Module | ChunkyPNG::Canvas::Drawing |
In: |
lib/chunky_png/canvas/drawing.rb
|
Module that adds some primitive drawing methods to {ChunkyPNG::Canvas}.
All of these methods change the current canvas instance and do not create a new one, even though the method names do not end with a bang.
@note Drawing operations will not fail when something is drawn outside of the bounds
of the canvas; these pixels will simply be ignored.
@see ChunkyPNG::Canvas
Draws a Bezier curve @param [Array, Point] A collection of control points @return [Chunky:PNG::Canvas] Itself, with the curve drawn
# File lib/chunky_png/canvas/drawing.rb, line 35 35: def bezier_curve(points, stroke_color = ChunkyPNG::Color::BLACK) 36: 37: points = ChunkyPNG::Vector(*points) 38: case points.length 39: when 0, 1; return self 40: when 2; return line(points[0].x, points[0].y, points[1].x, points[1].y, stroke_color) 41: end 42: 43: curve_points = Array.new 44: 45: t = 0 46: n = points.length - 1 47: bicof = 0 48: 49: while t <= 100 50: cur_p = ChunkyPNG::Point.new(0,0) 51: 52: # Generate a float of t. 53: t_f = t / 100.00 54: 55: cur_p.x += ((1 - t_f) ** n) * points[0].x 56: cur_p.y += ((1 - t_f) ** n) * points[0].y 57: 58: for i in 1...points.length - 1 59: bicof = binomial_coefficient(n , i) 60: 61: cur_p.x += (bicof * (1 - t_f) ** (n - i)) * (t_f ** i) * points[i].x 62: cur_p.y += (bicof * (1 - t_f) ** (n - i)) * (t_f ** i) * points[i].y 63: i += 1 64: end 65: 66: cur_p.x += (t_f ** n) * points[n].x 67: cur_p.y += (t_f ** n) * points[n].y 68: 69: curve_points << cur_p 70: 71: bicof = 0 72: t += 1 73: end 74: 75: curve_points.each_cons(2) do |p1, p2| 76: line_xiaolin_wu(p1.x.round, p1.y.round, p2.x.round, p2.y.round, stroke_color) 77: end 78: 79: return self 80: end
Draws a circle on the canvas.
@param [Integer] x0 The x-coordinate of the center of the circle. @param [Integer] y0 The y-coordinate of the center of the circle. @param [Integer] radius The radius of the circle from the center point. @param [Integer] stroke_color The color to use for the line. @param [Integer] fill_color The color to use that fills the circle. @return [ChunkyPNG::Canvas] Itself, with the circle drawn.
# File lib/chunky_png/canvas/drawing.rb, line 236 236: def circle(x0, y0, radius, stroke_color = ChunkyPNG::Color::BLACK, fill_color = ChunkyPNG::Color::TRANSPARENT) 237: 238: stroke_color = ChunkyPNG::Color.parse(stroke_color) 239: fill_color = ChunkyPNG::Color.parse(fill_color) 240: 241: f = 1 - radius 242: ddF_x = 1 243: ddF_y = -2 * radius 244: x = 0 245: y = radius 246: 247: compose_pixel(x0, y0 + radius, stroke_color) 248: compose_pixel(x0, y0 - radius, stroke_color) 249: compose_pixel(x0 + radius, y0, stroke_color) 250: compose_pixel(x0 - radius, y0, stroke_color) 251: 252: lines = [radius - 1] unless fill_color == ChunkyPNG::Color::TRANSPARENT 253: 254: while x < y 255: 256: if f >= 0 257: y -= 1 258: ddF_y += 2 259: f += ddF_y 260: end 261: 262: x += 1 263: ddF_x += 2 264: f += ddF_x 265: 266: unless fill_color == ChunkyPNG::Color::TRANSPARENT 267: lines[y] = lines[y] ? [lines[y], x - 1].min : x - 1 268: lines[x] = lines[x] ? [lines[x], y - 1].min : y - 1 269: end 270: 271: compose_pixel(x0 + x, y0 + y, stroke_color) 272: compose_pixel(x0 - x, y0 + y, stroke_color) 273: compose_pixel(x0 + x, y0 - y, stroke_color) 274: compose_pixel(x0 - x, y0 - y, stroke_color) 275: 276: unless x == y 277: compose_pixel(x0 + y, y0 + x, stroke_color) 278: compose_pixel(x0 - y, y0 + x, stroke_color) 279: compose_pixel(x0 + y, y0 - x, stroke_color) 280: compose_pixel(x0 - y, y0 - x, stroke_color) 281: end 282: end 283: 284: unless fill_color == ChunkyPNG::Color::TRANSPARENT 285: lines.each_with_index do |length, y| 286: line(x0 - length, y0 - y, x0 + length, y0 - y, fill_color) if length > 0 287: line(x0 - length, y0 + y, x0 + length, y0 + y, fill_color) if length > 0 && y > 0 288: end 289: end 290: 291: return self 292: end
Composes a pixel on the canvas by alpha blending a color with its background color. @param [Integer] x The x-coordinate of the pixel to blend. @param [Integer] y The y-coordinate of the pixel to blend. @param [Integer] color The foreground color to blend with @return [Integer] The composed color.
