To circumvent this problem I came up with the idea of showing the small photo in full-screen size once clicked on; another click brings the viewer back to the original view. In terms of LaTeX, Beamer and PDF this means adding a new slide containing only the up-scaled photo and creating click-sensitive hyper-references (a.k.a. links) in both directions between the small image on the regular slide and the big-photo-only slide. As the big-photo-only slide should not interfere with the presentation if you do not click on the small photo, those special slides have to be appended at the very end of your presentation.

Thus, to solve the problem stated above, three subproblems have to be solved:

1. Automatically creating a new slide at the end of your presentation
2. Showing the photo in full-screen size
3. Adding clickable links to jump between the regular slide and the big-photo-only slide

Of course, it should be as flexible and simple for the user as possible, so that it can be included in existing slide sets if necessary.

More Details

The process of creating slides for photos requires to scan through the document and memorize which photos to link to. This “memorization” is implemented in a LaTeX-like way by writing to a special .aux file using \newwrite and related commands. At the beginning, the file is opened for writing:

\newcounter{linkimagecounter}
\setcounter{linkimagecounter}{0}

\AtBeginDocument{%
% open file linkimage.aux for writing images' filenames to it
\newwrite\linkimageoutputstream
\immediate\openout\linkimageoutputstream=linkimage.aux
}

The .aux file only stores image filenames. The links are later generated using the linkimagecounter counter, so that the first link always points to the first file etc.

Whenever there is an image to link, the user uses the \linkimage command:

% use this command to link some content to a large picture at the end of your slides
\newcommand{\linkimage}[2]{%
% create link anchor where link from document's end points to
\hypertarget{linkimagerefbackward\arabic{linkimagecounter}}{%
% create link pointing forward to link source in frames at document's end
\hyperlink{linkimagerefforward\arabic{linkimagecounter}}{%
#1%
}} % close both hypertarget and hyperlink
\immediate\write\linkimageoutputstream{#2}
% step counter
\addtocounter{linkimagecounter}{1}
}

This command takes two arguments: First, the object which is the link source. This can be for example an \includegraphics, a \copyrightbox, or a \beamerbutton command. The second argument is the image’s filename; no includegraphics statement should be used here, as this will be called automatically when generating the big-photo-only slides.
Example:
\linkimage{\copyrightbox{\includegraphics[height=3em]{photo2}}{Thomas Fischer}}{photo2}
\linkimage{\beamerbutton{Show Photo}}{photo2}

Finally, at the end of your slide set after the slide with “questions now, please”, you have to call \flushlinkimages which will insert all big-photo-only slides.

% call this command at the very end of your presentation (even after "Now questions, please" slide)
\newcommand{\flushlinkimages}{%
% internal counter for loop over all linked images
\newcounter{linkimagetotal}
\setcounter{linkimagetotal}{\value{linkimagecounter}}
\setcounter{linkimagecounter}{0}

% close auxiliary file linkimage.aux and re-open it again for reading
\immediate\closeout\linkimageoutputstream
\newread\linkimageinputstream
\immediate\openin\linkimageinputstream=linkimage.aux

% loop over all linked images ...
\whiledo{\value{linkimagecounter}<\value{linkimagetotal}}{%
% read one line (one image filename) at a time (and strip new line character at end)
\endlinechar=-1\immediate\read\linkimageinputstream to \linkimagefilename
% create a new frame per image, center content
\begin{frame}\begin{center}
% create link pointing backward to link source in main document
\hyperlink{linkimagerefbackward\arabic{linkimagecounter}}{%
% create link anchor where link from main document points to
\hypertarget{linkimagerefforward\arabic{linkimagecounter}}{%
\includegraphics[width=\linewidth,height=0.75\paperheight,keepaspectratio]{\linkimagefilename}%
}% hypertarget
}% hyperlink
\end{center}\end{frame}
% step counter
\addtocounter{linkimagecounter}{1}
} % whiledo
% close file
\immediate\closein\linkimageinputstream
}

In above code, first some counters are initialized. As you remember, we use counters to match images and hyper-references. Next we close our .aux file (still open for writing) and open it for reading. This makes a single LaTeX run sufficient to generate the extra slides, as the .aux file is written and read in one pass.

