add gpkg samples

II/Referatas/layer2img.py

@@ -3,12 +3,15 @@
 
 import argparse
 import geopandas
+import psycopg2
 import matplotlib.pyplot as plt
 
-INCH = 25.4 # mm
+INCH = 25.4  # mm
+
 
 def plt_size(string):
     if not string:
+        # using default matplotlib dimensions
         return None
     try:
         w, h = string.split("x")
@@ -16,25 +19,36 @@ def plt_size(string):
     except Exception as e:
         raise argparse.ArgumentTypeError from e
 
+
 def parse_args():
-    parser = argparse.ArgumentParser(description='Convert layer to an image')
-    parser.add_argument('infile', type=str)
-    parser.add_argument('layer', type=str)
-    parser.add_argument('-o', '--output', metavar='<file>', type=str)
-    parser.add_argument('--size', type=plt_size, help='Figure size in mm (WWxHH)')
+    parser = argparse.ArgumentParser(
+            description='Convert geopackage to an image')
+    group = parser.add_mutually_exclusive_group(required=True)
+    group.add_argument('--infile', type=str)
+    group.add_argument('--table', type=str)
+    parser.add_argument('-o', '--outfile', metavar='<file>', type=str)
+    parser.add_argument(
+            '--size', type=plt_size, help='Figure size in mm (WWxHH)')
     return parser.parse_args()
 
+
 def main():
     args = parse_args()
-    f = geopandas.read_file(args.infile)
+    if args.table:
+        conn = psycopg2.connect("host=127.0.0.1 dbname=osm user=osm")
+        sql = "SELECT geom FROM %s" % args.table
+        f = geopandas.read_postgis(sql, con=conn, geom_col='geom')
+    else:
+        f = geopandas.read_file(args.infile)
     f.plot(figsize=args.size)
     plt.axis('off')
     plt.margins(0, 0)
     plt.tight_layout(0)
-    if args.output:
-        plt.savefig(args.output, bbox_inches=0, dpi=300)
+    if args.outfile:
+        plt.savefig(args.outfile, bbox_inches=0, dpi=300)
     else:
         plt.show()
 
+
 if __name__ == '__main__':
     main()