如何：使用 Win32 宿主容器执行命中测试

可以通过为可视化对象提供宿主窗口容器在 Win32 中创建可视化对象。 若要为包含的可视化对象提供事件处理，需要处理传递到宿主窗口容器的消息筛选器循环的消息。 有关如何在 Win32 窗口中承载可视化对象的更多信息，请参见教程：在 Win32 应用程序中承载 Visual 对象。

示例

下面的代码演示如何为用作可视化对象的宿主容器的 Win32 窗口设置鼠标事件处理程序。

' Constant values from the "winuser.h" header file.
Friend Const WM_LBUTTONUP As Integer = &H202, WM_RBUTTONUP As Integer = &H205

Friend Shared Function ApplicationMessageFilter(ByVal hwnd As IntPtr, ByVal message As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr, ByRef handled As Boolean) As IntPtr
    ' Handle messages passed to the visual.
    Select Case message
        ' Handle the left and right mouse button up messages.
        Case WM_LBUTTONUP, WM_RBUTTONUP
            Dim pt As New System.Windows.Point()
            pt.X = CUInt(lParam) And CUInt(&HFFFF) ' LOWORD = x
            pt.Y = CUInt(lParam) >> 16 ' HIWORD = y
            MyShape.OnHitTest(pt, message)
    End Select

    Return IntPtr.Zero
End Function

// Constant values from the "winuser.h" header file.
internal const int WM_LBUTTONUP = 0x0202,
                   WM_RBUTTONUP = 0x0205;

internal static IntPtr ApplicationMessageFilter(
    IntPtr hwnd, int message, IntPtr wParam, IntPtr lParam, ref bool handled)
{
    // Handle messages passed to the visual.
    switch (message)
    {
        // Handle the left and right mouse button up messages.
        case WM_LBUTTONUP:
        case WM_RBUTTONUP:
            System.Windows.Point pt = new System.Windows.Point();
            pt.X = (uint)lParam & (uint)0x0000ffff;  // LOWORD = x
            pt.Y = (uint)lParam >> 16;               // HIWORD = y
            MyShape.OnHitTest(pt, message);
            break;
    }

    return IntPtr.Zero;
}

下面的示例演示如何设置命中测试来响应捕获特定的鼠标事件。

        ' Constant values from the "winuser.h" header file.
        Public Const WM_LBUTTONUP As Integer = &H0202, WM_RBUTTONUP As Integer = &H0205

        ' Respond to WM_LBUTTONUP or WM_RBUTTONUP messages by determining which visual object was clicked.
        Public Shared Sub OnHitTest(ByVal pt As System.Windows.Point, ByVal msg As Integer)
            ' Clear the contents of the list used for hit test results.
            hitResultsList.Clear()

            ' Determine whether to change the color of the circle or to delete the shape.
            If msg = WM_LBUTTONUP Then
                MyWindow.changeColor = True
            End If
            If msg = WM_RBUTTONUP Then
                MyWindow.changeColor = False
            End If

            ' Set up a callback to receive the hit test results enumeration.
            VisualTreeHelper.HitTest(MyWindow.myHwndSource.RootVisual, Nothing, New HitTestResultCallback(AddressOf CircleHitTestResult), New PointHitTestParameters(pt))

            ' Perform actions on the hit test results list.
            If hitResultsList.Count > 0 Then
                ProcessHitTestResultsList()
            End If
        End Sub

// Constant values from the "winuser.h" header file.
public const int WM_LBUTTONUP = 0x0202,
                 WM_RBUTTONUP = 0x0205;

// Respond to WM_LBUTTONUP or WM_RBUTTONUP messages by determining which visual object was clicked.
public static void OnHitTest(System.Windows.Point pt, int msg)
{
    // Clear the contents of the list used for hit test results.
    hitResultsList.Clear();

    // Determine whether to change the color of the circle or to delete the shape.
    if (msg == WM_LBUTTONUP)
    {
        MyWindow.changeColor = true;
    }
    if (msg == WM_RBUTTONUP)
    {
        MyWindow.changeColor = false;
    }

    // Set up a callback to receive the hit test results enumeration.
    VisualTreeHelper.HitTest(MyWindow.myHwndSource.RootVisual,
                             null,
                             new HitTestResultCallback(CircleHitTestResult),
                             new PointHitTestParameters(pt));

    // Perform actions on the hit test results list.
    if (hitResultsList.Count > 0)
    {
        ProcessHitTestResultsList();
    }
}

HwndSource 对象表示 Win32 窗口中的 Windows Presentation Foundation (WPF) 内容。HwndSource 对象的 RootVisual 属性的值表示可视化树层次结构中的最顶层节点。

有关使用 Win32 宿主容器对对象进行命中测试的完整示例，请参见 Hit Test with Win32 Interoperation Sample（Win32 交互命中测试示例）。

请参见

参考

HwndSource

概念

可视化层中的命中测试

教程：在 Win32 应用程序中承载 Visual 对象