The interesting part is the loop, going through all photos. In each iteration, one filename is read from the .aux file and a simple frame environment is created holding an \includegraphics command maximizing the photo while keeping its aspect ratio. You may have to adjust the height parameter for your personal Beamer theme. Hyper-references (\hyperlink and \hypertarget) are generated as well, corresponding the commands created in the original \linkimage call.

As a clarification: All the LaTeX code above should be placed in a class or style file to be included in your presentation. Within your presentation, you should only use \linkimage and \flushlinkimages, everything else happens automatically.

I would be interested in hearing from you if you see ways to make it more efficient, simpler, or more flexible.

The multiframe environment

The Beamer package’s frame environment has the option allowframebreaks to automatically split a frame once it becomes full or split frames manually using the \framebreak command. Although this solution works, it has two drawbacks:

1. No animation steps can be included using e.g. \only or \pause.
2. The first frame is such a sequence of “split” frames sets its content with a slightly different vertical offset. This is very annoying, because flipping between slides makes the content jump up and down.

Therefore I designed my own solution. Although it is not perfect, it does not show above flaws. The idea is to define a new environment called multiframe via newenvironment and accept one optional parameter. This new environment acts as a replacement for the known frame environment. An important difference is the optional parameter: Whereas Beamer’s original frame parameter accepts a list of options such as allowframebreaks or fragile, multiframe‘s parameter is the frame’s title. Thus, the frame title is no longer set via \frametitle but with this parameter.

Now, the trick to get a sequence of frames is to omit the optional parameter with subsequent frames. In this case, the multiframe environment assumes that this new frame is part of sequence, reuses the previous frame title, but increases the sequence counter as shown in the title.

% new counter to now which frame it is within the sequence
\newcounter{multiframecounter}
% initialize buffer for previously used frame title
\gdef\lastframetitle{\textit{undefined}}
% new environment for a multi-frame
\newenvironment{multiframe}[1][]{%
\ifthenelse{\isempty{#1}}{%
% if no frame title was set via optional parameter,
% only increase sequence counter by 1
\addtocounter{multiframecounter}{1}%
}{%
% new frame title has been provided, thus
% reset sequence counter to 1 and buffer frame title for later use
\setcounter{multiframecounter}{1}%
\gdef\lastframetitle{#1}%
}%
% start conventional frame environment and
% automatically set frame title followed by sequence counter
\begin{frame}%
\frametitle{\lastframetitle~{\normalfont(\arabic{multiframecounter})}}%
}{%
\end{frame}%
}

Drawback with this solution is that it creates a completely new frame, whereas \framebreak can be used (nearly) everywhere in the frame. For example, you can use \framebreak inside an itemize list and split this list. In my solution, you have to close all environments up to the current multiframe and open again all environments as desired.

Example

Without my new environment, you would set plain, single frames using the frame environment. Nothing changes here:

\begin{frame}
\frametitle{The Frame's Title}
Some content \ldots
\end{frame}

Things get different for sequences of frames. With plain LaTeX Beamer, you would do something like this:

\begin{frame}[allowframebreaks]
\frametitle{The Frame's Title}
Some content \ldots
\framebreak
More content on next page
\end{frame}

With my new environment, the corresponding solution would look like this:

\begin{multiframe}[The Frame's Title]
Some content \ldots
\only<2>{Only seen in animation step}
\end{multiframe}
% this is like a frame break
\begin{multiframe}% no optional parameter here!
More content on next page
\end{multiframe}

The copyrightbox Command

When you include photos, images, or drawing on your slides, you should always give credit to the original creator and show license and origin. Some licenses require you to state where you got the image from and which rights have been granted. For someone who wants to reuse your slides or parts of it, it clarifies under which conditions the materials are accessible. From a legal aspect, it suffices in most cases to show all relevant information next to the included image, or collected at the end of your document in a single list.

