def _layers_locations(
instance: Union[Layer, Map],
compute_bbox: bool = False,
target_crs: str = "EPSG:3857") -> Tuple[List[List], List]:
"""
Function returning a list mapping instance's layers to their locations, enabling to construct a minimum
number of WMS request for multiple layers of the same OGC source (ensuring layers order for Maps)
:param instance: instance of Layer or Map models
:param compute_bbox: flag determining whether a BBOX containing the instance should be computed,
based on instance's layers
:param target_crs: valid only when compute_bbox is True - CRS of the returned BBOX
:return: a tuple with a list, which maps layers to their locations in a correct layers order
e.g.
[
["http://localhost:8080/geoserver/": ["geonode:layer1", "geonode:layer2]]
]
and a list optionally consisting of 5 elements containing west, east, south, north
instance's boundaries and CRS
"""
ogc_server_settings = OGC_Servers_Handler(settings.OGC_SERVER)["default"]
locations = []
bbox = []
if isinstance(instance, Layer):
# for local layers
if instance.remote_service is None:
locations.append(
[ogc_server_settings.LOCATION, [instance.alternate], []])
# for remote layers
else:
locations.append([
instance.remote_service.service_url, [instance.alternate], []
])
if compute_bbox:
if instance.ll_bbox_polygon:
bbox = utils.clean_bbox(instance.ll_bbox, target_crs)
elif (instance.bbox[-1].upper() != 'EPSG:3857'
and target_crs.upper() == 'EPSG:3857'
and utils.exceeds_epsg3857_area_of_use(instance.bbox)):
# handle exceeding the area of use of the default thumb's CRS
bbox = utils.transform_bbox(
utils.crop_to_3857_area_of_use(instance.bbox), target_crs)
else:
bbox = utils.transform_bbox(instance.bbox, target_crs)
elif isinstance(instance, Map):
map_layers = instance.layers.copy()
# ensure correct order of layers in the map (higher stack_order are printed on top of lower)
map_layers.sort(key=lambda l: l.stack_order)
for map_layer in map_layers:
if not map_layer.visibility:
logger.debug(
"Skipping not visible layer in the thumbnail generation.")
continue
if not map_layer.local and not map_layer.ows_url:
logger.warning(
"Incorrectly defined remote layer encountered (no OWS URL defined)."
"Skipping it in the thumbnail generation.")
continue
name = get_layer_name(map_layer)
store = map_layer.store
workspace = get_layer_workspace(map_layer)
try:
map_layer_style = json.loads(
map_layer.layer_params).get('style')
except json.decoder.JSONDecodeError:
map_layer_style = None
if store and Layer.objects.filter(
store=store, workspace=workspace, name=name).count() > 0:
layer = Layer.objects.filter(store=store,
workspace=workspace,
name=name).first()
elif workspace and Layer.objects.filter(workspace=workspace,
name=name).count() > 0:
layer = Layer.objects.filter(workspace=workspace,
name=name).first()
elif Layer.objects.filter(alternate=map_layer.name).count() > 0:
layer = Layer.objects.filter(alternate=map_layer.name).first()
else:
logger.warning(
f"Layer for MapLayer {name} was not found. Skipping it in the thumbnail."
