About a year ago, I wrote a small web browser, called De Vi­cen­zo just for fun.

But hey, some­one went and madeit use­ful for some­thing! Specif­i­cal­ly, to pro­vide pre­views when do­ing sphix docs

That's cool :)

I have writ­ten about this in the past, with the gen­er­al con­clu­sion be­ing "it's a pain in the as­s".

So, now, here is how it's done.

1. Start with a work­ing PyQt ap­­pli­­ca­­tion. In this ex­am­­ple, I will use de­vi­­cen­­zo.py most­­ly be­­cause:

   1. It is a work­ing PyQt ap­­­pli­­­ca­­­tion.

   2. It us­es a big chunk of PyQt

   3. It's easy to test

2. Now you need a set­up.py. Here's one that work­s, with ex­ten­sive com­m­ments.

# We will be using py2exe to build the binaries.
# You may use other tools, but I know this one.

from distutils.core import setup
import py2exe

# Now you need to pass arguments to setup
# windows is a list of scripts that have their own UI and
# thus don't need to run in a console.

setup(windows=['devicenzo.py'],
      options={

# And now, configure py2exe by passing more options;

          'py2exe': {

# This is magic: if you don't add these, your .exe may
# or may not work on older/newer versions of windows.

              "dll_excludes": [
                  "MSVCP90.dll",
                  "MSWSOCK.dll",
                  "mswsock.dll",
                  "powrprof.dll",
                  ],

# Py2exe will not figure out that you need these on its own.
# You may need one, the other, or both.

              'includes': [
                  'sip',
                  'PyQt4.QtNetwork',
                  ],

# Optional: make one big exe with everything in it, or
# a folder with many things in it. Your choice
#             'bundle_files': 1,
          }
      },

# Qt's dynamically loaded plugins and py2exe really don't
# get along.

data_files = [
            ('phonon_backend', [
                'C:\Python27\Lib\site-packages\PyQt4\plugins\phonon_backend\phonon_ds94.dll'
                ]),
            ('imageplugins', [
            'c:\Python27\lib\site-packages\PyQt4\plugins\imageformats\qgif4.dll',
            'c:\Python27\lib\site-packages\PyQt4\plugins\imageformats\qjpeg4.dll',
            'c:\Python27\lib\site-packages\PyQt4\plugins\imageformats\qsvg4.dll',
            ]),
],

# If you choose the bundle above, you may want to use this, too.
#     zipfile=None,
)

3. Run python set­up.py py2exe and get a dist fold­er full of bi­na­ry good­ness.

And that's it. Ex­cept of course, that's not it.

What this will do is cre­ate a bi­na­ry set, ei­ther a fold­er full of things, or a sin­gle EXE file. And that's not enough. You have to con­sid­er at least the fol­low­ing:

1. Put ev­ery­thing in re­­source files: im­ages, qss files, icon­s, etc. Ev­ery file your app need­s? Put it in a re­­source file and load it from there. That way you don't have to care about them if you go the "one ex­e" road.

2. Com­pile .ui files to .py (same rea­­son)

3. Fig­ure out if you use Qt's plu­g­in­s, and make them work. This in­­­cludes: us­ing Phonon, us­ing Qt­SQL, and us­ing any im­age for­­mats oth­­er than PNG.

Af­ter you have that, are you done? NO!

Your win­dows us­er will want an in­stall­er. I am not go­ing to go in­to de­tail­s, but I had a good time us­ing Bi­tRock­'s In­stall­Builder for Qt. It's a nice tool, and it work­s. That's a lot in this field.

But is that al­l? NO!

You have to take care of the Vis­ual Stu­dio Run­time. My sug­ges­tion? Get a copy of the 1.1MB vcre­dis­t_x86.exe (not the larg­er one, the 1.1MB one), and ei­ther tell peo­ple to in­stall it man­u­al­ly, or add it to your in­stall­er. You are legal­ly al­lowed (AFAIK) to re­dis­tribute that thing as a whole. But not what's in it (un­less you have a VS li­cense).

And we are done? NO!

Once you run your app "in­stalled", if it ev­er prints any­thing to stder­r, you will get ei­ther a di­a­log telling you it did, or worse (if you are in ay­thing new­er than XP), a di­a­log telling you it can't write to a log file, and the app will nev­er work again.

