Ruby Cookbook

Recipe 12.1. Thumbnailing Images Credit: Antonio Cangiano Problem Given an image, you want to create a smaller image to serve as a thumbnail. Solution Use RMagick, available from the rmagick or rmagick-win32 gems. Its Magick module ...

Recipe 12.2. Adding Text to an Image Credit: Antonio Cangiano Problem You want to add some text to an imageperhaps a caption or a copyright statement. Solution Create an RMagick Draw object and call its annotate method, passing i...

Recipe 12.3. Converting One Image Format to Another Credit: Antonio Cangiano Problem You want to convert an image to a different format. Solution With RMagick, you can just read in the file and write it out with a different extension. Th...

Recipe 12.4. Graphing Data Problem You want to convert a bunch of data into a graph; usually a line chart, bar chart, or pie chart. Solution Use the Gruff library, written by Geoffrey Grosenbach. Install the gruff gem and build...

Recipe 12.5. Adding Graphical Context with Sparklines Problem You want to display a small bit of statistical contexta trend or a set of percentagesin the middle of a piece of text, without breaking up the flow of the text. Solution I...

Recipe 12.6. Strongly Encrypting Data Problem You want to encrypt some data: to keep it private, or to keep it safe when sent through an insecure medium like email. Solution There are at least two good symmetric-key cryptography libr...

Recipe 12.7. Parsing Comma-Separated Data Problem You have a plain-text string in a comma-delimited format. You need to parse this string, either to build a data structure or to perform some operation on the data and write it back out. ...

Recipe 12.8. Parsing Not-Quite-Comma-Separated Data Problem You need to parse a plain- text string or file that's in a format similar to commadelimited format, but its delimiters are some strings other than commas and newlines. ...

Recipe 12.9. Generating and Parsing Excel Spreadsheets Problem Your program needs to parse data from Excel spreadsheets, or generate new Excel spreadsheets. Solution To generate Excel files, use the spreadsheet librar...

Recipe 12.10. Compressing and Archiving Files with Gzip and Tar Problem You want to write compressed data to a file to save space, or uncompress the contents of a compressed file. If you're compressing data, you might wan...

Recipe 12.11. Reading and Writing ZIP Files Problem You want to create or examine a ZIP archive from within Ruby code. Solution Use the rubyzip gem. Its Zip module gives you several ways of putting files into ZIP archives, and taking t...

Recipe 12.12. Reading and Writing Configuration Files Problem You want to store your application's configuration on disk, in a format parseable by Ruby but easily editable by someone with a text editor. Solution Put your config...

Recipe 12.13. Generating PDF Files Problem You want to create a text or graphical document as a PDF, where you have complete control over the layout. Solution Use Austin Zeigler's PDF::Writer library, available as the pdf-...