Skip to content

GradientLineCollection class has been added to support multicolored lines #19286

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
wants to merge 1 commit into from
Closed

GradientLineCollection class has been added to support multicolored lines #19286

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
99 changes: 99 additions & 0 deletions lib/matplotlib/collections.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2080,6 +2080,105 @@ def draw(self, renderer):
renderer.close_group(self.__class__.__name__)
self.stale = False

class GradientLineCollection(LineCollection):

def __color_for_position(self, percentage: float, gradient: list, alpha: float):

lower_class_index, upper_class_index = 0, len(gradient) - 1
for class_index in range(len(gradient)):
if gradient[class_index][0] <= percentage:
lower_class_index = class_index
for class_index in range(len(gradient) - 1, -1, -1):
if percentage < gradient[class_index][0]:
upper_class_index = class_index

if lower_class_index == upper_class_index:
return gradient[lower_class_index][1]

color_slope = (
(percentage - gradient[lower_class_index][0]) /
(gradient[upper_class_index][0] - gradient[lower_class_index][0])
)

rgba = []
for channel in range(4):
lower_class_color = gradient[lower_class_index][1][channel]
upper_class_color = gradient[upper_class_index][1][channel]
rgba.append((lower_class_color + color_slope * (upper_class_color - lower_class_color)))

rgba[3] *= alpha
return rgba

def __split_line(self, start_pos, end_pos, gradient: list, alpha=1.0, pieces=20):

end_y, end_x = end_pos
start_y, start_x = start_pos
spacing_y, spacing_x = (end_y - start_y) / pieces, (end_x - start_x) / pieces
step_opacity = 255 / pieces

segments, colors = [], []
for i in range(pieces):

segments.append(
[
[start_y + spacing_y * i, start_x + spacing_x * i],
[start_y + spacing_y * (i + 1), start_x + spacing_x * (i + 1)]
]
)
colors.append(
self.__color_for_position(
percentage=float(i) / pieces, gradient=gradient, alpha=alpha
)
)

return segments, colors

def __init__(self, segments: list, pieces: int, gradient: list, **kwargs):

# Number of old parameters should be expanded until (len(segments) * pieces)
new_segments = []
new_colors = []
new_kwargs = {}

if "colors" in kwargs:
kwargs.pop("colors")
if "alpha" in kwargs:
alpha = kwargs["alpha"]
kwargs.pop("alpha")
else:
alpha = 1

for kw, _ in kwargs.items():
new_kwargs.update({kw: []})

gradient = sorted(
[(pos, mpl.colors.to_rgba(color)) for pos, color in gradient.items()],
key=lambda x: x[0]
)

for i in range(len(segments)):
t_segments, t_colors = self.__split_line(
start_pos=segments[i][0],
end_pos=segments[i][1],
gradient=gradient,
alpha=alpha,
pieces=pieces,
)
new_segments += t_segments
new_colors += t_colors

# Duplicate each value of lists in kwargs from 1 to 'pieces'
for kw, _ in kwargs.items():
for j in range(pieces):
if type(kwargs[kw]) == type([]):
new_kwargs[kw].append(kwargs[kw][i])
else:
new_kwargs[kw] = kwargs[kw]

super(GradientLineCollection, self).__init__(new_segments, colors=new_colors, **new_kwargs)




_artist_kwdoc = artist.kwdoc(Collection)
for k in ('QuadMesh', 'TriMesh', 'PolyCollection', 'BrokenBarHCollection',
Expand Down