In the next-to-the-image case, it is common to set the information text in fine print along the bottom or right border of the image. But how to do it in LaTeX? For the solution I am presenting here, I am using a tikzpicture environment to set both the image and the accompanying text in two nodes next to each other. The new command \copyrightbox takes two mandatory parameters and one optional parameter. The first mandatory parameter is supposed to contain the command showing the image or drawing, e.g. an \includegraphics command. The second parameter takes the copyright statement and is usually plain text. The optional parameter is a single character describing the position of the text in relation to the image. Possible values include b (below), l (left), and r (right), where “right” is default if nothing else is specified.

Now, the tricky part is that the image should determine the copyrightbox‘s size and the text should follow this format. In particular, if the text is below the image, the text (more specific, the node containing the text) should be node wider than the image (more specific, the node containing the image); instead it should wrap around consuming several lines if necessary. The same applies to the height in case of left or right alignment. To get the width and height of a node in TikZ, I had to search for a proper solution on the Internet resulting in a quite long statement for commands ydiff and xdiff.

\makeatletter
\newdimen\tu@tmpa%
\newdimen\ydiffl%
\newdimen\xdiffl%
\newcommand\ydiff[2]{%
    \coordinate (tmpnamea) at (#1);%
    \coordinate (tmpnameb) at (#2);%
    \pgfextracty{\tu@tmpa}{\pgfpointanchor{tmpnamea}{center}}%
    \pgfextracty{\ydiffl}{\pgfpointanchor{tmpnameb}{center}}%
    \advance\ydiffl by -\tu@tmpa%
}
\newcommand\xdiff[2]{%
    \coordinate (tmpnamea) at (#1);%
    \coordinate (tmpnameb) at (#2);%
    \pgfextractx{\tu@tmpa}{\pgfpointanchor{tmpnamea}{center}}%
    \pgfextractx{\xdiffl}{\pgfpointanchor{tmpnameb}{center}}%
    \advance\xdiffl by -\tu@tmpa%
}
\makeatother
\newcommand{\copyrightbox}[3][r]{%
\begin{tikzpicture}%
\node[inner sep=0pt,minimum size=2em](ciimage){#2};
\usefont{OT1}{phv}{n}{n}\fontsize{4}{4}\selectfont
\ydiff{ciimage.south}{ciimage.north}
\xdiff{ciimage.west}{ciimage.east}
\ifthenelse{\equal{#1}{r}}{%
\node[inner sep=0pt,right=1ex of ciimage.south east,anchor=north west,rotate=90]%
{\raggedleft\color{black!33}\parbox{\the\ydiffl}{\raggedright{}#3}};%
}{%
\ifthenelse{\equal{#1}{l}}{%
\node[inner sep=0pt,right=1ex of ciimage.south west,anchor=south west,rotate=90]%
{\raggedleft\color{black!33}\parbox{\the\ydiffl}{\raggedright{}#3}};%
}{%
\node[inner sep=0pt,below=1ex of ciimage.south west,anchor=north west]%
{\raggedleft\color{black!33}\parbox{\the\xdiffl}{\raggedright{}#3}};%
}
}
\end{tikzpicture}
}

Example

To use this new command, you simply set the mandatory parameters with some useful values:

\copyrightbox{\includegraphics[width=0.5\linewidth]{images/osmphoto}}{CC-BY-SA, Thomas Fischer}
\copyrightbox[b]{\includegraphics[width=0.5\linewidth]{images/osmphoto}}{CC-BY-SA, Thomas Fischer}

The first example above creates a copyrightbox containing an image as loaded from images/osmphoto.jpg (pdflatex searches for known extensions if you do not specify one), scaled to 50% of the line width, and the copyright statement “CC-BY-SA, Thomas Fischer”. The text will be written on the image’s right side, starting in the lower right corner going upwards. In the second line, the text’s alignment is changed to b: Here the text starts in the lower left corner and goes to the right as usual.

Be aware that the copyrightbox‘s total size is a combination of both the image and text. It will thus be larger than the image alone (as specified with width or height).

On the other side, most browsers support a plugin technology originally coming from the good ol’ Netscape 2.0. Most prominently, it is used for the Flash plugin from Adobe and the PDF plugin as part of the of Acrobat Reader.

