Function arithmetic

pub fn arithmetic(
    k1: f32,
    k2: f32,
    k3: f32,
    k4: f32,
    enforce_pm_color: bool,
    background: impl Into<Option<RCHandle<SkImageFilter>>>,
    foreground: impl Into<Option<RCHandle<SkImageFilter>>>,
    crop_rect: impl Into<CropRect>,
) -> Option<RCHandle<SkImageFilter>>

Create a filter that implements a custom blend mode. Each output pixel is the result of combining the corresponding background and foreground pixels using the 4 coefficients: k1 * foreground * background + k2 * foreground + k3 * background + k4

• k1, k2, k3, k4 The four coefficients used to combine the foreground and background.
• enforce_pm_color - If true, the RGB channels will be clamped to the calculated alpha.
• background - The background content, using the source bitmap when this is null.
• foreground - The foreground content, using the source bitmap when this is null.
• crop_rect - Optional rectangle that crops the inputs and output.