1. qt
    1. Introduction
    2. Installation
      1. Windows
      2. N900
    3. Classes
    4. General
      1. qt:init
      2. qt:run
    5. Widgets
      1. qt:widget
      2. qt:delete
      3. qt:show
      4. qt:hide
      5. qt:find
      6. qt:pixmap
      7. qt:update
    6. Properties
      1. qt:property
    7. Signals and receivers
      1. qt:receiver
      2. qt:connect
      3. qt:emit-signal
      4. qt:invoke-method
    8. Timers
      1. qt:timer
      2. qt:start
      3. qt:stop
    9. Lists
      1. qt:clear
      2. qt:add
      3. qt:item
      4. qt:set-headers
    10. Text edit widgets
      1. qt:selection
      2. qt:insert
    11. Dialogs
      1. qt:message
    12. Sound
      1. qt:sound
      2. qt:play
      3. qt:stop
    13. Global keyboard shortcuts
      1. qt:shortcut
      2. qt:add-action
      3. qt:remove-action
    14. Miscellaneous
      1. qt:char-encoding
      2. qt:gl
      3. qt:classname
    15. DBus
      1. qt:dbus-connect
      2. qt:session-bus
      3. qt:system-bus
      4. qt:dbus-list-names
      5. qt:dbus-send-signal
      6. qt:dbus-register-method
      7. qt:dbus-call
      8. qt:dbus-call-with-callback
      9. qt:dbus-register-service
      10. qt:dbus-unregister-service
    16. Networking
      1. qt:make-http
      2. qt:destroy-http
      3. qt:http-set-host
      4. qt:http-get
      5. qt:http-read-string
    17. Variant list
      1. qt:make-variant-list
      2. qt:variant-list-remove-front
      3. qt:variant-list-insert-back
      4. qt:list->variant-list
      5. qt:variant-list->list
      6. qt:variant-list-length
    18. Example
    19. History
    20. License

qt

Introduction

This extension provides an easy to use interface to Trolltech's Qt 4 toolkit. It provides bindings for the GUI side of Qt, as well as for Qt's builtin networking and dbus libraries. A great way to get started with using this API is to check out the unit tests bundled with this egg, in tests.scm. They provide an example of many of the API calls described here and all of the more complex ones.

Memory management is completely manual (with the exception of child widgets, which are deleted when their parent is). To release the resources of a widget or other Qt objects, call qt:delete.

This Qt binding is necessarily incomplete since Qt is huge and testing every feature after adding it in would be too time consuming. If you miss certain functionality like widget-specific operations, contact the author. Most operations just need trivial 1 line changes to add.

Installation

The QTDIR environment variable must be set to the installation directory of Qt, like this:

QTDIR=/usr/local/Trolltech/Qt-4.2.0 chicken-install qt

Windows

This extension has been tested with the binary distribution of Qt, based on the mingw compiler included in the Qt distribution. It is recommended to use a custom build of CHICKEN that uses this particular gcc version and which is installed directly in the Qt installation directory. So assuming Qt is installed in `c:\Qt\2010.01`, do the following:

 <obtain chicken sources, and cd to that directory>
 
 c:\tmp\chicken> mingw32-make PREFIX=c:/Qt/2010.01 PLATFORM=mingw
 c:\tmp\chicken> mingw32-make PREFIX=c:/Qt/2010.01 PLATFORM=mingw install
 c:\tmp\chicken> chicken-install qt

Note that the author does not have a copy of Windows and as such will not provide any Windows support.

N900

This extension is known to work on at least one embedded device, the Nokia n900. More specific information is available here.

Classes

The following protobj classes are exposed:

<qt>
 <qt-action>
 <qt-dbus-connection>
 <qt-http>
 <qt-object>
  <at-application>
  <qt-widget>
   <qt-text-edit>
  <qt-receiver>
  <qt-timer>
  <qt-sound>
 <qt-pixmap>
 <qt-variant-list>

General

The basic mode of operation is that you create your UI using the qt designer, few bindings currently exist for creating widgets, and export them as an xml file. This file can then be read in to set up windows and widgets. By not having bindings for the widget creation routines we keep this egg at a manageable size, and the qt designer seems to be the best way to use Qt4 anyway. Widgets that must be created on the fly do have bindings.

qt:init

[procedure] (qt:init)

Initializes Qt (including any command-line processing) and returns the application object, an instance of <qt-application>. Performs an implicit

(qt:connect <application> "lastWindowClosed()" <application> "quit()")

qt:run

[procedure] (qt:run [ONCE])

Runs the Qt event loop. If ONCE is given and true, then the procedure returns once all pending events have been processed (use (qt:run #t) in a loop when you want to do some custom idle processing, for example).

