QML GUI

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Qml point 20100404.png

The QML GIU is designed to be a modern and flexible replacement of internal gui. It is based on Qt's modelling language UI framework, therefore it could be run on any Qt platform, including mobile platforms with touchscreens etc

Building it

Install from source or from distribution packages?

The following instructions are for installing the Qt libraries from source. On Linux, it is usually easier to install Qt from the package manager instead. See Dependencies for the packages to install.

Download Qt libraries

So you have decided to install from source? Fine.

First of all - you will need the Qt 4 libraries and headers installed. Navit needs Qt 4.7 or 4.8. This can be downloaded from:

Configure and build Qt

The following example instructions are for configuring and building Qt on Ubuntu 10.04. The procedure for your particular device may vary. Note: The "4.8.0" has to be adjusted depending on the version you install.

  • Unzip the archive into a folder of your choice. The following example has unzipped to ~/src.
  • cd to that folder in a terminal
cd ~/src/qt-everywhere-opensource-src-4.8.0/
  • Configure Qt
./configure
  • During configure:
    • Asks what type to use: Commercial or Open Source. Select Open Source ('o')
    • Asks to accept licence: Chose 'yes'
  • Make Qt (this may take a long time: ~5hrs on a netbook)
 make 
  • Install Qt
 sudo make install 

Add Qt to your environment

Issue the following commands at a terminal to ensure that Navit can find Qt:

PATH=/usr/local/Trolltech/Qt-4.8.0/bin:$PATH
export PATH
export PKG_CONFIG_PATH=/usr/local/Trolltech/Qt-4.8.0/lib/pkgconfig

Build Navit

Once you have prepared your Qt environment, it's time to build Navit. If Qt is installed correctly, the CMake build should pick it up and enable Qt support automatically.

At the script output you should have the following lines:

Enabled   qt_qpainter ( Qt libraries found )
[...]
Enabled   qml ( Qt Declarative found )

Both qt_qpainter and qml are required to successfully run the qml GUI. If those lines are present, do your usual make && make install/dpkg-buildpackage/your-platform-specific thing.

Configuring Navit.xml

Right now QML gui is compatible only with qt_qpainter graphics type. I hope there will be more graphics types in the future, but right now you have to switch to qt_qpainter:

    <graphics type="qt_qpainter"/>

And enable qml gui:

    <gui type="qml" enabled="yes"/>

All other gui modules MUST be disabled by setting

    enabled="no"

in their configuration stanzas.

Configuring QML GUI

QML gui doesn't require any special configuration, but it can be tuned. It supports the following parameters, which go inside the <gui> tag (default values in bold). You can have as many of the parameters as you want in the <gui> tag:

fullscreen

  • "0" - Start Navit in windowed mode (default)
  • "1" - Start Navit in fullscreen mode

Example:

 <gui type="qml" enabled="yes" fullscreen="1">

menu_on_map_click

  • "0" - Menu GUI is switched by a command (not yet implemented)
  • "1" - Single click on map will bring up the menu GUI (default)

Example:

 <gui type="qml" enabled="yes" menu_on_map_click="1">
(A bit useless since this is the default anyway...)

signal_on_map_click

  • "0" - When single clicking on the map, processing to be controlled by menu_on_map_click (default)
  • "1" - When single clicking on the map, send a DBus signal

radius

This takes a number, which is the distance in kilometres which POI search will restrict to

  • "10" - Default POI search radius, in kilometres (default)

Example:

 <gui type="qml" enabled="yes" radius="5">
(Restrict POI search to a 5km radius)

pitch

This takes a number, which is the angle of the 3D view in degrees with which Navit should start when in 3D mode.

  • "20" - Default 3D pitch, in degrees (default)

lazy

  • "0" - When menu GUI is called (such as when single-clicking on the map), always show the main menu page
  • "1" - When menu GUI is called (such as when single-clicking on the map), show the menu page which was last used (i.e. remember menu page states between calls) (default)

Example:

 <gui type="qml" enabled="yes" lazy="0">

width/height

This takes a number, which is the desired width/height of the GUI window, in pixels

  • width=800 - Default width of GUI window, in pixels (default)
  • height=600 - Default height of GUI window, in pixels (default)

source

This takes a directory path, pointing to the qml skins.

