Class: Postsvg::Translation::Handlers::PathHandler

Inherits:
Object
  • Object
show all
Extended by:
Shared
Defined in:
lib/postsvg/translation/handlers/path_handler.rb

Overview

SVG <path d="...">. Walks the PathData command list and emits equivalent PS path construction operators. Full SVG path grammar support:

  • M/m moveto (relative repeats as l)
  • L/l lineto
  • H/h vertical line
  • V/v horizontal line
  • C/c cubic bezier
  • S/s smooth cubic (reflects previous control point)
  • Q/q quadratic bezier (converted to cubic)
  • T/t smooth quadratic (converted to cubic)
  • A/a arc (converted to PS arc via center-point parametrization)
  • Z/z closepath

Defined Under Namespace

Classes: SmoothState

Class Method Summary collapse

Methods included from Shared

emit_fill, emit_paint, emit_paint_setup, emit_stroke, emit_transform, expand_bbox

Class Method Details

.adapt_curve_args(args, opcode, state) ⇒ Object

---- helpers ----



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# File 'lib/postsvg/translation/handlers/path_handler.rb', line 231

def self.adapt_curve_args(args, opcode, state)
  return args if opcode.upcase == opcode

  # Relative: dxN/dyN become xN = current + dxN
  x1 = state.current_x + args[0]
  y1 = state.current_y + args[1]
  x2 = state.current_x + args[2]
  y2 = state.current_y + args[3]
  x3 = state.current_x + args[4]
  y3 = state.current_y + args[5]
  [x1, y1, x2, y2, x3, y3]
end

.adapt_quadratic_args(args, opcode, state) ⇒ Object 



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# File 'lib/postsvg/translation/handlers/path_handler.rb', line 244

def self.adapt_quadratic_args(args, opcode, state)
  return args if opcode.upcase == opcode

  qx = state.current_x + args[0]
  qy = state.current_y + args[1]
  x3 = state.current_x + args[2]
  y3 = state.current_y + args[3]
  [qx, qy, x3, y3]
end

.call(element, context) ⇒ Object 



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# File 'lib/postsvg/translation/handlers/path_handler.rb', line 27

def self.call(element, context)
  context.emitter.emit(Model::Operators::GraphicsState::Gsave.new)
  emit_transform(element, context)
  context.emitter.emit(Model::Operators::Path::Newpath.new)

  state = PathState.new
  smooth = SmoothState.new(control_x: nil, control_y: nil, smoothable: false)
  element.commands.each do |cmd|
    dispatch_command(cmd, state, smooth, context)
  end
  emit_paint(element, context)
  context.emitter.emit(Model::Operators::GraphicsState::Grestore.new)
  expand_bbox(context, *state.bbox_points) if state.bbox_points.any?
end

.dispatch_command(cmd, state, smooth, context) ⇒ Object 



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# File 'lib/postsvg/translation/handlers/path_handler.rb', line 42

def self.dispatch_command(cmd, state, smooth, context)
  case cmd.opcode
  when "M", "m"
    handle_moveto(cmd, state, smooth, context)
  when "L", "l"
    handle_lineto(cmd, state, context)
  when "H", "h"
    handle_hv(cmd, state, context, horizontal: cmd.opcode.upcase == "H")
  when "V", "v"
    handle_hv(cmd, state, context, horizontal: cmd.opcode.upcase == "V")
  when "C", "c"
    handle_cubic(cmd, state, smooth, context)
  when "S", "s"
    handle_smooth_cubic(cmd, state, smooth, context)
  when "Q", "q"
    handle_quadratic(cmd, state, smooth, context)
  when "T", "t"
    handle_smooth_quadratic(cmd, state, smooth, context)
  when "A", "a"
    handle_arc(cmd, state, context)
  when "Z", "z"
    context.emitter.emit(Model::Operators::Path::Closepath.new)
    state.close!
  end
end

.handle_arc(cmd, state, context) ⇒ Object

Convert SVG elliptical arc to PS arc(s). SVG arc parametrizes by endpoint + flags; PS arc is center-based. Use the W3C-endorsed endpoint-to-center conversion.



