Question

有人能指出我拍摄照片并使用MVVMCross 存储照片的示例吗？

我一直在寻找，但只发现了这个：

Monodroid Take a picture with Camera（不实施MVVMCross）
Video Recording（这是视频而我无法正常工作：S）
The Oficialy Recipe Example（虽然有效，但未实施MVVMCross）

谢谢！

已解决！谢谢！
对未来参考文献:(使用Master Branch）
致Stuart的信用，我刚刚更改了代码以适应我的现实

using Cirrious.MvvmCross.ExtensionMethods;
using Cirrious.MvvmCross.Interfaces.Platform.Tasks;
using Cirrious.MvvmCross.Interfaces.ServiceProvider;
using SIGEP.DummyService;
using SIGEP.Mobile.Core.Interfaces;


namespace SIGEP.Mobile.Core.Models
{
 public class PhotoService : IMvxServiceConsumer<IMvxPictureChooserTask>
{
    private const int MaxPixelDimension = 1024;
    private const int DefaultJpegQuality = 92;

    public void GetNewPhoto()
    {
        this.GetService<IMvxPictureChooserTask>().TakePicture(
            MaxPixelDimension,
            DefaultJpegQuality,
            HandlePhotoAvailable,
            () => { /* cancel is ignored */ });

    }

    public event EventHandler<PhotoStreamEventArgs> PhotoStreamAvailable;

    private void HandlePhotoAvailable(Stream pictureStream)
    {
        var handler = PhotoStreamAvailable;
        if (handler != null)
        {
            handler(this, new PhotoStreamEventArgs() { PictureStream = pictureStream, OnSucessGettingPhotoFileName = OnSucessGettingPhotoFileName });
        }
    }



    public static void TakePhoto(Action<string> successFileName, Action<Exception> error)
    {
        var service = new PhotoService();
        service.OnSucessGettingPhotoFileName = successFileName;
        service.OnError = error;
        service.GetNewPhoto();
        service.PhotoStreamAvailable += new EventHandler<PhotoStreamEventArgs>(service_PhotoStreamAvailable);
    }

    static void service_PhotoStreamAvailable(object sender, PhotoStreamEventArgs e)
    {
        //grava pra ficheiro!!!
        var directory = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
        var filename = Path.Combine(directory, "photo.jpeg");
        string saveTo = filename;
        FileStream writeStream = new FileStream(saveTo, FileMode.Create, FileAccess.Write);
        ReadWriteStream(e.PictureStream, writeStream);

        e.OnSucessGettingPhotoFileName(filename);

    }
    private static void ReadWriteStream(Stream readStream, Stream writeStream)
    {
        int Length = 256;
        Byte[] buffer = new Byte[Length];
        int bytesRead = readStream.Read(buffer, 0, Length);
        // write the required bytes
        while (bytesRead > 0)
        {
            writeStream.Write(buffer, 0, bytesRead);
            bytesRead = readStream.Read(buffer, 0, Length);
        }
        readStream.Close();
        writeStream.Close();
    }

    public Action<string> OnSucessGettingPhotoFileName { get; set; }
    public Action<Exception> OnError { get; set; }
}

[Serializable]
[ComVisible(true)]
public class PhotoStreamEventArgs : EventArgs
{
    public Stream PictureStream { get; set; }

    public Action<string> OnSucessGettingPhotoFileName { get; set; }
}
}

Answer 1

我通常使用内置的IMvxPictureChooserTask实现服务（如果使用vNext，则在插件中）：

using Cirrious.MvvmCross.ExtensionMethods;
using Cirrious.MvvmCross.Interfaces.Platform.Tasks;
using Cirrious.MvvmCross.Interfaces.ServiceProvider;

public class PhotoService 
    : IMvxServiceConsumer<IMvxPictureChooserTask>
    , IPhotoService
{
    private const int MaxPixelDimension = 1024;
    private const int DefaultJpegQuality = 92;

    public void GetNewPhoto()
    {
        Trace.Info("Get a new photo started.");

        this.GetService<IMvxPictureChooserTask>().TakePicture(
            MaxPixelDimension,
            DefaultJpegQuality,
            HandlePhotoAvailable,
            () => { /* cancel is ignored */ });
    }

    public event EventHandler<PhotoStreamEventArgs> PhotoStreamAvailable;

    private void HandlePhotoAvailable(Stream pictureStream)
    {
        Trace.Info("Picture available");
        var handler = PhotoStreamAvailable;
        if (handler != null)
        {
            handler(this, new PhotoStreamEventArgs() { PictureStream = pictureStream });
        }
    }
}

我通常在启动时将此服务注册为单例，然后从ViewModel ICommand处理程序中调用它。

使用此服务的一个应用是Blooor示例 - 请参阅BaseEditProductViewModel.cs - 这不是我有任何关系的示例，但我相信它带来了拍照和ZXing - 两者都使用外部服务。

一个警告：在MonoDroid上，您可以看到一些奇怪/意外的Activity / ViewModel生命周期行为 - 基本上您可以看到拍摄照片的活动是在拍照期间从内存中卸载/擦除的。如果您的应用程序发生这种情况，那么您可能需要开始查看以下问题：Saving Android Activity state using Save Instance State - 这在MvvmCross中尚未自动处理。

我相信Blooor样本可能会遇到这个问题 - 但是用户是否会在正常的应用程序中看到它是有争议的。

作为IMvxPictureChooserTask服务的替代方案，您还可以查看使用Xamarin.Mobile中的一些跨平台API - 请参阅MvvmCross vnext : monodroid use a VideoView inside a plugin了解可能的起始位置 - 或仅针对Android可以轻松实现自己的。

需要一个用MonoDroid和MVVMCross拍照的例子

1 个答案: