3.2. Web Map Service (WMS)

The 1.1.1 and 1.3.0 WMS standards implemented in QGIS Server provide a HTTP interface to request map or legend images generated from a QGIS project. A typical WMS request defines the QGIS project to use, the layers to render as well as the image format to generate. Basic support is also available for Styled Layer Descriptor (SLD).

Specifications:

Standard requests provided by QGIS Server:

Request

Descriere

GetCapabilities

Returns XML metadata with information about the server

GetMap

Returns a map

GetFeatureInfo

Retrieves data (geometry and values) for a pixel location

GetLegendGraphics

Returns legend symbols

GetStyle(s)

Returns XML document with style description in SLD

DescribeLayer

Returns information about WFS and WCS availability respectively for vector and raster layers

Vendor requests provided by QGIS Server:

Request

Descriere

GetPrint

Returns a QGIS layout

GetProjectSettings

Returns specific information about QGIS Server

GetSchemaExtension

Returns XML metadata about optional extended capabilities

3.2.1. GetCapabilities

Standard parameters for the GetCapabilities request according to the OGC WMS 1.1.1 and 1.3.0 specifications:

Parametru

Required

Descriere

SERVICE

Da

Name of the service (WMS)

REQUEST

Da

Name of the request (GetCapabilities)

VERSION

Nu

Version of the service

The GetCapabilities request supports as well the following vendor parameters:

Parametru

Required

Descriere

MAP

Da

QGIS project file

URL example:

http://localhost/qgis_server?
SERVICE=WMS
&VERSION=1.3.0
&REQUEST=GetCapabilities

3.2.2. GetMap

Standard parameters for the GetMap request according to the OGC WMS 1.1.1 and 1.3.0 specifications:

Parametru

Required

Descriere

SERVICE

Da

Name of the service (WMS)

REQUEST

Da

Name of the request (GetMap)

VERSION

Da

Version of the service

LAYERS

Nu

Layers to display

STYLES

Nu

Layers» style

SRS / CRS

Da

Coordinate reference system

BBOX

Da

Map extent

WIDTH

Da

Width of the image in pixels

HEIGHT

Da

Height of the image in pixels

FORMAT

Nu

Image format

TRANSPARENT

Nu

Transparent background

SLD

Nu

URL of an SLD to be used for styling

SLD_BODY

Nu

In-line SLD (XML) to be used for styling

In addition to the standard ones, QGIS Server supports redlining, external WMS layers as well as the following extra parameters:

Parametru

Required

Descriere

MAP

Da

QGIS project file

BGCOLOR

Nu

Specify the background color

DPI

Nu

Specify the output resolution

IMAGE_QUALITY

Nu

JPEG compression

OPACITIES

Nu

Opacity for layer or group

FILTER

Nu

Subset of features

SELECTION

Nu

Highlight features

FILE_NAME

Nu

File name of the downloaded file

Only for FORMAT=application/dxf

FORMAT_OPTIONS

Nu

Options of the specified file format

Only for FORMAT=application/dxf

TILED

Nu

Working in tiled mode

URL example:

http://localhost/qgis_server?
SERVICE=WMS
&VERSION=1.3.0
&REQUEST=GetMap
&MAP=/home/qgis/projects/world.qgs
&LAYERS=mylayer1,mylayer2,mylayer3
&STYLES=style1,default,style3
&OPACITIES=125,200,125
&CRS=EPSG:4326
&WIDTH=400
&HEIGHT=400
&FORMAT=image/png
&TRANSPARENT=TRUE
&DPI=300
&TILED=TRUE

VERSION

This parameter allows to specify the version of the service to use. Available values for the VERSION parameter are:

  • 1.1.1

  • 1.3.0

According to the version number, slight differences have to be expected as explained later for the next parameters:

  • CRS / SRS

  • BBOX

LAYERS

This parameter allows to specify the layers to display on the map. Names have to be separated by a comma.

In addition, QGIS Server introduced some options to select layers by:

The project option allowing to select layers by their id is in QGIS Server ► WMS Capabilities menu of the Project ► Properties… dialog. Check the Use layer ids as names checkbox to activate this option.

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&LAYERS=mylayerid1,mylayerid2
&...

STYLES

This parameter can be used to specify a layer’s style for the rendering step. Styles have to be separated by a comma. The name of the default style is default.

SRS / CRS

This parameter allows to indicate the map output Spatial Reference System in WMS 1.1.1 and has to be formed like EPSG:XXXX. Note that CRS is also supported if current version is 1.1.1.

For WMS 1.3.0, CRS parameter is preferable but SRS is also supported.

Note that if both CRS and SRS parameters are indicated in the request, then it’s the current version indicated in VERSION parameter which is decisive.

In the next case, the SRS parameter is kept whatever the VERSION parameter because CRS is not indicated:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.3.0
&SRS=EPSG:2854
&...

In the next case, the SRS parameter is kept instead of CRS because of the VERSION parameter:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.1.1
&CRS=EPSG:4326
&SRS=EPSG:2854
&...