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# File 'lib/postsvg/translation/handlers/path_handler.rb', line 199

def self.handle_arc(cmd, state, context)
  rx, ry, x_axis_rotation, large_arc_flag, sweep_flag, x, y = cmd.args
  cx, cy, normalized_rx, normalized_ry, psi, theta1, theta2 =
    Postsvg::Translation::ArcConverter.endpoint_to_center(
      x1: state.current_x, y1: state.current_y,
      rx: rx, ry: ry, x_axis_rotation: x_axis_rotation,
      large_arc: large_arc_flag != 0, sweep: sweep_flag != 0,
      x2: x, y2: y,
    )
  # Emit arc with center, radius, angle range. For elliptical
  # arcs (rx != ry or non-zero rotation), emit scale/rotate
  # transforms around the arc.
  if x_axis_rotation.abs > 1e-6 || (rx - ry).abs > 1e-6
    context.emitter.emit(Model::Operators::GraphicsState::Gsave.new)
    context.emitter.emit(Model::Operators::Transformations::Concat.new(matrix: [
      Math.cos(psi), Math.sin(psi), -Math.sin(psi), Math.cos(psi), cx, cy,
    ]))
    context.emitter.emit(Model::Operators::Transformations::Scale.new(sx: normalized_rx, sy: normalized_ry))
    context.emitter.emit(Model::Operators::Path::Arc.new(
      x: 0, y: 0, radius: 1.0, angle1: theta1, angle2: theta2,
    ))
    context.emitter.emit(Model::Operators::GraphicsState::Grestore.new)
  else
    context.emitter.emit(Model::Operators::Path::Arc.new(
      x: cx, y: cy, radius: normalized_rx, angle1: theta1, angle2: theta2,
    ))
  end
  state.move_to(x, y)
end

.handle_cubic(cmd, state, smooth, context) ⇒ Object 



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# File 'lib/postsvg/translation/handlers/path_handler.rb', line 114

def self.handle_cubic(cmd, state, smooth, context)
  args = cmd.args
  x1, y1, x2, y2, x3, y3 = adapt_curve_args(args, cmd.opcode, state)
  state.curve_to(x3, y3)
  context.emitter.emit(Model::Operators::Path::Curveto.new(
    x1: x1, y1: y1, x2: x2, y2: y2, x3: x3, y3: y3,
  ))
  smooth.control_x = x2
  smooth.control_y = y2
  smooth.smoothable = true
end

.handle_hv(cmd, state, context, horizontal:) ⇒ Object 



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# File 'lib/postsvg/translation/handlers/path_handler.rb', line 93

def self.handle_hv(cmd, state, context, horizontal:)
  v = cmd.args[0]
  if cmd.opcode.upcase == cmd.opcode # absolute
    if horizontal
      new_x = v
      state.line_to(new_x, state.current_y)
      context.emitter.emit(Model::Operators::Path::Lineto.new(x: new_x, y: state.current_y))
    else
      new_y = v
      state.line_to(state.current_x, new_y)
      context.emitter.emit(Model::Operators::Path::Lineto.new(x: state.current_x, y: new_y))
    end
  elsif horizontal
    state.line_to_rel(v, 0)
    context.emitter.emit(Model::Operators::Path::Rlineto.new(dx: v, dy: 0))
  else
    state.line_to_rel(0, v)
    context.emitter.emit(Model::Operators::Path::Rlineto.new(dx: 0, dy: v))
  end
end

.handle_lineto(cmd, state, context) ⇒ Object 



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# File 'lib/postsvg/translation/handlers/path_handler.rb', line 82

def self.handle_lineto(cmd, state, context)
  x, y = cmd.args
  if cmd.opcode == "L"
    state.line_to(x, y)
    context.emitter.emit(Model::Operators::Path::Lineto.new(x: x, y: y))
  else
    state.line_to_rel(x, y)
    context.emitter.emit(Model::Operators::Path::Rlineto.new(dx: x, dy: y))
  end
end

.handle_moveto(cmd, state, smooth, context) ⇒ Object

---- per-command handlers ----



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# File 'lib/postsvg/translation/handlers/path_handler.rb', line 70

def self.handle_moveto(cmd, state, smooth, context)
  x, y = cmd.args
  if cmd.opcode == "M"
    state.move_to(x, y)
    context.emitter.emit(Model::Operators::Path::Moveto.new(x: x, y: y))
  else
    state.move_to_rel(x, y)
    context.emitter.emit(Model::Operators::Path::Rmoveto.new(dx: x, dy: y))
  end
  smooth.smoothable = false
end

