mapscript.layerObj

class mapscript.layerObj(map: Optional[mapObj] = None)

The LAYER object

Overview

The layerObj has the following relationships:

../../../_images/layerObj_classObj.png ../../../_images/layerObj_hashTableObj.png ../../../_images/layerObj_mapObj.png

Attributes

bandsitem

char The attribute from the index file used to select the source raster band(s) to be used - normally NULL for default bands processing

bindvals

hashTableObj immutable Relates to RFC59

classgroup

char See CLASSGROUP

classitem

char the attribute used to classify layer data - see CLASSITEM

cluster

clusterObj immutable See CLUSTER

compositer

LayerCompositer immutable See COMPOSITE

connection

char layer connection or data source name - see CONNECTION

connectionoptions

hashTableObj immutable See CONNECTIONOPTIONS

connectiontype

enum MS_CONNECTION_TYPE the layer connection type - see CONNECTIONTYPE

data

char Layer data definition, values depend upon connectiontype - see DATA

debug

int Enable debugging of layer- MS_ON or MS_OFF (default) - see DEBUG

encoding

char For iconving shape attributes, ignored if NULL or "utf-8" - see ENCODING

extent

rectObj immutable optional limiting extent for layer features - see EXTENT

filteritem

char Attribute defining filter - see FILTERITEM

footer

char filename to a template for result's footer - see FOOTER

group

char Name of a group of layers - see GROUP

header

char filename to a template for result's header - see HEADER

index

int immutable Index of layer within parent map's layers array

labelcache

int MS_ON (default) or MS_OFF - see LABELCACHE

labelitem

char attribute defining feature label text - see LABELITEM

labelmaxscaledenom

double See LABELMAXSCALEDENOM

labelminscaledenom

double See LABELMINSCALEDENOM

labelrequires

char Simple logical expression - see LABELREQUIRES

map

mapObj immutable Reference to parent map

mask

char See MASK

maxclasses

int immutable Used to track of the maximum number of classes - see RFC-17

maxfeatures

int Maximum number of layer features that will be drawn - see MAXFEATURES

maxgeowidth

double max map width (in map units) at which the layer should be drawn - see MAXGEOWIDTH

maxscaledenom

double Minimum scale at which layer will be drawn - see MAXSCALEDENOM

metadata

hashTableObj immutable See METADATA

minfeaturesize

int minimum feature size (in pixels) for shape

mingeowidth

double min map width (in map units) at which the layer should be drawn - see MAXGEOWIDTH

minscaledenom

double Maximum scale at which layer will be drawn - see MINSCALEDENOM

name

char See NAME - should be unique

numclasses

int immutable Number of layer classes

numitems

int immutable Number of layer feature attributes (items)

numjoins

int immutable Number of layer joins

numprocessing

int immutable Number of raster processing directives

offsite

colorObj transparent pixel value for raster images - see OFFSITE

plugin_library

char Used to select the library to load by MapServer

plugin_library_original

char this is needed for Mapfile writing

postlabelcache

int MS_ON or MS_OFF (default) - see POSTLABELCACHE

refcount

int immutable reference counting, RFC24

rendermode

enum MS_RENDER_MODE MS_FIRST_MATCHING_CLASS - default and historic MapServer behavior, MS_ALL_MATCHING_CLASSES - SLD behavior

requires

char Context expressions, simple enough to not use expressionObj - see REQUIRES

sizeunits

int applies to all classes - see SIZEUNITES

startindex

int Feature start index - used for paging

status

int See STATUSMS_ON, MS_OFF or MS_DEFAULT

styleitem

char item to be used for style lookup - can also be 'AUTO' - see STYLEITEM

symbolscaledenom

double scale at which symbols are default size - see SYMBOLSCALEDENOM

template

char See TEMPLATE - global template, used across all classes

thisown

The membership flag

tileindex

char layer index file for tiling support - see TILEINDEX

tileitem

char attribute defining tile paths - see TILEITEM

tilesrs

char name of the attribute that contains the SRS of an individual tile - see TILESRS