In the next case, the CRS parameter is kept instead of SRS because of the VERSION parameter:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.3.0
&CRS=EPSG:4326
&SRS=EPSG:2854
&...

BBOX

This parameter allows to specify the map extent with units according to the current CRS. Coordinates have to be separated by a comma.

The BBOX parameter is formed like min_a,min_b,max_a,max_b but a and b axis definition is different according to the current VERSION parameter:

  • in WMS 1.1.1, the axis ordering is always east/north

  • in WMS 1.3.0, the axis ordering depends on the CRS authority

For example in case of EPSG:4326 and WMS 1.1.1, a is the longitude (east) and b the latitude (north), leading to a request like:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.1.1
&SRS=epsg:4326
&BBOX=-180,-90,180,90
&...

But in case of WMS 1.3.0, the axis ordering defined in the EPSG database is north/east so a is the latitude and b the longitude:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.3.0
&CRS=epsg:4326
&BBOX=-90,-180,90,180
&...

WIDTH

This parameter allows to specify the width in pixels of the output image.

HEIGHT

This parameter allows to specify the height in pixels of the output image.

FORMAT

This parameter may be used to specify the format of map image. Available values are:

  • jpg

  • jpeg

  • image/jpeg

  • image/png

  • image/png; mode=1bit

  • image/png; mode=8bit

  • image/png; mode=16bit

  • application/dxf: only layers that have read access in the WFS service are exported in the DXF format

    URL example:

    http://localhost/qgisserver?
    SERVICE=WMS&VERSION=1.3.0
    &REQUEST=GetMap
    &FORMAT=application/dxf
    &LAYERS=Haltungen,Normschacht,Spezialbauwerke
    &CRS=EPSG%3A21781
    &BBOX=696136.28844801,245797.12108743,696318.91114315,245939.25832905
    &WIDTH=1042
    &HEIGHT=811
    &FORMAT_OPTIONS=MODE:SYMBOLLAYERSYMBOLOGY;SCALE:250
    &FILE_NAME=plan.dxf
    

TRANSPARENT

This boolean parameter can be used to specify the background transparency. Available values are (not case sensitive):

  • TRUE

  • FALSE

However, this parameter is ignored if the format of the image indicated with FORMAT is different from PNG.

BGCOLOR

This parameter allows to indicate a background color for the map image. However it cannot be combined with TRANSPARENT parameter in case of PNG images (transparency takes priority). The colour may be literal or in hexadecimal notation.

URL example with the literal notation:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.3.0
&BGCOLOR=green
&...

URL example with the hexadecimal notation:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.3.0
&BGCOLOR=0x00FF00
&...

DPI

This parameter can be used to specify the requested output resolution.

IMAGE_QUALITY

This parameter is only used for JPEG images. By default, the JPEG compression is -1.

You can change the default per QGIS project in the OWS Server ► WMS capabilities menu of the Project ► Properties… dialog. If you want to override it in a GetMap request you can do it using the IMAGE_QUALITY parameter.

OPACITIES

Comma separated list of opacity values. Opacity can be set on layer or group level. Allowed values range from 0 (fully transparent) to 255 (fully opaque).

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.3.0
&WIDTH=400
&HEIGHT=200
&CRS=EPSG:4326
&LAYERS=countries,places
&BBOX=42,-6,52,15
&OPACITIES=255,0
../../../_images/wms_getmap_opacities.png

Fig. 3.2 To the left OPACITIES=255,0 and to the right OPACITIES=255,255

FILTER

A subset of layers can be selected with the FILTER parameter. The syntax is basically the same as for the QGIS subset string. However, there are some restrictions to avoid SQL injections into databases via QGIS Server. If a dangerous string is found in the parameter, QGIS Server will return the next error:

<ServiceExceptionReport>
  <ServiceException code="Security">The filter string XXXXXXXXX has been rejected because of security reasons.
  Note: Text strings have to be enclosed in single or double quotes. A space between each word / special character is mandatory.
  Allowed Keywords and special characters are IS,NOT,NULL,AND,OR,IN,=,<,=<,>,>=,!=,',',(,),DMETAPHONE,SOUNDEX.
  Not allowed are semicolons in the filter expression.</ServiceException>
</ServiceExceptionReport>

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&VERSION=1.3.0
&WIDTH=400
&HEIGHT=300
&CRS=EPSG:4326
&BBOX=41,-6,52,10
&LAYERS=countries_shapeburst,countries,places
&FILTER=countries_shapeburst,countries:"name" = 'France';places: "name" = 'Paris'
../../../_images/wms_getmap_filter.png

Fig. 3.3 Server response to a GetMap request with FILTER parameter

In this example, the same filter "name" = 'France' is applied to layers countries and countries_shapeburst, while the filter "name" = 'Paris' is only applied to places.

Notă

It is possible to make attribute searches via GetFeatureInfo and omit the X/Y parameter if a FILTER is there. QGIS Server then returns info about the matching features and generates a combined bounding box in the XML output.

