add HPGL/2 viewer example script and sample plot files

Author: mozman

.gitignore

@@ -29,6 +29,6 @@ tox-all.ini
 /examples_dxf/insert_nesting_level_1.dxf
 /examples_dxf/mtext_simple_all_alignments.dxf
 /src/mypy-reports/
-/examples_hpgl2
+/examples_hpgl2_private
 /fonts/shapefiles
 /fonts/*.json

examples/addons/hpgl2_viewer.py

@@ -0,0 +1,26 @@
+#  Copyright (c) 2023, Manfred Moitzi
+#  License: MIT License
+from __future__ import annotations
+try:
+    from ezdxf.addons.xqt import QtWidgets
+except ImportError as e:
+    print(str(e))
+    exit(1)
+import sys
+import pathlib
+import signal
+from ezdxf.addons.hpgl2.viewer import HPGL2Viewer
+
+HPGL2_EXAMPLES = pathlib.Path(__file__).parent.parent.parent / "examples_hpgl2"
+
+
+def main():
+    signal.signal(signal.SIGINT, signal.SIG_DFL)  # handle Ctrl+C properly
+    app = QtWidgets.QApplication(sys.argv)
+    viewer = HPGL2Viewer()
+    viewer.load_plot_file(HPGL2_EXAMPLES / "BF_ISO.plt")
+    sys.exit(app.exec())
+
+
+if __name__ == '__main__':
+    main()