Building libfreenect with patched libusb under Mac OS X

You need:

• macports
• The following installed macports:
  • git-core
  • cmake
  • libtool
  • libusb-devel

1. Get sources:

• libfreenect:
  • git clone https://github.com/OpenKinect/libfreenect.git
• libusb:
  • git clone git://git.libusb.org/libusb.git

2. Apply patch and build libusb:

1. cd path/to/libusb
2. ./autogen.sh
3. patch -p1 < path/to/libfreenect/platform/osx/libusb-osx-kinect.diff
4. ./configure LDFLAGS=’-framework IOKit -framework CoreFoundation’
5. make
6. sudo make install

3. Start building libfreenect:

1. cd path/to/libfreenect
2. mkdir build
3. cd build
4. ccmake ..
   With the following changes:
   • LIBUSB_1_INCLUDE_DIR: /usr/local/include
   • LIBUSB_1_LIBRARY: /usr/local/lib/libusb-1.0.dylib
5. press ‘c’ and afterwards ‘g’ to generate and exit
6. cmake ..
7. make
8. sudo make install

Lisp: Emacs Autocomplete

Today I hacked some lisp in emacs because I got two new books (Let over Lambda & Land of Lisp).
After a while when the function-definitions became more frequent I missed a language-specific autocomplete (and didn’t only want to use the built-in autocomplete that completes words you wrote earlier) and after some research I found the solution: Emacs Autocomplete. It integrates different language-dictionaries and inserts new words on the fly (with the right settings).

After installing the autocomplete into .emacs.d I inserted the following lines into my .emacs-file to enable it:

;; add .emacs.d to load path
(add-to-list 'load-path "~/.emacs.d")

;; enable autocomplete
(require 'auto-complete-config)
(add-to-list 'ac-dictionary-directories "~/.emacs.d/ac-dict")
(ac-config-default)
(global-auto-complete-mode t)
(auto-complete-mode t)

To get a lisp-specific autocomplete you’ve got to include ac-slime (found at github): put it into your .emacs.d-folder and include it in your .emacs-file via

;; add lisp autocomplete-support
(require 'ac-slime)
(add-hook 'slime-mode-hook 'set-up-slime-ac)

and to switch on autocomplete globally you have to apply a “dirty fix”:

;; dirty fix for having AC everywhere
(define-globalized-minor-mode real-global-auto-complete-mode
  auto-complete-mode (lambda ()
                       (if (not (minibufferp (current-buffer)))
                         (auto-complete-mode 1))))
(real-global-auto-complete-mode t)

Now only one thing is missing: the mentioned inserting of new words on the fly:

;; create and add new words to the dictionary on the fly
(when (require 'auto-complete-config nil 'noerror)
(add-to-list 'ac-dictionary-directories "~/.emacs.d/ac-dict")
  (setq ac-comphist-file  "~/.emacs.d/ac-comphist.dat")
  (ac-config-default))

Emacs for Mac OS X

When switching from aquamacs to emacs you have to make some adjustments to use it properly under Mac OS X.
One of the adjustments is that you could not simply type in “alt-shift-7” to get the normal backslash “\”.
The solution:
Go to “Emacs” – “Preferences” – “Environment” – “Ns : GNUstep/Mac OS X specific features” and set

• the “Ns Command Modifier” -> “meta” and
• the “Ns Alternate Modifier” -> “No modifier“.

Now you can use your alt and meta-keys as usual.

Second I did not remember immediately how to set my previous colors and styles (e.g. the background color or the mouse color) so I will sum up my solution:

• open your “~/.emacs“
• type in (and replace my colors with your own)

(setq default-frame-alist
    (append default-frame-alist
        '((foreground-color . "LawnGreen")
          (background-color . "Black")
          (cursor-color . "LawnGreen"))))

And of course Emacs is much better than vim!

C++: Qt and SQL

Today I want to write something about Qt and its SQL-support. It is quite easy to use it, much more simple than working directly with ODBC and/or SQLite or other libraries because Qt has “build-in” support, you just have to add QT += sql to your .pro-file and specify which library you want to work with.