So, why not combine both technologies to use KDE parts in “normal” browsers?
With quite little effort, based on some examples by Qt/Nokia, I was able to hack a proof of concept: A small plugin which can be used with browsers such as Mozilla Firefox, Opera, Arora, or Chromium.

So far, the plugin supports PDF and PostScript files (via Okular), OpenDocument text, presentation, and spreadsheet (via KOffice) and MP3/OggVorbis files (via DragonPlayer). More file types can be added with only a few lines of code, given that there is a KDE part installed which can handle this file.

Interested? Visit the project’s homepage and try it out yourself!

After searching for options, I found a pointer to the tee device, which works similar like the tee command on the command line: You can transparently pipe data through it and a copy of all data will be written to a file as well. A new ALSA output device can be configured in ~/.asoundrc using the tee device. It can either record the default device or a specific device:

pcm.tee00 {
        type empty
        slave.pcm "tee:'plughw:0,0','/tmp/out0.wav',wav"
}

Above example will save all audio recording going through plughw:0,0 to file /tmp/out0.wav. If you have different recording and playback devices (e.g. an USB microphone and standard speakers), add multiple section with the corresponding plughw number (also change the device’s name, e.g. pcm.tee10).
In the VoIP application, you have to set the new sound devices for microphone and speakers accordingly:

(numbers and names of devices may differ for you!)

If you make a test call, you will get two output files: one with your microphone’s recording and one with your speaker’s recording. Using a sound editor like Audacity or SoX, you can edit and merge both files.

This approach, however, has one drawback. Every time an application “opens” a sound device, the output file will be recreated and the previous recording will be lost. With Skype, the hangup sound at the end of the recording is such a case. I haven’t found out if you can configure ALSA’s tee device to append to a file instead of overwriting it, but the solution I came up with is to copy the output files to a different location before the phone call is over. To automatize the process, I wrote the following shell script:

#!/bin/sh

while true ; do
        timestamp=$(date '+%Y%m%d-%H%M%S')
        for wav in /tmp/out*.wav ; do
                test -f "$wav" || break
                newwav="$HOME/out/"$(echo "$wav" | sed -e 's/\/tmp\///;s/.wav$/-'$timestamp'.wav/')
                echo "Copying  $wav  to  $newwav"
                cp "$wav" "$newwav"
        done
        sleep 10
done

When running, it will copy every 10 seconds all output wav files from /tmp/ to the out/ directory in your home and append a time stamp to the file name. You simply start this script before starting the phone call and exit it with Ctrl+C. Then, the largest of files out0*.wav or out1*.wav, respectively, in the out directory will be your microphone or speaker recording, respectively.

Wenn mal die Sonne scheint, muss man natürlich gleich die Gelegenheit nutzen und raus an die frische (sprich: eiskalte) Luft gehen.

Device Notifier

Clicking on this icon shows all attached devices, in my example it is a single USB flash drive named ’256MThFisch’.

Device Notifier plasma widget

Clicking on such a device brings up a list of possible actions, e.g. to browse the files with Dolphin or Konqueror, downloading all photos with digiKam, or playing music titles with Amarok.

List of actions with device

Well, this is quite nice for users relying on KDE software only. But what happens if you are a power-user, using terminals such as Konsole? Whenever you want to mount a device, you have to start an application such as Dolphin, Konqueror, or digiKam even if you do not want to use it …

Adding your own Action for Mounting

As KDE4 is very configurable, you can improve this situation. In the System Settings you can configure which action are available when a storage medium becomes available. Here, we are going to add our own action which ‘just’ mounts a device.

System Settings - Advanced

Configuration of Actions for Devices

To add you own action, click on the ‘Add’ button and enter a name for the new action, such as ‘Mount’.

Adding a new action

In this new action, you can an icon which resembles that action of mounting. In my case, I chose emblem-mounted.png from the emblems directory in the Oxygen icon set. For the command to execute, you can enter any command you like. If you want to see no feedback, use /bin/true. In my example, I used /usr/bin/kdialog --msgbox to get a message box showing a confirmation once the mount process is complete.

Next time you plug in an USB drive, a new option will show up to ‘just’ mount you device without starting any bloated application.

