How can I define the start point of an arrow in Tikz?

Question

I have the following problem: With the code

\documentclass[border=10pt]{standalone}

\usepackage{tikz}
\usetikzlibrary{shapes,arrows}

\everymath{\displaystyle}

\begin{document}
\tikzstyle{block} = [rectangle, draw, fill=blue!20,
  text centered, rounded corners, minimum height=4em]

\tikzstyle{line} = [-stealth, thick, draw]

\begin{tikzpicture}[node distance=5cm, text width=8em, auto]
  \node [block] (A) {Block 1};
  \node [block, right of=A] (B) {Block 2};
  \path [line] (A) edge node [midway] {Text} (B);
\end{tikzpicture}

\end{document}

I get the following image

The text description is not shown at the center of the arrow. It seems that the start point of the error is wrong. What do I need to do to have the arrow description at the right position (middle of arrow)?

My attempts: I can change midway to at end but this does not seem to be the right solution...

@CroCo: Is there another way to ensure that all nodes have the same width? — Stephan Kulla, Nov 15 '15 at 14:31
You already set its height, so it is similar for the width minimum width=6em — CroCo, Nov 15 '15 at 14:35
@CroCo: Unfortunately I have a block witdh long text. See section "Text Width" of https://www.sharelatex.com/blog/2013/08/29/tikz-series-pt3.html#Text%20Width How can I shorten the block node width without text width? — Stephan Kulla, Nov 15 '15 at 14:43
You can break the text into lines instead of increasing the width. — CroCo, Nov 15 '15 at 14:45
Maybe worth a look: Should \tikzset or \tikzstyle be used to define TikZ styles? — Tobi, Nov 15 '15 at 15:05
@Arne, with yshift=1cm does not guarantee the node being in the middle. Better to stick with the positioning package. In this case, it is set by default to be in the middle however due to the fact that text width is taking to much space, the text is shifted to the left. — CroCo, Nov 15 '15 at 15:33
@CroCo Indeed, it's working for this one, but not for every thing. So a quick but not a good answer. You could label the segment with ikz-euclide package, but that needs an other definition of block 1 and 2 — Arne Timperman, Nov 15 '15 at 20:20

score 2 · Accepted Answer · edited Jun 10 '20 at 12:32

The problem with text width=8em which takes too much space. The solution is to remove it. Therefore, the result should be

and the code is

\documentclass[border=10pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes,arrows}
\everymath{\displaystyle}
\begin{document}
\tikzstyle{block} = [rectangle, draw, fill=blue!20,
  text centered, rounded corners, minimum height=3em, minimum width=5em]
\tikzstyle{line} = [-stealth, thick, draw]
\begin{tikzpicture}[node distance=3.5cm, auto]
  \node [block] (A) {Block 1};
  \node [block, right of=A] (B) {Block 2};
  \path [line] (A) edge node [midway] {Text} (B);
\end{tikzpicture}
\end{document}

I've changed minimum height=3em and node distance=3.5cm. Also, I've added minimum width=5em as the OP requested in the comment.

Update: as @Zarko mentioned in below comments, the node is already placed in the midway, therefore, there is no need to explicitly add it to the node.

@Cr0Co, nodes on edges are always on the middle of them, so the option [midway] of their node is surplus. — Zarko, Nov 15 '15 at 14:45
@Zarko, I've addressed only the problem. And you're right. I will update it now. — CroCo, Nov 15 '15 at 14:48

How can I define the start point of an arrow in Tikz?

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