Background and desired functionality
Rectangles can be drawn with tikz in a number of ways, one way of doing so is to define a rectangle node as follows:
\node (rectangle) [draw, rectangle] {A rectangle};
% Strictly speaking, rectangle is not needed in the [] as nodes are rectangular by default
A useful feature of this is that, as a node, it has anchor points around it such as rectangle.north, rectangle.south west and so on.
Another way is to draw a rectangle path, like this:
\draw (0,0) rectangle (3,2);
I would like to be able to use this second path-based method* but also be able to have (some) named anchors on the path.
Approach from the time of asking
MWE:
The method I had for this is demonstrated by the following MWE (inspired by this inventive answer and later improved by Altermundus' comment):
\documentclass{report}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
\draw
(0,0)
coordinate [xshift=-{0.5\pgflinewidth},yshift=-{0.5\pgflinewidth}] (rectangle south west)
rectangle
coordinate (rectangle center)
(3,2)
coordinate [xshift={0.5\pgflinewidth},yshift={0.5\pgflinewidth}] (rectangle north east)
edge [draw=none]
coordinate (rectangle north)
(rectangle north east -| rectangle south west)
;
\end{tikzpicture}
\end{document}
Obviously this only defines anchors for center, north, north east, and south west, but it can be fairly easily extended to provide south, east, west, north west and south east (as demonstrated in my answer).
Caveat:
As pointed out by Andrew Stacey in his answer, there was a slight discrepancy between the positioning of these pseudo-anchor coordinates and the anchors on a normal rectangular node. The edge-based solution above originally placed the pseudo-anchors exactly on the coordinates of the rectangle whereas on a rectangular node they would be placed at the outside edge of the lines of the rectangle. Although this was only likely to cause issues with thick line widths I have now added some x/yshifting to the above code to compensate.
The following image shows the difference in anchor positioning between standard node rectangles, the original edge-based solution (without x/yshifting) and the above (revised) edge-based solution (with x/yshifting). The line widths for the lower pictures are set to 0.5cm.
Node rectangle labelling code to illustrate the key to the colours (and for the generally curious):
% styling yoinked from Altermundus' answer
\tikzset{dot/.style={circle,fill=#1,inner sep=0,minimum size=4pt}}
\node [dot=red] at (rectangle.south west) {};
\node [dot=blue] at (rectangle.center) {};
\node [dot=purple] at (rectangle.north east) {};
\node [dot=green] at (rectangle.north) {};
\node [dot=orange] at (rectangle.north west) {};
\node [dot=yellow] at (rectangle.south) {};
\node [dot=brown] at (rectangle.south east) {};
\node [dot=black] at (rectangle.east) {};
\node [dot=pink] at (rectangle.west) {};
Back to the question
Is there a neater/better way to establish node-anchor-like points on a rectangle path* than the method given in the MWE above?
* = An equivalent drawing method that also allows specifying a rectangle by corner coordinates would be more than acceptable!
edge [draw opacity=0]is not pretty and you can insert after (3,2)coordinate (path_rectangle center)– Alain Matthes Mar 12 '12 at 23:50rectangleyou can insert thecentercoordinate - but that's neat, I'll add it in to the question code, cheers. With regards to theedge [draw opacity=0]bit, would you consideredge [draw=none]prettier? (Now that I know about[draw=none], from Andrew's answer, I'm going to add it in anyway as it seems somewhat cleaner to me.) – Staves Mar 13 '12 at 11:41edgeyes you get a result but I don't like the long line of code. – Alain Matthes Mar 13 '12 at 15:35