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Improve autoscaling for high order Bezier curves #19214

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Merged
merged 2 commits into from
Feb 1, 2022
Merged

Improve autoscaling for high order Bezier curves #19214

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f71d7cd
Improve autoscaling for high order Bezier curves
dstansby Dec 28, 2021
7036d2d
Update pie test images
dstansby Dec 28, 2021
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5 changes: 5 additions & 0 deletions doc/api/next_api_changes/behavior/19214-DS.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
Improved autoscaling for bezier curves
--------------------------------------
Bezier curves are now autoscaled to their extents - previously they were
autoscaled to their ends and control points, which in some cases led to
unnecessarily large limits.
17 changes: 12 additions & 5 deletions lib/matplotlib/axes/_base.py
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Expand Up @@ -22,7 +22,6 @@
import matplotlib.image as mimage
import matplotlib.lines as mlines
import matplotlib.patches as mpatches
import matplotlib.path as mpath
from matplotlib.rcsetup import cycler, validate_axisbelow
import matplotlib.spines as mspines
import matplotlib.table as mtable
Expand Down Expand Up @@ -2375,10 +2374,18 @@ def _update_patch_limits(self, patch):
((not patch.get_width()) and (not patch.get_height()))):
return
p = patch.get_path()
vertices = p.vertices if p.codes is None else p.vertices[np.isin(
p.codes, (mpath.Path.CLOSEPOLY, mpath.Path.STOP), invert=True)]
if not vertices.size:
return
# Get all vertices on the path
# Loop through each sement to get extrema for Bezier curve sections
vertices = []
for curve, code in p.iter_bezier():
# Get distance along the curve of any extrema
_, dzeros = curve.axis_aligned_extrema()
# Calculate vertcies of start, end and any extrema in between
vertices.append(curve([0, *dzeros, 1]))

if len(vertices):
vertices = np.row_stack(vertices)
Comment on lines +2386 to +2387
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Do you not want to return here if empty any more?

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Perhaps? It's a private helper function and doesn't seem to break anything though - I guess we're always passing in input that has some vertices.

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That's because transform and update_datalim are safe to empty lists. I think this is more of an optimization to avoid decomposing the transform, etc.


patch_trf = patch.get_transform()
updatex, updatey = patch_trf.contains_branch_seperately(self.transData)
if not (updatex or updatey):
Expand Down
Binary file modified lib/matplotlib/tests/baseline_images/test_axes/pie_ccw_true.png
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Binary file modified lib/matplotlib/tests/baseline_images/test_axes/pie_center_radius.png
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Binary file modified lib/matplotlib/tests/baseline_images/test_axes/pie_default.png
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Binary file modified lib/matplotlib/tests/baseline_images/test_axes/pie_frame_grid.png
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Binary file modified lib/matplotlib/tests/baseline_images/test_axes/pie_linewidth_0.png
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Binary file modified lib/matplotlib/tests/baseline_images/test_axes/pie_linewidth_2.png
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Binary file modified lib/matplotlib/tests/baseline_images/test_axes/pie_no_label.png
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Binary file modified lib/matplotlib/tests/baseline_images/test_axes/pie_rotatelabels_true.png
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34 changes: 28 additions & 6 deletions lib/matplotlib/tests/test_axes.py
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Expand Up @@ -24,6 +24,7 @@
import matplotlib.font_manager as mfont_manager
import matplotlib.markers as mmarkers
import matplotlib.patches as mpatches
import matplotlib.path as mpath
import matplotlib.pyplot as plt
import matplotlib.ticker as mticker
import matplotlib.transforms as mtransforms
Expand Down Expand Up @@ -5042,7 +5043,7 @@ def test_pie_default():


@image_comparison(['pie_linewidth_0', 'pie_linewidth_0', 'pie_linewidth_0'],
extensions=['png'])
extensions=['png'], style='mpl20')
def test_pie_linewidth_0():
# The slices will be ordered and plotted counter-clockwise.
labels = 'Frogs', 'Hogs', 'Dogs', 'Logs'
Expand Down Expand Up @@ -5074,7 +5075,7 @@ def test_pie_linewidth_0():
plt.axis('equal')


@image_comparison(['pie_center_radius.png'])
@image_comparison(['pie_center_radius.png'], style='mpl20')
def test_pie_center_radius():
# The slices will be ordered and plotted counter-clockwise.
labels = 'Frogs', 'Hogs', 'Dogs', 'Logs'
Expand All @@ -5094,7 +5095,7 @@ def test_pie_center_radius():
plt.axis('equal')


@image_comparison(['pie_linewidth_2.png'])
@image_comparison(['pie_linewidth_2.png'], style='mpl20')
def test_pie_linewidth_2():
# The slices will be ordered and plotted counter-clockwise.
labels = 'Frogs', 'Hogs', 'Dogs', 'Logs'
Expand All @@ -5109,7 +5110,7 @@ def test_pie_linewidth_2():
plt.axis('equal')


@image_comparison(['pie_ccw_true.png'])
@image_comparison(['pie_ccw_true.png'], style='mpl20')
def test_pie_ccw_true():
# The slices will be ordered and plotted counter-clockwise.
labels = 'Frogs', 'Hogs', 'Dogs', 'Logs'
Expand All @@ -5124,7 +5125,7 @@ def test_pie_ccw_true():
plt.axis('equal')


@image_comparison(['pie_frame_grid.png'])
@image_comparison(['pie_frame_grid.png'], style='mpl20')
def test_pie_frame_grid():
# The slices will be ordered and plotted counter-clockwise.
labels = 'Frogs', 'Hogs', 'Dogs', 'Logs'
Expand All @@ -5151,7 +5152,7 @@ def test_pie_frame_grid():
plt.axis('equal')


@image_comparison(['pie_rotatelabels_true.png'])
@image_comparison(['pie_rotatelabels_true.png'], style='mpl20')
def test_pie_rotatelabels_true():
# The slices will be ordered and plotted counter-clockwise.
labels = 'Hogwarts', 'Frogs', 'Dogs', 'Logs'
Expand Down Expand Up @@ -7340,3 +7341,24 @@ def test_clim():
clim = (7, 8)
norm = plot_method(clim=clim).norm
assert (norm.vmin, norm.vmax) == clim


def test_bezier_autoscale():
# Check that bezier curves autoscale to their curves, and not their
# control points
verts = [[-1, 0],
[0, -1],
[1, 0],
[1, 0]]
codes = [mpath.Path.MOVETO,
mpath.Path.CURVE3,
mpath.Path.CURVE3,
mpath.Path.CLOSEPOLY]
p = mpath.Path(verts, codes)

fig, ax = plt.subplots()
ax.add_patch(mpatches.PathPatch(p))
ax.autoscale()
# Bottom ylim should be at the edge of the curve (-0.5), and not include
# the control point (at -1)
assert ax.get_ylim()[0] == -0.5