SELECTION

The SELECTION parameter can highlight features from one or more layers. Vector features can be selected by passing comma separated lists with feature ids.

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&LAYERS=mylayer1,mylayer2
&SELECTION=mylayer1:3,6,9;mylayer2:1,5,6
&...

The following image presents the response from a GetMap request using the SELECTION option e.g. http://myserver.com/...&SELECTION=countries:171,65.

As those features id’s correspond in the source dataset to France and Romania they’re highlighted in yellow.

../../../_images/server_selection_parameter.png

Fig. 3.4 Server response to a GetMap request with SELECTION parameter

FORMAT-OPTIONS

This parameter can be used to specify options for the selected format. Only for FORMAT=application/dxf. A list of key:value pairs separated by semicolon:

  • SCALE: to be used for symbology rules, filters and styles (not actual scaling of the data - data remains in the original scale).

  • MODE: corresponds to the export options offered in the QGIS Desktop DXF export dialog. Possible values are NOSYMBOLOGY, FEATURESYMBOLOGY and SYMBOLLAYERSYMBOLOGY.

  • LAYERSATTRIBUTES: specify a field that contains values for DXF layer names - if not specified, the original QGIS layer names are used.

  • USE_TITLE_AS_LAYERNAME: if enabled, the title of the layer will be used as layer name.

  • CODEC: specify a codec to be used for encoding. Default is ISO-8859-1 check the QGIS desktop DXF export dialog for valid values.

  • NO_MTEXT: Use TEXT instead of MTEXT for labels.

  • FORCE_2D: Force 2D output. This is required for polyline width.

TILED

For performance reasons, QGIS Server can be used in tiled mode. In this mode, the client requests several small fixed size tiles, and assembles them to form the whole map. Doing this, symbols at or near the boundary between two tiles may appeared cut, because they are only present in one of the tile.

Set the TILED parameter to TRUE to tell QGIS Server to work in tiled mode, and to apply the Tile buffer configured in the QGIS project (see Configure your project).

When TILED is TRUE and when a non-zero Tile buffer is configured in the QGIS project, features outside the tile extent are drawn to avoid cut symbols at tile boundaries.

TILED defaults to FALSE.

3.2.3. GetFeatureInfo

Standard parameters for the GetFeatureInfo request according to the OGC WMS 1.1.1 and 1.3.0 specifications:

Parametru

Required

Descriere

SERVICE

Da

Name of the service (WMS)

REQUEST

Da

Name of the request (GetFeatureInfo)

VERSION

Nu

Version of the service

QUERY_LAYERS

Da

Layers to query

LAYERS

Da

Layers to display (identical to QUERY_LAYERS)

STYLES

Nu

Layers» style

SRS / CRS

Da

Coordinate reference system

BBOX

Nu

Map extent

WIDTH

Da

Width of the image in pixels

HEIGHT

Da

Height of the image in pixels

TRANSPARENT

Nu

Transparent background

INFO_FORMAT

Nu

Output format

FEATURE_COUNT

Nu

Maximum number of features to return

I

Nu

Pixel column of the point to query

X

Nu

Same as I parameter, but in WMS 1.1.1

J

Nu

Pixel row of the point to query

Y

Nu

Same as J parameter, but in WMS 1.1.1

WMS_PRECISION

Nu

The precision (number of digits) to be used when returning geometry (see how to add geometry to feature response). The default value is -1 meaning that the precision defined in the project is used.

In addition to the standard ones, QGIS Server supports the following extra parameters:

Parametru

Required

Descriere

MAP

Da

QGIS project file

FILTER

Nu

Subset of features

FI_POINT_TOLERANCE

Nu

Tolerance in pixels for point layers

FI_LINE_TOLERANCE

Nu

Tolerance in pixels for line layers

FI_POLYGON_TOLERANCE

Nu

Tolerance in pixels for polygon layers

FILTER_GEOM

Nu

Geometry filtering

WITH_MAPTIP

Nu

Add map tips to the output

WITH_GEOMETRY

Nu

Add geometry to the output

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&VERSION=1.3.0
&REQUEST=GetMap
&MAP=/home/qgis/projects/world.qgs
&LAYERS=mylayer1,mylayer2,mylayer3
&CRS=EPSG:4326
&WIDTH=400
&HEIGHT=400
&INFO_FORMAT=text/xml
&TRANSPARENT=TRUE
&QUERY_LAYERS=mylayer1
&FEATURE_COUNT=3
&I=250
&J=250

INFO_FORMAT

This parameter may be used to specify the format of the result. Available values are:

  • text/xml

  • text/html

  • text/plain

  • application/vnd.ogc.gml

  • application/json

QUERY_LAYERS

This parameter specifies the layers to display on the map. Names are separated by a comma.

In addition, QGIS Server introduces options to select layers by:

  • short name

  • layer id

See the LAYERS parameter defined in GetMap for more information.

FEATURE_COUNT

This parameter specifies the maximum number of features per layer to return. For example if QUERY_LAYERS is set to layer1,layer2 and FEATURE_COUNT is set to 3 then a maximum of 3 features from layer1 will be returned. Likewise a maximun of 3 features from layer2 will be returned.

