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Stylet
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Change course slightly on ActionCommand

This commit is contained in:
Antony Male 2014-02-25 19:58:55 +00:00
parent 24c32e5290
commit 1689624062
1 changed files with 18 additions and 45 deletions
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63
Stylet/ActionCommand.cs
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@ -18,7 +18,7 @@ namespace Stylet
private FrameworkElement subject;
private string methodName;
private Func<bool> guardPropertyGetter;
private Func<object> methodInvoker;
private MethodInfo targetMethodInfo;
private object target;
@ -29,7 +29,6 @@ namespace Stylet
this.UpdateGuardHandler();
DependencyPropertyDescriptor.FromProperty(View.TargetProperty, typeof(View)).AddValueChanged(this.subject, (o, e) => this.UpdateGuardHandler());
}
@ -41,18 +40,24 @@ namespace Stylet
private void UpdateGuardHandler()
{
var newTarget = View.GetTarget(this.subject);
MethodInfo targetMethodInfo = null;
this.guardPropertyGetter = null;
if (newTarget != null)
{
var guardPropertyInfo = newTarget.GetType().GetProperty(this.GuardName);
var newTargetType = newTarget.GetType();
var guardPropertyInfo = newTargetType.GetProperty(this.GuardName);
if (guardPropertyInfo != null && guardPropertyInfo.PropertyType == typeof(bool))
{
var param = Expressions.Expression.Parameter(typeof(bool), "returnValue");
var propertyAccess = Expressions.Expression.Property(param, guardPropertyInfo);
this.guardPropertyGetter = Expressions.Expression.Lambda<Func<bool>>(propertyAccess, param).Compile();
}
targetMethodInfo = newTargetType.GetMethod(this.methodName);
if (targetMethodInfo == null)
throw new ArgumentException(String.Format("Unable to find method {0} on {1}", this.methodName, this.target.GetType().Name));
}
var oldTarget = this.target as INotifyPropertyChanged;
@ -65,40 +70,11 @@ namespace Stylet
if (this.guardPropertyGetter != null && inpc != null)
inpc.PropertyChanged += this.PropertyChangedHandler;
this.targetMethodInfo = targetMethodInfo;
this.UpdateCanExecute();
}
private void UpdateMethodInvoker()
{
if (this.target == null)
throw new ArgumentException("Target not set");
var methodInfo = this.target.GetType().GetMethod(this.methodName);
if (methodInfo == null)
throw new Exception(String.Format("Unable to find method {0} on {1}", this.methodName, this.target.GetType().Name));
var target = Expressions.Expression.Constant(this.target);
var param = Expressions.Expression.Parameter(typeof(object), "parameter");
Expressions.Expression call;
var methodParameters = methodInfo.GetParameters();
if (methodParameters.Length == 0)
{
call = Expressions.Expression.Call(target, methodInfo);
}
else if (methodParameters.Length == 1)
{
var convertedParam = Expressions.Expression.Convert(param, methodParameters[0].ParameterType);
call = Expressions.Expression.Call(target, methodInfo, convertedParam);
}
else
{
throw new Exception(String.Format("Method {0} must accept either 0 or 1 arguments", this.methodName));
}
this.methodInvoker = Expressions.Expression.Lambda<Func<object>>(call, param).Compile();
}
private void PropertyChangedHandler(object sender, PropertyChangedEventArgs e)
{
if (String.IsNullOrEmpty(e.PropertyName) || e.PropertyName == this.GuardName)
@ -116,6 +92,9 @@ namespace Stylet
public bool CanExecute(object parameter)
{
if (this.target == null)
return false;
if (this.guardPropertyGetter == null)
return true;
@ -126,18 +105,12 @@ namespace Stylet
public void Execute(object parameter)
{
// This is not going to be called very often, so don't bother to generate a delegate, in the way that we do for the method guard
if (this.target == null)
throw new ArgumentException("Target not set");
var methodInfo = this.target.GetType().GetMethod(this.methodName);
if (methodInfo == null)
throw new Exception(String.Format("Unable to find method {0} on {1}", this.methodName, this.target.GetType().Name));
if (methodInfo != null)
{
var parameters = methodInfo.GetParameters().Length == 1 ? new[] { parameter } : null;
methodInfo.Invoke(this.target, parameters);
}
var parameters = this.targetMethodInfo.GetParameters().Length == 1 ? new[] { parameter } : null;
this.targetMethodInfo.Invoke(this.target, parameters);
}
}
}