Skip to content
canvas
shapes
lines
draw_line_aa

draw_line_aa

Mojo function 🡭

draw_line_aa

fn def draw_line_aa(mut canvas: Canvas, x0: Int, y0: Int, x1: Int, y1: Int, color: Color, width: Float64 = 1, supersample: Int = Int(4), dashes: List[Float64] = List(), dash_offset: Float64 = 0, cap: LineCap = LineCap.ROUND, join: LineJoin = LineJoin.ROUND, miter_limit: Float64 = 4)

Anti-aliased line, width pixels wide (default 1), finished with cap at each end.

A one-segment polyline, and drawn as one: _draw_polyline_core_aa turns the stroke into an outline and fills it, so the cost follows the stroke’s area rather than its bounding box.

Args:

  • canvas (Canvas): Canvas to draw into.
  • x0 (Int): Start point x.
  • y0 (Int): Start point y.
  • x1 (Int): End point x.
  • y1 (Int): End point y.
  • color (Color): Line color.
  • width (Float64): Stroke width in pixels.
  • supersample (Int): Sub-pixel grid side length per pixel (N -> N*N samples) for the one stroke that still samples: a closed one whose inner ring inverts, the width being past the curve’s radius of curvature. Every other stroke rasterizes by exact area and ignores it. See _stroke_edges.
  • dashes (List[Float64]): On/off segment lengths in pixels, cycled along the line. Empty (default) draws a solid line.
  • dash_offset (Float64): Distance into the dash pattern the line starts at.
  • cap (LineCap): How the two ends are finished – see LineCap.
  • join (LineJoin): Unused for a single segment, which has no corners.
  • miter_limit (Float64): Unused for a single segment.
fn def draw_line_aa(mut canvas: Canvas, x0: Float64, y0: Float64, x1: Float64, y1: Float64, color: Color, width: Float64 = 1, supersample: Int = Int(4), dashes: List[Float64] = List(), dash_offset: Float64 = 0, cap: LineCap = LineCap.ROUND, join: LineJoin = LineJoin.ROUND, miter_limit: Float64 = 4)

draw_line_aa at sub-pixel endpoints – the same line, placed to a fraction of a pixel rather than snapped to the pixel grid.

This is the real implementation; the whole-pixel overload above converts and calls it. Placing a value at x = 103.7 rather than rounding to 104 shifts the line by a third of a pixel, which at a 1px stroke width is visible.

Args:

  • canvas (Canvas): Canvas to draw into.
  • x0 (Float64): Start point x.
  • y0 (Float64): Start point y.
  • x1 (Float64): End point x.
  • y1 (Float64): End point y.
  • color (Color): Line color.
  • width (Float64): Stroke width in pixels.
  • supersample (Int): Sub-pixel grid side length per pixel (N -> N*N samples) for the one stroke that still samples: a closed one whose inner ring inverts, the width being past the curve’s radius of curvature. Every other stroke rasterizes by exact area and ignores it. See _stroke_edges.
  • dashes (List[Float64]): On/off segment lengths in pixels, cycled along the line. Empty (default) draws a solid line.
  • dash_offset (Float64): Distance into the dash pattern the line starts at.
  • cap (LineCap): How the two ends are finished – see LineCap.
  • join (LineJoin): Unused for a single segment, which has no corners.
  • miter_limit (Float64): Unused for a single segment.
draw_linedraw_polygon