tolerance

double search buffer for point and line queries (in toleranceunits) - see TOLERANCE

toleranceunits

int See TOLERANCEUNITS

transform

int MS_TRUE (default) or MS_FALSE whether or not layer data is to be transformed to image units - see TRANSFORM

type

enum MS_LAYER_TYPE the layer type - see TYPE

units

int units of the layer - see UNITS

utfdata

expressionObj immutable See UTFDATA

utfitem

char See UTFITEM

utfitemindex

int See CLASSITEM

validation

hashTableObj immutable See VALIDATION

Methods

__init__(map: Optional[mapObj] = None)[source]

A layerObj is associated with mapObj. An instance of layerObj can exist outside of a mapObj

addFeature(shape: shapeObj) int[source]

Add a new inline feature on a layer. Returns -1 on error. TODO: Is this similar to inline features in a mapfile? Does it work for any kind of layer or connection type?

addProcessing(directive: char const) void[source]

Adds a new processing directive line to a layer, similar to the PROCESSING directive in a map file. Processing directives supported are specific to the layer type and underlying renderer.

applySLD(sld: char, stylelayer: char) int[source]

Apply the SLD document to the layer object. The matching between the SLD document and the layer will be done using the layer’s name. If a stylelayer argument is passed (argument is optional), the NamedLayer in the SLD that matches it will be used to style the layer. See SLD HOWTO for more information on the SLD support.

applySLDURL(sld: char, stylelayer: char) int[source]

Apply the SLD document pointed by the URL to the layer object. The matching between the SLD document and the layer will be done using the layer’s name. If a stylelayer argument is passed (argument is optional), the NamedLayer in the SLD that matches it will be used to style the layer. See SLD HOWTO for more information on the SLD support.

clearProcessing() int[source]

Clears the layer’s raster processing directives. Returns the subsequent number of directives, which will equal MS_SUCCESS if the directives have been cleared.

clone() layerObj[source]

Return an independent copy of the layer with no parent map.

close() void[source]

Close the underlying layer.

convertToString() char[source]

Output the layerObj object as a Mapfile string. Provides the inverse option for layerObj.updateFromString().

draw(map: mapObj, image: imageObj) int[source]

Renders this layer into the target image, adding labels to the cache if required. Returns MS_SUCCESS or MS_FAILURE.

drawQuery(map: mapObj, image: imageObj) int[source]

Draw query map for a single layer into the target image. Returns MS_SUCCESS or MS_FAILURE.

executeWFSGetFeature(layer: layerObj) char[source]

Executes a GetFeature request on a WFS layer and returns the name of the temporary GML file created. Returns an empty string on error.

generateSLD() char[source]

Returns an SLD XML string based on all the classes found in the layer (the layer must have STATUS ON`).

getClass()[source]
getClassIndex(map: mapObj, shape: shapeObj, classgroup: Optional[int] = None, numclasses: int = 0) int[source]

Get the class index for a shape in the layer.

getExtent() rectObj[source]

Fetches the extents of the data in the layer. This normally requires a full read pass through the features of the layer and does not work for raster layers.

getFilterString() char[source]

Returns the current filter expression.

getGeomTransform() char[source]

Return the geomtransform string for the layer.

getItem(i: int) char[source]

Returns the requested item. Items are attribute fields, and this method returns the item name (field name). The numitems field contains the number of items available, and the first item is index zero.

getItemDefinitions()[source]

Python MapScript only

Return item (field) names and their types if available. Field types are specified using GML metadata and can be one of the following:

Integer|Long|Real|Character|Date|Boolean

getItemType(i: int) char[source]

Returns the requested item’s field type. A layer must be open to retrieve the item definition.

