Paths#
A path is a sequence of straight line segments and/or Bezier curves. A path may be filled and/or stroked. A path may have attached arrow to beginning and/or end.
Paths are drawn in Nelsie by constructing a Path instance and calling .draw() method on a box. Path can be stroked
from nelsie import Path, Stroke
@deck.slide()
def path_demo(slide):
stroke = Stroke(color="orange", width=40)
path = Path(fill_color="blue", stroke=stroke) \
.move_to(204, 300) \
.line_to(819, 300) \
.line_to(512, 600)
slide.draw(path)
Path methods#
Path constructor create an empty instance of a path. You can create line segments or Bezeier curves by calling the following methods:
.move_to(x, y)-- move the cursor to a given position without visible effect.line_to(x, y)-- create a line segment.quad_to(x1, y1, x, y)-- create a quadratic bezier curve.cubic_to(x1, y1, x2, y2, x, y)-- create a cubic bezier curve.close()-- create a line segment to the initial point of the path
@deck.slide()
def path_demo(slide):
path = Path(fill_color="red") \
.move_to(200, 600) \
.quad_to(500, 200, 800, 600) \
.close()
slide.draw(path)
Path coordinates#
Path coordinates can be given as:
floator a string with digits, (e.g.100,"100") - a position in pixels relative to a box where a path is drawn- string in format "XX%" (e.g.
"50%") - a position relative to the box where the path is drawn with respect to its size. LayoutExpr- a position defined as a layout expression (see Layout expressions)
@deck.slide()
def path_demo(slide):
path = Path(fill_color="red") \
.move_to("50%", "50%") \
.line_to("100%", "100%") \
.line_to("50%", "100%")
slide.draw(path)
@deck.slide()
def path_demo(slide):
box = slide.text("Hello world", TextStyle(size=80), bg_color="orange")
path = Path(fill_color="red") \
.move_to(box.x(), box.y(1.0)) \
.line_to("100%", "100%") \
.line_to("50%", "100%")
slide.draw(path)
Path.oval method#
You can create a Path representing an oval (or a circle) by calling Path.oval(x1, y1, x2, y2)
from nelsie import Path
@deck.slide()
def path_demo(slide):
path = Path.oval(200, 200, 400, 400, fill_color="green")
slide.draw(path)
Drawing more paths#
A path is drawn by calling .draw() method on a box. You can draw more paths at once by providing a list of paths.
Stroke class#
Stroke class defines how a path is stroked; you can configure a color, width, and line dash.
from nelsie import Stroke
@deck.slide()
def stroke_demo(slide):
box = slide.box(width=700, height=140, m_bottom=60)
box.draw(
[
Path(stroke=Stroke(color="red", width=10)).move_to(0, 0).line_to(700, 0),
Path(stroke=Stroke(color="green", width=20, dash_array=[10, 20], dash_offset=15))
.move_to(0, "50%")
.line_to(700, "50%"),
Path(stroke=Stroke(color="blue", width=30, dash_array=[30, 10, 5, 10])).move_to(0, "100%").line_to(700, "100%"),
]
)
Arrows#
You can attach an arrow to the beginning and/or end of a path. An arrow is created as an instance of Arrow and can be passed to the constructor of a can be passed to the constructor of Path in the parameters arrow_start and arrow_end. A color, size, angle, line width and position of the inner point can be configured.
from nelsie import Arrow
@deck.slide()
def arrow_demo(slide):
box = slide.box(width=700, height=220)
arrow1 = Arrow(size=80)
stroke = Stroke(color="black", width=10)
box.draw(
Path(stroke=stroke, arrow_start=arrow1, arrow_end=arrow1)
.move_to(0, 0)
.line_to(700, 0),
)
Color of arrows#
If parameter color is not defined, then arrow will have the same color as the path.
@deck.slide()
def arrow_demo(slide):
box = slide.box(width=700, height=220)
stroke = Stroke(color="green", width=10)
box.draw(
[
Path(stroke=stroke, arrow_end=Arrow(size=80))
.move_to(0, 0)
.line_to(700, 0),
Path(stroke=stroke, arrow_end=Arrow(size=80, color="red"))
.move_to(0, 120)
.line_to(700, 120),
]
)
Size of arrows#
@deck.slide()
def arrow_demo(slide):
box = slide.box(width=700, height=220)
stroke = Stroke(color="black", width=10)
box.draw(
[
Path(stroke=stroke, arrow_end=Arrow(size=30))
.move_to(0, 0)
.line_to(700, 0),
Path(stroke=stroke, arrow_end=Arrow(size=80))
.move_to(0, 150)
.line_to(700, 150),
Path(stroke=stroke, arrow_end=Arrow(size=120))
.move_to(0, 300)
.line_to(700, 300),
]
)
Angle of arrows#
from nelsie import Arrow
@deck.slide()
def arrow_demo(slide):
box = slide.box(width=700, height=220)
stroke = Stroke(color="black", width=10)
box.draw(
[
Path(stroke=stroke, arrow_end=Arrow(size=80, angle=60))
.move_to(0, 0)
.line_to(700, 0),
Path(stroke=stroke, arrow_end=Arrow(size=80, angle=45))
.move_to(0, 150)
.line_to(700, 150),
Path(stroke=stroke, arrow_end=Arrow(size=80, angle=20))
.move_to(0, 300)
.line_to(700, 300),
]
)
Stroked arrows#
If stroked_width is not None then the arrow is not filled but stroked.
@deck.slide()
def arrow_demo(slide):
box = slide.box(width=700, height=220)
stroke = Stroke(color="black", width=10)
box.draw(
[
Path(stroke=stroke, arrow_end=Arrow(size=80))
.move_to(0, 0)
.line_to(700, 0),
Path(stroke=stroke, arrow_end=Arrow(size=80, stroke_width=10))
.move_to(0, 150)
.line_to(700, 150),
Path(stroke=stroke, arrow_end=Arrow(size=80, stroke_width=30))
.move_to(0, 300)
.line_to(700, 300),
]
)
Inner point#
@deck.slide()
def arrow_demo(slide):
box = slide.box(width=700, height=220)
stroke = Stroke(color="black", width=10)
box.draw(
[
Path(stroke=stroke, arrow_end=Arrow(size=80, inner_point=0.5))
.move_to(0, 0)
.line_to(700, 0),
Path(stroke=stroke, arrow_end=Arrow(size=80, inner_point=1.0))
.move_to(0, 150)
.line_to(700, 150),
Path(stroke=stroke, arrow_end=Arrow(size=80, inner_point=2.5))
.move_to(0, 300)
.line_to(700, 300),
]
)
InSteps and paths#
Parameters of Path and Arrow do not take InSteps values; however .draw() method of the box accepts InSteps values:
@deck.slide()
def draw_insteps_demo(slide):
box = slide.box(width=700, height=220)
stroke = Stroke(color="black", width=10)
path1 = Path(stroke=stroke).move_to(0, 0).line_to(700, 0)
path2 = Path(stroke=stroke).move_to(0, 100).line_to(700, 100)
path3 = Path(stroke=stroke).move_to(0, 200).line_to(700, 200)
box.draw(InSteps({1 : path1, 2: [path2, path3]}))