Instance Method

setAlpha(_:)

Sets the opacity level for objects drawn in a graphics context.

Declaration

func setAlpha(_ alpha: CGFloat)

Parameters

alpha

A value that specifies the opacity level. Values can range from 0.0 (transparent) to 1.0 (opaque). Values outside this range are clipped to 0.0 or 1.0.

Discussion

This function sets the alpha value parameter for the specified graphics context. To clear the contents of the drawing canvas, use clear(_:).

See Also

Setting Fill, Stroke, and Shadow Colors

func setFillColor(CGColor)

Sets the current fill color in a graphics context, using a CGColor.

func setFillColor(UnsafePointer<CGFloat>)

Sets the current fill color.

func setFillColor(cyan: CGFloat, magenta: CGFloat, yellow: CGFloat, black: CGFloat, alpha: CGFloat)

Sets the current fill color to a value in the DeviceCMYK color space.

func setFillColor(gray: CGFloat, alpha: CGFloat)

Sets the current fill color to a value in the DeviceGray color space.

func setFillColor(red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat)

Sets the current fill color to a value in the DeviceRGB color space.

func setFillColorSpace(CGColorSpace)

Sets the fill color space in a graphics context.

func setShadow(offset: CGSize, blur: CGFloat)

Enables shadowing in a graphics context.

func setShadow(offset: CGSize, blur: CGFloat, color: CGColor?)

Enables shadowing with color a graphics context.

func setStrokeColor(CGColor)

Sets the current stroke color in a context, using a CGColor.

func setStrokeColor(UnsafePointer<CGFloat>)

Sets the current stroke color.

func setStrokeColor(cyan: CGFloat, magenta: CGFloat, yellow: CGFloat, black: CGFloat, alpha: CGFloat)

Sets the current stroke color to a value in the DeviceCMYK color space.

func setStrokeColor(gray: CGFloat, alpha: CGFloat)

Sets the current stroke color to a value in the DeviceGray color space.

func setStrokeColor(red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat)

Sets the current stroke color to a value in the DeviceRGB color space.

func setStrokeColorSpace(CGColorSpace)

Sets the stroke color space in a graphics context.

func setStrokePattern(CGPattern, colorComponents: UnsafePointer<CGFloat>)

Sets the stroke pattern in the specified graphics context.