Created
November 13, 2018 15:24
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forms navservice for mvvmlvght
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public class NavigationService : INavigationService | |
{ | |
readonly Dictionary<string, Type> _pagesByKey = new Dictionary<string, Type>(); | |
NavigationPage _navigation; | |
public string CurrentPageKey | |
{ | |
get | |
{ | |
lock (_pagesByKey) | |
{ | |
if (_navigation.CurrentPage == null) | |
{ | |
return null; | |
} | |
var pageType = _navigation.CurrentPage.GetType(); | |
return _pagesByKey.ContainsValue(pageType) | |
? _pagesByKey.First(p => p.Value == pageType).Key | |
: null; | |
} | |
} | |
} | |
public void GoBack() | |
{ | |
Device.BeginInvokeOnMainThread(() => _navigation.PopAsync()); | |
} | |
public void NavigateTo(string pageKey) | |
{ | |
NavigateTo(pageKey, null); | |
} | |
public void NavigateTo(string pageKey, object parameter) | |
{ | |
lock (_pagesByKey) | |
{ | |
if (_pagesByKey.ContainsKey(pageKey)) | |
{ | |
var type = _pagesByKey[pageKey]; | |
ConstructorInfo constructor; | |
object[] parameters; | |
if (parameter == null) | |
{ | |
constructor = type.GetTypeInfo() | |
.DeclaredConstructors | |
.FirstOrDefault(c => !c.GetParameters().Any()); | |
parameters = new object[] | |
{ | |
}; | |
} | |
else | |
{ | |
constructor = type.GetTypeInfo() | |
.DeclaredConstructors | |
.FirstOrDefault( | |
c => | |
{ | |
var p = c.GetParameters(); | |
return p.Count() == 1 | |
&& p[0].ParameterType == parameter.GetType(); | |
}); | |
parameters = new[] | |
{ | |
parameter | |
}; | |
} | |
if (constructor == null) | |
{ | |
throw new InvalidOperationException( | |
"No suitable constructor found for page " + pageKey); | |
} | |
var page = constructor.Invoke(parameters) as Page; | |
_navigation.PushAsync(page); | |
} | |
else | |
{ | |
throw new ArgumentException( | |
string.Format( | |
"No such page: {0}. Did you forget to call NavigationService.Configure?", | |
pageKey), | |
"pageKey"); | |
} | |
} | |
} | |
public void Configure(string pageKey, Type pageType) | |
{ | |
lock (_pagesByKey) | |
{ | |
if (_pagesByKey.ContainsKey(pageKey)) | |
{ | |
_pagesByKey[pageKey] = pageType; | |
} | |
else | |
{ | |
_pagesByKey.Add(pageKey, pageType); | |
} | |
} | |
} | |
public void Initialize(NavigationPage navigation) | |
{ | |
_navigation = navigation; | |
navigation.BarBackgroundColor = Color.FromHex("022330"); | |
navigation.BarTextColor = Color.White; | |
} | |
} |
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