Instance Property

alphaInfo

Returns the alpha channel information for a bitmap image.

Declaration

var alphaInfo: CGImageAlphaInfo { get }

Parameters

image

The image to examine.

Return Value

A CGImageAlphaInfo constant that specifies (1) whether the bitmap contains an alpha channel, (2) where the alpha bits are located in the image data, and (3) whether the alpha value is premultiplied. For possible values, see Constants. The function returns CGImageAlphaInfo.none if the image parameter refers to an image mask.

Discussion

The alpha value is what determines the opacity of a pixel when it is drawn.

See Also

Examining an Image

var isMask: Bool

Returns whether a bitmap image is an image mask.

var width: Int

Returns the width of a bitmap image.

var height: Int

Returns the height of a bitmap image.

var bitsPerComponent: Int

Returns the number of bits allocated for a single color component of a bitmap image.

var bitsPerPixel: Int

Returns the number of bits allocated for a single pixel in a bitmap image.

var bytesPerRow: Int

Returns the number of bytes allocated for a single row of a bitmap image.

var colorSpace: CGColorSpace?

Return the color space for a bitmap image.

enum CGImageAlphaInfo

Storage options for alpha component data.

var dataProvider: CGDataProvider?

Returns the data provider for a bitmap image.

var decode: UnsafePointer<CGFloat>?

Returns the decode array for a bitmap image.

var shouldInterpolate: Bool

Returns the interpolation setting for a bitmap image.

var renderingIntent: CGColorRenderingIntent

Returns the rendering intent setting for a bitmap image.

var bitmapInfo: CGBitmapInfo

Returns the bitmap information for a bitmap image.

struct CGBitmapInfo

Component information for a bitmap image.

var utType: CFString?

The Universal Type Identifier for the image.

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