Android 11 Api 30 使用 Xamarin Essentials 拍照并保存到设备

Question

是否可以使用 Xamarin Essentials 拍摄 Android 11 - Api 30 的照片并将其保存到设备中？我过去曾使用 Xam.Media.Plugin 来执行此操作。但我更愿意只使用 Xamarin Essentials。我目前让我的应用程序拍照，然后以编程方式将每张照片上传到 Azure（运行良好）。但是，我还想在互联网连接不佳时将照片副本保存到设备上作为备份，我的用户经常遇到这种情况。下面的代码没有捕获并显示下面的两个警报，但是没有任何内容保存到我的设备中。我的代码包含在下面：

        private async void TakePhoto()
        {
            try
            {
                Console.WriteLine("Camera started");

                string fN = "RI-" + Asset_ID.Text + lblUniqueName.Text + ".jpg";

                var file = await MediaPicker.CapturePhotoAsync();

                if (file == null)
                    return;

                var content = new MultipartFormDataContent();
                content.Add(new StreamContent(await file.OpenReadAsync()), "file", fN);

                string directory = Environment.GetFolderPath(System.Environment.SpecialFolder.Personal) + "/pictures";
                string filePath = Path.Combine(directory, fN);

                DirectoryInfo info = new DirectoryInfo(directory);
                if (!info.Exists)
                {
                    info.Create();
                }

                Stream fileStream = await file.OpenReadAsync();
                await DisplayAlert("1", "Stream Read", "OK");
                using (FileStream outputFileStream = new FileStream(filePath, FileMode.Create))
                {
                    fileStream.CopyTo(outputFileStream);
                }
                await DisplayAlert("2", "Stream Saved", "OK");
                var httpClient = new HttpClient();

                var response = await httpClient.PostAsync("https://tasmanoperationsportal.azurewebsites.net/UploadFile", content);

                Console.WriteLine("App Returned");
                await DisplayAlert("Successful", "Photo uploaded to the cloud", "OK");
            }
            catch
            {
                await DisplayAlert("Unsuccessful", "No internet connectivity, use default camera App and upload later", "OK");
            }
        }

Android清单

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" android:versionCode="1" android:versionName="1.0" package="com.companyname.tcminspect2_0" android:installLocation="auto">
    <uses-sdk android:minSdkVersion="19" android:targetSdkVersion="30" />
    <application android:label="TCmInspect2_0.Android" android:theme="@style/MainTheme" android:requestLegacyExternalStorage="true" ></application>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.CAMERA" />
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-feature android:name="android.hardware.location" android:required="false" />
    <uses-feature android:name="android.hardware.location.gps" android:required="false" />
    <uses-feature android:name="android.hardware.location.network" android:required="false" />
    <uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
</manifest>

Answer 1

可以参考Media Picker官方文档 (https://docs.microsoft.com/en-us/xamarin/essentials/media-picker?context=xamarin%2Fandroid&tabs=android)

根据你的代码，你使用后string filePath = Path.Combine(directory, fN);就可以使用

using (var stream = await file.OpenReadAsync())
using (var newStream = File.OpenWrite(filePath))
    await stream.CopyToAsync(newStream);
PhotoPath = filePath;

PhotoPath为文件所在路径saved.Then只需要调用PhotoPath即可获取本地存储的图片

我创建了一个简单的示例供您参考（我创建了一个按钮来拍照并将其保存到设备）：

cs页面代码如下：

public string PhotoPath { get; set; } = null;
public MainPage()
{
    InitializeComponent();
}

private async void Button_Clicked(object sender, EventArgs e)
{
    var file = await MediaPicker.CapturePhotoAsync();
    await LoadPhotoAsync(file);
    if (file == null)
        return;
    async Task LoadPhotoAsync(FileResult photo)
    {
        // canceled
        if (photo == null)
        {
            PhotoPath = null;
            return;
        }
        // save the file into local storage
        var newFile = Path.Combine(FileSystem.CacheDirectory, photo.FileName);
        using (var stream = await photo.OpenReadAsync())
        using (var newStream = File.OpenWrite(newFile))
            await stream.CopyToAsync(newStream);
        PhotoPath = newFile;
        myImg.Source = PhotoPath;//Show on the front page
    }
}

截图如下：

Android 11 Api 30 使用 Xamarin Essentials 拍照并保存到设备

Android 11 Api 30 with Xamarin Essentials Take Photo and save to device

android

save

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