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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Runtime.CompilerServices;
using Microsoft.Office;
using Windows.Win32.System.Com;
using ComIMessageFilter = Windows.Win32.Media.Audio.IMessageFilter;
using ComIServiceProvider = Windows.Win32.System.Com.IServiceProvider;
namespace System.Windows.Forms;
public sealed partial class Application
{
/// <summary>
/// <see cref="ThreadContext"/> that supports <see cref="IMsoComponent"/>.
/// </summary>
internal sealed unsafe class ComponentThreadContext :
ThreadContext,
IMsoComponent.Interface,
IManagedWrapper<IMsoComponent>
{
private bool _trackingComponent;
private static readonly nuint s_invalidId = unchecked((nuint)(-1));
// IMsoComponentManager stuff
private IMsoComponentManager.Interface? _componentManager;
private bool _externalComponentManager;
private bool _fetchingComponentManager;
// IMsoComponent stuff
private nuint _componentID = s_invalidId;
// We need to set this flag if we have started the ModalMessageLoop so that we don't create the ThreadWindows
// when the ComponentManager calls on us (as IMSOComponent) during the OnEnterState.
private bool _ourModalLoop;
public override void EnsureReadyForIdle() =>
// Ensure the component manager is created.
_ = ComponentManager;
/// <summary>
/// Retrieves the component manager for this process. If there is no component manager
/// currently installed, we install our own.
/// </summary>
internal IMsoComponentManager.Interface? ComponentManager
{
get
{
if (_componentManager is not null || _fetchingComponentManager)
{
return _componentManager;
}
// The CLR is a good COM citizen and will pump messages when things are waiting.
// This is nice; it keeps the world responsive. But, it is also very hard for
// us because most of the code below causes waits, and the likelihood that
// a message will come in and need a component manager is very high. Recursing
// here is very very bad, and will almost certainly lead to application failure
// later on as we come out of the recursion. So, we guard it here and return
// null. EVERYONE who accesses the component manager must handle a NULL return!
_fetchingComponentManager = true;
try
{
// Attempt to obtain the Host Application MSOComponentManager
_componentManager = GetExternalComponentManager();
if (_componentManager is not null)
{
_externalComponentManager = true;
}
else
{
_componentManager = new ComponentManager();
}
RegisterComponentManager();
}
finally
{
_fetchingComponentManager = false;
}
return _componentManager;
static IMsoComponentManager.Interface? GetExternalComponentManager()
{
Application.OleRequired();
using ComScope<ComIMessageFilter> messageFilter = new(null);
// Clear the thread's message filter to see if there was an existing filter
if (PInvoke.CoRegisterMessageFilter(null, messageFilter).Failed || messageFilter.IsNull)
{
return null;
}
// There was an existing filter, reregister it
ComIMessageFilter* dummy = default;
PInvoke.CoRegisterMessageFilter(messageFilter, &dummy);
// Now look to see if it implements the native IServiceProvider
using var serviceProvider = messageFilter.TryQuery<ComIServiceProvider>(out HRESULT hr);
if (hr.Failed)
{
return null;
}
// Check the service provider for the service that provides IMsoComponentManager
using ComScope<IUnknown> serviceHandle = new(null);
Guid sid = new(MsoComponentIds.SID_SMsoComponentManager);
Guid iid = new(MsoComponentIds.IID_IMsoComponentManager);
if (serviceProvider.Value->QueryService(&sid, &iid, serviceHandle).Failed || serviceHandle.IsNull)
{
return null;
}
// We have the component manager service, now get the component manager interface
var componentManager = serviceHandle.TryQuery<IMsoComponentManager>(out hr);
if (hr.Succeeded && !componentManager.IsNull)
{
return new IMsoComponentManager.NativeAdapter(componentManager);
}
return null;
}
void RegisterComponentManager()
{
MSOCRINFO info = new()
{
cbSize = (uint)sizeof(MSOCRINFO),
uIdleTimeInterval = 0,
grfcrf = msocrf.PreTranslateAll | msocrf.NeedIdleTime,
grfcadvf = msocadvf.Modal
};
UIntPtr id;
bool result = _componentManager.FRegisterComponent(ComHelpers.GetComPointer<IMsoComponent>(this), &info, &id);
_componentID = id;
Debug.Assert(_componentID != s_invalidId, "Our ID sentinel was returned as a valid ID");
if (result && _componentManager is not Application.ComponentManager)
{
_messageLoopCount++;
}
Debug.Assert(result,
$"Failed to register WindowsForms with the ComponentManager -- DoEvents and modal dialogs will be broken. size: {info.cbSize}");
}
}
}
protected override void BeginModalMessageLoop()
{
// Set the ourModalLoop flag so that the "IMSOComponent.OnEnterState" is a NOOP since we started the ModalMessageLoop.