.handle_quadratic(cmd, state, smooth, context) ⇒ Object 



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# File 'lib/postsvg/translation/handlers/path_handler.rb', line 148

def self.handle_quadratic(cmd, state, smooth, context)
  args = cmd.args
  qx, qy, x3, y3 = adapt_quadratic_args(args, cmd.opcode, state)
  # Convert quadratic to cubic: c1 = p0 + 2/3*(q-p0),
  # c2 = p3 + 2/3*(q-p3).
  p0x, p0y = state.current_x, state.current_y
  c1x = p0x + (2.0 / 3.0) * (qx - p0x)
  c1y = p0y + (2.0 / 3.0) * (qy - p0y)
  c2x = x3 + (2.0 / 3.0) * (qx - x3)
  c2y = y3 + (2.0 / 3.0) * (qy - y3)
  state.curve_to(x3, y3)
  context.emitter.emit(Model::Operators::Path::Curveto.new(
    x1: c1x, y1: c1y, x2: c2x, y2: c2y, x3: x3, y3: y3,
  ))
  smooth.control_x = qx
  smooth.control_y = qy
  smooth.smoothable = true
end

.handle_smooth_cubic(cmd, state, smooth, context) ⇒ Object 



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# File 'lib/postsvg/translation/handlers/path_handler.rb', line 126

def self.handle_smooth_cubic(cmd, state, smooth, context)
  x2, y2, x3, y3 = cmd.args
  if cmd.opcode == "S"
    x1, y1 = reflect_control(smooth, state)
    state.curve_to(x3, y3)
    context.emitter.emit(Model::Operators::Path::Curveto.new(
      x1: x1, y1: y1, x2: x2, y2: y2, x3: x3, y3: y3,
    ))
  else
    dx1, dy1 = reflect_control_rel(smooth, state)
    state.curve_to_rel(dx2: x2, dy2: y2, dx3: x3, dy3: y3, dx1: dx1, dy1: dy1)
    context.emitter.emit(Model::Operators::Path::Rcurveto.new(
      dx1: dx1, dy1: dy1, dx2: x2, dy2: y2, dx3: x3, dy3: y3,
    ))
    x2 = state.current_x - x2
    y2 = state.current_y - y2
  end
  smooth.control_x = state.current_x + (x2 - state.current_x)
  smooth.control_y = state.current_y + (y2 - state.current_y)
  smooth.smoothable = true
end

.handle_smooth_quadratic(cmd, state, smooth, context) ⇒ Object 



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# File 'lib/postsvg/translation/handlers/path_handler.rb', line 167

def self.handle_smooth_quadratic(cmd, state, smooth, context)
  x3, y3 = cmd.args
  qx, qy =
    if smooth.smoothable
      [reflect_x(smooth.control_x, state), reflect_y(smooth.control_y, state)]
    else
      [state.current_x, state.current_y]
    end
  p0x, p0y = state.current_x, state.current_y
  c1x = p0x + (2.0 / 3.0) * (qx - p0x)
  c1y = p0y + (2.0 / 3.0) * (qy - p0y)
  c2x = x3 + (2.0 / 3.0) * (qx - x3)
  c2y = y3 + (2.0 / 3.0) * (qy - y3)
  if cmd.opcode == "T"
    state.curve_to(x3, y3)
  else
    state.curve_to_rel(x3 - p0x, y3 - p0y) # treat as rel target
    # Re-anchor to absolute target for emission below.
    state.current_x = p0x + x3
    state.current_y = p0y + y3
  end
  context.emitter.emit(Model::Operators::Path::Curveto.new(
    x1: c1x, y1: c1y, x2: c2x, y2: c2y, x3: state.current_x, y3: state.current_y,
  ))
  smooth.control_x = qx
  smooth.control_y = qy
  smooth.smoothable = true
end

.reflect_control(smooth, state) ⇒ Object 



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# File 'lib/postsvg/translation/handlers/path_handler.rb', line 254

def self.reflect_control(smooth, state)
  return [state.current_x, state.current_y] unless smooth.smoothable

  [reflect_x(smooth.control_x, state), reflect_y(smooth.control_y, state)]
end

.reflect_control_rel(smooth, state) ⇒ Object 



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# File 'lib/postsvg/translation/handlers/path_handler.rb', line 260

def self.reflect_control_rel(smooth, state)
  abs_x, abs_y = reflect_control(smooth, state)
  [abs_x - state.current_x, abs_y - state.current_y]
end

.reflect_x(control_x, state) ⇒ Object 



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# File 'lib/postsvg/translation/handlers/path_handler.rb', line 265

def self.reflect_x(control_x, state)
  2 * state.current_x - control_x
end

.reflect_y(control_y, state) ⇒ Object 



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# File 'lib/postsvg/translation/handlers/path_handler.rb', line 269

def self.reflect_y(control_y, state)
  2 * state.current_y - control_y
end