Graphics Reference
In-Depth Information
interfering with display of other more important information. Some of the
best icons often use only one color for fill. If there is a chance that the
background will include the same color as the fill, a contrasting outline is
also important.
Warning
Avoid icons with color except when communicating properties of the
data. Use of complex colored icons is a common way to wreck
visualization.
Icon Libraries
Icon design is a time-consuming task that requires both skills and software
programs that many people don't have. So, what are the best sources for
icons, and how can they be integrated into a visualization? In keeping with
the theme of this topic, here are a number of open source options that
highlight the different approaches.
Unicode
is the standard map of character codes to font glyphs, which
enables the same text to appear correctly in any font. As shown in
Figure
used in some of the visualizations in Chapter 11 is an example of a Unicode
symbol.
Figure 16-5:
Unicode includes code blocks for thousands of icons, such as
the weather and transportation icons shown here in the Segoe UI Symbol
font. Few fonts, however, include these characters.
The great thing about Unicode is that it can take advantage of symbols that
are already present on your computer system and are coded consistently
across fonts. The drawback, however, is that Unicode is far too big for
any one font to support in entirety, so relatively few fonts include these
characters, and the quality of those that do can vary widely. The other
limitation is that the set of defined Unicode symbols is finite and not
particularly well-curated.
The second option is to use a specially crafted font that contains only
symbols, where the symbols are inserted in place of normal character codes
