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Avoid nested loops for intermediate intrinsic percentage widths

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Fix #1155.
This commit is contained in:
Guillaume Ayoub 2024-08-11 00:23:51 +02:00
parent 1b8ac91004
commit f17bd4bfca
1 changed files with 41 additions and 34 deletions
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75
weasyprint/layout/preferred.py
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@ -9,6 +9,7 @@ Baron's unofficial draft (https://dbaron.org/css/intrinsic/).
"""
import sys
from functools import cache
from math import inf
from ..formatting_structure import boxes
@ -453,6 +454,7 @@ def table_and_columns_preferred_widths(context, box, outer=True):
break
colspan_cells = []
colspans = set()
# Define the intermediate content widths
min_content_widths = [0] * grid_width
@ -480,6 +482,7 @@ def table_and_columns_preferred_widths(context, box, outer=True):
intrinsic_percentages[i], _percentage_contribution(cell))
else:
colspan_cells.append(cell)
colspans.add(cell.colspan - 1)
# Intermediate content widths for span > 1 is wrong in the 4.1 section, as
# explained in its third issue. Min- and max-content widths are handled by
@ -487,45 +490,49 @@ def table_and_columns_preferred_widths(context, box, outer=True):
# widths to columns that have originating cells.
# Intermediate intrinsic percentage widths for span > 1
for span in range(1, grid_width):
rows_origins = []
for y, row in enumerate(grid):
origin = None
rows_origins.append(row_origins := [])
for x, cell in enumerate(row):
if cell:
origin = x
row_origins.append(origin)
@cache
def get_percentage_contribution(origin_cell, origin, max_content_width):
# Cached for big colspan values, see #1155.
cell_slice = slice(origin, origin + origin_cell.colspan)
baseline_percentage = sum(intrinsic_percentages[cell_slice])
cell_percentage_contribution = _percentage_contribution(origin_cell)
diff = max(0, cell_percentage_contribution - baseline_percentage)
other_columns_contributions = [
max_content_widths[j]
for j in range(origin, origin + origin_cell.colspan)
if intrinsic_percentages[j] == 0]
other_columns_contributions_sum = sum(other_columns_contributions)
if other_columns_contributions_sum == 0:
ratio = 1 / (len(other_columns_contributions) or 1)
else:
ratio = max_content_width / other_columns_contributions_sum
return diff * ratio
for span in sorted(colspans):
percentage_contributions = []
for i in range(grid_width):
percentage_contribution = intrinsic_percentages[i]
for j in range(len(zipped_grid[i])):
indexes = [k for k in range(i + 1) if grid[j][k]]
if not indexes:
if percentage_contribution := intrinsic_percentages[i]:
percentage_contributions.append(percentage_contribution)
continue
for row, row_origins in zip(grid, rows_origins):
if (origin := row_origins[i]) is None:
continue
origin = max(indexes)
origin_cell = grid[j][origin]
origin_cell = row[origin]
if origin_cell.colspan - 1 != span:
continue
cell_slice = slice(origin, origin + origin_cell.colspan)
baseline_percentage = sum(intrinsic_percentages[cell_slice])
# Cell contribution to intrinsic percentage width
if intrinsic_percentages[i] == 0:
diff = max(
0,
_percentage_contribution(origin_cell) -
baseline_percentage)
other_columns_contributions = [
max_content_widths[j]
for j in range(origin, origin + origin_cell.colspan)
if intrinsic_percentages[j] == 0]
other_columns_contributions_sum = sum(
other_columns_contributions)
if other_columns_contributions_sum == 0:
if other_columns_contributions:
ratio = 1 / len(other_columns_contributions)
else:
ratio = 1
else:
ratio = (
max_content_widths[i] /
other_columns_contributions_sum)
percentage_contribution = max(
percentage_contribution,
diff * ratio)
cell_percentage_contribution = get_percentage_contribution(
origin_cell, origin, max_content_widths[i])
percentage_contribution = max(
percentage_contribution, cell_percentage_contribution)
percentage_contributions.append(percentage_contribution)