feat[rio-pmtiles]: allow min and/or max zoom to be omitted when specifying zoom levels (#623)

* Allow min and/or max zoom to be omitted when specifying zoom levels

* Fix help message for `--zoom-levels`

* Add tests

python/rio-pmtiles/rio_pmtiles/scripts/cli.py

@@ -150,10 +150,12 @@ def guess_maxzoom(crs, bounds, width, height, tile_size):
     "--zoom-levels",
     default=None,
     metavar="MIN..MAX",
-    help="A min...max range of export zoom levels. "
+    help="A min..max range of export zoom levels. "
-    "The default zoom level "
+    "The default min zoom level is 0 (dataset "
-    "is the one at which the dataset is contained within "
+    "contained in a single tile), and the default "
-    "a single tile.",
+    "max is calculated based on the available "
+    "detail in the dataset. Either or both of "
+    "min/max may be omitted.",
 )
 @click.option(
     "-j",
@@ -337,7 +339,11 @@ def pmtiles(
         # Resolve the minimum and maximum zoom levels for export.
         maxzoom_in_file = guess_maxzoom(src.crs, src.bounds, src.width, src.height, tile_size)
         if zoom_levels:
-            minzoom, maxzoom = map(int, zoom_levels.split(".."))
+            specified_levels = zoom_levels.split("..")
+            minzoom = specified_levels[0]
+            minzoom = 0 if minzoom == "" else int(minzoom)
+            maxzoom = specified_levels[1]
+            maxzoom = maxzoom_in_file if maxzoom == "" else int(maxzoom)
         else:
             minzoom = 0
             maxzoom = maxzoom_in_file

python/rio-pmtiles/tests/test_cli.py

@@ -75,7 +75,8 @@ def test_export_tiles(tmpdir, data):
         src = MmapSource(f)
         assert len(list(all_tiles(src))) == 19
 
-def test_export_zoom(tmpdir, data):
+
+def test_export_zoom_both(tmpdir, data):
     inputfile = str(data.join("RGB.byte.tif"))
     outputfile = str(tmpdir.join("export.pmtiles"))
     runner = CliRunner()
@@ -88,6 +89,46 @@ def test_export_zoom(tmpdir, data):
         src = MmapSource(f)
         assert len(list(all_tiles(src))) == 6
 
+def test_export_zoom_neither(tmpdir, data):
+    inputfile = str(data.join("RGB.byte.tif"))
+    outputfile = str(tmpdir.join("export.pmtiles"))
+    runner = CliRunner()
+    result = runner.invoke(
+        main_group, ["pmtiles", inputfile, outputfile, "--zoom-levels", ".."]
+    )
+    assert result.exit_code == 0
+
+    with open(outputfile, "rb") as f:
+        src = MmapSource(f)
+        assert len(list(all_tiles(src))) == 19
+
+def test_export_zoom_only_min(tmpdir, data):
+    inputfile = str(data.join("RGB.byte.tif"))
+    outputfile = str(tmpdir.join("export.pmtiles"))
+    runner = CliRunner()
+    result = runner.invoke(
+        main_group, ["pmtiles", inputfile, outputfile, "--zoom-levels", "6.."]
+    )
+    assert result.exit_code == 0
+
+    with open(outputfile, "rb") as f:
+        src = MmapSource(f)
+        assert len(list(all_tiles(src))) == 12
+
+def test_export_zoom_only_max(tmpdir, data):
+    inputfile = str(data.join("RGB.byte.tif"))
+    outputfile = str(tmpdir.join("export.pmtiles"))
+    runner = CliRunner()
+    result = runner.invoke(
+        main_group, ["pmtiles", inputfile, outputfile, "--zoom-levels", "..7"]
+    )
+    assert result.exit_code == 0
+
+    with open(outputfile, "rb") as f:
+        src = MmapSource(f)
+        assert len(list(all_tiles(src))) == 13
+
+
 def test_export_jobs(tmpdir, data):
     inputfile = str(data.join("RGB.byte.tif"))
     outputfile = str(tmpdir.join("export.pmtiles"))