This is be­cause py2exe catch­es stderr and tries to save it on a log­file. Which it tries to cre­ate in the same fold­er as the bi­na­ry. Which is usu­al­ly not al­lowed be­cause of per­mis­sion­s.

So­lu­tion? Your app should nev­er write to stder­r. Write an ex­cepthook and catch that. And then re­move stderr or re­place it with a log file, or some­thing. Just don't let py2exe do it, be­cause the way py2exe does it is bro­ken.

And is that it?

Well, ba­si­cal­ly yes. Of course you should get 4 or 5 dif­fer­ent ver­sions of win­dows to test it on, but you are pret­ty much free to ship your app as you wish. Oh, mind you, don't up­load it to down­load­s.­com be­cause they will wrap your in­stall­er in a larg­er one that in­stalls bloat­ware and crap.

So, there you go.

In the spir­it of the De Vi­cen­zo web browser, I am start­ing a new pro­gram, called Pa­to Cabr­era. Here are the rules:

• Twit­ter client (no iden­ti.­­ca in the first ver­­sion, but to be added lat­er)

• Has these fea­­tures: http://­­paste­bin.lug­­men.org.ar/6464

• Has to be im­­ple­­men­t­ed be­­fore April 4th

• Smal­l­­er than 16384 bytes (of python code) but may be larg­er be­­cause of art­­work.

Let's see how it works :-)

I have al­ready post­ed a cou­ple of times (1, 2) about De Vi­cen­zo , an at­tempt to im­ple­ment the rest of the browser, start­ing with PyQt's We­bKit... lim­it­ing my­self to 128 lines of code.

Of course I could do more, but I have my stan­dard­s!

• No us­ing ;

• No if what­ev­er: f()

Oth­er than that, I did a lot of dirty trick­s, but right now, it's a fair­ly com­plete browser, and it has 127 lines of code (ac­cord­ing to sloc­coun­t) so that's enough play­ing and it's time to go back to re­al work.

But first, let's con­sid­er how some fea­tures were im­ple­ment­ed (I'll wrap the lines so they page stays rea­son­ably nar­row), and al­so look at the "nor­mal" ver­sions of the same (the "nor­mal" code is not test­ed, please tell me if it's bro­ken ;-).

This is not some­thing you should learn how to do. In fac­t, this is al­most a trea­tise on how not to do things. This is some of the least python­ic, less clear code you will see this week.

It is short, and it is ex­pres­sive. But it is ug­ly.

I'll dis­cuss this ver­sion.

 proxy_url = QtCore.QUrl(os.environ.get('http_proxy', ''))
 QtNetwork.QNetworkProxy.setApplicationProxy(QtNetwork.QNetworkProxy(\
 QtNetwork.QNetworkProxy.HttpProxy if unicode(proxy_url.scheme()).startswith('http')\
 else QtNetwork.QNetworkProxy.Socks5Proxy, proxy_url.host(),\
 proxy_url.port(), proxy_url.userName(), proxy_url.password())) if\
'http_proxy' in os.environ else None

if 'http_proxy' in os.environ:
    proxy_url = QtCore.QUrl(os.environ['http_proxy'])
    if unicode(proxy_url.scheme()).starstswith('http'):
        protocol = QtNetwork.QNetworkProxy.HttpProxy
    else:
        protocol = QtNetwork.QNetworkProxy.Socks5Proxy
    QtNetwork.QNetworkProxy.setApplicationProxy(
        QtNetwork.QNetworkProxy(
            protocol,
            proxy_url.host(),
            proxy_url.port(),
            proxy_url.userName(),
            proxy_url.password()))

def put(self, key, value):
    "Persist an object somewhere under a given key"
    settings.setValue(key, json.dumps(value))
    settings.sync()

def get(self, key, default=None):
    "Get the object stored under 'key' in persistent storage, or the default value"
    v = settings.value(key)
    return json.loads(unicode(v.toString())) if v.isValid() else default

# Save the cookies, in the window's closeEvent
self.put("cookiejar", [str(c.toRawForm()) for c in self.cookies.allCookies()])

# Restore the cookies, in the window's __init__
self.cookies.setAllCookies([QtNetwork.QNetworkCookie.parseCookies(c)[0]\
for c in self.get("cookiejar", [])])