Pass in the attribute index to retrieve the type. The layer’s numitems property contains the number of items available, and the first item is index zero.

getNumFeatures() int[source]

Returns the number of inline features in a layer. TODO: is this really only online features or will it return the number of non-inline features on a regular layer?

getNumResults() int[source]

Returns the number of entries in the query result cache for this layer.

getOpacity() int[source]

Returns the opacity value for the layer.

getProcessing(index: int) char[source]

Return the raster processing directive at index.

getProcessingKey(key: char const) char[source]

Return the processing directive specified by key.

getProjection() char[source]

Returns the PROJ definition of the layer’s projection.

getResult(i: int) resultObj[source]

Fetches the requested query result cache entry, or NULL if the index is outside the range of available results. This method would normally only be used after issuing a query operation.

getResults() resultCacheObj[source]

Returns a reference to layer’s result cache. Should be NULL prior to any query, or after a failed query or query with no results.

getResultsBounds() rectObj[source]

Returns the bounds of the features in the result cache.

getShape(record: resultObj) shapeObj[source]

Get a shape from layer data. Argument is a result cache member from layerObj.getResult()

getWMSFeatureInfoURL(map: mapObj, click_x: int, click_y: int, feature_count: int, info_format: char) char[source]

Return a WMS GetFeatureInfo URL (works only for WMS layers) clickX, clickY is the location of to query in pixel coordinates with (0,0) at the top left of the image. featureCount is the number of results to return. infoFormat is the format the format in which the result should be requested. Depends on remote server’s capabilities. MapServer WMS servers support only “MIME” (and should support “GML.1” soon). Returns “” and outputs a warning if layer is not a WMS layer or if it is not queryable.

insertClass()[source]
isVisible() int[source]

Returns MS_TRUE or MS_FALSE after considering the layer status, minscaledenom, and maxscaledenom within the context of the parent map.

moveClassDown(index: int) int[source]

The class specified by the class index will be moved up into the array of classes. Returns MS_SUCCESS or MS_FAILURE. For example moveClassDown(1) will have the effect of moving class 1 down to position 2, and the class at position 2 will be moved to position 1.

moveClassUp(index: int) int[source]

The class specified by the class index will be moved up in the array of classes. Returns MS_SUCCESS or MS_FAILURE. For example moveClassUp(1) will have the effect of moving class 1 up to position 0, and the class at position 0 will be moved to position 1.

nextShape() shapeObj[source]

Called after layerObj.whichShapes() has been called to actually retrieve shapes within a given area returns a shape object or MS_FALSE Example of usage:

mapObj map = new mapObj("d:/msapps/gmap-ms40/htdocs/gmap75.map");
layerObj layer = map.getLayerByName('road');
int status = layer.open();
status = layer.whichShapes(map.extent);
shapeObj shape;
while ((shape = layer.nextShape()) != null)
{
  ...
}
layer.close();
open() int[source]

Opens the underlying layer. This is required before operations like layerObj.getResult() will work, but is not required before a draw or query call.

queryByAttributes(map: mapObj, qitem: char, qstring: char, mode: int) int[source]

Query layer for shapes that intersect current map extents. qitem is the item (attribute) on which the query is performed, and qstring is the expression to match. The query is performed on all the shapes that are part of a CLASS that contains a TEMPLATE value or that match any class in a layer that contains a LAYER TEMPLATE value. Note that the layer’s FILTER/FILTERITEM are ignored by this function. mode is MS_SINGLE or MS_MULTIPLE depending on number of results you want. Returns MS_SUCCESS if shapes were found or MS_FAILURE if nothing was found or if some other error happened.

queryByFeatures(map: mapObj, slayer: int) int[source]

Perform a query set based on a previous set of results from another layer. At present the results MUST be based on a polygon layer. Returns MS_SUCCESS if shapes were found or MS_FAILURE if nothing was found or if some other error happened.

queryByFilter(map: mapObj, string: char) int[source]

Query by the filter string. For querying, we switch layer status ON and then back to original value before returning.

queryByIndex(map: mapObj, tileindex: int, shapeindex: int, bAddToQuery: int = 0) int[source]