# File lib/chunky_png/canvas/drawing.rb, line 19 19: def compose_pixel(x, y, color) 20: return unless include_xy?(x, y) 21: compose_pixel_unsafe(x, y, ChunkyPNG::Color.parse(color)) 22: end
Composes a pixel on the canvas by alpha blending a color with its background color, without bounds checking. @param (see compose_pixel) @return [Integer] The composed color.
# File lib/chunky_png/canvas/drawing.rb, line 28 28: def compose_pixel_unsafe(x, y, color) 29: set_pixel(x, y, ChunkyPNG::Color.compose(color, get_pixel(x, y))) 30: end
Draws an anti-aliased line using Xiaolin Wu‘s algorithm.
@param [Integer] x0 The x-coordinate of the first control point. @param [Integer] y0 The y-coordinate of the first control point. @param [Integer] x1 The x-coordinate of the second control point. @param [Integer] y1 The y-coordinate of the second control point. @param [Integer] stroke_color The color to use for this line. @param [true, false] inclusive Whether to draw the last pixel.
Set to false when drawing multiple lines in a path.
@return [ChunkyPNG::Canvas] Itself, with the line drawn.
# File lib/chunky_png/canvas/drawing.rb, line 93 93: def line_xiaolin_wu(x0, y0, x1, y1, stroke_color, inclusive = true) 94: 95: stroke_color = ChunkyPNG::Color.parse(stroke_color) 96: 97: dx = x1 - x0 98: sx = dx < 0 ? -1 : 1 99: dx *= sx 100: dy = y1 - y0 101: sy = dy < 0 ? -1 : 1 102: dy *= sy 103: 104: if dy == 0 # vertical line 105: x0.step(inclusive ? x1 : x1 - sx, sx) do |x| 106: compose_pixel(x, y0, stroke_color) 107: end 108: 109: elsif dx == 0 # horizontal line 110: y0.step(inclusive ? y1 : y1 - sy, sy) do |y| 111: compose_pixel(x0, y, stroke_color) 112: end 113: 114: elsif dx == dy # diagonal 115: x0.step(inclusive ? x1 : x1 - sx, sx) do |x| 116: compose_pixel(x, y0, stroke_color) 117: y0 += sy 118: end 119: 120: elsif dy > dx # vertical displacement 121: compose_pixel(x0, y0, stroke_color) 122: e_acc = 0 123: e = ((dx << 16) / dy.to_f).round 124: (dy - 1).downto(0) do |i| 125: e_acc_temp, e_acc = e_acc, (e_acc + e) & 0xffff 126: x0 += sx if (e_acc <= e_acc_temp) 127: w = 0xff - (e_acc >> 8) 128: compose_pixel(x0, y0, ChunkyPNG::Color.fade(stroke_color, w)) 129: compose_pixel(x0 + sx, y0 + sy, ChunkyPNG::Color.fade(stroke_color, 0xff - w)) if inclusive || i > 0 130: y0 += sy 131: end 132: compose_pixel(x1, y1, stroke_color) if inclusive 133: 134: else # horizontal displacement 135: compose_pixel(x0, y0, stroke_color) 136: e_acc = 0 137: e = ((dy << 16) / dx.to_f).round 138: (dx - 1).downto(0) do |i| 139: e_acc_temp, e_acc = e_acc, (e_acc + e) & 0xffff 140: y0 += sy if (e_acc <= e_acc_temp) 141: w = 0xff - (e_acc >> 8) 142: compose_pixel(x0, y0, ChunkyPNG::Color.fade(stroke_color, w)) 143: compose_pixel(x0 + sx, y0 + sy, ChunkyPNG::Color.fade(stroke_color, 0xff - w)) if inclusive || i > 0 144: x0 += sx 145: end 146: compose_pixel(x1, y1, stroke_color) if inclusive 147: end 148: 149: return self 150: end
Draws a polygon on the canvas using the stroke_color, filled using the fill_color if any.