Widgets

qt:widget

[procedure] (qt:widget UIXML [PARENT])

Parses the UI description in the string UIXML, which should be the XML representation of a user interface created by the Qt designer application. Returns an instance of <qt-widget>, the toplevel widget. If PARENT is given, the newly created widget will be a child of this.

qt:delete

[procedure] (qt:delete OBJECT)

Deletes OBJECT, which should be an instance of <qt-object> or <qt-pixmap>.

qt:show

[procedure] (qt:show WIDGET)

Shows the given widget.

qt:hide

[procedure] (qt:hide WIDGET)

Hides the widget from view.

qt:find

[procedure] (qt:find WIDGET NAME)

Returns the direct or indirect child widget of WIDGET named NAME (a string) or #f if no such child widget could be found.

qt:pixmap

[procedure] (qt:pixmap FILENAME)

Loads an image file and returns an instance of <qt-image>.

qt:update

[procedure] (qt:update WIDGET)

Schedules a repaint event for the given widget.

Properties

qt:property

[procedure] (qt:property WIDGET PROP)
 (set! (qt:property WIDGET PROP) VALUE)

Get or set a widget property with the name PROP (a string or symbol). See the Qt documentation for more information about which widget supports which properties. Value conversion is automatically, the following value types are supported:

Property (C++) type    Scheme type
QString                string
int                    integer
double                 number
bool                   boolean
char                   char
QPixmap                <qt-image>
Point                  s32vector
Size                   s32vector
Rect                   s32vector
PointF                 f64vector
SizeF                  f64vector
RectF                  f64vector

Signals and receivers

qt:receiver

[procedure] (qt:receiver THUNK)

Returns an instance of <qt-receiver> that when connected to a Qt signal will invoke PROC once the signal is emitted.

qt:connect

[procedure] (qt:connect SOURCE SIGNAL DESTINATION [SLOT])

Connects the signal SIGNAL from the <qt-object> SOURCE to the slot SLOT from DESTINATION. If no slot is given then slot will have the same signature and name as the SIGNAL. Signals and slots should be strings and follow the normal syntax used by Qt. DESTINATION can be a <qt-object> or a scheme function. SLOT can have any number of arguments as long as they can be marshalled back to scheme, the types currently are: int, string, bool, uint and double. Dispatch is handled entirely by Qt using a fake object per call to qt:connect meaning that all of the rules for matching types and numbers of arguments still apply. Returns a procedure that disconnects and frees the memory used by this connection.

qt:emit-signal

[procedure] (qt:emit-signal OBJECT SLOT . ARGUMENTS)

Emit a signal to an object with any number of arguments.

qt:invoke-method

[procedure] (qt:invoke-method OBJECT SLOT [RESULT?] . ARGUMENTS)

Emit a signal to an object, if a RESULT? is true then the return value of the invoked singal will be returned.

Timers

qt:timer

[procedure] (qt:timer SECONDS)

Creates and returns a timer object which can be connected to a receiver and which will emit "timeout()" signals every SECONDS.

qt:start

[procedure] (qt:start TIMER)

Starts the given timer.

qt:stop

[procedure] (qt:stop TIMER)

Stops the given timer.

Lists

qt:clear

[procedure] (qt:clear WIDGET)

Clears all entries from WIDGET which should be a QListWidget.

qt:add

[procedure] (qt:add WIDGET STRING)

Adds a new entry to a QListWidget, QComboBox or QTreeWidget. In the latter case, the columns should be separated by the | character (vertical bar).

qt:item

[procedure] (qt:item WIDGET INDEX)

Returns the text of the QListWidget item with the given index.

qt:set-headers

[procedure] (qt:set-headers WIDGET STRING)

Sets the column headers in a QTreeWidget. Columns should be separated by the | character (vertical bar).

Text edit widgets

qt:selection

[procedure] (qt:selection TEXTEDIT)

Returns the text of the currently active selection, or the empty string, if no text is selected.

qt:insert

[procedure] (qt:insert TEXTEDIT STRING)

Inserts STRING at the current cursor location.

Dialogs

qt:message

[procedure] (qt:message TEXT #!key caption parent button1 button2 button3)

Opens a QMessageBox with the given properties and returns the index of the pressed button.