By default, only 1 feature per layer is returned.

I

This parameter, defined in WMS 1.3.0, allows you to specify the pixel column of the query point.

X

Same parameter as I, but defined in WMS 1.1.1.

J

This parameter, defined in WMS 1.3.0, allows you to specify the pixel row of the query point.

Y

Same parameter as J, but defined in WMS 1.1.1.

FI_POINT_TOLERANCE

This parameter specifies the tolerance in pixels for point layers.

FI_LINE_TOLERANCE

This parameter specifies the tolerance in pixels for line layers.

FI_POLYGON_TOLERANCE

This parameter specifies the tolerance in pixels for polygon layers.

FILTER_GEOM

This parameter specifies a WKT geometry with which features have to intersect.

WITH_MAPTIP

This parameter specifies whether to add map tips to the output.

Available values are (not case sensitive):

  • TRUE

  • FALSE

WITH_GEOMETRY

This parameter specifies whether to add geometries to the output. To use this feature you must first enable the Add geometry to feature response option in the QGIS project. See Configure your project.

Available values are (not case sensitive):

  • TRUE

  • FALSE

3.2.4. GetLegendGraphics

Standard parameters for the GetLegendGraphics request according to the OGC WMS 1.1.1 and 1.3.0 specifications:

Parametru

Required

Descriere

SERVICE

Da

Name of the service (WMS)

REQUEST

Da

Name of the request (GetLegendGraphics)

VERSION

Nu

Version of the service

LAYERS

Da

Layers to display

STYLES

Nu

Layers» style

SRS / CRS

Nu

Coordinate reference system

BBOX

Nu

Map extent

WIDTH

Nu

Width of the image in pixels

HEIGHT

Nu

Height of the image in pixels

FORMAT

Nu

Legend format

TRANSPARENT

Nu

Transparent background

In addition to the standard ones, QGIS Server supports extra parameters to change the size of the legend elements or the font properties for layer titles and item labels:

Parametru

Required

Descriere

MAP

Da

QGIS project file

SRCWIDTH

Nu

Map width

SRCHEIGHT

Nu

Map height

SHOWFEATURECOUNT

Nu

Add feature count of features

RULE

Nu

Rule symbol to render

RULELABEL

Nu

Item labels rendering

BOXSPACE

Nu

Space between legend frame and content (mm)

LAYERSPACE

Nu

Vertical space between layers (mm)

LAYERTITLESPACE

Nu

Vertical space between layer title and items (mm)

SYMBOLSPACE

Nu

Vertical space between symbol and items (mm)

ICONLABELSPACE

Nu

Horizontal space between symbol and label (mm)

SYMBOLWIDTH

Nu

Width of the symbol preview (mm)

SYMBOLHEIGHT

Nu

Height of the symbol preview (mm)

LAYERTITLE

Nu

Layer title rendering

LAYERFONTFAMILY

Nu

Layer font family

LAYERFONTBOLD

Nu

Layer title bold rendering

LAYERFONTSIZE

Nu

Layer title font size (pt)

LAYERFONTITALIC

Nu

Layer title italic rendering

LAYERFONTCOLOR

Nu

Layer title color

ITEMFONTFAMILY

Nu

Item font family

ITEMFONTBOLD

Nu

Item label bold rendering

ITEMFONTSIZE

Nu

Item label font size (pt)

ITEMFONTITALIC

Nu

Item label italic rendering

ITEMFONTCOLOR

Nu

Item label color

BBOX

This parameter can be used to specify the geographical area for which the legend should be built (its format is described here) but cannot be combined with the RULE parameter. The SRS/CRS parameter becomes mandatory when using the BBOX parameter.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=countries,airports
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326

Notă

When the BBOX parameter is defined, the legend is referred to as a content based legend.

WIDTH

This parameter is not used by default but becomes mandatory when the RULE parameter is set. In this case it allows to specify the width in pixels of the output image.

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYER=testlayer%20%C3%A8%C3%A9
&RULE=rule1
&WIDTH=30
&HEIGHT=30

HEIGHT

This parameter is not used by default but becomes mandatory when the RULE parameter is set. In this case it allows to specify the height in pixels of the output image.

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYER=testlayer%20%C3%A8%C3%A9
&RULE=rule1
&WIDTH=30
&HEIGHT=30

FORMAT

This parameter may be used to specify the format of legend image. Available values are:

  • image/jpeg

  • image/png

  • application/json

For JSON, symbols are encoded with Base64 and most other options related to layout or fonts are not taken into account because the legend must be built on the client side. The RULE parameter cannot be combined with this format.

URL example with the corresponding JSON output:

http://localhost/qgisserver?
SERVICE=WMS&
REQUEST=GetLegendGraphics&
LAYERS=airports&
FORMAT=application/json

And the corresponding JSON output:

{
  "nodes":[
    {
      "icon":"<base64 icon>",
      "title":"airports",
      "type":"layer"
    }
  ],
  "title":""
}

SRCWIDTH

This parameter may de defined when the RULE parameter is set. In this case, the SRCWIDTH value is forwarded to the underlying GetMap request as the WIDTH parameter while the WIDTH parameter of GetLegendGraphics is used for the image legend size.