List of actions, 'just mount' option included

Once you activate the ‘Mount’ option, it takes 1-2 seconds and a message box pops up confirming the mount operation. The device is read to use in any application.

Message box

Current Issues

The current approach has some minor issues which may get addressed in later improvements:

• Cases where the mounting operation fails are not handled
• The message box does not show the devices name, type or mount point

Still, good luck with testing this ‘hack’

An besagtem Reitsonntag sind wir zu viert nach Kyrkekvarn zu einem Reithof gefahren und haben eine 2-Stunden-Tour gebucht. Am Stall angekommen, mussten wir uns erstmal Ausrüstung (Helm) aus dem Lager aussuchen und vor dem Tor aufstellen. Von einer der Tourleiterinnen wurde uns der Umgang mit Pferden erklärt, wie man Sattel und Saum einstellt und auf das Pferd auf- und absteigt. Jeder von uns wurde zu einem passenden Pferd im Stall eingeteilt und durfte es nach draußen führen. Nachdem alle aufgestiegen und alle Gurte überprüft waren, durften wir zum “Aufwärmen” in einer kleinen Koppel im Kreis reiten um etwas Gefühl für das Tier zu bekommen.

Danach ging es los in die Berge. Zwischendurch wurde immer wieder Halt gemacht, um einige Dinge zu erklären, z.B. die Gangarten. Eine Besonderheit von Islandpferden ist ihre Fähigkeit zum Tölt, eine Gangart, die einen ruhigen Ritt erlauben soll. Ich bin mir aber nicht sicher, ob das bei mir so richtig funktioniert hat, bin trotzdem gut durchgeschüttelt worden…

Da die gesamte Reittruppe aus ca. 15–20 Leute bestand, sind wir als eine lange Kette geritten. Mein Pferd („Blakkur“) kannte die Ausflugsroute schon sehr gut und ist praktisch ohne Lenken der Strecke gefolgt. Auf den Strecken, wo wir galoppieren durften, ist das Pferd von alleine losgerannt.

Etwa auf halber Strecke wurde Rast eingelegt mit Tee/Kaffee und belegten Broten. Für die Pferde gab es Knäckebrot. Danach wurde die Gruppe in eine “langsame” und eine “schnelle” Hälfte aufgeteilt. Als Anfänger sollte ich in der langsamen Gruppe bleiben, aber mein Pferd wollte unbedingt bei der schnellen Gruppe (zuerst weitergeritten) dabei sein. Nur mit kräftigen Zerren ließ es sich zum Warten überreden.

Auf dem Rückweg, überwiegend bergab, hatte man einen schönen Überblick über die Umgebung, trotz des leichten Regens, der dann einsetzte. Zurück am Stall mussten die Pferde versorgt, Zaumzeug abgemacht, gereinigt und ins Lager gebracht werden. Mit dem Wetter hatten wir insgesamt Glück, erst auf der Rückfahrt setzte der Wolkenbruch ein.

Insgesamt ein schöner Ausflug, kann ich jedem Schweden-Touristen wärmstens empfehlen.

Unten die Karte zeigt meinen GPS-Trace von der Reittour. Leider habe ich das Gerät erst ab der Rast eingeschaltet, daher fehlt die erste Tourhälfte.

Kyrekvarn (medium scale, Västra Götaland, Skövde and Jönköping)

Natürlich dürfen die obligatorischen Fotos nicht fehlen. Leider sind nicht alle Fotos auf Grund der wackligen und dunklen Bedingungen scharf geworden.

Aus aktuellem Anlass möchte ich auf den Wahltag am kommenden Sonntag hinweisen. Wer noch nicht so wie ich per Briefwahl abgestimmt hat, kann also noch dem großen Moment des Kreuzchen-machens entgegenfiebern.

Wer sich noch nicht sicher ist, was er wählen soll, sollte sich in der Parteienlandschaft außerhalb der “großen” Parteien umschauen. Bei mehr als 10 weiteren Parteien für die Zweistimme sollte sich eigentlich für jeden etwas finden. Gerade für computer-affine Bürger hat sich in den letzten Monaten eine Alternative entwickelt. Stimmen für kleine Parteien sind übrigens keine verschenkten Stimmen, da Parteien pro erhaltene Stimme Geld vom Staat bekommen können.

