Text Rendering

Text Features can have the following properties to define their visualisation:

• Font. This may be set using the Style Combo Box. See for further information. Users producing maps for X11 systems should be aware of certain limitations of font support. To inhibit display of Text, set a Font Style of None.
• Colour. This may be set using the Colour Palette. See Colour Palettes for further information
• Vertical and Horizontal Alignment. Together, these Combo Boxes allow for adjustment of where the text will be displayed, relative to the defined position. This release of MapLink Pro supports multi-line text features. Each line must be terminated by a carriage return. MapLink Pro takes into account all lines when applying the text alignment.
• Rotatability. This Combo Box allows you to enable or disable text rotation. In addition to text rotation being defined by the datasource, the Output Coordinate System may attempt to rotate text. Use this property to force the text to be horizontal.
• Offset. This group of properties allows you to specify an offset for text from the defined position. It is often useful to do this, for example, where text and symbols have the same defined position in the datasource. It has the following sub-properties.
• Offset Units. This Dimension Units Combo Box defines the units for the following X and Y offset parameters. Note that setting this property to 'As Parent' will force all Offset properties to be read from the parent feature.
• X offset. This may be set using the Numeric Value Text Box. It defines the horizontal offset, in units as defined above.
• Y offset. This may be set using the Numeric Value Text Box. It defines the vertical offset, in units as defined above.
• Size. This group of properties allows you to specify the height of the text. See below for a discussion of text sizing. It has the following sub-properties:
• Size Factor. This may be set using the Numeric Value Text Box. It defines the height of the text, interpreted according to the Size Factor Units property. Note that setting this value to 'As Parent' will also force the minimum and maximium sizes properties to be read from the parent Feature Class.
• Size Factor Units. This Dimension Units Combo Box defines the units for the Size Factor property.
• Minimum Size This may be set using the Numeric Value Text Box. It defines the minimum height of the Text Primitive, in pixel units. The calculated height of the text will be clamped to be no smaller than this.
• Maximum Size This may be set using the Numeric Value Text Box. It defines the maximum height of the Text Primitive, in pixel units. The calculated height of the text will be clamped to be no greater than this.
• Background. This group of properties allows you to specify a background for the text. See below for a discussion of text background. It has the following sub-properties:
• Mode. This may be set using the Combo Box. It defines what type of background the text primitive has. Note that setting this value to 'As Parent' will force all background sub-properties to be read from the parent.
• Background Colour. This may be set using the Colour Palette. See Colour Palettes for further information. Depending upon the background mode chosen, this will either be the fill colour of the rectangle, or the colour of the halo.
• Fill Style. This may be set using the Style Combo Box. See Fill Styles for further information. For hollow polygons, choose a fill style of None. This sub-property is only relevant to background rectangles. If necessary, it could be a translucent fill style.
• Edge Colour. This may be set using the Colour Palette. See Colour Palettes for further information. This sub-property is only relevant to background rectangles. The edges of background rectangles are always single pixel, solid lines.

Text Sizing

Certain datasources, such as NTF, contain topographic text primitives and therefore define a height in the data itself. Most other datasources have text generated by the data filter with a nominal defined height. MapLink Pro allows full flexibility when defining the text size through the use of the Size Factor Units property. This may currently be set to one of

• Scale Factor. Usually applied to topographic text. Earlier releases of MapLink Pro used this as a percentage scaling of the text. The text height will vary according to the zoom level but is also dependent upon the data source to define the height which is scaled. Use of this is deprecated, but is kept for compatibility with existing MapLink Pro Studio Projects.
• Pixels. This fixes the height of the text in device units, usually pixels. This will mean that the text is always drawn at the same size on the screen regardless of the zoom level.
• Map Units. This fixes the height of the text in Map Units, usually metres. The text height will vary according to the zoom level but is independent of the data source.

Further Size Factor Units, such as Points, may be added in future releases of MapLink Pro. Note that the minimum and maximum sizes are always defined in pixels and are applied regardless of the Size Factor Units.

The calculated size is the height of the font used to display the text, not the size of the text itself. This means that the font used will be consistent whether the text is on a single line, or spread over multiple lines.

Text Background

It can sometimes be difficult to see text clearly against all underlying features. For example, a piece of text may cross both a Sea polygon and a Land polygon with different colours. MapLink Pro allows two different types of background to be applied to text features to help combat this problem.

A Background Rectangle of defined style and colour may be drawn around the text. This rectangle automatically scales and moves with the contents of the text string being displayed. If necessary (and your platform supports it), the fill style may be translucent, thus allowing the underlying features to still show through.

A text Halo may be applied around text. This is a single pixel border, of specified colour, displayed around the text string. On some systems, this type of text background can result in reduced performance if large numbers of text primitives are displayed. It is recommended that some experimentation is performed on your target system before applying this style widely.