テキストボックスなどで予測入力を表示させない方法は？

Question

Windowsフォームを使ってアプリケーションを作成しているのですが、
テキストボックスとIMEについて質問があります。

テキストボックスに文字を入力する際に表示される予測変換を
プログラム側で表示させなくする方法はあるでしょうか？

IMEの詳細設定の｢予測入力｣タブにある｢予測入力を使用する｣の
チェックを外した状態をプログラムで実現したいのです。
(レジストリでこの設定の値を変更する等の方法は避けたいです)

よろしくお願い致します。

※
VB.NET
.NET Framework 4
VisualStudio2010

Answer 1

IMEの種類やバージョンやOSについて何も書いてないので、Win10+MSIME

'要TSF.TypeLib
'.Net4.5以降ならNugetでhttps://www.nuget.org/packages/TSF.TypeLibを追加しておく
'.Net4ならhttps://github.com/NyaRuRu/TSF-TypeLibからソースを入手してdllをビルドすること
Imports TSF.InteropTypes
Imports TSF.TypeLib

Public Class Form1
	Private elementSink As New UIElementSink

	Sub New()
		'InitializeComponent()

		Application.AddMessageFilter(elementSink)

		Dim chk As New CheckBox
		chk.Text = "予測候補表示"
		chk.Checked = elementSink.EnableSuggestion
		chk.Left = 5

		AddHandler chk.CheckedChanged,
			 Sub(s, e)
				 elementSink.EnableSuggestion = chk.Checked
			 End Sub

		Dim txb As New TextBox
		txb.Top = 30
		txb.Left = 5
		txb.Width = Me.ClientRectangle.Width - 10
		txb.Anchor = AnchorStyles.Top Or AnchorStyles.Left Or AnchorStyles.Right

		Me.Controls.Add(chk)
		Me.Controls.Add(txb)

	End Sub

	Protected Overrides Sub OnShown(e As EventArgs)
		MyBase.OnShown(e)
		If (elementSink.Start()) Then
			Me.Text = "開始しました"
		End If
	End Sub

	Protected Overrides Sub OnClosed(e As EventArgs)
		Me.elementSink.Dispose()

		MyBase.OnClosed(e)
	End Sub
End Class

Class UIElementSink
	Implements TSF.TypeLib.ITfUIElementSink
	Implements IMessageFilter
	Implements IDisposable

	Private thmgr As TSF.TypeLib.ITfThreadMgr
	Private uimgr As TSF.TypeLib.ITfUIElementMgr
	Private source As TSF.TypeLib.ITfSource

	Private cookie As UInteger
	Private context As System.Threading.SynchronizationContext

	Private Const WM_KEYDOWN = &H100
	Private lastKey As Keys
	Private islastKeyIsChar As Boolean

	Public Property EnableSuggestion As Boolean = True

	Public Function PreFilterMessage(ByRef m As Message) As Boolean Implements IMessageFilter.PreFilterMessage
		If (TypeOf Control.FromHandle(m.HWnd) Is TextBox) Then
			Select Case m.Msg
				Case WM_KEYDOWN
					lastKey = CType(m.WParam.ToInt64(), Keys)
					If m.WParam.ToInt64() = Keys.ProcessKey Then
						lastKey = CType(ImmGetVirtualKey(m.HWnd), Keys)
					End If

					Debug.WriteLine(lastKey)
					islastKeyIsChar = True
					Select Case lastKey
						Case Keys.Space
						Case Keys.D0 To Keys.D9
						Case Keys.A To Keys.Z
						Case Keys.NumPad0 To Keys.NumPad9
						Case Keys.Multiply To Keys.Oem102

						Case Else
							islastKeyIsChar = False
					End Select
			End Select
		End If
		Return False
	End Function



	Public Function Start() As Boolean
		context = System.Threading.SynchronizationContext.Current
		If (context Is Nothing) Then
			context = System.Threading.SynchronizationContext.Current
		End If

		thmgr = GetThreadManager()
		uimgr = TryCast(thmgr, TSF.TypeLib.ITfUIElementMgr)
		source = TryCast(thmgr, TSF.TypeLib.ITfSource)
		If (source IsNot Nothing) Then
			Dim iid = GetGUID(GetType(TSF.TypeLib.ITfUIElementSink))
			If (source.AdviseSink(iid, Me, cookie).Succeeded) Then
				Return True
			End If
		End If