Hilfe bei der Entscheidungsfindung bietet übrigens die Bundeszentrale für politische Bildung (kennen einige von uns sicher noch von den Heftchen aus dem Gemeinschaftskundeunterricht) mit ihrem Wahl-O-Mat.

Tip: Wenn keiner der Kandidaten der Erststimme zusagt (insbesondere keiner der beiden großen Blockparteien), kann die Erststimme auch getrennt von der Zweitstimme ungültig gemacht werden (z.B. durch Durchstreichen).

On the other side, Konqueror has a similar adblocking functionality built-in since KDE 3.5 (late 2005). In the configuration dialog, users can add fragments or regular expressions of URLs to be blocked. Maintaining such a list yourself is quite cumbersome, especially if you have accounts on several computers. At least since March 2007 there has been a feature request in KDE’s bug tracking system to add an automatic updater to Konqueror’s ad-filtering.

Last weekend, I started to scratch the itch and implemented an automatic filter list updater. Luckily, the internal format of AdBlock entries in Konqueror matches the one use by AdBlock Plus, except that some advanced features are not (yet) supported. Based on the then-current KDE 4.2.4 code I made changes to both kdelibs and kdebase. The former one contains the KHTML component including the actual filter, the latter contains the code for Konqueror’s settings GUI.

The changes I made to kdelibs work as follows: Read the khtmlrc configuration file to get a list of filter files following the format used by AdBlock Plus. My example configuration file contains several lists from easylist.adblock.org. The filter list files are downloaded and cached if no local copy is available or if it is outdated. Each filter list file is loaded and added to Konqueror’s current filter list each time the browser is started. The user-configured filter list is not modified, as the changes occur in memory only.

If you edit your khtmlrc manually to add new filter lists, this works already fine without GUI. For a better usability experience, I modified Konqueror’s settings dialog so that users can select from a list of preconfigured filter lists (currently, all lists from EasyList) which to actually use. Additionally, the time interval to refresh the lists can be configured.

I refrained from adding an option to add, modify or delete list entries in the GUI. This is simply for two reasons: (1) Users may tend to enter filter lists that do not follow the format (e.g. from other adblocking filter sites) and (2) the list of available filter lists does not change that often that it cannot be changed in the next monthly update of KDE. If users are eager to add more lists not officially approved, they can still edit their configuration files manually.

All patches and an example configuration file are available from bug report 143495 in KDE’s bug tracking system. If you have constructive suggestions, please add you comments to the bug report (do not post comments in this blog, that won’t help). To support the patch in getting approved and added to the official code base, vote for the bug (login required).

Update (20091201): I posted the patches on KDE’s Review Board a few days ago and got a review from David Faure. There are some minor issues to change and fix, but his overall comment was “Nice (but obviously not for 4.4 due to the feature freeze, it will have to be for 4.5)”

Update (20100812): My AdBlock extension has become part of KDE 4.5 Check out this screen shot:

Nun, wir haben die Gelegenheit genutzt, eine kleine Nachtwanderung auf den Hausberg Billingen zu machen.
Die drei folgenden Bilder zeigen den gleichen See (fragt mich nicht nach dem Namen), wobei die dunklen von Norden nach Süden und das helle Bild von Süden nach Norden jeweils gegen Mitternacht aufgenommen wurden. Der Nebel deutet an, daß es gar nicht trocken-sommerlich warm war…

Midsommar auf Billingen

Midsommar auf Billingen

Midsommar auf Billingen

Von besagtem Billingen aus hat man auch eine schöne Sicht auf die Stadt Skövde (wobei es auf dem Bild etwas heller aussieht, als es wirklich war):

Midsommar: Blick auf Skövde

Mit diesen Bildern gehe ich in den Sommerurlaub und wünsche allen ein schönes Mittsommerfest!

^* Anders als in Deutschland üblich verkaufen Lebensmittelgeschäfte, die sonntags offen haben, normalerweise kein Benzin.