But let’s start now. I want to demonstrate how easy it is to create a simple timetable with SQLite that looks something like this if you wrap it into a GUI:

Here are the includes:

#include <QTableView>
#include <QSqlDriver>
#include <QSqlDatabase>
#include <QSqlQuery>
#include <QSqlTableModel>
// #include <QSqlError>

At first, create the database using SQLite via

QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
db.setDatabaseName("databaseName");

Then open it (and check it meanwhile) with

if(!db.open()) {
   exit(0); // or do something else
}

Now insert the table using a SQL query:

QSqlQuery query;
query.exec("CREATE TABLE IF NOT EXISTS tableName ("
           "monday varchar(200), "
           "tuesday varchar(200), "
           "wednesday varchar(200), "
           "thursday varchar(200), "
           "friday varchar(200), "
           "saturday varchar(200), "
           "sunday varchar(200))");

After that create a model:

QSqlTableModel model;
model.setTable("tableName");
model.setEditStrategy(QSqlTableModel::OnManualSubmit);

If you choose “OnManualSubmit” as edit strategy you have to save the changes you make inside the model by your own (explanation comes later).
Then set the model header data (Monday-Sunday in the picture):

model.setHeaderData(0, Qt::Horizontal, "Monday");
model.setHeaderData(1, Qt::Horizontal, "Tuesday");
model.setHeaderData(2, Qt::Horizontal, "Wednesday");
model.setHeaderData(3, Qt::Horizontal, "Thursday");
model.setHeaderData(4, Qt::Horizontal, "Friday");
model.setHeaderData(5, Qt::Horizontal, "Saturday");
model.setHeaderData(6, Qt::Horizontal, "Sunday");

and set the model to the view to display it:

model.select();
QTableView view;
view.setModel(model);

But what if you want to add an additional line with an entry in every row? The best news is that you don’t have to write any SQL for adding or deleting if you don’t want to:

int rowCnt = model.rowCount();
model.insertRow(rowCnt);
for(int i = 0; i < model.columnCount(); i++) {
   model.setData(model.index(rowCnt, i), "Put this Entry in every Row");
}
model.submitAll();
model.select();
view.setModel(model);

And if you want to delete the last row:

model.removeRow(model.rowCount() - 1);
model.submitAll();
model.select();
view.setModel(model);

You have to call “submitAll” because of the selected strategy ”OnManualSubmit” that doesn’t save by it’s own.
To clear the whole database, drop the table by querying

query.exec("DROP TABLE IF EXISTS tableName");

After setting up a model and a view you can change your table inside the view, press “save” and everything else is “done by Qt”!

You can find the whole Application at CallToPower – Software – qTimeTable, have fun experimenting with it!

Java, C++: ClassLoader and Qt Resource System

Here a little comparison between the Java ClassLoader and the Qt Resource System:
If you want to load an icon and/or an image e.g. in a Java .jar-file you have to do it this way:

Icon icon;
Image image;
ClassLoader CLDR = this.getClass().getClassLoader();
String path = "src/to/images/name.png";
URL url = CLDR.getResource(path);
// An icon
if (!(url == null)) {
    icon = new ImageIcon(url);
}
// An image
try {
    image = ImageIO.read(CLDR.getResource(path));
} catch (IOException e) {
    // ExceptionHandling here
}

In Qt there is another approach:
The resources associated with an application are specified in a XML-based .qrc-file.
The specified paths are relative to the directory containing the .qrc-file (listed files must be located in the same directory or any sub-directory).
In the source-code the resources are accessible under the same name they have in the source tree, with a “:/” prefix.
Here an example:

<RCC>
    <qresource prefix="/dir/subDir" lang="en">
        <file alias="AliasName">subDir/FileName<file>
    <qresource>
</RCC>

In your source code you can access FileName (if FileName e.g. is a QFile) via

QFile file(":/dir/subdir/AliasName");

after adding the following line to your .pro-file:

RESOURCES = yourRsrcFileName.qrc

The option lang=”langCode” (here: “en”) is for the localization:
If you want to add another language to your application you have to have the file “AliasName_langCode” in your source tree.

And, of course, you don’t have to write the ressource file on your own if you use the QtCreator, there is a nice GUI included.

SICK Robot Day 2009

Today’s the SICK Robot Day 2009 (Link1 | Link2).
I worked on it for the University of Osnabrueck.
Our Robot named KURT avoids collisions, respects the rule “left yields right”, is able to detect numbers as well as markers and drives to the right numbers from 0-9 and/or vice versa.
So…good luck to everyone in Waldkirch.
Here some photos of Kurt2 at our self-made parcours:

And some Videos:

Java: Properties under Mac OS X

Today I changed the Properties from jPortscanner and jNotice under Mac OS X:
At first check if the current System is Mac OS X:

if(System.getProperty("os.name").startsWith("Mac")) { ... }

Then put the Application Name on the MenuBar (leftmost):

System.setProperty("com.apple.mrj.application.apple.menu.about.name",
                    "YourAppName");

Set the MenuBar to the Top of the Screen:

System.setProperty("apple.laf.useScreenMenuBar", "true");

Set the default Look and Feel

UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());

And last but not least it’s possible to set a Dock Icon:

com.apple.eawt.Application.getApplication().setDockIconImage(
ImageIO.read(CLDR.getResource("path/image"));

Here an Image.

