更新:
在我之前的回答中,展示了如何在webview上添加相机权限。
您提供的链接现在可以使用:https://xamarin.swappsdev.net/。它似乎提供了相机预览功能,需要在API 23+上检查权限。
在Xamarin.Forms中,您可以使用Permissions插件:https://github.com/jamesmontemagno/PermissionsPlugin
首先,在Android清单文件中添加相机权限:在Your Project.Android> Properties> Android Manifest> Required permissions> Camera中进行添加。然后,它将在AndroidManifest.xml中生成用户权限。
<uses-permission android:name="android.permission.CAMERA" />
创建一个 Utils.cs 文件。
public static class Utils
{
public static async Task<PermissionStatus> CheckPermissions(Permission permission)
{
var permissionStatus = await CrossPermissions.Current.CheckPermissionStatusAsync(permission);
bool request = false;
if (permissionStatus == PermissionStatus.Denied)
{
if (Device.RuntimePlatform == Device.iOS)
{
var title = $"{permission} Permission";
var question = $"To use this plugin the {permission} permission is required. Please go into Settings and turn on {permission} for the app.";
var positive = "Settings";
var negative = "Maybe Later";
var task = Application.Current?.MainPage?.DisplayAlert(title, question, positive, negative);
if (task == null)
return permissionStatus;
var result = await task;
if (result)
{
CrossPermissions.Current.OpenAppSettings();
}
return permissionStatus;
}
request = true;
}
if (request || permissionStatus != PermissionStatus.Granted)
{
var newStatus = await CrossPermissions.Current.RequestPermissionsAsync(permission);
if (!newStatus.ContainsKey(permission))
{
return permissionStatus;
}
permissionStatus = newStatus[permission];
if (newStatus[permission] != PermissionStatus.Granted)
{
permissionStatus = newStatus[permission];
var title = $"{permission} Permission";
var question = $"To use the plugin the {permission} permission is required.";
var positive = "Settings";
var negative = "Maybe Later";
var task = Application.Current?.MainPage?.DisplayAlert(title, question, positive, negative);
if (task == null)
return permissionStatus;
var result = await task;
if (result)
{
CrossPermissions.Current.OpenAppSettings();
}
return permissionStatus;
}
}
return permissionStatus;
}
}
在MainActivity.cs中,在OnCreate方法中添加以下代码。
Plugin.CurrentActivity.CrossCurrentActivity.Current.Init(this, savedInstanceState);
需要在MainActivity.cs中添加OnRequestPermissionsResult方法。
public override void OnRequestPermissionsResult(int requestCode, string[] permissions,
[GeneratedEnum] Android.Content.PM.Permission[] grantResults)
{
PermissionsImplementation.Current.OnRequestPermissionsResult(requestCode, permissions, grantResults);
base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
}
然后实现它。
private async void _button_Clicked(object sender, EventArgs e)
{
webView.Source = "https://xamarin.swappsdev.net/";
var status = PermissionStatus.Unknown;
status = await CrossPermissions.Current.CheckPermissionStatusAsync(Permission.Camera);
if (status != PermissionStatus.Granted)
{
status = await Utils.CheckPermissions(Permission.Camera);
}
}
![在此输入图片描述](https://istack.dev59.com/wKMZ1.gif)
我已经将它上传到我的GitHub。请检查文件夹Test/CameraRuntimePermission_WebView/RuntimePermission。
https://github.com/WendyZang/Test.git
编辑:
如果您不想在按钮单击事件中调用它,您可以删除MainPage.xaml中的按钮。
MainPage.xaml.cs
public MainPage()
{
InitializeComponent();
webView.Source = "https://xamarin.swappsdev.net/";
}
protected override void OnAppearing()
{
base.OnAppearing();
RunTimePermission();
}
public async void RunTimePermission()
{
var status = PermissionStatus.Unknown;
status = await CrossPermissions.Current.CheckPermissionStatusAsync(Permission.Camera);
if (status != PermissionStatus.Granted)
{
status = await Utils.CheckPermissions(Permission.Camera);
}
}
![enter image description here](https://istack.dev59.com/HFp8F.gif)