TEXT WITHIN LITES2

Text features in maps are different from other data, in that they generally have no physical equivalent on the ground.
This section of the user manual explains in detail how text is handled within LITES2.

CHARACTERISTICS COMMON TO ALL TEXT FEATURES

Text features are handled in LITES2 by storing (at least) the following characteristics in the IFF file:

The style and category are characteristics that are specific to Ordnance Survey maps, and may be set to 0 (or even used for other purposes) with non-Ordnance Survey type data.

In addition, a flag is set to indicate that the feature is a text. This flag is set for the use of other programs which may not use the FRT mechanism.

SIZE OF TEXT

The area that a text occupies on the map depends on:

The height of a text can either be stored in the IFF file or in the FRT file, and which method is chosen depends on the setting of the HEIGHT option. If this is enabled (using the ENABLE HEIGHT command), then the height is stored in the IFF file and as a consequence is variable, for any feature code. By default the HEIGHT option is disabled, and this means that the height of any text feature is defined by its feature code; the actual height is read from the FRT.

Heights are stored in the FRT as mm at map scale.

When heights are stored in the IFF file, there are two possibilities:

JUSTIFICATION OF TEXT

By enabling the positioning option (ENABLE POSITION - enabled by default) a locating (or justification) position can be stored with each text. This is an integer in the range 0 - 8, indicating one of the nine possible locating points as shown in the following diagram:

                     2-------------5-------------8
                                               _
                     1-------------4-------------7
                                               _
                     0-------------3-------------6
This is the point of the text that will lie over its digitised point.

If the location option is disabled, LITES2 treats all texts as if locating position 0 has been chosen.

Each character in a font is usually terminated by some blank space, so that the characters in strings of text are separated. When the length of a text string is required (e_.g_. when drawing a box around it), this space must be subtracted from the last character.

The TOLERANCE JUSTIFY command sets the amount to be subtracted from a text string to represent this blank space. The argument is the proportion of the height of the text that is blank space. By default the value 0.333333 is used.

COMPOSITE TEXT

There is an additional (licensed) feature in LITES2 to allow the construction and manipulation of composite text features. Access to this feature is achieved by enabling the COMPOSITE option (disabled by default).

Composite texts are texts that consist of several text strings, all of which have their own characteristics. It is possible to either manipulate the text feature as a whole, or to edit each sub-text individually. When editing the whole feature, then LITES2 will be in MODIFY state; when editing the sub_texts then LITES2 goes into MODIFY (part) state.

LITES2 commands that are specifically for manipulating composite texts are:

   THIS, FIRST, NEXT, PREVIOUS, LAST,
   WHOLE, COLLAPSE,
   PARAGRAPH, SPLIT, BEND