Pop a query result member into the layer’s result cache. By default clobbers existing cache. Returns MS_SUCCESS or MS_FAILURE

queryByPoint(map: mapObj, point: pointObj, mode: int, buffer: double) int[source]

Query layer at point location specified in georeferenced map coordinates (i.e. not pixels). The query is performed on all the shapes that are part of a CLASS that contains a TEMPLATE value or that match any class in a layer that contains a LAYER TEMPLATE value. Note that the layer’s FILTER/FILTERITEM are ignored by this function. mode is MS_SINGLE or MS_MULTIPLE depending on number of results you want. Returns MS_SUCCESS if shapes were found or MS_FAILURE if nothing was found or if some other error happened.

queryByRect(map: mapObj, rect: rectObj) int[source]

Query layer using a rectangle specified in georeferenced map coordinates (i.e. not pixels). The query is performed on all the shapes that are part of a CLASS that contains a TEMPLATE value or that match any class in a layer that contains a LAYER TEMPLATE value. Note that the layer’s FILTER/FILTERITEM are ignored by this function. The MS_MULTIPLE mode is set by default. Returns MS_SUCCESS if shapes were found or MS_FAILURE if nothing was found or if some other error happened.

queryByShape(map: mapObj, shape: shapeObj) int[source]

Query layer based on a single shape, the shape has to be a polygon at this point. Returns MS_SUCCESS if shapes were found or MS_FAILURE if nothing was found or if some other error happened.

removeClass(index: int) classObj[source]

Removes the class at index and returns a copy, or NULL in the case of a failure. Note that subsequent classes will be renumbered by this operation. The numclasses field contains the number of classes available.

setConnectionType(connectiontype: int, library_str: char const) int[source]

Changes the connectiontype of the layer and recreates the vtable according to the new connection type. This method should be used instead of setting the connectiontype parameter directly. In case when the layer.connectiontype = MS_PLUGIN the library_str parameter should also be specified so as to select the library to load by MapServer. For the other connection types this parameter is not used.

setExtent(minx: double = -1.0, miny: double = -1.0, maxx: double = -1.0, maxy: double = -1.0) int[source]

Sets the extent of a layer. Returns MS_SUCCESS or MS_FAILURE

setFilter(filter: char) int[source]

Sets a filter expression similarly to the FILTER expression in a map file. Returns MS_SUCCESS or MS_FAILURE if the expression fails to parse.

setGeomTransform(transform: char) void[source]

Set the geomtransform string for the layer.

setItems(items: char, numitems: int) int[source]

Set the items to be retrieved with a particular shape.

setOpacity(opacity: int) void[source]

Sets an opacity for the layer, where the value is an integer in range [0, 100]. A new COMPOSITE block is generated, containing this OPACITY value.

setProcessingKey(key: char const, value: char const) void[source]

Adds or replaces a processing directive of the form “key=value”. Unlike the layerObj.addProcessing() function, this will replace an existing processing directive for the given key value. Processing directives supported are specific to the layer type and underlying renderer.

setProjection(proj4: char) int[source]

Set the layer projection using a PROJ format projection definition (i.e. “+proj=utm +zone=11 +datum=WGS84” or “init=EPSG:26911”). Returns MS_SUCCESS or MS_FAILURE

setWKTProjection(wkt: char) int[source]

Set the layer projection using OpenGIS Well Known Text format. Returns MS_SUCCESS or MS_FAILURE

updateFromString(snippet: char) int[source]

Update a layerObj from a string snippet. Returns MS_SUCCESS or MS_FAILURE

whichShapes(rect: rectObj) int[source]

Performs a spatial, and optionally an attribute based feature search. The function basically prepares things so that candidate features can be accessed by query or drawing functions (e.g using layerObj.nextShape() function). Returns MS_SUCCESS, MS_FAILURE or MS_DONE. MS_DONE is returned if the layer extent does not overlap rect.