Image.GetAlphaMask Method

Definition

Namespace:

Windows.UI.Xaml.Controls

Returns a mask that represents the alpha channel of an image as a CompositionBrush.

public:
 virtual CompositionBrush ^ GetAlphaMask() = GetAlphaMask;

CompositionBrush GetAlphaMask();

public CompositionBrush GetAlphaMask();

function getAlphaMask()

Public Function GetAlphaMask () As CompositionBrush

Returns

CompositionBrush

A mask that represents the alpha channel of an image.

Windows requirements

Device family	Windows 10 Anniversary Edition (introduced in 10.0.14393.0)
API contract	Windows.Foundation.UniversalApiContract (introduced in v3.0)

Remarks

This method gets an alpha mask from an image as a CompositionBrush that you can use as an input to composition shadows and effects. The alpha mask CompositionBrush has the same alignment and stretch property values that the source XAML element applies to its rendered content so that you can use those values to correctly position shadows or effects relative to the XAML element.

Version compatibility

The GetAlphaMask method is not available prior to Windows 10, version 1607. If your app’s 'minimum platform version' setting in Microsoft Visual Studio is less than the 'introduced version' shown in the Requirements block later in this page, you must design and test your app to account for this. For more info, see Version adaptive code.

To avoid exceptions when your app runs on previous versions of Windows 10, do not call this method without first performing a runtime check. This example shows how to use the ApiInformation class to check for the presence of this method before you use it.

if (ApiInformation.IsMethodPresent("Windows.UI.Xaml.Controls.Image", "GetAlphaMask"))
{
    var compositionBrush = image1.GetAlphaMask();
}