bool wasOurLoop = _ourModalLoop;
_ourModalLoop = true;
try
{
ComponentManager?.OnComponentEnterState(_componentID, msocstate.Modal, msoccontext.All, 0, null, 0);
}
finally
{
_ourModalLoop = wasOurLoop;
}
}
protected override void Dispose(bool disposing)
{
try
{
// If we had a component manager, detach from it.
if (disposing && _componentManager is not null)
{
RevokeComponent();
}
}
catch (Exception ex)
{
Debug.Fail($"Unexpected exception thrown during Dispose: {ex.Message}");
}
finally
{
base.Dispose(disposing);
}
}
protected override void EndModalMessageLoop()
{
bool wasOurLoop = _ourModalLoop;
_ourModalLoop = true;
try
{
// If We started the ModalMessageLoop .. this will call us back on the IMSOComponent.OnStateEnter and not do anything ...
IMsoComponentManager.Interface? cm = ComponentManager;
cm?.FOnComponentExitState(_componentID, msocstate.Modal, msoccontext.All, 0, null);
}
finally
{
// Reset the flag since we are exiting out of a ModalMessageLoop.
_ourModalLoop = wasOurLoop;
}
}
internal override void FormActivated(bool activate)
{
if (activate && ComponentManager is { } manager && manager is not Application.ComponentManager)
{
manager.FOnComponentActivate(_componentID);
}
}
internal override void TrackInput(bool track)
{
// Protect against double setting, as this causes asserts in the VS component manager.
if (_trackingComponent != track && ComponentManager is { } manager && manager is not Application.ComponentManager)
{
manager.FSetTrackingComponent(_componentID, track);
_trackingComponent = track;
}
}
protected override bool? GetMessageLoopInternal(bool mustBeActive, int loopCount)
{
// If we are already running a loop, we're fine.
// If we are running in external manager we may need to make sure first the loop is active
if (loopCount > (mustBeActive && _externalComponentManager ? 1 : 0))
{
return true;
}
// Also, access the ComponentManager property to demand create it, and we're also
// fine if it is an external manager, because it has already pushed a loop.
if (ComponentManager is not null && _externalComponentManager)
{
if (!mustBeActive)
{
return true;
}
using ComScope<IMsoComponent> component = new(null);
if (ComponentManager.FGetActiveComponent(msogac.Active, component, null, 0))
{
return ComHelpers.WrapsManagedObject(this, component.Value);
}
}
return null;
}
protected override bool RunMessageLoop(msoloop reason, bool fullModal)
{
bool result;
if ((!fullModal && reason != msoloop.DoEventsModal) || ComponentManager is ComponentManager)
{
result = ComponentManager!.FPushMessageLoop(_componentID, reason, null);
}
else if (reason is msoloop.DoEvents or msoloop.DoEventsModal)
{
result = LocalModalMessageLoop(null);
}
else
{
result = LocalModalMessageLoop(CurrentForm);
}
return result;
}
protected override void EndOuterMessageLoop()
{
if (_componentManager is not null)
{
// If we had a component manager, detach from it.
RevokeComponent();
}
}
private bool LocalModalMessageLoop(Form? form)
{
try
{
// Execute the message loop until the active component tells us to stop.
MSG msg = default;
bool continueLoop = true;
while (continueLoop)
{
if (PInvoke.GetMessage(&msg, HWND.Null, 0, 0))
{
if (!PreTranslateMessage(ref msg))
{
PInvoke.TranslateMessage(msg);
PInvoke.DispatchMessage(&msg);
}
if (form is not null)
{
continueLoop = !form.CheckCloseDialog(false);
}
}
else if (form is null)
{
break;
}
else if (!PInvoke.PeekMessage(&msg, HWND.Null, 0, 0, PEEK_MESSAGE_REMOVE_TYPE.PM_NOREMOVE))
{
PInvoke.WaitMessage();
}
}
return continueLoop;
}
catch
{
return false;
}
}
/// <summary>
/// Revokes our component from the active component manager. Does nothing if there is no active
/// component manager or we are already invoked.
