Microsoft.Toolkit.Wpf.UI.XamlHost.WindowsXamlHost.OpacityMask can not work

GuoLearn 251

when set the WindowsXamlHost.OpacityMask =ImageBrush it not Effective ，the WindowsXamlHost background color is white any way.
how can i make the WindowsXamlHost background color is Transparent

Roy Li - MSFT 32,731 Reputation points Microsoft Vendor

2021-08-31T02:11:58.157+00:00

Could you please tell me what kind of app you are developing? A WPF app, a windows forms app or a UWP app?
GuoLearn 251 Reputation points

2021-08-31T02:36:26.473+00:00
A WPF app
Hui Liu-MSFT 47,341 Reputation points Microsoft Vendor

2021-08-31T08:39:44.393+00:00

Hi,@ GuoLearn-6547. It seems difficult to set WindowsXamlHost.OpacityMask directly.You could use work around to set WindowsXamlHost to the same size as the child control, and then use the background color of the child control as the color of WindowsXamlHost to solve this problem. You can also try to refer to here.
GuoLearn 251 Reputation points

2021-08-31T09:23:58.213+00:00

Hi,@Roy Li - MSFT I try the refer
<Grid Background="LightCoral">
<InkCanvas x:Name="InkCanvas" Loaded="InkCanvas_OnLoaded"></InkCanvas>
</Grid>
And I change the Backgound="LightCoral" to Backgound="Transparent" ,
But when I run WPF app ,the Backgound is white not Transparent,
I hope the backgound is Transparent ,and i need some help
GuoLearn 251 Reputation points

2021-08-31T09:58:11.703+00:00
if it can not transparent,is there any way to make the WindowsXamlHost rotate an angle ? when i set

<xaml:WindowsXamlHost.RenderTransform>
<TransformGroup>
<RotateTransform Angle="30"/>
</TransformGroup>
</xaml:WindowsXamlHost.RenderTransform>

the children （ClassLibrary1.MyUserControl1） of the WindowsXamlHost is not rotate ,if the ClassLibrary1.MyUserControl1 and the
WindowsXamlHost can rotate the same angle is Awesome

1 answer

Castorix31 83,206 Reputation points

2021-08-31T10:23:24.683+00:00
You can change the background color of the container control
With a Grid :

Windows.UI.Xaml.Controls.Grid grid = null; private void WindowsXamlHost_ChildChanged(object sender, EventArgs e) { WindowsXamlHost windowsXamlHost = (WindowsXamlHost)sender; grid = (Windows.UI.Xaml.Controls.Grid)windowsXamlHost.Child; if (grid != null) { var brush1 = new Windows.UI.Xaml.Media.SolidColorBrush(Windows.UI.Colors.BlueViolet); grid.Background = brush1; Windows.UI.Xaml.Controls.InkCanvas MyControl2 = new Windows.UI.Xaml.Controls.InkCanvas(); MyControl2.Name = "InkCanvas1"; MyControl2.InkPresenter.InputDeviceTypes = Windows.UI.Core.CoreInputDeviceTypes.Mouse | Windows.UI.Core.CoreInputDeviceTypes.Pen | Windows.UI.Core.CoreInputDeviceTypes.Touch; grid.Children.Add(MyControl2); } }

in XAML :

<XamlHost:WindowsXamlHost HorizontalAlignment="Left" Height="183" Margin="46,64,0,0" VerticalAlignment="Top" Width="426" InitialTypeName="Windows.UI.Xaml.Controls.Grid" ChildChanged="WindowsXamlHost_ChildChanged" Grid.ColumnSpan="2"/>
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GuoLearn 251 Reputation points

2021-08-31T10:40:36.527+00:00

I change the Grid background color
var brush1 = new Windows.UI.Xaml.Media.SolidColorBrush(Windows.UI.Colors.BlueViolet);
grid.Background = brush1;
To

var brush1 = new Windows.UI.Xaml.Media.SolidColorBrush(Windows.UI.Colors.Transparent); grid.Background = brush1;

But when I run APP the Background of Transparent not work ,the Backround show me White not the Transparent,

And what i need is Transparent not color white

Castorix31 83,206 Reputation points

2021-08-31T12:48:38.793+00:00

But which effect are you trying to do ?
II can set it transparent if I set the whole window transparent too :

GuoLearn 251 Reputation points

2021-09-01T01:17:41.5+00:00

The effect I try to do is the WindowsXamlHost and windowsXamlHost.Child background is transparent But the whole window is not transparent
The real reason i try to do it, becouse the WindowsXamlHost and windowsXamlHost.Child can not rotate the same angle ,like this code

<xaml:WindowsXamlHost.RenderTransform>

<TransformGroup>
<RotateTransform Angle="30"/>
</TransformGroup>
</xaml:WindowsXamlHost.RenderTransform>

the angel=30 do not work , so I rotate the windowsXamlHost.Child , but the WindowsXamlHost's background had the white color so i neet it transparent. Is there any way can WindowsXamlHost and windowsXamlHost.Child rotate the same angle , If can do it, it's also helpful me a lot

Castorix31 83,206 Reputation points

2021-09-01T08:03:22.613+00:00

so I rotate the windowsXamlHost.Child , but the WindowsXamlHost's background had the white color so i neet it transparent.

If I add a child button and I rotate it , the background is not white :

GuoLearn 251 Reputation points

2021-09-01T08:31:12.797+00:00

The 128235-windowsxamlhost-color2.jpg what you upload, i can't see it ,it is damaged.

I do't know you mean not white . it is transparent?
I need it transparent, not another color

Castorix31 83,206 Reputation points

2021-09-01T08:35:45.3+00:00

I need it transparent, not another color

You want to see the desktop or other windows only behind WindowsXamlHost ?

GuoLearn 251 Reputation points

2021-09-01T09:05:56.407+00:00

Yes,i want other windows only behind WindowsXamlHost （behind the The white color）

I want the white color to transparent or be cuted ,Yes i want to see it behind the white color.
``But when i Rotate the UWP button there have some white color Like this ,and i want it is you upload “UWP button”（now i can see you upload）
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Microsoft.Toolkit.Wpf.UI.XamlHost.WindowsXamlHost.OpacityMask can not work

1 answer