2.
Class
Document Actions
- BACKGROUNDCOLOR [r] [g] [b]
- Color to use for non-transparent symbols.
- COLOR [r] [g] [b]
- Color to use for drawing features.
- DEBUG [on|off]
- Enables debugging of the class object. Verbose output is generated and sent to the standard error output (STDERR) or the MapServe r logfile if one is set using the LOG parameter in the WEB object.
- EXPRESSION [string]
Four types of expressions are now supported to define class membership. String comparisons, regular expressions, simple logical expressions, and string functions. If no expression is given, then all features are said to belong to this class.
String comparisons are case sensitive and are the fastest to evaluate. No special delimiters are necessary although string must be quoted if they contain special characters. (As a matter of good habit, it is recommended you quote all strings).
Regular expressions function just like previous versions of MapServer. However, you must now delimit a regular expression using /regex/. No quotes should be used.
Logical expressions allow you to build fairly complex tests based on one or more attributes and therefore are only available with shapefiles. Logical expressions are delimited by parentheses "(expression)". Attribute names are delimited by square brackets "[ATTRIBUTE]". These names are case sensitive and must match the items in the shapefile. For example: EXPRESSION ([POPULATION] > 50000 AND '[LANGUAGE]' eq 'FRENCH') ... The following logical operators are supported: =,>,<,<=,>=,=,or,and,lt,gt,ge,le,eq,ne. As you might expect this level of complexity is slower to process.
One string function exists: length(). This obviously computes the length of a string. An example follows:
EXPRESSION (length('[NAME_E]') < 8)String comparisons and regular expressions work from the classitem defined at the layer level. You may mix expression types within the different classes of a layer.
- JOIN
- Signals the start of a JOIN object.
- KEYIMAGE [filename]
- Full filename of the legend image for the CLASS. This image is used when building a legend (or requesting a legend icon via MapScript or the CGI application).
- LABEL
- Signals the start of a LABEL object.
- MAXSCALE [double]
- Maximum scale at which this CLASS is drawn.
- MAXSIZE [integer]
- Maximum size in pixels to draw a symbol. Default is 50.
- MINSCALE [double]
- Minimum scale at which this CLASS is drawn.
- MINSIZE [integer]
- Minimum size in pixels to draw a symbol. Default is 0.
- NAME [string]
- Name to use in legends for this class. If not set class won't show up in legend.
- OUTLINECOLOR [r] [g] [b]
- Color to use for outlining polygons and certain marker symbols. Line symbols do not support outline colors.
- SIZE [integer]
- Height, in pixels, of the symbol/pattern to be used. Only useful with scalable symbols. For vector (and ellipse) symbol types the default size is based on the range of Y values in the POINTS defining the symbol. For pixmaps, the default is the vertical size of the image. Default size is 1 for TTF symbols.
- STYLE
- Signals the start of a STYLE object. A class can contain multiple styles.
- SYMBOL [integer|string|filename]
The symbol name or number to use for all features if attribute tables are not used. The number is the index of the symbol in the symbol file, starting at 1, the 5th symbol in the file is therefore symbol number 5. You can also give your symbols names using the NAME keyword in the symbol definition file, and use those to refer to them. Default is 0, which results in a single pixel, single width line, or solid polygon fill, depending on layer type.
You can also specify a gif or png filename. The path is relative to the location of the mapfile.
- TEMPLATE [filename]
- Template file or URL to use in presenting query results to the user.
- TEXT [string]
- Static text to label features in this class with. This overrides values obtained from the LABELTIEM. The string may be given as an expression delimited using the ()'s. This allows you to concatenate multiple attributes into a single label. For example: ([FIRSTNAME],[LASTNAME]).
You can also "stack" 2 symbols to achieve interesting effects. You define the second symbol, which effectively sits "on top" of the symbol normally defined above.
The following parameters allow you to define the symbol, and they are equivalent to their non-overlay counterparts:
- OVERLAYBACKGROUNDCOLOR
- OVERLAYCOLOR
- OVERLAYOUTLINECOLOR
- OVERLAYSIZE
- OVERLAYMINSIZE
- OVERLAYMAXSIZE
- OVERLAYSYMBOL
MINSCALE and MAXSCALE
MINSCALE and MAXSCALE are feature matching criteria. This means, this CLASS would be used when the scale is between MINSCALE and MAXSCALE. Otherwise the CLASS is treated as non-existent for that particular feature. MINSCALE and MAXSCALE are checked before the EXPRESSION is evaluated.
MAXSCALE/MINSCALE
Normal terminology is that 1:1000 is a *larger* scale than 1:100000. This should be stated explicitly in the documentation. Suggestions for new explanations:
MAXSCALE [double]
Minimum scale at which this interface is valid (Mapserver terminology is the opposite of normal terminology for scales). When a user requests a map at a smaller scale, MapServer automatically returns the map at this scale. This effectively prevents the user from zooming too far out.
MINSCALE [double]
Maximum scale at which this interface is valid (Mapserver terminology is the opposite of normal terminology for scales). When a user reuqests a map at a larger scale, MapServer automatically returns the map at this scale. This effectively prevents the user from zooming in too far in.
An alternative is to "clean" this up by changing the the keywords to MINSCALE_DENOMINATOR and MAXSCALE_DENOMINATOR.