/// </summary>
private void RevokeComponent()
{
if (_componentManager is { } manager && _componentID != s_invalidId)
{
try
{
_componentManager = null;
using (manager as IDisposable)
{
manager.FRevokeComponent(_componentID);
}
}
finally
{
_componentID = s_invalidId;
}
}
}
// Things to test in VS when you change the IMsoComponent code:
//
// - You can bring up dialogs multiple times (ie, the editor for TextBox.Lines)
// - Double-click DataFormWizard, cancel wizard
// - When a dialog is open and you switch to another application, when you switch
// back to VS the dialog gets the focus
// - If one modal dialog launches another, they are all modal (Try web forms Table\Rows\Cell)
// - When a dialog is up, VS is completely disabled, including moving and resizing VS.
// - After doing all this, you can ctrl-shift-N start a new project and VS is enabled.
BOOL IMsoComponent.Interface.FDebugMessage(nint hInst, uint msg, WPARAM wparam, LPARAM lparam)
=> true;
BOOL IMsoComponent.Interface.FPreTranslateMessage(MSG* msg)
=> PreTranslateMessage(ref Unsafe.AsRef<MSG>(msg));
void IMsoComponent.Interface.OnEnterState(msocstate uStateID, BOOL fEnter)
{
// Return if our (WINFORMS) Modal Loop is still running.
if (_ourModalLoop)
{
return;
}
if (uStateID == msocstate.Modal)
{
// We should only be messing with windows we own. See the "ctrl-shift-N" test above.
if (fEnter)
{
DisableWindowsForModalLoop(true, null); // WinFormsOnly = true
}
else
{
EnableWindowsForModalLoop(true, null); // WinFormsOnly = true
}
}
}
void IMsoComponent.Interface.OnAppActivate(BOOL fActive, uint dwOtherThreadID)
{
}
void IMsoComponent.Interface.OnLoseActivation()
{
}
void IMsoComponent.Interface.OnActivationChange(
IMsoComponent* component,
BOOL fSameComponent,
MSOCRINFO* pcrinfo,
BOOL fHostIsActivating,
nint pchostinfo,
uint dwReserved)
{
}
BOOL IMsoComponent.Interface.FDoIdle(msoidlef grfidlef)
{
_idleHandler?.Invoke(Thread.CurrentThread, EventArgs.Empty);
return false;
}
BOOL IMsoComponent.Interface.FContinueMessageLoop(
msoloop uReason,
void* pvLoopData,
MSG* pMsgPeeked)
{
bool continueLoop = true;
// If we get a null message, and we have previously posted the WM_QUIT message,
// then someone ate the message.
if (pMsgPeeked is null && PostedQuit)
{
continueLoop = false;
}
else
{
switch (uReason)
{
case msoloop.FocusWait:
// For focus wait, check to see if we are now the active application.
PInvoke.GetWindowThreadProcessId(PInvoke.GetActiveWindow(), out uint pid);
if (pid == PInvoke.GetCurrentProcessId())
{
continueLoop = false;
}
break;
case msoloop.ModalAlert:
case msoloop.ModalForm:
// For modal forms, check to see if the current active form has been
// dismissed. If there is no active form, then it is an error that
// we got into here, so we terminate the loop.
if (CurrentForm is null || CurrentForm.CheckCloseDialog(false))
{
continueLoop = false;
}
break;
case msoloop.DoEvents:
case msoloop.DoEventsModal:
// For DoEvents, just see if there are more messages on the queue.
MSG temp = default;
if (!PInvoke.PeekMessage(&temp, HWND.Null, 0, 0, PEEK_MESSAGE_REMOVE_TYPE.PM_NOREMOVE))
{
continueLoop = false;
}
break;
}
}
return continueLoop;
}
BOOL IMsoComponent.Interface.FQueryTerminate(BOOL fPromptUser) => true;
void IMsoComponent.Interface.Terminate()
{
if (_messageLoopCount > 0 && ComponentManager is not Application.ComponentManager)
{
_messageLoopCount--;
}
Dispose(false);
}
HWND IMsoComponent.Interface.HwndGetWindow(msocWindow dwWhich, uint dwReserved) => HWND.Null;
}
}
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