Add a gallery example showing the usage of text symbols (#1522)

Co-authored-by: Dongdong Tian <[email protected]>

Author: michaelgrund

examples/gallery/symbols/text_symbols.py

@@ -0,0 +1,43 @@
+r"""
+Text symbols
+------------
+The :meth:`pygmt.Figure.plot` method allows to plot text symbols. Text is
+normally placed with the :meth:`pygmt.Figure.text` method but there are times
+we wish to treat a character or even a string as a plottable symbol.
+A text symbol can be drawn by passing **l**\ *size*\ **+t**\ *string* to
+the ``style`` parameter where *size* defines the size of the text symbol
+(note: the size is only approximate; no individual scaling is done for
+different characters) and *string* can be a letter or a text string
+(less than 256 characters). Optionally, you can append **+f**\ *font* to
+select a particular font [Default is :gmt-term:`FONT_ANNOT_PRIMARY`] as well as
+**+j**\ *justify* to change the justification [Default is CM]. Outline
+and fill color of the text symbols can be customized via the ``pen``
+and ``color`` parameters, respectively.
+
+For all supported octal codes and fonts see the GMT cookbook
+:gmt-docs:`cookbook/octal-codes.html` and
+:gmt-docs:`cookbook/postscript-fonts.html`.
+"""
+
+import pygmt
+
+fig = pygmt.Figure()
+
+fig.basemap(region=[0, 8, 0, 3], projection="X12c/4c", frame=True)
+
+pen = "1.5p"
+# plot an uppercase "A" of size 3.5c, color fill is set to "dodgerblue3"
+fig.plot(x=1, y=1.5, style="l3.5c+tA", color="dodgerblue3", pen=pen)
+# plot an "asterisk" of size 3.5c, color fill is set to "red3"
+fig.plot(x=2.5, y=1, style="l3.5c+t*", color="red3", pen=pen)
+# plot an uppercase "Z" of size 3.5c and use the "Courier-Bold" font,
+# color fill is set to "seagreen"
+fig.plot(x=4, y=1.5, style="l3.5c+tZ+fCourier-Bold", color="seagreen", pen=pen)
+# plot a lowercase "s" of size 3.5c and use the "Times-Italic" font,
+# color fill is set to "gold"
+fig.plot(x=5.5, y=1.5, style="l3.5c+ts+fTimes-Italic", color="gold", pen=pen)
+# plot the pi symbol (\160 is octal code for pi) of size 3.5c, for this use
+# the "Symbol" font, color fill is set to "magenta4"
+fig.plot(x=7, y=1.5, style="l3.5c+t\160+fSymbol", color="magenta4", pen=pen)
+
+fig.show()