@param [Array, String] The control point vector. Accepts everything {ChunkyPNG.Vector} accepts. @param [Integer] stroke_color The stroke color to use for this polygon. @param [Integer] fill_color The fill color to use for this polygon. @return [ChunkyPNG::Canvas] Itself, with the polygon drawn.
# File lib/chunky_png/canvas/drawing.rb, line 161 161: def polygon(path, stroke_color = ChunkyPNG::Color::BLACK, fill_color = ChunkyPNG::Color::TRANSPARENT) 162: 163: vector = ChunkyPNG::Vector(*path) 164: raise ArgumentError, "A polygon requires at least 3 points" if path.length < 3 165: 166: stroke_color = ChunkyPNG::Color.parse(stroke_color) 167: fill_color = ChunkyPNG::Color.parse(fill_color) 168: 169: # Fill 170: unless fill_color == ChunkyPNG::Color::TRANSPARENT 171: vector.y_range.each do |y| 172: intersections = [] 173: vector.edges.each do |p1, p2| 174: if (p1.y < y && p2.y >= y) || (p2.y < y && p1.y >= y) 175: intersections << (p1.x + (y - p1.y).to_f / (p2.y - p1.y) * (p2.x - p1.x)).round 176: end 177: end 178: 179: intersections.sort! 180: 0.step(intersections.length - 1, 2) do |i| 181: intersections[i].upto(intersections[i + 1]) do |x| 182: compose_pixel(x, y, fill_color) 183: end 184: end 185: end 186: end 187: 188: # Stroke 189: vector.each_edge do |(from_x, from_y), (to_x, to_y)| 190: line(from_x, from_y, to_x, to_y, stroke_color, false) 191: end 192: 193: return self 194: end
Draws a rectangle on the canvas, using two control points.
@param [Integer] x0 The x-coordinate of the first control point. @param [Integer] y0 The y-coordinate of the first control point. @param [Integer] x1 The x-coordinate of the second control point. @param [Integer] y1 The y-coordinate of the second control point. @param [Integer] stroke_color The line color to use for this rectangle. @param [Integer] fill_color The fill color to use for this rectangle. @return [ChunkyPNG::Canvas] Itself, with the rectangle drawn.
# File lib/chunky_png/canvas/drawing.rb, line 205 205: def rect(x0, y0, x1, y1, stroke_color = ChunkyPNG::Color::BLACK, fill_color = ChunkyPNG::Color::TRANSPARENT) 206: 207: stroke_color = ChunkyPNG::Color.parse(stroke_color) 208: fill_color = ChunkyPNG::Color.parse(fill_color) 209: 210: # Fill 211: unless fill_color == ChunkyPNG::Color::TRANSPARENT 212: [x0, x1].min.upto([x0, x1].max) do |x| 213: [y0, y1].min.upto([y0, y1].max) do |y| 214: compose_pixel(x, y, fill_color) 215: end 216: end 217: end 218: 219: # Stroke 220: line(x0, y0, x0, y1, stroke_color, false) 221: line(x0, y1, x1, y1, stroke_color, false) 222: line(x1, y1, x1, y0, stroke_color, false) 223: line(x1, y0, x0, y0, stroke_color, false) 224: 225: return self 226: end