The designs presented in the section called “Bright Designs under X Window System” and the section called “Dark Designs under X Window System” address normal usage, hyper-sensitive, astigmatism and to some extent diminished eyesight. All of this might still not suffice to create a usable Graphical User Interface, which will be addressed in this section.

Diminished eyesight requires large fonts and icons. Jeszra is a fully vectorized application. There are no bitmaps whatsoever being used inside the Graphical User Interface.

Jeszra’s icons are font glyphs from the »Gestalt.ttf« font or complex vector graphics. . The font »Gestalt.ttf« must have been installed for using glyphs as icons. Otherwise Jeszra deploys bitmaps as a fall-back solution.

The simplest method to increase fonts and icons is to heighten the resolution. Tcl/Tk features a special command tk scaling, which queries the display resolution and allows to redefine the resolution for the running application. tk scaling must be altered before any window –except for the Tk-root window– gets created. Specifying tk scaling later results in a mostly unusable Graphical User Interface, featuring elements with mixed resolutions.

#!/bin/sh
# Restart with WISH \
  exec wish "$0" ${1+"$@"}

tk scaling 1.5
source ./lightX11.tcl
...

Example 5.3, “Using tk scaling” sets the resolution to 108ppi. The icons and fonts increase by 50%. The default value for scaling is 1.0, which is identical to 72ppi.

Most X Window System servers are configured with the wrong resolution. In most situations the resolution is set to 72ppi, which results in to small fonts. Today, display resolution varies between 86ppi and 150ppi. The display, I am writing this, features 92ppi and scaling should report 1.28, it reports 1.04. Setting scaling to 1.5 makes fonts and icons only 20% to large, on default X Window System fonts and icons are 30% to small!

Example 5.3, “Using tk scaling” calls lightX11 and it has to be placed inside the same directory –indicated by the leading dot-slash ./ – the Jeszra home directory. Of course, all the presented designs are resolution independent and may be used with any scaling value.

Every non functional aspect of Jeszra is customized through the Option Database. The various designs, ranging from AQUA® to the section called “Inside Documentation”, are nothing else but Option Database variations. There is an alternative approach to customizing the Option Database: The Option Database is inspired by the X Resource Database and can be utilized in the same way. was already mentioned. Jeszra seeks to load a special resource file Jeszra from the XAPPLRESDIR. The Jeszra resource file is located in the following order:

The ~/app-defaults directory , in the user’s home-directory, gets searched whenever the environment variable XAPPLRESDIR is undefined.

The resource file »BigFonts« customizes the »highlightThickness« and »font« properties of some window classes. An increased »highlightThickness« is very desirable on mobile devices –even for people with normal eyesight.

...
*Button.highlightThickness: 5p
*Menubutton.highlightThickness: 5p
*Radiobutton.highlightThickness: 5p
*Checkbutton.highlightThickness: 5p
*Rtl_gridwin.highlightthickness: 5p
*Gistbox.highlightThickness: 5p
*Rtl_combobox.highlightthickness: 5p
*Rtl_gridwin*Text.borderWidth: 0
*Rtl_gridwin*Text.highlightThickness: 0
*Rtl_gridwin*Listbox.highlightThickness: 0
...

Example 5.4, “BigFonts highlightThickness” displays an excerpt from BigFonts related to »highlightThickness«. higlightThickness is set to 5 point for every »Button« control. The »p« (point) after 5 instructs Tk, that »5« is an resolution independent value.

...
*font: {bitstream vera sans} 18
*Rtl_mlistbox.headerFont: {bitstream vera sans} 12
*Entry.font: {bitstream vera sans} 18
*Listbox.font: {bitstream vera sans} 18
*Message.font: {bitstream vera sans} 12
*Goolbar.font: {bitstream vera sans} 18
*Text.font: {bitstream vera sans mono} 18
*Rtl_tree.font: {bitstream vera sans} 18
*Rtl_tabset.font: {bitstream vera sans} 18

*Rtl_tree.fontfamily: {bitstream vera sans}
*Rtl_tree.fontsize: 18

*document*glyphFontFamily: Gestalt
*document*glyphFontSize: 24
*Gestalt.mbar*font: {bitstream vera sans} 21

»glyphFontFamily« and »glyphFontSize« in Example 5.7, “Jeszra Specific Resources” defines the icon font inside the Jeszra hierarchy view. These entries are application specific and thus the full window pathname is stated, starting from the window with class »Gestalt«: *Gestalt.space.document.hierarchy.

The resource entries »fontfamily« and »fontsize« in Example 5.6, “TkPath Specific Resources” are TkPath related entries. The Rtl_tabset window uses separate font definitions for Tk fonts and those originating from TkPath.

The Aquaish resource file gets used in combination with AQUA®. Its purpose is to vectorize the entire Graphical User Interface under AQUA®, with the intent to create Scalable Vector Graphics from it. These resource file instructs Gstripes to ignore the original AQUA® controls and to supplant them. The Gstripes Option Database property ».force« controls this behavior.

The conventional AQUA® controls in Tk, are created from bitmaps, which limits the possible resolution of a printout, Scalable Vector Graphics or PDF to the resolution of the display. The default resolution setting for AQUA® is 72dpi–actual ppi . Aquaish replaces most of these controls through vector graphics and thus utilizes the resolution of the target medium–the printer for example.

Aquaish deploys multiple layered, semi-transparent gradients to generate the AQUA®-look. Support for transparency and layered gradients is currently incomplete in FOP, which is why Figure 5.6, “Aquaish General Preferences” differs markedly from the original Scalable Vector Graphics.

Figure 5.6. Aquaish General Preferences