diff --git a/Lib/fontTools/colorLib/builder.py b/Lib/fontTools/colorLib/builder.py index 56a048de9..998ab60d1 100644 --- a/Lib/fontTools/colorLib/builder.py +++ b/Lib/fontTools/colorLib/builder.py @@ -6,6 +6,7 @@ import collections import copy import enum from functools import partial +from math import ceil, log from typing import ( Any, Dict, @@ -632,7 +633,10 @@ class LayerV1ListBuilder: ot_paint.Format = int(ot.Paint.Format.PaintColrLayers) self.slices.append(ot_paint) - paints = [self.buildPaint(p) for p in paints] + paints = [ + self.buildPaint(p) + for p in _build_n_ary_tree(paints, n=MAX_PAINT_COLR_LAYER_COUNT) + ] # Look for reuse, with preference to longer sequences found_reuse = True @@ -776,3 +780,45 @@ def buildColrV1( glyphs.BaseGlyphCount = len(baseGlyphs) glyphs.BaseGlyphV1Record = baseGlyphs return (layers, glyphs) + + +def _build_n_ary_tree(leaves, n): + """Build N-ary tree from sequence of leaf nodes. + + Return a list of lists where each non-leaf node is a list containing + max n nodes. + """ + if not leaves: + return [] + + assert n > 1 + + depth = ceil(log(len(leaves), n)) + + if depth <= 1: + return list(leaves) + + # Fully populate complete subtrees of root until we have enough leaves left + root = [] + unassigned = None + full_step = n ** (depth - 1) + for i in range(0, len(leaves), full_step): + subtree = leaves[i : i + full_step] + if len(subtree) < full_step: + unassigned = subtree + break + while len(subtree) > n: + subtree = [subtree[k : k + n] for k in range(0, len(subtree), n)] + root.append(subtree) + + if unassigned: + # Recurse to fill the last subtree, which is the only partially populated one + subtree = _build_n_ary_tree(unassigned, n) + if len(subtree) <= n - len(root): + # replace last subtree with its children if they can still fit + root.extend(subtree) + else: + root.append(subtree) + assert len(root) <= n + + return root diff --git a/Tests/colorLib/builder_test.py b/Tests/colorLib/builder_test.py index 003e53d97..75aacfb1e 100644 --- a/Tests/colorLib/builder_test.py +++ b/Tests/colorLib/builder_test.py @@ -2,7 +2,7 @@ from fontTools.ttLib import newTable from fontTools.ttLib.tables import otTables as ot from fontTools.colorLib import builder from fontTools.colorLib.geometry import round_start_circle_stable_containment, Circle -from fontTools.colorLib.builder import LayerV1ListBuilder +from fontTools.colorLib.builder import LayerV1ListBuilder, _build_n_ary_tree from fontTools.colorLib.errors import ColorLibError import pytest from typing import List @@ -1105,3 +1105,81 @@ class TrickyRadialGradientTest: ) def test_nudge_start_circle_position(self, c0, r0, c1, r1, inside, expected): assert self.round_start_circle(c0, r0, c1, r1, inside) == expected + + +@pytest.mark.parametrize( + "lst, n, expected", + [ + ([0], 2, [0]), + ([0, 1], 2, [0, 1]), + ([0, 1, 2], 2, [[0, 1], 2]), + ([0, 1, 2], 3, [0, 1, 2]), + ([0, 1, 2, 3], 2, [[0, 1], [2, 3]]), + ([0, 1, 2, 3], 3, [[0, 1, 2], 3]), + ([0, 1, 2, 3, 4], 3, [[0, 1, 2], 3, 4]), + ([0, 1, 2, 3, 4, 5], 3, [[0, 1, 2], [3, 4, 5]]), + (list(range(7)), 3, [[0, 1, 2], [3, 4, 5], 6]), + (list(range(8)), 3, [[0, 1, 2], [3, 4, 5], [6, 7]]), + (list(range(9)), 3, [[0, 1, 2], [3, 4, 5], [6, 7, 8]]), + (list(range(10)), 3, [[[0, 1, 2], [3, 4, 5], [6, 7, 8]], 9]), + (list(range(11)), 3, [[[0, 1, 2], [3, 4, 5], [6, 7, 8]], 9, 10]), + (list(range(12)), 3, [[[0, 1, 2], [3, 4, 5], [6, 7, 8]], [9, 10, 11]]), + (list(range(13)), 3, [[[0, 1, 2], [3, 4, 5], [6, 7, 8]], [9, 10, 11], 12]), + ( + list(range(14)), + 3, + [[[0, 1, 2], [3, 4, 5], [6, 7, 8]], [[9, 10, 11], 12, 13]], + ), + ( + list(range(15)), + 3, + [[[0, 1, 2], [3, 4, 5], [6, 7, 8]], [9, 10, 11], [12, 13, 14]], + ), + ( + list(range(16)), + 3, + [[[0, 1, 2], [3, 4, 5], [6, 7, 8]], [[9, 10, 11], [12, 13, 14], 15]], + ), + ( + list(range(23)), + 3, + [ + [[0, 1, 2], [3, 4, 5], [6, 7, 8]], + [[9, 10, 11], [12, 13, 14], [15, 16, 17]], + [[18, 19, 20], 21, 22], + ], + ), + ( + list(range(27)), + 3, + [ + [[0, 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]], + ], + ), + ( + list(range(28)), + 3, + [ + [ + [[0, 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, + ], + ), + (list(range(257)), 256, [list(range(256)), 256]), + (list(range(258)), 256, [list(range(256)), 256, 257]), + (list(range(512)), 256, [list(range(256)), list(range(256, 512))]), + (list(range(512 + 1)), 256, [list(range(256)), list(range(256, 512)), 512]), + ( + list(range(256 ** 2)), + 256, + [list(range(k * 256, k * 256 + 256)) for k in range(256)], + ), + ], +) +def test_build_n_ary_tree(lst, n, expected): + assert _build_n_ary_tree(lst, n) == expected