From c57ede8ca3f1015e5d34a52b38ee820a22774cf1 Mon Sep 17 00:00:00 2001
From: vocx-fc <vocx-fc@users.noreply.github.com>
Date: Tue, 15 Sep 2020 12:57:23 -0500
Subject: [PATCH] Draft: clean up SVG processing code, add comments

For the try-except blocks we should trap a specific `Exception`,
not just any type. It seems string handling was an issue
with Python 2, so the string needed UTF8 decoding.

When the software no longer supports Python 2, these
blocks can be removed.
---
 src/Mod/Draft/draftfunctions/svg.py | 38 +++++++++++++++++++++++++----
 1 file changed, 33 insertions(+), 5 deletions(-)

diff --git a/src/Mod/Draft/draftfunctions/svg.py b/src/Mod/Draft/draftfunctions/svg.py
index bf45cb2756..145cd082ca 100644
--- a/src/Mod/Draft/draftfunctions/svg.py
+++ b/src/Mod/Draft/draftfunctions/svg.py
@@ -21,7 +21,13 @@
 # *   USA                                                                   *
 # *                                                                         *
 # ***************************************************************************
-"""Provides functions to return the SVG representation of various shapes."""
+"""Provides functions to return the SVG representation of various shapes.
+
+Warning: this still uses the `Drawing.projectToSVG` method to provide
+the SVG representation of certain objects.
+Therefore, even if the Drawing Workbench is obsolete, the `Drawing` module
+may not be removed completely yet. This must be checked.
+"""
 ## @package svg
 # \ingroup draftfuctions
 # \brief Provides functions to return the SVG representation of shapes.
@@ -69,6 +75,8 @@ def get_line_style(line_style, scale):
             style = ",".join([str(float(d)/scale) for d in style])
             # print("lstyle ", style)
         except:
+            # TODO: trap only specific exception; what is the problem?
+            # Bad string specification?
             return "none"
         else:
             return style
@@ -85,6 +93,11 @@ def getLineStyle(linestyle, scale):
 def get_proj(vec, plane=None):
     """Get a projection of the vector in the plane's u and v directions.
 
+    TODO: check if the same function for SVG and DXF projection can be used
+    so that this function is not just duplicated code.
+    This function may also be present elsewhere, like `WorkingPlane`
+    or `DraftGeomUtils`, so we should avoid code duplication.
+
     Parameters
     ----------
     vec: Base::Vector3
@@ -251,7 +264,7 @@ def get_arrow(obj,
     _rotate = 'rotate({},{},{})'.format(math.degrees(angle),
                                         point.x, point.y)
     _transl = 'translate({},{})'.format(point.x, point.y)
-    _scale = 'scale({},{})'.format(arrowsize, arrowsize)
+    _scale = 'scale({size},{size})'.format(size=arrowsize)
     _style = 'style="stroke-miterlimit:4;stroke-dasharray:none"'
 
     if obj.ViewObject.ArrowType == "Circle":
@@ -443,6 +456,9 @@ def get_text(plane, techdraw,
                 _t = text[0].replace("&", "&amp;").replace("<", "&lt;")
                 svg += _t.replace(">", "&gt;")
             except:
+                # TODO: trap only specific exception; what is the problem?
+                # Bad UTF8 string specification? This can be removed
+                # once the code is only used with Python 3.
                 _t = text[0].decode("utf8")
                 _t = _t.replace("&", "&amp;").replace("<", "&lt;")
                 svg += _t.replace(">", "&gt;")
@@ -457,6 +473,9 @@ def get_text(plane, techdraw,
                     _t = text[i].replace("&", "&amp;").replace("<", "&lt;")
                     svg += _t.replace(">", "&gt;")
                 except:
+                    # TODO: trap only specific exception; what is the problem?
+                    # Bad UTF8 string specification? This can be removed
+                    # once the code is only used with Python 3.
                     _t = text[i].decode("utf8")
                     _t = _t.replace("&", "&amp;").replace("<", "&lt;")
                     svg += _t.replace(">", "&gt;")
@@ -487,7 +506,11 @@ def get_path(obj, plane,
              fill, pathdata, stroke, linewidth, lstyle,
              fill_opacity=None,
              edges=[], wires=[], pathname=None):
-    """Get the SVG representation from an object's edges or wires."""
+    """Get the SVG representation from an object's edges or wires.
+
+    TODO: the `edges` and `wires` must not default to empty list `[]`
+    but to `None`. Verify that the code doesn't break with this change.
+    """
     svg = "<path "
 
     if pathname is None:
@@ -558,9 +581,14 @@ def get_path(obj, plane,
                                 _a = _a.split('"')[0]
                                 _a = _a.split("A")[1]
                                 A = "A " + _a
-                            except:
+                            except IndexError:
+                                # TODO: trap only specific exception;
+                                # what is the problem?
+                                # split didn't produce a two element list?
                                 _wrn("Circle or ellipse: "
-                                     "error splitting the projection snip")
+                                     "not possible to split the projection "
+                                     "snip obtained by Drawing.projectToSVG, "
+                                     "continue manually.")
                             else:
                                 edata += A
                                 done = True