5.1 Scales

The Scale menu which allows to view the document at different sizes is divided into two parts. The first part shows a list of available scale bases, the second part, separated by a line, lists the relative scales which are applied with respect to the selected scale base.

By default two scales bases are available, the Natural size and the Pixel based base. When choosing the Pixel based scale base a relative scale of 1.0 causes one postscript point to correspond to one pixel on the screen.

When viewing a document at a relative scale of 1.0 using the Natural size base the page should appear in its real size, as if printed on paper. For the Natural size base to work properly gv has to know the correct size of the root window. Automatic detection of this size unfortunately only provides approximate results, therefore it is best if it is provided by the user. To do so the resource

   GV.screenSize:  <width> x <height>

should be added to the SCREEN_RESOURCES property of the screen the document is viewed on, with width and height describing the width and height of the root window in units of millimeters. For instance by using the command

   echo "GV.screenSize: 396 x 291" | xrdb -override -screen

a width of 346 mm and a height of 291 mm will be used for the Natural size scale base. Alternatively the resource

   GV.screenSize_<machine>_<disp>_<scr>:  <width> x <height>

may be added to a resource file read by gv. Here machine ,disp and ANGLED describe the display on which gv displays the document. For instance, if the display is set to tic.tac.toe.wo:0.1 the resource should be specified as

   GV.screenSize_tic_0_1: 396 x 291

Note that this method doesn’t work on VMS. As a last alternative the resource

   GV.screenSize:  <width> x <height>

may be added to one of the resource files. However, for obvious reasons this method should be used only on single user machines.