

        private async void DoEdit_Click(object sender, RoutedEventArgs e)
        {
            if (file_demonstration == null)
                return;

            var token = SharedStorageAccessManager.AddFile(file_demonstration);
            ValueSet inputData = new ValueSet();
            inputData.Add("EditFileToken", token);
            await EditGeometry(true, inputData);
        }
    }
}

如果你连拷贝代码都懒得话，就下载这个sample的压缩文件吧！