View Slides

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Description & Goals

  For the general public

The View Slides activity is meant to allow the XO laptop to read view the contents of a Zip file containing images named sequentially. Project Gutenberg has a few books as raw scanned images, and this can be a useful format for picture books, comic books, magazine articles, photo essays, etc.

The interface to View Slides is similar to the core Read activity, which should not be surprising as the toolbar code was adapted from Read's toolbar. You can use the up and down arrows or the game controller to move from page to page.

The image files can be JPEGs, GIFs, TIFFs, or PNGs. Currently they must be in the root of the Zip file. To make a file like this first create some image files and name them sequentially:

image001.jpg, image002.jpg, image003.jpg, ...

In Linux you can create the file with the zip command:

zip bookname *.jpg

will create a file named bookname.zip and put all the JPEGs in the current directory in it. I recommend using the suffix .zip for all of your files, especially if you plan to distribute them using a web server. The Apache web server uses the file suffix to determine the MIME type of the file. If you use a different suffix you may find that the Browse activity does not put the MIME type of the file in the Journal correctly and as a result the Journal entry won't have View Slides on its "Resume" menu.

A file you can use to try out View Slides can be downloaded from Project Gutenberg. Look for the file format "Raw page images".

Screenshots

Launching the Activity from the Journal
The View Slides Activity in action
The View Slides Activity, showing scanned text

Current Features

  • Currently you can load a zip file containing images and page through them in sequence like a book. The images will be resized to best fit in the current screen resolution without scrolling.
  • You can share documents with other users, using code adapted from the core Read activity. Currently this is not reliable.
  • Aggresive power management using code from Read activity.

Planned Features

  • With the name "View Slides" it would be reasonable to expect a slideshow feature, possibly with fancy transitions. I may add another tab to the toolbox to provide this.

Activity .xo file


Bugs

  • When you change the display orientation the current image should be resized to match the new orientation. Currently it doesn't, but when you go to a new image that image will be sized correctly.
  • When you exit the activity it should save the current page number and resume on that page number when you resume the activity. This actually works, but because of a known bug in Journal the page number meta data does not persist after a reboot. Also, again because of a Journal bug, the page number cannot be saved when the images are loaded from an SD card or USB drive.
  • On some versions of the XO OS the Journal cannot deal with large files (15 mb or larger). This will prevent you from using larger files containing images. You can fix this by updating the OS, which currently requires getting a developer key.
  • The document sharing code is not reliable.

Source

http://dev.laptop.org/git?p=activities/view-slides