SRCHEIGHT

This parameter may de defined when the RULE parameter is set. In this case, the SRCHEIGHT value is forwarded to the underlying GetMap request as the HEIGHT parameter while the HEIGHT parameter of GetLegendGraphics is used for the image legend size.

SHOWFEATURECOUNT

This parameter can be used to activate feature count in the legend. Available values are (not case sensitive):

  • TRUE

  • FALSE

For example:

../../../_images/getfeaturecount_legend.png

RULE

This parameter is available on layers with Rule-based rendering and allows to build a legend with only the named rule symbol. It cannot be combined with BBOX parameter nor the JSON format.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=mylayer,
&RULE=myrulename

RULELABEL

This parameter allows to control the item label rendering. Available values are (not case sensitive):

  • TRUE: display item label

  • FALSE: hide item label

  • AUTO: hide item label for layers with Single symbol rendering

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=countries,airports
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&RULELABEL=AUTO
../../../_images/wms_getlegendgraphics_rulelabel.png

Fig. 3.5 Legend rendering without label for single symbol layers

BOXSPACE

This parameter allows to specify the space between legend frame and content in millimeters. By default, the space value is 2 mm.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=airports
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&BOXSPACE=0
../../../_images/wms_getlegendgraphics_boxspace.png

Fig. 3.6 To the left BOXSPACE=0 and to the right BOXSPACE=15

LAYERSPACE

This parameter allows to specify the vertical space between layers in millimeters. By default, the space value is 3 mm.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&LAYERSPACE=0
../../../_images/wms_getlegendgraphics_layerspace.png

Fig. 3.7 To the left LAYERSPACE=0 and to the right LAYERSPACE=10

LAYERTITLESPACE

This parameter allows to specify the vertical space between layer title and items following in millimeters. By default the space value is 3 mm.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&LAYERTITLESPACE=0
../../../_images/wms_getlegendgraphics_layertitlespace.png

Fig. 3.8 To the left LAYERTITLESPACE=0 and to the right LAYERTITLESPACE=10

SYMBOLSPACE

This parameter allows to specify the vertical space between symbol and item following in millimeters. By default the space value is 2 mm.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=countries
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&SYMBOLSPACE=0
../../../_images/wms_getlegendgraphics_symbolspace.png

Fig. 3.9 To the left SYMBOLSPACE=0 and to the right SYMBOLSPACE=5

ICONLABELSPACE

This parameter allows to specify the horizontal space between symbol and label text in millimeters. By default the space value is 2 mm.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=countries,
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&ICONLABELSPACE=0
../../../_images/wms_getlegendgraphics_iconlabelspace.png

Fig. 3.10 To the left ICONLABELSPACE=0 and to the right ICONLABELSPACE=10

SYMBOLWIDTH

This parameter allows to specify the width of the symbol preview in millimeters. By default the width value is 7 mm.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=countries,
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&SYMBOLWIDTH=2
../../../_images/wms_getlegendgraphics_symbolwidth.png

Fig. 3.11 To the left SYMBOLWIDTH=2 and to the right SYMBOLWIDTH=20

SYMBOLHEIGHT

This parameter allows to specify the height of the symbol preview in millimeters. By default the height value is 4 mm.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=countries,
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&SYMBOLHEIGHT=2
../../../_images/wms_getlegendgraphics_symbolheight.png

Fig. 3.12 To the left SYMBOLHEIGHT=2 and to the right SYMBOLHEIGHT=6

LAYERTITLE

This parameter specifies whether to render layer title.

Available values are (not case sensitive):

  • TRUE (default value)

  • FALSE

LAYERFONTFAMILY

This parameter specifies the font family to use for rendering layer title.

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=countries
&LAYERFONTFAMILY=monospace

LAYERFONTBOLD

This parameter specifies whether the layer title is rendered in bold. Available values are (not case sensitive):

  • TRUE

  • FALSE

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&LAYERFONTBOLD=TRUE
../../../_images/wms_getlegendgraphics_layerfontbold.png

Fig. 3.13 Legend with LAYERFONTBOLD=TRUE

LAYERFONTSIZE

This parameter specifies the font size for rendering layer title in point.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&LAYERFONTSIZE=20
../../../_images/wms_getlegendgraphics_layerfontsize.png

Fig. 3.14 Legend with LAYERFONTSIZE=20

LAYERFONTITALIC

This parameter specifies whether the layer title is rendered in italic. Available values are (not case sensitive):

  • TRUE

  • FALSE

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&LAYERFONTITALIC=TRUE
../../../_images/wms_getlegendgraphics_layerfontitalic.png

Fig. 3.15 Legend with LAYERFONTITALIC=TRUE

LAYERFONTCOLOR

This parameter specifies the layer title color. The color may be literal (red, green, ..) or in hexadecimal notation (0xFF0000, 0x00FF00, …).