  • "NAVIT_SHAREDIR/gui/qml/skins" - Default qml skins directory (default)

Example:

 <gui type="qml" enabled="yes" source="/home/netbook/src/navit/navit/gui/qml/skins">
(Use the full path, not "~/")

skin

This takes a string of text, with the name of the skin to use for the menu GUI. These are defined within the skins folder (see above).

  • "navit" - Default menu GUI skin (default)

icon_src

This takes a directory path, pointing to the icons for the menu GUI

  • "NAVIT_SHAREDIR/xpm/" - Default menu GUI icons directory (default)

Using it

I can't give any advices on using this gui, cause it is very flexible by it's nature, so there could be a lot of variations and customizations on it, but there are exists some hardcoded things. With click on map (or touchscreen tap) gui is usually switched on. This behavior could be controlled by two attributes:

   * menu_on_map_click - controls whether menu should be called on map click or not

and

   * signal_on_map_click - controls whether signal should be sent on map click or usual click processing should be used

Depending on "lazy" attribute, menu will be reset to point page before switching to or not, but current point is always updated after click.

Redesigning it

The gui qml skin is just a directory containing qml application of any kind of complexity (yes, you CAN add twitter client into gui, no problem at all). Navit requires that qml app must contain two files:

   * main.qml
   * command.js

main.qml is used as a menu entry page.command.js is used to handle a OSD command. Every other aspect of gui structure and desigg is controlled by you, but gui qml module provides some helper functions.

gui object

Gui qml module injects a 'gui' object into global qml namespace. This object contains following properties:

   * width - current width of gui's window
   * height - current height of gui's window
   * localeName *langName *ctryName - Name of POSIX locale and WIN32 language and country names (READ ONLY)
   * iconPath - Directory for icons (READ ONLY)
   * commandFunction - name of a command to execute, see commands section for details (READ ONLY)

gui object also have some slots:

   * backToMap
   * pushPage(QString)
   * popPage()
   * lengthPage()

Those slots are related to 'page switch helper'. backToMap switches between map and gui widget, obviously. The *Page() slots are more interesting - pushPage(QString) puts some string value into the stack and popPage() returns top string from the stach. lengthPage() return stack's size. This stack could be used for keeping page switching history, so you 'push' a page when you switch to it and 'pop' a page to know, where to get back.

Proxy objects

The gui object above is a kind of a proxy object Navit is written in pure C and QML is based on Qt, so there are no direct way of exposing Navit's data to qml engine, so we have to use proxies between them. Generic proxy object is based on NGQProxy class

class NGQProxy : public QObject {
	Q_OBJECT;

public:
    NGQProxy(struct gui_priv* this_,QObject *parent) : QObject(parent);
public slots:
	//Attribute read/write
	QString getAttr(const QString &attr_name);
	void setAttr(const QString &attr_name, const QString &attr_string);
};

NGQProxy provides generic setAttr/getAttr functions, that are mediating between QML and Navit's attributes system. I have to metion specially here - setAttr will convert "true" and "false" in attr_string variable to "1" and "0". It's not a bug :-)

NGQProxy inherited by the following classes:

NGQProxySearch

Object of this class is injected into qml namespace as a search and provides access to the Navit's search API.

class NGQProxySearch : public NGQProxy {

	Q_PROPERTY(QString countryName READ countryName WRITE setCountryName NOTIFY countryNameSignal);
	Q_PROPERTY(QString countryISO2 READ countryISO2 WRITE setCountryISO2 NOTIFY countryISO2Signal);
	Q_PROPERTY(QString townName READ townName WRITE setTownName NOTIFY townNameSignal);
	Q_PROPERTY(QString streetName READ streetName WRITE setStreetName NOTIFY streetNameSignal);