[procedure] (qt:get-open-filename CAPTION DIRECTORY #!key parent options filter)

Shows a modal file-selection dialog and returns the selected filename (or "", if the dialog was canceled). options should be a list with zero or more of the following keywords:

#:show-dirs-only
#:dont-resolve-symlinks
#:dont-confirm-overwrites
#:dont-use-sheet
#:dont-use-native-dialog
[procedure] (qt:get-save-filename CAPTION DIRECTORY #!key parent options filter)

Shows a modal file-selection for saving.

[procedure] (qt:get-directory CAPTION DIRECTORY #!key parent options filter)

Shows a modal directory-selection dialog.

Sound

qt:sound

[procedure] (qt:sound FILENAME)

Loads a sound-file and returns an instance of <qt-sound>.

qt:play

[procedure] (qt:play SOUND)

Plays the sound asynchronously.

qt:stop

[procedure] (qt:stop SOUND)

Stops a currently playing sound.

Global keyboard shortcuts

qt:shortcut

[procedure] (qt:shortcut KEY)

Creates a keyboard-shortcut action for KEY, which should be a string naming a key-sequence, for example "Ctrl+E". See the Qt documentation for the interpretation of this string. qt:shortcut returns an <qt-action> instance that can be added to a widget with qt:add-action.

qt:add-action

[procedure] (qt:add-action WIDGET ACTION)

Adds the given action to WIDGET.

qt:remove-action

[procedure] (qt:remove-action WIDGET ACTION)

Removes ACTION from WIDGET.

Miscellaneous

qt:char-encoding

[procedure] (qt:char-encoding [ENCODING])

Selects the default character encoding for strings passed to and received from Qt. ENCODING may be one of the symbols ascii, latin1 or utf8. The default is latin1. If no argument is given, then qt:char-encoding returns the current encoding.

qt:gl

[procedure] (qt:gl NAME PARENT INIT RESIZE PAINT)

Creates and returns a QGLWidget. INIT should be zero-argument procedure called to initialize the OpenGL context. RESIZE should be a two-argument procedure called when the widget is resized and receives the new width and height. PAINT is a zero-argument procedure called when the widget should repaint itself. GL output will be automatically flushed.

qt:classname

[procedure] (qt:classname OBJECT)

Returns the name of the Qt class of which OBJECT is an instance.

DBus

Most of the functionality of the DBus API is exposed by these bindings.

qt:dbus-connect

[procedure] (qt:dbus-connect BUS SERVICE OBJECT INTERFACE SIGNAL TO [SLOT])

Unfortunately dbus connections are handled differently in Qt from regular singal/slot connections and this has leaked over. This function works indentically to qt:connect and can connect to both Qt objects and scheme functions.

qt:session-bus

[procedure] (qt:session-bus)

Returns a handle to the session bus.

qt:system-bus

[procedure] (qt:system-bus)

Returns a handle to the system bus.

qt:dbus-list-names

[procedure] (qt:list-names BUS)

Returns the name of a bus (eg: (qt:dbus-list-names (qt:system-bus)) returns "System bus"). The unfortunate name of this function was the choice of the DBus API not the maintainer of the bindings.

qt:dbus-send-signal

[procedure] (qt:dbus-send-signal BUS OBJECT INTERFACE SIGNAL . ARGUMENTS)

Send a signal to a bus.

qt:dbus-register-method

[procedure] (qt:dbus-register-method BUS PATH FUNCTION NAME)

Register a function on a bus with a name and a path, the function must be a scheme function, but it can take arguments and name must conform to the standard Qt slot naming rules.

qt:dbus-call

[procedure] (qt:dbus-call BUS SERVICE PATH INTERFACE METHOD . ARGUMENTS)

Call a method on a bus with any number of arguments.

qt:dbus-call-with-callback

[procedure] (qt:dbus-call-with-callback BUS SERVICE PATH INTERFACE METHOD FUNCTION SLOT . ARGUMENTS)

Call a method on a bus with any number of arguments and connect the output to a function on a slot. The destination must be a scheme function.

qt:dbus-register-service

[procedure] (qt:dbus-register-service bus service)

Register a service on a bus.

qt:dbus-unregister-service

[procedure] (qt:dbus-unregister-service bus service)
    

Unregister a service on a bus.

