SVG: Properly handle values in exponential notation

Some SVG exporters outputs small values in an exponential
notation. There is no big reason to reject those files.

This change makes it so any notation of the value is accepted.
Only do it in the path point parsing, since other areas are
already dealing with this correct.

Also covered the array parsing covered with a unit test which
can be run as a stand-alone application.

The parsing code is from Jacques Lucke, thanks!

Differential Revision: https://developer.blender.org/D4234

1 files changed, 50 insertions, 0 deletions

diff --git a/io_curve_svg/svg_util.py b/io_curve_svg/svg_util.py
new file mode 100644
index 00000000..a3e1613c
--- /dev/null
+++ b/io_curve_svg/svg_util.py
@@ -0,0 +1,50 @@
+# ##### BEGIN GPL LICENSE BLOCK #####
+#
+#  This program is free software; you can redistribute it and/or
+#  modify it under the terms of the GNU General Public License
+#  as published by the Free Software Foundation; either version 2
+#  of the License, or (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software Foundation,
+#  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+#
+# ##### END GPL LICENSE BLOCK #####
+
+# <pep8 compliant>
+
+import re
+
+def srgb_to_linearrgb(c):
+    if c < 0.04045:
+        return 0.0 if c < 0.0 else c * (1.0 / 12.92)
+    else:
+        return pow((c + 0.055) * (1.0 / 1.055), 2.4)
+
+
+def check_points_equal(point_a, point_b):
+    return (abs(point_a[0] - point_b[0]) < 1e-6 and
+            abs(point_a[1] - point_b[1]) < 1e-6)
+
+match_number = r"-?\d+([eE][-+]?\d+)?"
+match_first_comma = r"^\s*(?=,)"
+match_comma_pair = r",\s*(?=,)"
+match_last_comma = r",\s*$"
+
+pattern = f"({match_number})|{match_first_comma}|{match_comma_pair}|{match_last_comma}"
+re_pattern = re.compile(pattern)
+
+def parse_array_of_floats(text):
+    elements = re_pattern.findall(text)
+    return [value_to_float(v[0]) for v in elements]
+
+def value_to_float(value_encoded: str):
+    if len(value_encoded) == 0:
+        return 0
+    return float(value_encoded)
+