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&LAYERFONTCOLOR=0x5f9930
../../../_images/wms_getlegendgraphics_layerfontcolor.png

Fig. 3.16 Legend with LAYERFONTCOLOR=0x5f9930

ITEMFONTFAMILY

This parameter specifies the font family to use for rendering item label.

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=countries
&ITEMFONTFAMILY=monospace

ITEMFONTBOLD

This parameter specifies whether the item label is rendered in bold. Available values are (not case sensitive):

  • TRUE

  • FALSE

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&ITEMFONTBOLD=TRUE
../../../_images/wms_getlegendgraphics_itemfontbold.png

Fig. 3.17 Legend with ITEMFONTBOLD=TRUE

ITEMFONTSIZE

This parameter specifies the font size for rendering layer title in point.

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&ITEMFONTSIZE=20
../../../_images/wms_getlegendgraphics_itemfontsize.png

Fig. 3.18 Legend with ITEMFONTSIZE=30

ITEMFONTITALIC

This parameter specifies whether the item label is rendered in italic. Available values are (not case sensitive):

  • TRUE

  • FALSE

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&ITEMFONTITALIC=TRUE
../../../_images/wms_getlegendgraphics_itemfontitalic.png

Fig. 3.19 Legend with ITEMFONTITALIC=TRUE

ITEMFONTCOLOR

This parameter specifies the item label color. The color may be literal (red, green, ..) or in hexadecimal notation (0xFF0000, 0x00FF00, …).

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetLegendGraphics
&LAYERS=airports,places
&BBOX=43.20,-2.93,49.35,8.32
&CRS=EPSG:4326
&TRANSPARENT=TRUE
&ITEMFONTCOLOR=0x5f9930
../../../_images/wms_getlegendgraphics_itemfontcolor.png

Fig. 3.20 Legend with ITEMFONTCOLOR=0x5f9930

3.2.5. GetStyle(s)

Standard parameters for the GetStyle (or GetStyles) request according to the OGC WMS 1.1.1 specifications:

Parametru

Required

Descriere

SERVICE

Da

Name of the service (WMS)

REQUEST

Da

Name of the request (GetStyle or GetStyles)

LAYERS

Da

Layers to query

The GetStyle request supports as well the following vendor parameters:

Parametru

Required

Descriere

MAP

Da

QGIS project file

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetStyles
&LAYERS=mylayer1,mylayer2

3.2.6. DescribeLayer

Standard parameters for the DescribeLayer request according to the OGC WMS 1.1.1 and 1.3.0 specifications:

Parametru

Required

Descriere

SERVICE

Da

Name of the service (WMS)

REQUEST

Da

Name of the request (DescribeLayer)

LAYERS

Da

Layers to describe

SLD_VERSION

Da

SLD version

The DescribeLayer request supports as well the following vendor parameters:

Parametru

Required

Descriere

MAP

Da

QGIS project file

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=DescribeLayer
&SLD_VERSION=1.1.0
&LAYERS=mylayer1

The XML document looks like:

<DescribeLayerResponse xmlns="http://www.opengis.net/sld" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ows="http://www.opengis.net/ows" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:se="http://www.opengis.net/se" xsi:schemaLocation="http://www.opengis.net/sld http://schemas.opengis.net/sld/1.1.0/DescribeLayer.xsd">
    <Version>1.1.0</Version>
    <LayerDescription>
        <owsType>wfs</owsType>
        <se:OnlineResource xlink:href="http://localhost/qgis_server" xlink:type="simple"/>
        <TypeName>
            <se:FeatureTypeName>my_vector_layer</se:FeatureTypeName>
        </TypeName>
    </LayerDescription>
    <LayerDescription>
        <owsType>wcs</owsType>
        <se:OnlineResource xlink:href="http://localhost/qgis_server" xlink:type="simple"/>
        <TypeName>
            <se:FeatureTypeName>my_raster_layer</se:FeatureTypeName>
        </TypeName>
    </LayerDescription>
</DescribeLayerResponse>

SLD_VERSION

This parameter allows to specify the version of SLD. Only the value 1.1.0 is available.

3.2.7. GetPrint

QGIS Server has the capability to create print layout output in pdf or pixel format. Print layout windows in the published project are used as templates. In the GetPrint request, the client has the possibility to specify parameters of the contained layout maps and labels.