)
continue
if layer.storeType == "remoteStore":
# limit number of locations, ensuring layer order
if len(locations) and locations[-1][
0] == layer.remote_service.service_url:
# if previous layer's location is the same as the current one - append current layer there
locations[-1][1].append(layer.alternate)
# update the styles too
if map_layer_style:
locations[-1][2].append(map_layer_style)
else:
locations.append([
layer.remote_service.service_url, [layer.alternate],
[map_layer_style] if map_layer_style else []
])
else:
# limit number of locations, ensuring layer order
if len(locations) and locations[-1][0] == settings.OGC_SERVER[
"default"]["LOCATION"]:
# if previous layer's location is the same as the current one - append current layer there
locations[-1][1].append(layer.alternate)
# update the styles too
if map_layer_style:
locations[-1][2].append(map_layer_style)
else:
locations.append([
settings.OGC_SERVER["default"]["LOCATION"],
[layer.alternate],
[map_layer_style] if map_layer_style else []
])
if compute_bbox:
if layer.ll_bbox_polygon:
layer_bbox = utils.clean_bbox(layer.ll_bbox, target_crs)
elif (layer.bbox[-1].upper() != 'EPSG:3857'
and target_crs.upper() == 'EPSG:3857'
and utils.exceeds_epsg3857_area_of_use(layer.bbox)):
# handle exceeding the area of use of the default thumb's CRS
layer_bbox = utils.transform_bbox(
utils.crop_to_3857_area_of_use(layer.bbox), target_crs)
else:
layer_bbox = utils.transform_bbox(layer.bbox, target_crs)
if not bbox:
bbox = layer_bbox
else:
# layer's BBOX: (left, right, bottom, top)
bbox = [
min(bbox[0], layer_bbox[0]),
max(bbox[1], layer_bbox[1]),
min(bbox[2], layer_bbox[2]),
max(bbox[3], layer_bbox[3]),
]
if bbox and len(bbox) < 5:
bbox = list(bbox) + [target_crs] # convert bbox to list, if it's tuple
return locations, bbox
def create_thumbnail(
instance: Union[Layer, Map],
wms_version: str = settings.OGC_SERVER["default"].get(
"WMS_VERSION", "1.1.1"),
bbox: Optional[Union[List, Tuple]] = None,
forced_crs: Optional[str] = None,
styles: Optional[List] = None,
overwrite: bool = False,
background_zoom: Optional[int] = None,
) -> None:
"""
Function generating and saving a thumbnail of the given instance (Layer or Map), which is composed of
outcomes of WMS GetMap queries to the instance's layers providers, and an outcome of querying background
provider for thumbnail's background (by default Slippy Map provider).
:param instance: instance of Layer or Map models
:param wms_version: WMS version of the query
:param bbox: bounding box of the thumbnail in format: (west, east, south, north, CRS), where CRS is in format
"EPSG:XXXX"
:param forced_crs: CRS which should be used to fetch data from WMS services in format "EPSG:XXXX". By default
all data is translated and retrieved in EPSG:3857, since this enables background fetching from
Slippy Maps providers. Forcing another CRS can cause skipping background generation in
the thumbnail
:param styles: styles, which OGC server should use for rendering an image
:param overwrite: overwrite existing thumbnail
:param background_zoom: zoom of the XYZ Slippy Map used to retrieve background image,
if Slippy Map is used as background
"""
instance.refresh_from_db()
default_thumbnail_name = _generate_thumbnail_name(instance)
mime_type = "image/png"
width = settings.THUMBNAIL_SIZE["width"]
height = settings.THUMBNAIL_SIZE["height"]
if default_thumbnail_name is None:
# instance is Map and has no layers defined
utils.assign_missing_thumbnail(instance)
return
# handle custom, uploaded thumbnails, which may have different extensions from the default thumbnail
thumbnail_exists = False
if instance.thumbnail_url and instance.thumbnail_url != settings.MISSING_THUMBNAIL:
thumbnail_exists = utils.thumb_exists(
instance.thumbnail_url.rsplit('/')[-1])
if (thumbnail_exists
or utils.thumb_exists(default_thumbnail_name)) and not overwrite:
logger.debug(
f"Thumbnail for {instance.name} already exists. Skipping thumbnail generation."
)
return
# --- determine target CRS and bbox ---
target_crs = forced_crs.upper() if forced_crs is not None else "EPSG:3857"
compute_bbox_from_layers = False
is_map_with_datasets = False
if isinstance(instance, Map):
is_map_with_datasets = MapLayer.objects.filter(
map=instance, visibility=True, local=True).exclude(
ows_url__isnull=True).exclude(ows_url__exact='').count() > 0
if bbox:
bbox = utils.clean_bbox(bbox, target_crs)
elif instance.ll_bbox_polygon:
bbox = utils.clean_bbox(instance.ll_bbox, target_crs)
else:
compute_bbox_from_layers = True
# --- define layer locations ---
locations, layers_bbox = _layers_locations(
instance, compute_bbox=compute_bbox_from_layers, target_crs=target_crs)
if compute_bbox_from_layers and is_map_with_datasets:
if not layers_bbox:
raise ThumbnailError(
f"Thumbnail generation couldn't determine a BBOX for: {instance}."