	Q_PROPERTY(QString searchContext READ searchContext WRITE setSearchContext);

public slots:
	void setPointToResult();
	QString searchXml();
};

To search something, we need to set a

   * 'searchContext' property to one of the search targets: country,town,street,number
   * put your query into corresponding *Name property
   * call searchXML

the searchXML return search result in the following format

    <search>
        <item>
            <id></id>
            <name></name>
            <icon></icon>
        </item>
        ....more items here...
    </search>

So it can be easily used with XmlListModel. Search expected to be used in hierarchical way, that means that you should first select a country, then city, then street and, finally, house number. You may stop at any level you want, actually :) Search will work, if you start with some sub-level, without searching for upper levels, but will react much more slowly.

NGQProxyGui

Object of this class is injected into qml namespace as a gui and described above.

NGQProxyBookmarks

Object of this class is injected into qml namespace as a bookmarks. This object provides access to the bookmark manager. It have following slots:

   * getAttrList
   * AddBookmark(name)
   * Cut(name)
   * Copy(name)
   * Paste(name)
   * Delete(name)
   * setPoint(name)

and single property:

   * currentPath

It doesn't provides valid setAttr/getAttr functions! They will always fail. For AddBookmark/Cut/Copy/Page/Delete/setPoint you MUST specify full bookmark name, with path, but for Paste just a PATH, without name part, should be specified. AddBookmark uses coordinates from a current 'point' object (see below) and setPoint sets the current 'point' object to point in the bookmark. currentPath property used for traversing the bookmarks tree and positioning in it. getAttrList provides QML namespace with 'listModel' object of type NGQStandardItemModel (see below) for bookmarks list view.

NGQProxyNavit

Object of this class is injected into qml namespace as a navit. This object provides access to the global navit object. Slots are:

   * quit - quits the Navit immediately
   * setObjectByName(name,value) - sets the current values of various objects by their name (only 'layout' and 'vehicle' supported right now)
   * setDestination/setPosition - sets the destination/position to the current point
   * getAttrList - Proveds QML nameSpaces with 'listModel' object (see below) containing lists of different types of attributes ('layout' and 'vehicle' only at the moment)


The current point concept

There are special object 'point' of type NGQPoint that represents a 'current point'. Current point is a point on map (with coordinates and may be with name and other attributes) which is used by other proxy objects. So you don't pass the coordinates or something to navit.setDestination or bookmarks.AddBookmark. You set current point object to their values and call a function, that processes it. The current point object is set in following cases:

  * Click on map
  * navit.getPosition/navit.getDestination call
  * bookmarks.setPoint call
  * point.setNewPoint call

Point could have a type:

    enum NGQPointTypes {MapPoint,Bookmark,Position,Destination,PointOfInterest};

which could be used for conditional rendering etc

Point object provides three properties:

   * coordString - Formatted textual representation of point's coordinates.
   * pointName - Name of a point, either specified during point creation/setting or calculated from map data.
   * pointType - Name of point's type.

The listModel

In a few words - listModel is a way to represent list data to qml. It is a variation of QStandardItemModel, but with several new roles defined:

	enum listRoles {ItemId=Qt::UserRole+1,ItemName=Qt::UserRole+2,ItemIcon=Qt::UserRole+3,ItemPath=Qt::UserRole+4};

the listModel is filled by getAttrList call andstored in global QML namespace. That also means, that you only can use a single list on a page :-)

Commands

Navit supports scriptable commands, usually found in OSD, but not limited to and those commands are another one way of user interaction with gui. Commands are usually defined in a form of a:

    object.command(attribute=value,attribute=value,...,attribute=value)

so gui (our object) gets a call from navit to execute a command with some parameters. In qml gui we delegate execution function to command.qml which should read the current command from a gui.commandFunction and execute it somehow. It is designed to be very flexible, so command to this gui should be in form of:

    gui.command(attribute=value)

The internal callback handler reads the function name and stores it in the gui.commandFunction property, so adding a new command does not requires a c++ coding.