Instance Method インスタンスメソッド

luminanceToAlpha()

Adds a luminance to alpha effect to this view. ある輝度をこのビューへのアルファ効果に加えます。

Declaration 宣言 

func luminanceToAlpha() -> some View

Return Value 戻り値

A view with the luminance to alpha effect applied.

Discussion 議論

Use this modifier to create a semitransparent mask, with the opacity of each part of the modified view controlled by the luminance of the corresponding part of the original view. Regions of lower luminance become more transparent, while higher luminance yields greater opacity.

In particular, the modifier maps the red, green, and blue components of each input pixel’s color to a grayscale value, and that value becomes the alpha component of a black pixel in the output. This modifier produces an effect that’s equivalent to using the feColorMatrix filter primitive with the luminanceToAlpha type attribute, as defined by the Scalable Vector Graphics (SVG) 2 specification.

The example below defines a Palette view as a series of rectangles, each composed as a Color with a particular white value, and then displays two versions of the palette over a blue background:


struct Palette: View {
    var body: some View {
        HStack(spacing: 0) {
            ForEach(0..<10) { index in
                Color(white: Double(index) / Double(9))
                    .frame(width: 20, height: 40)
            }
        }
    }
}


struct LuminanceToAlphaExample: View {
    var body: some View {
        VStack(spacing: 20) {
            Palette()


            Palette()
                .luminanceToAlpha()
        }
        .padding()
        .background(.blue)
    }
}

The unmodified version of the palette contains rectangles that range from solid black to solid white, thus with increasing luminance. The second version of the palette, which has the luminanceToAlpha() modifier applied, allows the background to show through in an amount that corresponds inversely to the luminance of the input.

A screenshot of a blue background with two wide rectangles on it,

See Also 参照

Graphical Effects

func blur(radius: CGFloat, opaque: Bool) -> some View
Applies a Gaussian blur to this view. ガウシアンぼかしをこのビューに適用します。
func opacity(Double) -> some View
Sets the transparency of this view. このビューの透明度を設定します。
func brightness(Double) -> some View
Brightens this view by the specified amount. このビューをこの指定された量だけ明るくします。
func contrast(Double) -> some View
Sets the contrast and separation between similar colors in this view. このビューにおいて同系色の間のコントラストと分離を設定します。
func colorInvert() -> some View
Inverts the colors in this view. このビューにおいて色を逆にします。
func colorMultiply(Color) -> some View
Adds a color multiplication effect to this view. 色乗算効果をこのビューに加えます。
func saturation(Double) -> some View
Adjusts the color saturation of this view. このビューの色彩度を調整します。
func grayscale(Double) -> some View
Adds a grayscale effect to this view. グレイスケール効果をこのビューに加えます。
func hueRotation(Angle) -> some View
Applies a hue rotation effect to this view. 色相回転効果をこのビューに適用します。
func shadow(color: Color, radius: CGFloat, x: CGFloat, y: CGFloat) -> some View
Adds a shadow to this view. 影をこのビューに加えます。