在Xamarin.Forms中访问相机

Question

我需要使用Xamarin Forms PCL访问相机。 我找不到任何可行的样本。

我尝试安装XLab并使用其示例代码，但它有例外。 例如，使用XLabs示例我使用以下内容：

/// <summary>
/// Takes the picture.
/// </summary>
/// <returns>Take Picture Task.</returns>
internal async Task<MediaFile> TakePicture()
{
    Setup();

    ImageSource = null;

    return await _mediaPicker.TakePhotoAsync(new CameraMediaStorageOptions { DefaultCamera = CameraDevice.Front, MaxPixelDimension = 400 }).ContinueWith(t =>
    {
        if (t.IsFaulted)
        {
            Status = t.Exception.InnerException.ToString();
        }
        else if (t.IsCanceled)
        {
            Status = "Canceled";
        }
        else
        {
            var mediaFile = t.Result;

            ImageSource = ImageSource.FromStream(() => mediaFile.Source);

            return mediaFile;
        }

        return null;
    }, _scheduler);
}

/// <summary>
/// Setups this instance.
/// </summary>
private void Setup()
{
    if (_mediaPicker != null)
    {
        return;
    }

    var device = Resolver.Resolve<IDevice>();

    ////RM: hack for working on windows phone? 
    _mediaPicker = DependencyService.Get<IMediaPicker>() ?? device.MediaPicker;
}

我在Resolver.Resolve<IDevice>():上得到以下异常Resolver.Resolve<IDevice>(): IResolver has not been set. Please set it by calling Resolver.SetResolver(resolver) IResolver has not been set. Please set it by calling Resolver.SetResolver(resolver)

我如何使用这个或其他替代方法用Xamarin.Forms拍照？ 感谢提前提示！

Answer 1

在您的Droid项目中添加MainActivity类代码

protected override void OnCreate (Bundle bundle)
{
    base.OnCreate (bundle);
    #region Resolver Init
    SimpleContainer container = new SimpleContainer();
    container.Register<IDevice>(t => AndroidDevice.CurrentDevice);
    container.Register<IDisplay>(t => t.Resolve<IDevice>().Display);
    container.Register<INetwork>(t => t.Resolve<IDevice>().Network);

    Resolver.SetResolver(container.GetResolver());
    #endregion
    ....
}

在IOS类AppDelegate中这一个：

public override bool FinishedLaunching(UIApplication app, NSDictionary options)
{
    #region Resolver Init
    SimpleContainer container = new SimpleContainer();
    container.Register<IDevice>(t => AppleDevice.CurrentDevice);
    container.Register<IDisplay>(t => t.Resolve<IDevice>().Display);
    container.Register<INetwork>(t => t.Resolve<IDevice>().Network);

    Resolver.SetResolver(container.GetResolver());
    #endregion
    ....
}

Answer 2

以下是xLabs Camera的示例代码：
https://www.dropbox.com/s/9paojg1q43ahnqk/XPA_PickMedia_XLabs_XFP.zip?dl=0在论坛上找到它： https ： //forums.xamarin.com/discussion/35636/a-sample-project-using-摄像机控制-mediapicker-的-xlabs

Answer 3

您无法直接访问Xamarin.Forms中的本机功能。 您必须使用Dependency Service来访问本机功能，如访问Camrera，音频等。

试试这个： http ： //developer.xamarin.com/guides/cross-platform/xamarin-forms/dependency-service/

Answer 4

您必须配置IoC才能使其正常工作，并使用Resolver.SetResolver方法将IoC提供程序设置为Resolver。 在这里阅读更多内容， https：//github.com/XLabs/Xamarin-Forms-Labs/wiki/IOC