C++: Qt: "qBaseConverter"

Today I implemented a Base Converter in C++ using Qt and after about 15 Minutes first successes have become apparent. You can convert from any Base you want to to any Base you want to (you only have to fix the “Number of Bases”-Variable if the default 30 Bases aren’t enough for you):

The basic Function (Slot) is – guess – “void convert()” that gets a Signal whenever a ComboBox or the Text at the LineEdit gets changed:

bool BaseConverter::getInputNumber(long long &number, int base) {
    bool ok;
    // Get Input-Number
    number = ui->lineEdit_input->text().toULongLong(&ok, base);
    // Return if Conversion ok
    return ok;
}

void BaseConverter::convert() {
    // Base to convert from
    int baseFrom = ui->comboBox_choiceFrom->currentIndex() + 2;
    // Base to convert to
    int baseTo = ui->comboBox_choiceTo->currentIndex() + 2;

    long long number;
    // If there is a valid Input
    if(getInputNumber(number, baseFrom)) {
        // Display the converted Number
        ui->lineEdit_output->setText(QString::number(number, baseTo));
    }
}

Lisp: Implementation Competition between Programming Languages

Today I have found an ‘Implementation Competition between Programming Languages’ at fefe´s Blog.

A simple Problem has been implemented and tested in different Languages [ReadMe]:

1. Read in from stdio
2. Split into Words
3. Count the Words
4. Sort Words
5. Print sorted Words

I saw that it wasn´t implemented in LISP yet so I asked Christopher if we don´t want to do that!

So here is the Program in LISP:

; Splits the given 'string' at 'split-string'-Sequence
(defun string-split (split-string string)
(loop with l = (length split-string)
   for n = 0 then (+ pos l)
   for pos = (search split-string string :start2 n)
   if pos collect (subseq string n pos)
   else collect (subseq string n)
   while pos))

; If 'word' in the Hashtable 'ht', increment + 1
; else create new Key-/Value-Pair with Value = 1
(defun insert-key-value (word ht)
  (when (and (stringp word)
	     (string/= word "")
	     (string/= word " ")
	     (not (null word))))   ; no blank words
    (if (gethash word ht)
	(incf (gethash word ht))
	(setf (gethash word ht) 1)))

; Gets a Hashtable 'ht' and a Sort-Function 'sort-fn'
; Optional Parameter: 'by' can be :keys or :values
; Returns a sorted Hashtable of key-value-Pairs
(defun sort-hash-table (ht sort-fn &optional &key (by :keys))
  (let ((sorted-entries nil))
    (maphash #'(lambda (k v) (push (cons k v) sorted-entries)) ht)
    (let ((sort-key #'car))
      (if (equal by :values)
	  (setf sort-key #'cdr))
      (sort sorted-entries sort-fn :key sort-key))))

; Prints a given Hash-Entry = Key-Value-Pair formatted
(defun print-hash-entry (key-value-pair)
  (format t "key: ~t~t~t~S  -  value: ~t~t~t~S~&" (cdr key-value-pair) (car key-value-pair)))

; Counts the Words in a Line and puts them into a Hashtable
;   - Gets a line 'line-in' and a Hashtable
;   - Splits the String into Words
;   - Puts the Words into a Hashmap
(defun count-words (line-in ht)
  (mapcar #'(lambda (word)
	      (insert-key-value word ht))
	  (string-split " " line-in)))

; Creates a Hashtable 'ht'
;   - Reads in Lines fom the Prompt
;   - Calls Count-Words
;   - Sorts and prints the Hash-Table
(let ((ht (make-hash-table :test 'equal)))
  (do ((line-in t))
      ((null line-in) nil)
    (setf line-in (read-line *query-io* nil nil nil))
    (count-words line-in ht))
  (mapcar #'print-hash-entry (sort-hash-table ht #'> :by :values)))

Here the other Implementations and here the Timings.