Milian Wolff

Let’s assume you want to display the logo of your company in your Qt app. Most probably that logo has just single color with an alpha channel.But: Having the color hard coded in the image is not nice, there are users (like me!) out there, who use a custom (dark!) color scheme. Meaning: If your logo is black/dark and assumes a bright background and you just embed it blindly in your app, I probably won’t see it since the background will be dark in my case.

Here is a solution for the simple case of a mono-colored PNG with an alpha channel which I came up with:

  QLabel* label = new QLabel;
  // load your image
  QImage img(QString("..."));
  // morph it into a grayscale image
  img = img.alphaChannel();
  // the new color we want the logo to have
  QColor foreground = label->palette().foreground().color();
  // now replace the colors in the image
  for(int i = 0; i < img.colorCount(); ++i) {
    foreground.setAlpha(qGray(img.color(i)));
    img.setColor(i, foreground.rgba());
  }
  // display the new logo
  label->setPixmap(QPixmap::fromImage(img));
  label->show();

This seems to work just fine for me. YMMV.

Unit tests are in my eyes a very important part of programming. KDE uses them, KDevelop does - the PHP plugin I help writing does as well. cmake comes with a ctest program which does quite well to give you a quick glance on which test suite you just broke with your new fance feature :)

But I am very dissatisfied with it. Right now I usually do the following

# lets assume I'm in the source directory
cb && ctest
# look for failed test suites
cd $failed_test_suite_path
./$failed_test_suite.shell | less
# search for FAIL
cs
cd $to_whereever_I_was_before

That’s pretty much for just running a test. Especially all that cding and lessing became very tedious. Tedious is good, because I eventually fix it:

introducing kdetest

I wrote a bash function (with autocompletion!!!) called kdetest. Calling it without any parameter will run all test suites and gives a nice report of failed functions at the end. Here’s an example (run via cs php && kdetest).

kdetest
# ... lots of test output
 
 --- ALL PASSED TESTS ---
...
PASS   : Php::TestCompletion::implementMethods()
PASS   : Php::TestCompletion::inArray()
PASS   : Php::TestCompletion::cleanupTestCase()
 
143 passed tests in total
 
 --- ALL FAILED TESTS ---
FAIL!  : Php::TestCompletion::newExtends() Compared values are not the same
FAIL!  : Php::TestCompletion::updateExtends() '! forbiddenIdentifiers.contains(item->declaration()->identifier().toString())' returned FALSE. ()
FAIL!  : Php::TestCompletion::updateExtends() '! forbiddenIdentifiers.contains(item->declaration()->identifier().toString())' returned FALSE. ()
FAIL!  : Php::TestCompletion::updateExtends() Compared values are not the same
FAIL!  : Php::TestCompletion::newImplements() Compared values are not the same
FAIL!  : Php::TestCompletion::updateImplements() Compared values are not the same
 
6 failed tests in total

usage

• kdetest, i.e. without any arguments runs all tests in this directory and below
• kdetest path/to/test.shell ... runs that test suite only, ... can by any argument the test suite accepts.

autocompletion

kdetest comes with full support for autocompletion of tests and functions, for example:

milian@odin:~/projects/kde4/php$ kdetest TABTAB
completion/tests/completiontest.shell     duchain/tests/expressionparsertest.shell  parser/test/lexertest.shell
duchain/tests/duchaintest.shell           duchain/tests/usestest.shell
milian@odin:~/projects/kde4/php$ kdetest duchain/tests/usestest.shell TABTAB
classAndConstWithSameName          classSelf                          interfaceExtendsMultiple           staticMemberFunctionCall
classAndFunctionWithSameName       constAndVariableWithSameName       memberFunctionCall                 staticMemberVariable
classConstant                      constant                           memberFunctionInString             variable
classExtends                       constantInClassMember              memberVariable                     variableTwoDeclarations
classImplements                    functionAndClassWithSameName       memberVarInString                  variableTwoDeclarationsInFunction
classImplementsMultiple            functionCall                       newObject                          varInString
classParent                        interfaceExtends                   objectWithClassName

the code

You can find the code below, or you can obtain the most up-to-date version on github. Just head over to my shell-helpers repo and peek into the bash_setup_kde4_programming file.

Everyone who uses the command line regularly has a bunch of (at least for him) useful helper scripts. I now took the liberty to put mine on github for general consumption.

