Scripted Screenshots

I recently needed to make a screenshot of an entire web page, i.e. not just the part the fits on the screen (or in the viewport), but the whole thing from top to bottom.

Somehow I missed the possibility that there might be a zillion browser extensions for just this purpose. From writing features (acceptance tests) with Cucumber I’m familiar with PhantomJS, a “headless”, scriptable browser based on WebKit.

Here’s how it works:

$ webshot --help
Usage: webshot [OPTIONS]... URL IMAGE_FILE

          -j|--jquery           Inject jQuery into the page.
         +-e|--exec «value»     Execute script in page context.
         +-f|--file «value»     Execute script file in page context.
          -v|--viewport «value» Viewport size WxH; default 1280x800.

          (* mandatory option)
          (+ repeatable option)

Luckily, I didn’t have to write the commandline parsing myself. But it was fun to figure out how Deferreds might be implemented.

Getting a view at views

The structure of Rails views can become rather complicated with templates, layouts and partials inclusions multiple levels deep. Here are two tools for disentangling views.

The first one adds HTML comments to generated markup. These comments identify the file where the markup originated. Place it in config/initializers/show_view_structure.rb

The second tool works offline. It prints the hierarchical structure of template inclusions

There’s a limitation in that only explicit partial renderings are recognized. Layouts are not taken into account and partials rendered from helpers are not recognized either.

Better Rake Bash completion

What’s new?

  1. Rake tasks are cached (thanks to turadb).
  2. If there is no Rakefile in the current directory, ancestor directories are searched in the way Rake itself does.


Copy the file to /etc/bash_completion.d or possibly /usr/share/bash-completion/completions or to another place where it is loaded when your Bash shell is started.

Eclipse: Printing Editor Templates using XSLT, CSS, and Firefox

I’m using Eclipse with RadRails to edit my Ruby and Rails code (and, yes, I’ve used it for Java, way back when).

Inside Eclipse the various text editors offer so-called templates. These are snippets of common code with placeholders for variable bits. Type in the abbreviation for a template, then type Ctrl-Space and the abbreviation is expanded to the template code. For editing Ruby/Rails templates are available from the RadRails Templates site.

I’ve only recently started to use templates and I’m still early on the learning curve, that is, I haven’t memorized many of the abbreviations. Unfortunately, Eclipse itself only has a list of templates with their expansions in its modal Preferences window. That’s not very helpful when coding. What Eclipse does have is a function to export templates to XML and that’s what I did.

The exported file looks like this

<?xml version="1.0" encoding="UTF-8"?>
  <template autoinsert="true" context="ruby" deleted="false" description="tm - all? { |e| .. }" enabled="true" name="all">all? { |${e}| ${cursor} }
  <template autoinsert="true" context="ruby" deleted="false" description="tm - alias_method .." enabled="true" name="am">alias_method :${new_name}, :${old_name}

The easiest approach I could think of to make this into something printable is this. First, transform it into HTML using an XSL stylesheet, then make the HTML pretty by styling it with an CSS stylesheet. Luckily, most of this can be done inside a web browser such as Firefox that understands XSLT.

Here’s the XSLT

<?xml version="1.0" encoding="iso-8859-1"?>
<xsl:stylesheet version="1.0" xmlns:xsl="">

<xsl:template match="/">
      <xsl:apply-templates mode="head" />
      <link rel="stylesheet" type="text/css" href="templates.css" />
      <xsl:apply-templates mode="body" />

<xsl:template match="title" mode="head">
    <xsl:value-of select="." />

<xsl:template match="title" mode="body">
    <xsl:value-of select="." />

<xsl:template match="templates" mode="body">
    <xsl:apply-templates mode="body" />

<xsl:template match="template" mode="body">
    <xsl:value-of select="@name" />
    <xsl:value-of select="." />


And the CSS stylesheet

html {
  font-family: sans-serif;

dt {
  border-top: 1px solid #aaa;
  padding-top: 0.2em;
  font-weight: bold;

dd {
  margin-top: 0.3em;
  margin-bottom: 1em;
  white-space: pre;
  font-family: monospace;

Now, these parts need to be connected. For this, it is necessary to slightly edit the original XML template file. For good measure, I throw in a title.

<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl" href="templates.xsl" ?>
  <title>RadRails Ruby Templates</title>
  <template ...>

You may find that the indentation for the template code looks wrong. The reason is that the code contains tabs for indentation. Ruby convention is to indent by 2 spaces for each level, by contrast, Firefox apparently expands tabs to 8 spaces. A small glitch that can be rectified easily

$ sed -i 's/\t/  /g' template.xml