WPF Control hosted Winforms using WPF ElementHost has Mouse Wheel Issue under Win 7 Only

Question

I have a WPF ElementHost I am using with Bing Maps. Everything works great in , but zooming with the MouseWheel will not work in .中一切正常，但在中无法使用鼠标滚轮进行缩放。

I have tried making sure the hosted element has focus by adding an event handler for and calling .添加事件处理程序并调用来确保托管元素具有焦点。 I verified that it is firing. Still - it does not work under Windows 7, but does work under Windows 10. Sadly - I have plenty of customers stuck with Win7 for the foreseeable future...

My XAML for the user control

<UserControl x:Class="BingMapUC"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         xmlns:m="clr-namespace:Microsoft.Maps.MapControl.WPF;assembly=Microsoft.Maps.MapControl.WPF"
         mc:Ignorable="d" 
         d:DesignHeight="393" d:DesignWidth="644" IsHitTestVisible="True" Focusable="True">
<UserControl.Resources >
    <ControlTemplate x:Key="Default" TargetType="m:Pushpin">
        <Grid x:Name="ContentGrid" HorizontalAlignment="Center" VerticalAlignment="Center">
            <StackPanel>
                <Grid Margin="0" Width="24" Height="23">
                    <Rectangle HorizontalAlignment="Left"  Margin="0,3.238,0,-2.146" Width="23" Height="18" Fill="SteelBlue" Stroke="Black"  RenderTransformOrigin="0.5,0.62">
                        <Rectangle.RenderTransform>
                            <TransformGroup>
                                <ScaleTransform/>
                                <SkewTransform AngleY="0" AngleX="-23"/>
                                <RotateTransform Angle="123"/>
                                <TranslateTransform/>
                            </TransformGroup>
                        </Rectangle.RenderTransform>
                    </Rectangle>

                    <Rectangle Fill="{TemplateBinding Background}" Stroke="Black" RadiusX="5" RadiusY="5"/>

                    <ContentPresenter HorizontalAlignment="Center"
                                                            VerticalAlignment="Center"
                                                            Content="{TemplateBinding Content}"
                                                            ContentTemplate="{TemplateBinding ContentTemplate}"
                                                            Margin="0" TextBlock.FontFamily="Segoe UI" TextBlock.FontWeight="Bold" TextBlock.Foreground="Black" >
                    </ContentPresenter>
                </Grid>
            </StackPanel>
        </Grid>
    </ControlTemplate>
</UserControl.Resources>
<Grid>
    <m:Map Name="Map" ZoomLevel="3.5" Center="38.8282,-95.5795" Cursor="Hand" CredentialsProvider="xxxxxxxxxxxxxxxxxx" Height="393" UseInertia="True" Margin="0" MaxWidth="644" MaxHeight="393" MinWidth="644" MinHeight="393" ScrollViewer.VerticalScrollBarVisibility="Disabled" Width="635" ScaleVisibility="Hidden"/>
</Grid>
</UserControl>

I'm hoping I have overlooked some esoteric setting(s)...

Answer 1

As it turns out another control on the same form was stealing the MouseWheel events away from the WPF ElementHost (in my case it was hosting a BingMap called BingMapUC). It was only doing it under Windows 7 (SP1), but not in Windows 10. I was able to fix the problem in my VB.NET source by manually adding handlers for the ElementHost MouseEnter event.

AddHandler BingMapUC.MouseEnter, AddressOf BingMap_MouseEnter

In that event I manually take the mouse control away from the ListView control (that was the one stealing the MouseWheel events) with

lsvControl.Capture = False

and then I make sure the BingMapUC (the hosted WPF) gets the focus

BingMapUC.Focus()

This works under both Windows 10 and Windows 7 so I don't have to check.

I did also make sure I gave mouse control back to the listview on its MouseEnter event with

lsvControl.Capture = True

So it would scroll when the mouse was over it.