HOM Feed Example: Part 3 Implementation

Supporting files for this example are in $HFS/mozilla/documents/hom/cookbook/feed/part3, also found in the cookbook/feed/part3 directory of cookbook_files.tar.gz.

For this part of the example, we’ll move the code into the hou.session module. The shelf button will simply call a hou.session function, and the geometry object pick scripts will also call a function there.

Shelf code:

hou.session.createObjects()

hou.session:

# The webbrowser module is distributed with Python.  The feedloader module
# is part of this example and its code is listed below.
import webbrowser
import feedloader

use_help_browser = False

links = []

def openLink(index):
    """Open the URL for a given link index."""
    openURL(links[index][1])

def openURL(url):
    """Open a given URL in the browser."""
    if use_help_browser:
        # If a help browser is already open, use it.
        desktop = hou.ui.curDesktop()
        browser = desktop.paneTabOfType(hou.paneTabType.HelpBrowser)
        if browser is None:
            browser = desktop.createFloatingPane(hou.paneTabType.HelpBrowser)
        browser.setUrl(url)
    else:
        webbrowser.open_new(url)

def createObjects():
    """Load the RSS feed and create objects containing the titles.  When
       you click on the objects, they'll open the link in the browser.
    """
    # Load from an RSS feed into the links global variable, storing
    # (title, url) tuples.
    global links
    links = feedloader.loadLinks()

    # Delete all the existing objects in /obj.
    for child in hou.node("/obj").children():
        child.destroy()

    y_pos = 0
    for index in range(len(links)):
        text, url = links[index]

        geo = hou.node("/obj").createNode("geo", run_init_scripts=False)
        font = geo.createNode("font")
        font.parm("text").set(text)

        color = geo.createNode("color")
        color.setFirstInput(font)
        color.parmTuple("color").set((0, 0, 0))
        color.setDisplayFlag(True)

        geo.parm("ty").set(y_pos)
        y_pos -= 2
        geo.parm("pickscript").set(
            'python -c "hou.session.openLink(%d)"' % index)
    hou.node("/obj").layoutChildren()

For reference, the contents of the feedloader module are listed below. The feedloader module is part of this example, and it internally uses the feedparser module from to download a particular RSS news feed. It then discards non-ascii characters and decodes html-encoded characters. It also lets you read from a file instead of a feed, in case you don’t have internet access.

:

"""Set use_file to True to read from a file on disk instead of from a real
   RSS feed.
"""
use_file = False

import htmllib

def textToAscii(text):
    """Convert unicode, HTML-encoded text into ASCII so Houdini can
       understand it."""
    # First decode the html escaped portions.
    parser = htmllib.HTMLParser(None)
    parser.save_bgn()
    parser.feed(text)
    decoded_text = parser.save_end()

    # Now discard non-ascii characters.
    return "".join(x for x in decoded_text if 32 <= ord(x) < 128)

def loadLinks(url="http://news.google.com/news?ned=us&topic=t&output=rss"):
    """Return the contents of an RSS feed in the form of (title, url) tuples."""
    if use_file:
        return _loadLinksFromFile()

    # Print out a message in case it takes a long time to download the feed,
    # or in case we're not connected to the internet.
    import feedparser
    print "downloading feed..."
    document = feedparser.parse(url)
    print "...done"

    links = []
    for entry in document['entries']:
        title = textToAscii(entry['title'])
        url = textToAscii(entry['link'])
        links.append((title, url))
    return links

def _loadLinksFromFile(file_name="sample_links.txt"):
    """Pretend to load an RSS feed by reading from a file."""
    links = []

    f = file(file_name, "r")
    while True:
        title = f.readline().rstrip("\n")
        if not title:
            break;
        url = f.readline().rstrip("\n")
        links.append((title, url))
    f.close()

    return links

Visit for information about the feedparser module.

Previous: part 2