1 files changed, 121 insertions, 0 deletions
diff --git a/share/extensions/dhw_input.py b/share/extensions/dhw_input.py
new file mode 100755
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--- /dev/null
+++ b/share/extensions/dhw_input.py
@@ -0,0 +1,121 @@
+#!/usr/bin/env python
+# coding=utf-8
+#
+# Copyright (C) 2009 Kevin Lindsey, https://github.com/thelonious/DM2SVG
+#               2011 Nikita Kitaev, https://github.com/nikitakit/DM2SVG
+#                    Chris Morgan,  https://gist.github.com/1471691
+#               2019 Martin Owens, <doctormo@gmail.com>
+#
+# 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.
+#
+"""
+Import a DHW file from ACECAD DigiMemo, a hardware based digitiser
+"""
+
+import struct
+
+import inkex
+from inkex import AbortExtension, errormsg, Group, Polyline
+from inkex.localization import inkex_gettext as _
+
+inkex.NSS["dm"] = "http://github.com/nikitakit/DM2SVG"
+
+
+class DhwInput(inkex.InputExtension):
+    """Open DHW files and convert to svg on the fly"""
+
+    template = """<svg viewBox="0 0 {w} {h}"
+  fill="none" stroke="black" stroke-width="10" stroke-linecap="round" stroke-linejoin="round"
+  xmlns="http://www.w3.org/2000/svg"
+  xmlns:svg="http://www.w3.org/2000/svg"
+  xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+  xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+  xmlns:dm="http://github.com/nikitakit/DM2SVG">
+    <metadata>
+      <dm:page
+        version="{v}"
+        width="{w}"
+        height="{h}"
+        page_type="{p}">
+      </dm:page>
+    </metadata>
+    <rect width="{w}" height="{h}" fill="aliceblue"/>
+    <g inkscape:groupmode="layer" id="layer1"></g>
+</svg>"""
+
+    def load(self, stream):
+        """Load the steam as if it were an open DHW file"""
+        header = list(struct.unpack("<32sBHHBxx", stream.read(40)))
+        doc = header.pop(0).decode()
+        if doc != "ACECAD_DIGIMEMO_HANDWRITING_____":
+            raise AbortExtension(_("Could not load file, not a ACECAD DHW file!"))
+
+        height = int(header[2])
+        doc = self.get_template(**dict(zip(("v", "w", "h", "p"), header)))
+        svg = doc.getroot()
+
+        timestamp = 0
+        layer = svg.getElementById("layer1")
+
+        while True:
+            tag = stream.read(1)
+            if tag == b"":
+                break
+
+            if ord(tag) <= 128:
+                errormsg(_("Unsupported tag: {}\n").format(tag))
+                continue
+
+            if tag == b"\x90":
+                # New Layer element
+                timestamp = 0
+                name = "layer{:d}".format(ord(stream.read(1)) + 1)
+                layer = svg.add(Group(inkscape_groupmode="layer", id=name))
+            elif tag == b"\x88":
+                # Read the timestamp next
+                timestamp += ord(stream.read(1)) * 20
+            else:
+                # Pen down
+                coords = [p for p in iter(lambda: read_point(stream, height), None)]
+                # Pen up
+                coords.append(read_point(stream, height))
+
+                poly = layer.add(Polyline())
+                poly.path = coords
+                poly.set("dm:timestamp", timestamp)
+
+        return doc
+
+
+def read_point(stream, ymax):
+    """If the next byte is a stop byte, return None. Otherwise read 4 bytes
+    (in total) and return a 2D point.
+    """
+    # read first byte, it might be a stop byte
+    x1 = struct.unpack("B", stream.read(1))[0]
+
+    if x1 >= 0x80:
+        return None
+
+    x2, y1, y2 = struct.unpack("BBB", stream.read(3))
+
+    x = x1 | x2 << 7
+    y = y1 | y2 << 7
+
+    return x, ymax - y
+
+
+if __name__ == "__main__":
+    DhwInput().run()