)
else:
bbox = layers_bbox
# --- expand the BBOX to match the set thumbnail's ratio (prevent thumbnail's distortions) ---
bbox = utils.expand_bbox_to_ratio(bbox) if bbox else None
# --- add default style ---
if not styles and hasattr(instance, "default_style"):
if instance.default_style:
styles = [instance.default_style.name]
# --- fetch WMS layers ---
partial_thumbs = []
for ogc_server, layers, _styles in locations:
if isinstance(instance, Map) and len(layers) == len(_styles):
styles = _styles
try:
partial_thumbs.append(
utils.get_map(
ogc_server,
layers,
wms_version=wms_version,
bbox=bbox,
mime_type=mime_type,
styles=styles,
width=width,
height=height,
))
except Exception as e:
logger.error(
f"Exception occurred while fetching partial thumbnail for {instance.title}."
)
logger.exception(e)
if not partial_thumbs and is_map_with_datasets:
utils.assign_missing_thumbnail(instance)
raise ThumbnailError(
"Thumbnail generation failed - no image retrieved from WMS services."
)
# --- merge retrieved WMS images ---
merged_partial_thumbs = Image.new("RGBA", (width, height),
(255, 255, 255, 0))
for image in partial_thumbs:
if image:
content = BytesIO(image)
try:
img = Image.open(content)
img.verify() # verify that it is, in fact an image
img = Image.open(
BytesIO(image)
) # "re-open" the file (required after running verify method)
merged_partial_thumbs.paste(img, mask=img.convert('RGBA'))
except UnidentifiedImageError as e:
logger.error(
f"Thumbnail generation. Error occurred while fetching layer image: {image}"
)
logger.exception(e)
# --- fetch background image ---
try:
BackgroundGenerator = import_string(
settings.THUMBNAIL_BACKGROUND["class"])
background = BackgroundGenerator(width, height).fetch(
bbox, background_zoom) if bbox else None
except Exception as e:
logger.error(
f"Thumbnail generation. Error occurred while fetching background image: {e}"
)
logger.exception(e)
background = None
# --- overlay image with background ---
thumbnail = Image.new("RGB", (width, height), (250, 250, 250))
if background is not None:
thumbnail.paste(background, (0, 0))
thumbnail.paste(merged_partial_thumbs, (0, 0), merged_partial_thumbs)
# convert image to the format required by save_thumbnail
with BytesIO() as output:
thumbnail.save(output, format="PNG")
content = output.getvalue()
# save thumbnail
instance.save_thumbnail(default_thumbnail_name, image=content)
return instance.thumbnail_url
def _datasets_locations(
instance: Union[Dataset, Map],
compute_bbox: bool = False,
target_crs: str = "EPSG:3857") -> Tuple[List[List], List]:
"""
Function returning a list mapping instance's datasets to their locations, enabling to construct a minimum
number of WMS request for multiple datasets of the same OGC source (ensuring datasets order for Maps)
:param instance: instance of Dataset or Map models
:param compute_bbox: flag determining whether a BBOX containing the instance should be computed,
based on instance's datasets
:param target_crs: valid only when compute_bbox is True - CRS of the returned BBOX
:return: a tuple with a list, which maps datasets to their locations in a correct datasets order
e.g.