You can find them at: http://github.com/milianw/shell-helpers/tree/master

Some of these might be more useful than others, you decide :) Personally, I can’t live without the following:

apupgrade

a shortcut to update your Debian system with one command - no questions asked

openurl

opens a given URL in an already opened browser instance or starts a new browser session. Not only one browser is checked. I use it because firefox is slow to start and konqueror is blazingly fast to start. But when firefox is already open I want to use that.

xerr

shortcut for fast error checking in your Xorg log

clipboard

makes KDE4 Klipper contents available on the CLI (read and write access!)

debug

shortcut to start a GDB session: debug APP APP_ARGS is all you have to do. Its basically the same as doing:

$ gdb APP
> run APP_ARGS

Seems like quite some people are interested in my bash script for downloading ebooks from http://springerlink.com.

That script has some quirks, the greatest of all that it was written in bash which makes it kind of hard to implement new features. And one which was requested was support for books which span multiple pages on SpringerLink.

So here I present springer_download.py - a Python rewrite which should handle all the old links and some more. This is the very first program I’ve written in Python. And since it has to run on the Zedat servers it’s limited to Python 2.4.x without any fancy shmancy additions (a pity, since I’d love to use urlgrabber or pycurl).

the script

You can find the sources on GitHub: http://milianw.github.com/springer_download/

I plan to put all my future code snippets in public repositories on GitHub. That way you can easily track changes and stay up to date. GitHub also has a nice “download” feature which you can use to get the current version. You can find my profile and my repositories at http://github.com/milianw

Note: This script is intended to be run under Linux or other *nix’es which fulfill the requirements (Python 2.4.x, iconv and pdftk). Windows is not supported.

TODO

• introduce multithreading for faster / simultaneous downloads
• add speed to progressbar
• use progressbar in source-downloader
• use one git-repo per project (makes links work properly)

After a long period of silence I present you the following bash script for downloading books from http://springerlink.com. This is not a way to circumvent their login mechanisms, you will need proper rights to download books. But many students in Germany get free access to those ebooks via their universities. I for example study at the FU Berlin and put the script in my Zedat home folder and start the download process via SSH from home. Afterwards I download the tarball to my home system.

Read on for the script.

NOTE: find most recent version on github: https://github.com/milianw/shell-helpers/blob/master/clipboard

Here’s a little script you can save in your path and do things like

# paste current clipboard into file
clipboard > "some_file"
# copy some file into clipboard
cat "some_file" | clipboard

Actually I find it rather useful so I thought I should share it.

#!/bin/bash
 
# Access your KDE 4 klipper on the command line
# usage:
#  ./clipboard
#    will output current contents of klipper
#  echo "foobar" | ./clipboard
#    will put "foobar" into your clipboard/klipper
 
# check for stdin
if ! tty -s && stdin=$(</dev/stdin) && [[ "$stdin" ]]; then
  # get the rest of stdin
  stdin=$stdin$'\n'$(cat)
  # oh, nice - user input! we set that as current
  # clipboard content
  qdbus org.kde.klipper /klipper setClipboardContents "$stdin"
  exit
fi
 
# if we reach this point no user input was given and we
# print out the current contents of the clipboard
qdbus org.kde.klipper /klipper getClipboardContents

As usually, save the file (attached below) in your $PATH and make it executable.

PS: Thanks to Martin Vidner for his article on D-BUS btw. - it gave me the proper dbus commands. PPS: Thanks the the various comments below!

Every now and then I want to profile a given part of PHP code. For example I want to quickly check wether my current changeset to GeSHi works faster or is horribly slower. For a big change I’ll stick to Xdebug and KCachegrind. But for a quick overview? Overkill in my eyes.

Say hello to profile.class.php, a simple timer class for PHP5 which you can use to get an overview about where how much time is spent. This is in no way a scientific method nor should you take the results of a single run as a basis for you decisions.

I’ve set an emphasize on an easy API so you don’t have to pollute your code with arbitrary hoops and whistles.

UPDATE: You can find the current updated source in the SVN repo of GeSHi.

So just yesterday I’ve published a bash script which rips the audio stream of Flash Videos (*.flv) to mp3 format. It’s nice, fast and imo all-purpose. But I didn’t like the audio quality. Thus below you can find a second version of the script which is using mplayer and lame instead of ffmpeg. Usage and behaviour should be pretty much the same. Only the audio quality should be better on cost of a bit more computing.

Since it relies on the fact that the input *.flv video already uses MP3 encoding for its audio stream this might not work for every flash file! Youtube works just fine though. You can find the script after the break, it’s also attached below. For usage / installation / more information read the old article.

If you wonder why I reencode the audiodump with lame: The dumped mp3 file is considered by most (all?) audio players to be ~10x the length. A five minute video gets a 45 minute audio dumpfile. It plays fine but seeking is a mess. Reencoding fixes this. If you know an alternative which does not require reencoding or is generally faster - please drop a comment!