Remove cairo-based backends from backend fallback.

anntzer · anntzer · commit 928aa7619676 · 2019-01-16T12:24:17.000+01:00
They would never be selected by the fallback machinery anyways.
diff --git a/lib/matplotlib/pyplot.py b/lib/matplotlib/pyplot.py
@@ -190,8 +190,11 @@ def switch_backend(newbackend):
     close("all")
 
     if newbackend is rcsetup._auto_backend_sentinel:
-        for candidate in ["macosx", "qt5agg", "qt4agg", "gtk3agg", "gtk3cairo",
-                          "tkagg", "wxagg", "agg", "cairo"]:
+        # Don't try to fallback on the cairo-based backends as they each have
+        # an additional dependency (pycairo) over the agg-based backend, and
+        # are of worse quality.
+        for candidate in ["macosx", "qt5agg", "qt4agg", "gtk3agg", "tkagg",
+                          "wxagg", "agg"]:
             try:
                 switch_backend(candidate)
             except ImportError:
diff --git a/matplotlibrc.template b/matplotlibrc.template
@@ -31,9 +31,10 @@
 
 ## The default backend. If you omit this parameter, the first
 ## working backend from the following list is used:
-## MacOSX Qt5Agg Qt4Agg Gtk3Agg GTK3Cairo TkAgg WxAgg Agg Cairo
+## MacOSX Qt5Agg Qt4Agg Gtk3Agg TkAgg WxAgg Agg
 ##
-## Other choices include: WX PS PDF SVG Template.
+## Other choices include:
+## Qt5Cairo Qt5Cairo GTK3Cairo TkCairo WxCairo Cairo Wx PS PDF SVG Template.
 ##
 ## You can also deploy your own backend outside of matplotlib by
 ## referring to the module name (which must be in the PYTHONPATH) as