# get("tabs") is a list of URLs
[self.addTab(QtCore.QUrl(u)) for u in self.get("tabs", [])]

QtWebKit.QWebView.__init__(self, loadProgress=lambda v:\
(self.pbar.show(), self.pbar.setValue(v)) if self.amCurrent() else\
None, loadFinished=self.pbar.hide, loadStarted=lambda:\
self.pbar.show() if self.amCurrent() else None, titleChanged=lambda\
t: container.tabs.setTabText(container.tabs.indexOf(self), t) or\
(container.setWindowTitle(t) if self.amCurrent() else None))

loadStarted=lambda:\
    self.pbar.show() if self.amCurrent() else None

loadProgress=lambda v:\
(self.pbar.show(), self.pbar.setValue(v)) if self.amCurrent() else\
None

def fetch(self, reply):
    destination = QtGui.QFileDialog.getSaveFileName(self, \
        "Save File", os.path.expanduser(os.path.join('~',\
            unicode(reply.url().path()).split('/')[-1])))
    if destination:
        bar = QtGui.QProgressBar(format='%p% - ' +
            os.path.basename(unicode(destination)))
        self.statusBar().addPermanentWidget(bar)
        reply.downloadProgress.connect(self.progress)
        reply.finished.connect(self.finished)
        self.bars[unicode(reply.url().toString())] = [bar, reply,\
            unicode(destination)]

progress = lambda self, received, total:\
    self.bars[unicode(self.sender().url().toString())][0]\
    .setValue(100. * received / total)

def finished(self):
    reply = self.sender()
    url = unicode(reply.url().toString())
    bar, _, fname = self.bars[url]
    redirURL = unicode(reply.attribute(QtNetwork.QNetworkRequest.\
        RedirectionTargetAttribute).toString())
    del self.bars[url]
    bar.deleteLater()
    if redirURL and redirURL != url:
        return self.fetch(redirURL, fname)
    with open(fname, 'wb') as f:
        f.write(str(reply.readAll()))

self.previewer = QtGui.QPrintPreviewDialog(\
    paintRequested=self.print_)
self.do_print = QtGui.QShortcut("Ctrl+p",\
    self, activated=self.previewer.exec_)

It seems it was on­ly a few days ago that I start­ed this projec­t. Oh, wait, yes, it was just a few days ago!

If you don't want to read that again, the idea is to see just how much code is need­ed to turn Qt's We­bKit en­gine in­to a ful­ly-fledged brows­er.

To do that, I set my­self a com­plete­ly ar­bi­trary lim­it: 128 lines of code.

So, as of now, I de­clare it fea­ture-­com­plete.

The new fea­tures are:

• Tabbed brows­ing (y­ou can ad­d/re­­move tab­s)

• Book­­marks (y­ou can ad­d/re­­move them, and choose them from a drop-­­down menu)

This is what al­ready worked:

• Zoom in (C­tr­l++)

• Zoom out (C­tr­l+-)

• Re­set Zoom (C­tr­l+=)

• Find (C­tr­l+F)

• Hide find (Esc)

• But­­tons for back­­/­­for­ward and reload

• URL en­try that match­es the page + au­­to­­com­­plete from his­­to­ry + smart en­try (adds http://, that kind of thing)

• Plug­ins sup­­port (in­­clud­ing flash)

• The win­­dow ti­­tle shows the page ti­­tle (with­­out brows­er ad­ver­tis­ing ;-)

• Progress bar for page load­­ing

• Sta­­tus­bar that shows hov­­ered links URL

• Takes a URL on the com­­mand line, or opens http://python.org

• Mul­ti­­plat­­form (works in any place QtWe­bKit work­s)

So... how much code was need­ed for this? 87 LINES OF CODE

Or if you want the PEP8-­com­pli­ant ver­sion, 115 LINES OF CODE.

Be­fore any­one says it: yes, I know the ren­der­ing en­gine and the tool­kit are huge. What I wrote is just the chrome around them, just like Aro­ra, Rekon­q, Ga­le­on, Epiphany and a bunch of oth­ers do.

It's sim­ple, min­i­mal­is­tic chrome, but it works pret­ty good, IMVHO.

Here it is in (bug­gy) ac­tion:

It's more or less fea­ture-­com­plete for what I ex­pect­ed to be achiev­able, but it still needs some fix­es.

You can see the code at it's own home page: http://de­vi­cen­zo.­google­code.­com