refactor everything out of lib/__init__.py

1 files changed, 105 insertions, 0 deletions

diff --git a/lib/svg/units.py b/lib/svg/units.py
new file mode 100644
index 00000000..015da60e
--- /dev/null
+++ b/lib/svg/units.py
@@ -0,0 +1,105 @@
+import simpletransform
+
+from ..utils import cache
+
+# modern versions of Inkscape use 96 pixels per inch as per the CSS standard
+PIXELS_PER_MM = 96 / 25.4
+
+# cribbed from inkscape-silhouette
+def parse_length_with_units( str ):
+
+    '''
+    Parse an SVG value which may or may not have units attached
+    This version is greatly simplified in that it only allows: no units,
+    units of px, mm, and %.  Everything else, it returns None for.
+    There is a more general routine to consider in scour.py if more
+    generality is ever needed.
+    '''
+
+    u = 'px'
+    s = str.strip()
+    if s[-2:] == 'px':
+        s = s[:-2]
+    elif s[-2:] == 'mm':
+        u = 'mm'
+        s = s[:-2]
+    elif s[-2:] == 'pt':
+        u = 'pt'
+        s = s[:-2]
+    elif s[-2:] == 'pc':
+        u = 'pc'
+        s = s[:-2]
+    elif s[-2:] == 'cm':
+        u = 'cm'
+        s = s[:-2]
+    elif s[-2:] == 'in':
+        u = 'in'
+        s = s[:-2]
+    elif s[-1:] == '%':
+        u = '%'
+        s = s[:-1]
+    try:
+        v = float( s )
+    except:
+        raise ValueError(_("parseLengthWithUnits: unknown unit %s") % s)
+
+    return v, u
+
+
+def convert_length(length):
+    value, units = parse_length_with_units(length)
+
+    if not units or units == "px":
+        return value
+
+    if units == 'pt':
+       value /= 72
+       units = 'in'
+
+    if units == 'pc':
+       value /= 6
+       units = 'in'
+
+    if units == 'cm':
+       value *= 10
+       units = 'mm'
+
+    if units == 'mm':
+        value = value / 25.4
+        units = 'in'
+
+    if units == 'in':
+        # modern versions of Inkscape use CSS's 96 pixels per inch.  When you
+        # open an old document, inkscape will add a viewbox for you.
+        return value * 96
+
+    raise ValueError(_("Unknown unit: %s") % units)
+
+
+@cache
+def get_doc_size(svg):
+    doc_width = convert_length(svg.get('width'))
+    doc_height = convert_length(svg.get('height'))
+
+    return doc_width, doc_height
+
+@cache
+def get_viewbox_transform(node):
+    # somewhat cribbed from inkscape-silhouette
+    doc_width, doc_height = get_doc_size(node)
+
+    viewbox = node.get('viewBox').strip().replace(',', ' ').split()
+
+    dx = -float(viewbox[0])
+    dy = -float(viewbox[1])
+    transform = simpletransform.parseTransform("translate(%f, %f)" % (dx, dy))
+
+    try:
+        sx = doc_width / float(viewbox[2])
+        sy = doc_height / float(viewbox[3])
+        scale_transform = simpletransform.parseTransform("scale(%f, %f)" % (sx, sy))
+        transform = simpletransform.composeTransform(transform, scale_transform)
+    except ZeroDivisionError:
+        pass
+
+    return transform