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9f084b2 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 | """Baseline operations — for text line baselines.
A baseline is defined by a sequence of points, typically from left to right.
"""
from __future__ import annotations
BaselinePoints = list[tuple[float, float]]
def baseline_length(points: BaselinePoints) -> float:
"""Compute the total length of a baseline polyline."""
if len(points) < 2:
return 0.0
total = 0.0
for i in range(len(points) - 1):
dx = points[i + 1][0] - points[i][0]
dy = points[i + 1][1] - points[i][1]
total += (dx * dx + dy * dy) ** 0.5
return total
def baseline_angle(points: BaselinePoints) -> float:
"""Compute the angle (in degrees) of a baseline from start to end.
Returns 0.0 for a horizontal baseline, positive for downward slope.
Returns 0.0 if the baseline has fewer than 2 points.
"""
if len(points) < 2:
return 0.0
import math
dx = points[-1][0] - points[0][0]
dy = points[-1][1] - points[0][1]
if dx == 0 and dy == 0:
return 0.0
return math.degrees(math.atan2(dy, dx))
def interpolate_baseline(points: BaselinePoints, t: float) -> tuple[float, float]:
"""Interpolate a point along the baseline at parameter t in [0, 1].
t=0 returns the start, t=1 returns the end.
For multi-segment baselines, t is proportional to total arc length.
"""
if len(points) < 2:
if points:
return points[0]
raise ValueError("Cannot interpolate an empty baseline")
t = max(0.0, min(1.0, t))
total_len = baseline_length(points)
if total_len == 0:
return points[0]
target = t * total_len
accumulated = 0.0
for i in range(len(points) - 1):
dx = points[i + 1][0] - points[i][0]
dy = points[i + 1][1] - points[i][1]
seg_len = (dx * dx + dy * dy) ** 0.5
if accumulated + seg_len >= target:
frac = (target - accumulated) / seg_len if seg_len > 0 else 0.0
return (
points[i][0] + frac * dx,
points[i][1] + frac * dy,
)
accumulated += seg_len
return points[-1]
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