[
["http://localhost:8080/geoserver/": ["geonode:layer1", "geonode:layer2]]
]
and a list optionally consisting of 5 elements containing west, east, south, north
instance's boundaries and CRS
"""
ogc_server_settings = OGC_Servers_Handler(settings.OGC_SERVER)["default"]
locations = []
bbox = []
if isinstance(instance, Dataset):
locations.append([
instance.ows_url or ogc_server_settings.LOCATION,
[instance.alternate], []
])
if compute_bbox:
if instance.ll_bbox_polygon:
bbox = utils.clean_bbox(instance.ll_bbox, target_crs)
elif (instance.bbox[-1].upper() != 'EPSG:3857'
and target_crs.upper() == 'EPSG:3857'
and utils.exceeds_epsg3857_area_of_use(instance.bbox)):
# handle exceeding the area of use of the default thumb's CRS
bbox = utils.transform_bbox(
utils.crop_to_3857_area_of_use(instance.bbox), target_crs)
else:
bbox = utils.transform_bbox(instance.bbox, target_crs)
elif isinstance(instance, Map):
for map_dataset in instance.maplayers.iterator():
if not map_dataset.local and not map_dataset.ows_url:
logger.warning(
"Incorrectly defined remote dataset encountered (no OWS URL defined)."
"Skipping it in the thumbnail generation.")
continue
name = get_dataset_name(map_dataset)
store = map_dataset.store
workspace = get_dataset_workspace(map_dataset)
map_dataset_style = map_dataset.current_style
if store and Dataset.objects.filter(
store=store, workspace=workspace, name=name).count() > 0:
dataset = Dataset.objects.filter(store=store,
workspace=workspace,
name=name).first()
elif workspace and Dataset.objects.filter(workspace=workspace,
name=name).count() > 0:
dataset = Dataset.objects.filter(workspace=workspace,
name=name).first()
elif Dataset.objects.filter(
alternate=map_dataset.name).count() > 0:
dataset = Dataset.objects.filter(
alternate=map_dataset.name).first()
else:
logger.warning(
f"Dataset for MapLayer {name} was not found. Skipping it in the thumbnail."
)
continue
if dataset.subtype in ['tileStore', 'remote']:
# limit number of locations, ensuring dataset order
if len(locations) and locations[-1][
0] == dataset.remote_service.service_url:
# if previous dataset's location is the same as the current one - append current dataset there
locations[-1][1].append(dataset.alternate)
# update the styles too
if map_dataset_style:
locations[-1][2].append(map_dataset_style)
else:
locations.append([
dataset.remote_service.service_url,
[dataset.alternate],
[map_dataset_style] if map_dataset_style else []
])
else:
# limit number of locations, ensuring dataset order
if len(locations) and locations[-1][0] == settings.OGC_SERVER[
"default"]["LOCATION"]:
# if previous dataset's location is the same as the current one - append current dataset there
locations[-1][1].append(dataset.alternate)
# update the styles too
if map_dataset_style:
locations[-1][2].append(map_dataset_style)
else:
locations.append([
settings.OGC_SERVER["default"]["LOCATION"],
[dataset.alternate],
[map_dataset_style] if map_dataset_style else []
])
if compute_bbox:
if dataset.ll_bbox_polygon:
dataset_bbox = utils.clean_bbox(dataset.ll_bbox,
target_crs)
elif (dataset.bbox[-1].upper() != 'EPSG:3857'
and target_crs.upper() == 'EPSG:3857'
and utils.exceeds_epsg3857_area_of_use(dataset.bbox)):
# handle exceeding the area of use of the default thumb's CRS
dataset_bbox = utils.transform_bbox(
utils.crop_to_3857_area_of_use(dataset.bbox),
target_crs)
else:
dataset_bbox = utils.transform_bbox(
dataset.bbox, target_crs)
if not bbox:
bbox = dataset_bbox
else:
# dataset's BBOX: (left, right, bottom, top)
bbox = [
min(bbox[0], dataset_bbox[0]),
max(bbox[1], dataset_bbox[1]),
min(bbox[2], dataset_bbox[2]),
max(bbox[3], dataset_bbox[3]),
]
if bbox and len(bbox) < 5:
bbox = list(bbox) + [target_crs] # convert bbox to list, if it's tuple
return locations, bbox