Struct GraphicsLayer 

pub struct GraphicsLayer {

    pub alpha: f32,
    pub scale: f32,
    pub scale_x: f32,
    pub scale_y: f32,
    pub rotation_x: f32,
    pub rotation_y: f32,
    pub rotation_z: f32,
    pub camera_distance: f32,
    pub transform_origin: TransformOrigin,
    pub translation_x: f32,
    pub translation_y: f32,
    pub shadow_elevation: f32,
    pub ambient_shadow_color: Color,
    pub spot_shadow_color: Color,
    pub shape: LayerShape,
    pub clip: bool,
    pub compositing_strategy: CompositingStrategy,
    pub blend_mode: BlendMode,
    pub color_filter: Option<ColorFilter>,
    pub render_effect: Option<RenderEffect>,
    pub backdrop_effect: Option<RenderEffect>,
}

Fields

alpha: f32

scale: f32

scale_x: f32

scale_y: f32

rotation_x: f32

rotation_y: f32

rotation_z: f32

camera_distance: f32

transform_origin: TransformOrigin

translation_x: f32

translation_y: f32

shadow_elevation: f32

ambient_shadow_color: Color

spot_shadow_color: Color

shape: LayerShape

clip: bool

compositing_strategy: CompositingStrategy

blend_mode: BlendMode

color_filter: Option<ColorFilter>

render_effect: Option<RenderEffect>

backdrop_effect: Option<RenderEffect>

Implementations

impl GraphicsLayer

pub fn composite_alpha_8bit(alpha: f32) -> f32

The alpha an isolated layer is composited at: an eight-bit one, truncated.

The platform never composites a layer at a float alpha. HWUI hands an isolated RenderNode to the rasterizer as canvas->saveLayerAlpha(&bounds, (int)(properties.getAlpha() * 255)) (frameworks/base/libs/hwui/pipeline/skia/RenderNodeDrawable.cpp, setViewProperties), and (int) truncates — 0.5 composites at 127/255, not at 128/255. The fraction below that byte is gone before a single pixel is blended, so anything that keeps it lands a level out wherever the byte and the float fall on opposite sides of a half.

The sibling branch is a float on purpose: where getHasOverlappingRendering() is false HWUI takes *alphaMultiplier = properties.getAlpha() and folds it into each draw without ever making a byte of it. That is what CompositingStrategy::ModulateAlpha names.

Truncating here and rounding in Color::srgb_8bit is not an inconsistency: they are different call sites in the platform. A colour’s own alpha is snapped by Color’s constructor, which adds the half; a layer’s alpha is snapped by HWUI’s cast, which does not. Anything modelling a faded layer without allocating one — a canvas drawing a list row’s fade by hand, say — wants this rule and not the other.

Trait Implementations

impl Clone for GraphicsLayer

fn clone(&self) -> GraphicsLayer

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for GraphicsLayer

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for GraphicsLayer

fn default() -> GraphicsLayer

Returns the “default value” for a type.

impl PartialEq for GraphicsLayer

fn eq(&self, other: &GraphicsLayer) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for GraphicsLayer