BitmapExtensionsGetReadWriteBitmapData(Bitmap, Color, Byte) Method

public static IReadWriteBitmapData GetReadWriteBitmapData(
	this Bitmap bitmap,
	Color backColor = default,
	byte alphaThreshold = 128
)

<ExtensionAttribute>
Public Shared Function GetReadWriteBitmapData ( 
	bitmap As Bitmap,
	Optional backColor As Color = Nothing,
	Optional alphaThreshold As Byte = 128
) As IReadWriteBitmapData

public:
[ExtensionAttribute]
static IReadWriteBitmapData^ GetReadWriteBitmapData(
	Bitmap^ bitmap, 
	Color backColor = Color(), 
	unsigned char alphaThreshold = 128
)

[<ExtensionAttribute>]
static member GetReadWriteBitmapData : 
        bitmap : Bitmap * 
        ?backColor : Color * 
        ?alphaThreshold : byte 
(* Defaults:
        let _backColor = defaultArg backColor new Color()
        let _alphaThreshold = defaultArg alphaThreshold 128
*)
-> IReadWriteBitmapData 

Parameters

bitmap  Bitmap

A Bitmap instance, whose data is about to be accessed.

backColor  Color  (Optional)

When setting pixels of indexed bitmaps and bitmaps without alpha support or with single bit alpha, specifies the color of the background. Color values with alpha, which are considered opaque will be blended with this color before setting the pixel in the result bitmap data. The alpha value (Color.A property) of the specified background color is ignored. This parameter is optional.
Default value: Color.Empty, which has the same RGB values as Black.

alphaThreshold  Byte  (Optional)

When setting pixels of bitmaps with single bit alpha or with a palette that has a transparent color, then specifies a threshold value for the Color.A property, under which the color is considered transparent. If 0, then the pixels to be set will never be transparent. This parameter is optional.
Default value: 128.

Return Value

Usage Note

All possible PixelFormats are supported, of which a Bitmap can be created in the current operating system.

If alphaThreshold is zero, then setting a fully transparent pixel in a bitmap with indexed or single-bit-alpha pixel format will blend the pixel to set with backColor even if the bitmap can handle transparent pixels.

If alphaThreshold is 1, then the result color of setting a pixel of a bitmap with indexed or single-bit-alpha pixel format will be transparent only if the color to set is completely transparent (has zero alpha).

If alphaThreshold is 255, then the result color of setting a pixel of a bitmap with indexed or single-bit-alpha pixel format will be opaque only if the color to set is completely opaque (its alpha value is 255).

If a pixel of a bitmap without alpha gradient support is set by the IWritableBitmapData.SetPixel/IWritableBitmapDataRow.SetColor methods or by the IReadWriteBitmapDataRow indexer, and the pixel has an alpha value that is greater than alphaThreshold, then the pixel to set will be blended with backColor.

Reference