    

Networking

Currently their its infancy the networking bindings support only http. See the unit tests bundled in tests.scm for how to best use this functionality.

qt:make-http

[procedure] (qt:make-http)

Make an http object, will have to be destroyed in the end with qt:destroy-http.

qt:destroy-http

[procedure] (qt:destroy-http)

Destroy an http object.

qt:http-set-host

[procedure] (qt:http-set-host HTTP SERVER PORT)

Set the host of an http connection.

qt:http-get

[procedure] (qt:http-get HTTP PATH)

Send an HTTP GET.

qt:http-read-string

[procedure] (qt:http-read-string HTTP)

Read back a string from the object, this is non-blocking. The best way to use this is to connect to "done(bool)" and possibly "dataReadProgress(int,int)" on the http object to be notified when the data is available.

Variant list

The basic way of exchanging data with Qt is through QtVariantList.

qt:make-variant-list

[procedure] (qt:make-variant-list)

These will automatically be destroyed by the garbage collector when they are no longer referenced.

qt:variant-list-remove-front

[procedure] (qt:variant-list-remove-front VARIANTLIST)

Remove and return one element from the front of a variant list.

qt:variant-list-insert-back

[procedure] (qt:variant-list-insert-back VARIANTLIST OBJ [SIGNED?])

Insert one element to the back of a variant list. If SIGNED? is not provided it is assumed to be true, this only affects integers.

qt:list->variant-list

[procedure] (qt:list->variant-list LIST)

Convert a scheme list to a variant list.

qt:variant-list->list

[procedure] (qt:variant-list->list VARIANTLIST)

Convert a variant list to a scheme list.

qt:variant-list-length

[procedure] (qt:variant-list-length VARIANTLIST)

Return the length of a variant list.

Example

Given the file hello.ui:

<ui version="4.0" >
<class>Form</class>
<widget class="QWidget" name="Form" >
 <property name="geometry" >
  <rect>
   <x>0</x>
   <y>0</y>
   <width>295</width>
   <height>144</height>
  </rect>
 </property>
 <property name="windowTitle" >
  <string/>
 </property>
 <widget class="QLabel" name="label" >
  <property name="geometry" >
   <rect>
    <x>40</x>
    <y>30</y>
    <width>121</width>
    <height>31</height>
   </rect>
  </property>
  <property name="font" >
   <font>
    <pointsize>15</pointsize>
    <weight>75</weight>
    <bold>true</bold>
   </font>
  </property>
  <property name="text" >
   <string>Hello, world!</string>
  </property>
  <property name="alignment" >
   <set>Qt::AlignCenter</set>
  </property>
 </widget>
 <widget class="QPushButton" name="quitButton" >
  <property name="geometry" >
   <rect>
    <x>180</x>
    <y>90</y>
    <width>75</width>
    <height>31</height>
   </rect>
  </property>
  <property name="text" >
   <string>Quit</string>
  </property>
 </widget>
</widget>
<resources/>
<connections/>
</ui>

Run this to display the Window:

(use qt utils)

(define a (qt:init))
(define w (qt:widget (read-all "hello.ui")))
(qt:connect (qt:find w "quitButton") "clicked()" a "quit()")
(qt:show w)
(qt:run)

A more interesting example can be found here: egg-browser.zip.

History

0.100.3
ported build system from the qt-light egg. This egg has been set as obsolete, see the qt-light egg for qt bindings.
1.0
revamped the qt egg
0.93
(hopefully) fixed more build problems (thanks to Mario)
0.9
fixed Linux build problems and added qt:char-encoding
0.8
I forgot what I did for 0.8
0.7
added support for Windows
0.6
qt.pro is generated by setup script to force usage of correct csc (thanks to Mario Goulart)
0.5
fixed bug in string-result handling that caused random crashes (reported by Christian Kellermann and Mario Domenench Goulart)
0.4
ported to CHICKEN 4, removed Mac OS X support
0.3
generated application bundle on Mac OS X
0.2
added file dialogs and QSound support, fixed bug by making qt:show "safe"
0.1
initial release

License

Copyright (c) 2010, Andrei Barbu
Copyright (c) 2006-2010, Felix L. Winkelmann
All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following
conditions are met:
  Redistributions of source code must retain the above copyright notice, this list of conditions and the following
    disclaimer. 
  Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
    disclaimer in the documentation and/or other materials provided with the distribution. 
  Neither the name of the author nor the names of its contributors may be used to endorse or promote
    products derived from this software without specific prior written permission. 
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS
OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
Send bugs, suggestions and ideas to: 
andrei@0xab.com
Andrei Barbu
Purdue University