class Opal::UI::MaskMap

• Opal::UI::MaskMap
• Reference
• Object

Overview

A 2D normalized weight map (values from 0.0 to 1.0) used for alpha stencil masking, spotlights, and feathered dithering effects in terminal screen buffers.

Defined in:

opal/ui/mask.cr

Constant Summary

DITHER_CHARS = Opal::Glyphs::Shades

Shading characters for dithering fractional alpha values: 0.0 -> 1.0

Constructors

• .box(bx : Int32, by : Int32, bw : Int32, bh : Int32, feather : Float64 = 0.0, width : Int32 = 80, height : Int32 = 25) : MaskMap

  Generates a rectangular box mask with optional feathering around its perimeter

• .checkerboard(tile_w : Int32 = 4, tile_h : Int32 = 2, width : Int32 = 80, height : Int32 = 25) : MaskMap

  Generates a checkerboard mask pattern

• .linear_gradient(angle_degrees : Float64, width : Int32 = 80, height : Int32 = 25, start_val : Float64 = 0.0, end_val : Float64 = 1.0) : MaskMap

  Generates a linear gradient mask along a specified angle (in degrees, 0 = left-to-right, 90 = top-to-bottom)

• .new(width : Int32, height : Int32, initial_weight : Float64 = 1.0)
• .radial(cx : Float64 | Int32, cy : Float64 | Int32, radius : Float64, feather : Float64 = 0.0, width : Int32 = 80, height : Int32 = 25, aspect_ratio : Float64 = 2.0) : MaskMap

  Generates a circular or elliptical radial mask centered at (cx, cy) with optional feathering.

• .stencil(lines : Array(String), width : Int32 | Nil = nil, height : Int32 | Nil = nil) : MaskMap

  Generates a stencil mask from an array of ASCII strings (non-space characters become 1.0)

Class Method Summary

• .dither_char(weight : Float64) : Char

  Returns a dither shade character for a given alpha weight (0.0..1.0)

Instance Method Summary

• #[](x : Int32, y : Int32) : Float64
• #[]=(x : Int32, y : Int32, weight : Float64) : Nil
• #blend(other : MaskMap, mode : Symbol = :multiply) : MaskMap

  Blends this mask with another mask using :multiply, :screen, :add, or :subtract

• #fill(weight : Float64) : Nil
• #get(x : Int32, y : Int32) : Float64
• #height : Int32
• #in_bounds?(x : Int32, y : Int32) : Bool
• #invert : MaskMap

  Inverts all mask weights (1.0 - weight)

• #set(x : Int32, y : Int32, weight : Float64) : Nil
• #weights : Array(Float64)
• #width : Int32

Constructor Detail

Class Method Detail

Instance Method Detail