The GetPrint request supports redlining, external WMS layers as well as the following parameters:

Parametru

Required

Descriere

MAP

Da

QGIS project file

SERVICE

Da

Name of the service (WMS)

REQUEST

Da

Name of the request (GetPrint)

VERSION

Nu

Version of the service

LAYERS

Nu

Layers to display

TEMPLATE

Da

Layout template to use

SRS / CRS

Da

Coordinate reference system

FORMAT

Nu

Output format

ATLAS_PK

Nu

Atlas features

STYLES

Nu

Layers» style

TRANSPARENT

Nu

Transparent background

OPACITIES

Nu

Opacity for layer or group

SELECTION

Nu

Highlight features

mapX:EXTENT

Nu

Extent of the map «X»

mapX:LAYERS

Nu

Layers of the map «X»

mapX:STYLES

Nu

Layers» style of the map «X»

mapX:SCALE

Nu

Layers» scale of the map «X»

mapX:ROTATION

Nu

Rotation of the map «X»

mapX:GRID_INTERVAL_X

Nu

Grid interval on x axis of the map «X»

mapX:GRID_INTERVAL_Y

Nu

Grid interval on y axis of the map «X»

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&VERSION=1.3.0
&REQUEST=GetPrint
&MAP=/home/qgis/projects/world.qgs
&CRS=EPSG:4326
&FORMAT=png
&TEMPLATE=Layout%201
&map0:EXTENT=-180,-90,180,90
&map0:LAYERS=mylayer1,mylayer2,mylayer3
&map0:OPACITIES=125,200,125
&map0:ROTATION=45

Note that the layout template may contain more than one map. In this way, if you want to configure a specific map, you have to use mapX: parameters where X is a positive number that you can retrieve thanks to the GetProjectSettings request.

For example:

<WMS_Capabilities>
...
<ComposerTemplates xsi:type="wms:_ExtendedCapabilities">
<ComposerTemplate width="297" height="210" name="Druckzusammenstellung 1">
<ComposerMap width="171" height="133" name="map0"/>
<ComposerMap width="49" height="46" name="map1"/></ComposerTemplate>
</ComposerTemplates>
...
</WMS_Capabilities>

TEMPLATE

This parameter can be used to specify the name of a layout template to use for printing.

FORMAT

This parameter specifies the format of map image. Available values are:

  • png (default value)

  • image/png

  • jpg

  • jpeg

  • image/jpeg

  • svg

  • image/svg

  • image/svg+xml

  • pdf

  • application/pdf

If the FORMAT parameter is different from one of these values, then an exception is returned.

ATLAS_PK

This parameter allows activation of Atlas rendering by indicating which features we want to print. In order to retrieve an atlas with all features, the * symbol may be used (according to the maximum number of features allowed in the project configuration).

When FORMAT is pdf, a single PDF document combining the feature pages is returned. For all other formats, a single page is returned.

mapX:EXTENT

This parameter specifies the extent for a layout map item as xmin,ymin,xmax,ymax.

mapX:ROTATION

This parameter specifies the map rotation in degrees.

mapX:GRID_INTERVAL_X

This parameter specifies the grid line density in the X direction.

mapX:GRID_INTERVAL_Y

This parameter specifies the grid line density in the Y direction.

mapX:SCALE

This parameter specifies the map scale for a layout map item. This is useful to ensure scale based visibility of layers and labels even if client and server may have different algorithms to calculate the scale denominator.

mapX:LAYERS

This parameter specifies the layers for a layout map item. See GetMap Layers for more information on this parameter.

mapX:STYLES

This parameter specifies the layers» styles defined in a specific layout map item. See GetMap Styles for more information on this parameter.

3.2.8. GetProjectSettings

This request type works similar to GetCapabilities, but it is more specific to QGIS Server and allows a client to read additional information which are not available in the GetCapabilities output:

  • initial visibility of layers

  • information about vector attributes and their edit types

  • information about layer order and drawing order

  • list of layers published in WFS

  • show if a group in the layer tree is mutually exclusive

The GetProjectSettings request supports the following parameters:

Parametru

Required

Descriere

MAP

Da

QGIS project file

SERVICE

Da

Name of the service (WMS)

REQUEST

Da

Name of the request (GetProjectSettings)

3.2.9. GetSchemaExtension

The GetSchemaExtension request allows to retrieve optional extended capabilities and operations of the WMS service such as implemented by QGIS Server.

Parametru

Required

Descriere

MAP

Da

QGIS project file

SERVICE

Da

Name of the service (WMS)

REQUEST

Da

Name of the request (GetSchemaExtension)

URL example:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetSchemaExtension

The XML document looks like:

<schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:wms="http://www.opengis.net/wms" xmlns:qgs="http://www.qgis.org/wms" targetNamespace="http://www.qgis.org/wms" elementFormDefault="qualified" version="1.0.0">
    <import namespace="http://www.opengis.net/wms" schemaLocation="http://schemas.opengis.net/wms/1.3.0/capabilities_1_3_0.xsd"/>
    <element name="GetPrint" type="wms:OperationType" substitutionGroup="wms:_ExtendedOperation"/>
    <element name="GetStyles" type="wms:OperationType" substitutionGroup="wms:_ExtendedOperation"/>
</schema>

3.2.10. External WMS layers

QGIS Server allows including layers from external WMS servers in WMS GetMap and WMS GetPrint requests. This is especially useful if a web client uses an external background layer in the web map. For performance reasons, such layers should be directly requested by the web client (not cascaded via QGIS server). For printing however, these layers should be cascaded via QGIS server in order to appear in the printed map.

