In the course of editing vectorial styles rather often it becomes necessary to specify linear sizes of different graphic primitives of the style: length of segments, width of lines, width of section, hatch step, size of inscriptions and so on. A grid of points to which graphic primitives are bound is usually displayed in the editing pane. The distance between neighboring grid points corresponds to the unit of editing pane. A question arises how these units are correlated with real sizes which graphic primitives will have in map display.
When displaying a map on the monitor screen the unit of the editing pane for styles of lines and hatches corresponds to one pixel of the screen. So when monitor resolution is changed, the shape of the corresponding styles is slightly changed: for higher resolution actual pixel sizes are reduced, that is why line dashes will be shorter, inscriptions and hatch steps – smaller.
When outputting a map to a printer or a plotter the value 0.2 mm corresponds to the unit of the editing pane (and to the screen pixel accordingly). For example, let the length of 20 units and width of 3 units be specified for some line segment. Then this segment will have the length of 20 pixels and width of 3 pixels on the screen, and on a printer – 4 mm and 0.6 mm accordingly.
The situation is a little bit different with vectorial map symbols. Since these symbols can change their sizes within some range when the map displaying scale is changed, units of the editing pane have conditional character for them. Real sizes of a vectorial symbol in the course of map display depend on displaying scale as well as on monitor resolution (chapter 17 “Adding and editing features”, subsection “Adding and editing point features”).
Width of lines for all types of vectorial styles is indicated in pixels. Thus, lines have the same width in editing as in displaying a map on the screen not depending on displaying scale used in the course of editing. When outputting to a printer, line width 0.2 mm corresponds to one pixel.
When editing raster styles (fill styles and raster map symbols) a matrix is displayed in the editing pane instead of the grid. Each square of the matrix corresponds to one screen pixel. When outputting raster styles to a printer the size corresponding to one pixel is calculated taking into account the correlation of printer and monitor resolution so that the sizes of graphic primitives on the printer were roughly equal to their sizes on the screen.
Style displaying scale in editing (that is, visual distance between grid points) can be selected at random for convenience. This scale does not affect display of style in the course of displaying a map on the screen or on the printer. In the sample pane which is present in windows of style editors one can see real sizes of the style being edited on the screen (the only exception is the sample of vectorial map symbol).
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