Enum BlendMode 

pub enum BlendMode {
    Normal,
    Multiply,
    Screen,
    Overlay,
    SoftLight,
    HardLight,
    ColorDodge,
    ColorBurn,
    Darken,
    Lighten,
    Difference,
    Exclusion,
    Add,
    Subtract,
    Hue,
    Saturation,
    Color,
    Luminosity,
    PorterDuffOver,
    PorterDuffUnder,
    PorterDuffIn,
    PorterDuffOut,
    PorterDuffAtop,
    PorterDuffXor,
}

Specifies how two video layers are combined during compositing.

Variants are grouped into two families:

• Photographic blend modes (18) — operate on pixel values; both layers are typically opaque. Implemented via FFmpeg’s blend filter with the all_mode option, except BlendMode::Normal which uses overlay.

• Porter-Duff alpha compositing (6) — operate on the alpha channel; at least the top layer must carry an alpha channel (e.g. rgba or yuva420p pixel format).

Implementation status

All 14 arithmetic photographic modes and all 6 Porter-Duff operations are fully implemented and covered by regression tests (issues #327–#347).

The four HSL-space modes — BlendMode::Hue, BlendMode::Saturation, BlendMode::Color, and BlendMode::Luminosity — are accepted by the builder but produce no output at runtime: FFmpeg’s blend filter does not include these mode names in the bundled version. The builder returns FilterError::BuildFailed when the filter graph cannot be configured for these modes.

Variants

Normal

Standard alpha-over composite (top * opacity + bottom * (1 − opacity)).

Implemented via FFmpeg’s overlay=format=auto:shortest=1.

Multiply

Multiply per-channel pixel values; darkens the result.

Maps to blend all_mode=multiply.

Screen

Inverse of multiply; lightens the result.

Maps to blend all_mode=screen.

Overlay

Combines Multiply and Screen based on base-layer luminance.

Maps to blend all_mode=overlay.

SoftLight

Gentle contrast enhancement; 50 % gray top layer is identity.

Maps to blend all_mode=softlight.

HardLight

Harsher version of Overlay; driven by the top layer’s luminance.

Maps to blend all_mode=hardlight.

ColorDodge

Brightens the base by dividing it by the inverse of the blend.

Maps to blend all_mode=dodge.

ColorBurn

Darkens the base; inverse of Color Dodge.

Maps to blend all_mode=burn.

Darken

Retains the darker of the two pixels per channel.

Maps to blend all_mode=darken.

Lighten

Retains the lighter of the two pixels per channel.

Maps to blend all_mode=lighten.

Difference

Per-channel absolute difference. Useful for alignment verification.

Maps to blend all_mode=difference.

Exclusion

Similar to Difference but with lower contrast in mid-tones.

Maps to blend all_mode=exclusion.

Add

Linear addition, clamped at maximum.

Maps to blend all_mode=addition.

Subtract

Linear subtraction, clamped at minimum.

Maps to blend all_mode=subtract.

Hue

Applies the top layer’s hue to the base’s saturation and luminance.

Maps to blend all_mode=hue.

Note: not supported by the bundled FFmpeg blend filter; graph construction succeeds but no output frame is produced at runtime.

Saturation

Applies the top layer’s saturation to the base’s hue and luminance.

Maps to blend all_mode=saturation.

Note: not supported by the bundled FFmpeg blend filter; graph construction succeeds but no output frame is produced at runtime.

Color

Applies the top layer’s hue + saturation to the base’s luminance.

Maps to blend all_mode=color.

Note: not supported by the bundled FFmpeg blend filter; graph construction succeeds but no output frame is produced at runtime.

Luminosity

Applies the top layer’s luminance to the base’s hue and saturation.

Maps to blend all_mode=luminosity.

Note: not supported by the bundled FFmpeg blend filter; graph construction succeeds but no output frame is produced at runtime.

PorterDuffOver

Top layer rendered over the bottom (standard alpha compositing).

Implemented via overlay=format=auto:shortest=1.

PorterDuffUnder

Bottom layer rendered over the top; equivalent to Over with inputs swapped.

PorterDuffIn

Top layer masked by the bottom layer’s alpha (intersection).

PorterDuffOut

Top layer visible only where the bottom layer is transparent.

PorterDuffAtop

Top layer placed atop the bottom; visible only where the bottom is opaque.

PorterDuffXor

Pixels from exactly one layer (XOR of opaque regions).

Trait Implementations

impl Clone for BlendMode

fn clone(&self) -> BlendMode

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for BlendMode

impl Debug for BlendMode

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

Formats the value using the given formatter.

impl Eq for BlendMode

impl PartialEq for BlendMode

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for BlendMode