External layers can be added to the LAYERS parameter as EXTERNAL_WMS:<layername>. The parameters for the external WMS layers (e.g. url, format, dpiMode, crs, layers, styles) can later be given as service parameters <layername>:<parameter>. In a GetMap request, this might look like this:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetMap
&LAYERS=EXTERNAL_WMS:basemap,layer1,layer2
&STYLES=,,
&basemap:url=http://externalserver.com/wms.fcgi
&basemap:format=image/jpeg
&basemap:dpiMode=7
&basemap:crs=EPSG:2056
&basemap:layers=orthofoto
&basemap:styles=default

Similarly, external layers can be used in GetPrint requests:

http://localhost/qgisserver?
SERVICE=WMS
&REQUEST=GetPrint
&TEMPLATE=A4
&map0:layers=EXTERNAL_WMS:basemap,layer1,layer2
&map0:EXTENT=<minx,miny,maxx,maxy>
&basemap:url=http://externalserver.com/wms.fcgi
&basemap:format=image/jpeg
&basemap:dpiMode=7
&basemap:crs=EPSG:2056
&basemap:layers=orthofoto
&basemap:styles=default

3.2.11. Redlining

This feature is available and can be used with GetMap and GetPrint requests.

The redlining feature can be used to pass geometries and labels in the request which are overlapped by the server over the standard returned image (map). This permits the user to put emphasis or maybe add some comments (labels) to some areas, locations etc. that are not in the standard map.

The GetMap request is in the format:

http://localhost/qgisserver?
SERVICE=WMS
&VERSION=1.3.0
&REQUEST=GetMap
&HIGHLIGHT_GEOM=POLYGON((590000 5647000, 590000 6110620, 2500000 6110620, 2500000 5647000, 590000 5647000))
&HIGHLIGHT_SYMBOL=<StyledLayerDescriptor><UserStyle><Name>Highlight</Name><FeatureTypeStyle><Rule><Name>Symbol</Name><LineSymbolizer><Stroke><SvgParameter name="stroke">%23ea1173</SvgParameter><SvgParameter name="stroke-opacity">1</SvgParameter><SvgParameter name="stroke-width">1.6</SvgParameter></Stroke></LineSymbolizer></Rule></FeatureTypeStyle></UserStyle></StyledLayerDescriptor>
&HIGHLIGHT_LABELSTRING=Write label here
&HIGHLIGHT_LABELSIZE=16
&HIGHLIGHT_LABELCOLOR=%23000000
&HIGHLIGHT_LABELBUFFERCOLOR=%23FFFFFF
&HIGHLIGHT_LABELBUFFERSIZE=1.5

The GetPrint equivalent is in the format (note that mapX: parameter is added to tell which map has redlining):

http://localhost/qgisserver?
SERVICE=WMS
&VERSION=1.3.0
&REQUEST=GetPrint
&map0:HIGHLIGHT_GEOM=POLYGON((590000 5647000, 590000 6110620, 2500000 6110620, 2500000 5647000, 590000 5647000))
&map0:HIGHLIGHT_SYMBOL=<StyledLayerDescriptor><UserStyle><Name>Highlight</Name><FeatureTypeStyle><Rule><Name>Symbol</Name><LineSymbolizer><Stroke><SvgParameter name="stroke">%23ea1173</SvgParameter><SvgParameter name="stroke-opacity">1</SvgParameter><SvgParameter name="stroke-width">1.6</SvgParameter></Stroke></LineSymbolizer></Rule></FeatureTypeStyle></UserStyle></StyledLayerDescriptor>
&map0:HIGHLIGHT_LABELSTRING=Write label here
&map0:HIGHLIGHT_LABELSIZE=16
&map0:HIGHLIGHT_LABELCOLOR=%23000000
&map0:HIGHLIGHT_LABELBUFFERCOLOR=%23FFFFFF
&map0:HIGHLIGHT_LABELBUFFERSIZE=1.5

Here is the image outputed by the above request in which a polygon and a label are drawn on top of the normal map:

../../../_images/server_redlining.png

Fig. 3.21 Server response to a GetMap request with redlining parameters

You can see there are several parameters in this request:

  • HIGHLIGHT_GEOM: You can add POINT, MULTILINESTRING, POLYGON etc. It supports multipart geometries. Here is an example: HIGHLIGHT_GEOM=MULTILINESTRING((0 0, 0 1, 1 1)). The coordinates should be in the CRS of the GetMap/GetPrint request.

  • HIGHLIGHT_SYMBOL: This controls how the geometry is outlined and you can change the stroke width, color and opacity.

  • HIGHLIGHT_LABELSTRING: You can pass your labeling text to this parameter.

  • HIGHLIGHT_LABELSIZE: This parameter controls the size of the label.

  • HIGHLIGHT_LABELFONT: This parameter controls the font of the label (e.g. Arial)

  • HIGHLIGHT_LABELCOLOR: This parameter controls the label color.

  • HIGHLIGHT_LABELBUFFERCOLOR: This parameter controls the label buffer color.

  • HIGHLIGHT_LABELBUFFERSIZE: This parameter controls the label buffer size.