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// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
#if WINDOWSPHONE7
#if !DEBUG_NO_AGENT_SUPPORT
//
// The Windows Phone Marketplace Test Kit disallows usage of types
// in the Microsoft.Phone.Shell namespace, determined by static code
// analysis, for background agents.
//
// However, with a null check for PhoneApplicationService.Current,
// we can safely use this the lifecycle events for dormant state
// transitions. In a background agent this property will be null;
// trying to create an instance of PhoneApplicationService throws
// a ComException and is required to set the Current property.
//
// In order to access the PhoneApplicationService functionality for
// non-background agent assemblies, we build a late bound wrapper
// around the APIs.
//
// See appplat\src\Frameworks\Microsoft\Phone\PhoneApplicationService.cs
// for implementation details of the class we use.
//
namespace System.Reactive.PlatformServices.Phone.Shell
{
using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Reflection;
using Microsoft.Phone;
class PhoneApplicationService
{
private static readonly object s_gate = new object();
internal static readonly Assembly s_phshAsm;
private static readonly Type s_pasType;
private static readonly PropertyInfo s_curProp;
private static readonly EventInfo s_actdEvt;
private static readonly EventInfo s_deacEvt;
private readonly object _target;
static PhoneApplicationService()
{
s_phshAsm = typeof(BackgroundAgent).Assembly; // Has to be in Microsoft.Phone.dll.
s_pasType = s_phshAsm.GetType("Microsoft.Phone.Shell.PhoneApplicationService");
s_curProp = s_pasType.GetProperty("Current", BindingFlags.Public | BindingFlags.Static);
s_actdEvt = s_curProp.PropertyType.GetEvent("Activated", BindingFlags.Public | BindingFlags.Instance);
s_deacEvt = s_curProp.PropertyType.GetEvent("Deactivated", BindingFlags.Public | BindingFlags.Instance);
}
private PhoneApplicationService(object target)
{
_target = target;
}
private static PhoneApplicationService s_current;
public static PhoneApplicationService Current
{
get
{
lock (s_gate)
{
if (s_current == null)
{
var current = s_curProp.GetValue(null, null);
if (current == null)
return null;
//
// Current provides a singleton. The constructor
// of PhoneApplicationService guarantees this,
// throwing an InvalidOperationException if more
// than one instance is created.
//
s_current = new PhoneApplicationService(current);
}
}
return s_current;
}
}
private Dictionary<object, object> _actdHandlers = new Dictionary<object, object>();
public event EventHandler<ActivatedEventArgs> Activated
{
add
{
AddHandler<ActivatedEventArgs>(s_actdEvt, _actdHandlers, value);
}
remove
{
RemoveHandler(s_actdEvt, _actdHandlers, value);
}
}
private Dictionary<object, object> _deacHandlers = new Dictionary<object, object>();
public event EventHandler<DeactivatedEventArgs> Deactivated
{
add
{
AddHandler<DeactivatedEventArgs>(s_deacEvt, _deacHandlers, value);
}
remove
{
RemoveHandler(s_deacEvt, _deacHandlers, value);
}
}
private void AddHandler<TEventArgs>(EventInfo evt, Dictionary<object, object> map, object handler)
where TEventArgs : EventArgs
{
var h = GetHandler<TEventArgs>(evt, handler);
var add = evt.GetAddMethod();
lock (s_gate)
{
map.Add(handler, h);
add.Invoke(_target, new object[] { h });
}
}
private void RemoveHandler(EventInfo evt, Dictionary<object, object> map, object handler)
{
var rem = evt.GetRemoveMethod();
lock (s_gate)
{
var h = default(object);
if (map.TryGetValue(handler, out h))
{
//
// We assume only one handler will be attached to
// the event, hence we shouldn't worry about having
// multiple delegate instances with the same target
// being attached. This guarantee is made by the
// reference counting in HostLifecycleService.
//
// The use of a dictionary allows for reuse with
// multiple distinct handlers going forward.
//
map.Remove(handler);
rem.Invoke(_target, new object[] { h });
}
}
}
private static object GetHandler<TEventArgsThunk>(EventInfo evt, object call)
where TEventArgsThunk : EventArgs
{
var ht = evt.EventHandlerType;
var hp = ht.GetMethod("Invoke").GetParameters();
var po = Expression.Parameter(hp[0].ParameterType, hp[0].Name);
var pe = Expression.Parameter(hp[1].ParameterType, hp[1].Name);
var h = Expression.Lambda(
ht,
Expression.Invoke(
Expression.Constant(call),
po,
Expression.New(
typeof(TEventArgsThunk).GetConstructor(new[] { typeof(object) }),
pe
)
),
po,
pe
);
return h.Compile();
}
}
class ActivatedEventArgs : EventArgs
{
private static readonly Type s_aeaType;
private static readonly PropertyInfo s_aipProp;
private readonly object _target;
static ActivatedEventArgs()
{
s_aeaType = PhoneApplicationService.s_phshAsm.GetType("Microsoft.Phone.Shell.ActivatedEventArgs");
s_aipProp = s_aeaType.GetProperty("IsApplicationInstancePreserved", BindingFlags.Public | BindingFlags.Instance);
}
public ActivatedEventArgs(object target)
{
_target = target;
}
public bool IsApplicationInstancePreserved
{
get
{
return (bool)s_aipProp.GetValue(_target, null);
}
}
}
class DeactivatedEventArgs : EventArgs
{
public DeactivatedEventArgs(object target)
{
}
}
}
#endif
#endif
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