From 9b2e2ee4b5c38d27e05e453f016f738b129d15cd Mon Sep 17 00:00:00 2001
From: "W. Trevor King" <wking@tremily.us>
Date: Wed, 15 May 2013 17:00:36 -0400
Subject: [PATCH] pyafm/stack.tex: Add detail to the fig:pyafm:stack caption

We declare a new \tikzline command to make it easier to draw sample
lines in captions (which can't handle fragile commands).  Hopefully
the figure is intelligable to folks now :).
---
 src/local_cmmds.tex |  5 +++++
 src/pyafm/stack.tex | 16 ++++++++++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/local_cmmds.tex b/src/local_cmmds.tex
index d7c9fc4..0ebbb37 100644
--- a/src/local_cmmds.tex
+++ b/src/local_cmmds.tex
@@ -195,6 +195,11 @@
 \newcommand{\stepper}{\citetalias{stepper}}
 \newcommand{\unfoldprotein}{\citetalias{unfold-protein}}
 
+% draw a line TikZ (useful for captions explaining figures)
+% usage: \tikzline{style}
+\DeclareRobustCommand{\tikzline}[1]{%
+  \protect\tikz \draw[#1] (0,0) -- (14pt,6pt);}
+
 % draw a thermometer in TikZ
 % usage: \thermometer{bulb-location}
 \newcommand{\thermometer}[1]{
diff --git a/src/pyafm/stack.tex b/src/pyafm/stack.tex
index 69d2f75..d020cde 100644
--- a/src/pyafm/stack.tex
+++ b/src/pyafm/stack.tex
@@ -14,8 +14,20 @@ spectroscopy (\cref{fig:pyafm:stack}).
 
 \begin{figure}
   \tikzstack{}{black!20}
-  \caption{Dependency graph for my modular experiment control
-    stack.\label{fig:pyafm:stack}}
+  \caption{Dependency graph for my modular experiment control stack.
+    The dashed line (\tikzline{black!20,dashed}) separates the
+    software components (on the left) from their associated hardware
+    (on the right).  The data flow between components is shown with
+    arrows.  For example, the \stepper\ package calls \pycomedi, which
+    talks to the DAQ card, to write digital output that controls the
+    stepper motor (\tikzline{blue,->}, \cref{sec:pyafm:stepper}).  The
+    \pypiezo\ package, on the other hand, uses two-way communication
+    with the DAQ card (\tikzline{red,<->}), writing driving voltages
+    to position the piezo and recording photodiode voltages to monitor
+    the cantilever deflection (\cref{sec:pyafm:pypiezo}).  The
+    \pypid\ package measures the buffer temperature using a
+    thermocouple inserted in the fluid cell (\tikzline{purple,<-},
+    \cref{sec:pyafm:pypid}).\label{fig:pyafm:stack}}
 \end{figure}
 
 \subsection{Pycomedi}
-- 
2.26.2