		System.Runtime.InteropServices.Marshal.ReleaseComObject(source)
		System.Runtime.InteropServices.Marshal.ReleaseComObject(uimgr)
		System.Runtime.InteropServices.Marshal.ReleaseComObject(thmgr)
		Return False
	End Function

	Private Function BeginUIElement(dwUIElementId As UInteger, ByRef pbShow As Boolean) As HRESULT Implements ITfUIElementSink.BeginUIElement
		Debug.WriteLine("BeginUIElement")
		pbShow = True

		If (Not EnableSuggestion) Then

			Dim elem As TSF.TypeLib.ITfUIElement = Nothing
			If (uimgr.GetUIElement(dwUIElementId, elem).Succeeded) Then
				Try
					Dim candidataElement = TryCast(elem, TSF.TypeLib.ITfCandidateListUIElement)
					If (candidataElement IsNot Nothing) Then
						pbShow = Not islastKeyIsChar
					End If
				Finally
					System.Runtime.InteropServices.Marshal.ReleaseComObject(elem)
				End Try
			End If
		End If
		Return New HRESULT() With {.Code = 0}
	End Function

	Private Function EndUIElement(dwUIElementId As UInteger) As HRESULT Implements ITfUIElementSink.EndUIElement
		Debug.WriteLine("EndUIElement")
	End Function

	Private Function UpdateUIElement(dwUIElementId As UInteger) As HRESULT Implements ITfUIElementSink.UpdateUIElement
		Debug.WriteLine("UpdateUIElement")
	End Function

#Region "IDisposable Support"
	Private disposedValue As Boolean

	Protected Overridable Sub Dispose(disposing As Boolean)
		If Not disposedValue Then
			If (cookie <> 0 AndAlso source IsNot Nothing) Then
				source.UnadviseSink(cookie)
			End If

			System.Runtime.InteropServices.Marshal.ReleaseComObject(source)
			System.Runtime.InteropServices.Marshal.ReleaseComObject(uimgr)
			System.Runtime.InteropServices.Marshal.ReleaseComObject(thmgr)

			source = Nothing
			uimgr = Nothing
			thmgr = Nothing

		End If
		disposedValue = True
	End Sub

	Public Sub Dispose() Implements IDisposable.Dispose
		Dispose(True)
		GC.SuppressFinalize(Me)
	End Sub
#End Region

	<System.Runtime.InteropServices.DllImport("Msctf.dll")>
	Private Shared Function TF_GetThreadMgr(ByRef x As TSF.TypeLib.ITfThreadMgr) As TSF.InteropTypes.HRESULT
	End Function

	Private Shared Function GetThreadManager() As TSF.TypeLib.ITfThreadMgr
		Dim mgr As TSF.TypeLib.ITfThreadMgr = Nothing
		If (Not TF_GetThreadMgr(mgr).Succeeded) Then
			Dim o As Object = Type.GetTypeFromCLSID(GetGUID(GetType(TSF.TypeLib.ITfThreadMgr)))
			mgr = TryCast(o, TSF.TypeLib.ITfThreadMgr)
		End If
		Return mgr
	End Function

	Private Shared Function GetGUID(ByVal t As Type) As Guid
		Return New Guid(t.GetCustomAttributes(True).OfType(Of System.Runtime.InteropServices.GuidAttribute).First().Value)
	End Function

	<System.Runtime.InteropServices.DllImport("Imm32.dll")>
	Private Shared Function ImmGetVirtualKey(ByVal hwnd As IntPtr) As UInteger
	End Function
End Class

---

個別に明示されていない限りgekkaがフォーラムに投稿したコードにはフォーラム使用条件に基づき「MICROSOFT LIMITED PUBLIC LICENSE」が適用されます。(かなり自由に使ってOK!)

Answer 2

gekkaさん、ご返答ありがとうございます。

教えて頂いたコードで、望み通りの結果が得られました！
ありがとうございました。