QML GUI

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Revision as of 11:18, 29 March 2010 by Akashihi (talk | contribs) (Added gui qml description)
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QML gui is designed to be a modern and flexible replacement of internal gui. It is based on Qt's Declarative UI framework, therefore it could be run on ant Qt platform, including mobile platforms with touchscreens etc

Building it

First of all - you have to install Qt 4.6 and a SNAPSHOT of a Declarative UI With snapshot mentioned above you have to use exactly Qt version 4.6.0, for other 4.6.x releases you have to manually checkout Declarative UI from git. Qt version 4.7 is unsupported yet.

When you have prepared your Qt environment, it's time to build Navit:

./configure --enable-gui-qml

At the script output you should have the following lines:

Graphics types: yes (default)
  qt_qpainter:       yes (default)
GUI types:
  qml:               yes (configure parameter)

both of them are required for gui qml. So if those lines present, do your usual make && make install/dpkg-buildpackage/your platform specific thing.

Configuring it

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

QML gui doesn't requires any special configuration, but it could be tuned. It support the following parameters:

   * fullscreen - "1"-Default is fullscreen mode,"0"-Default is windows mode
   * menu_on_map_click - "1"-single click on map will switch to gui,"0"-Gui could be switched only by command (not yet implemented)
   * signal_on_map_click - "1"-DBus signal will be sent on single click on map,"0"-map click processing will be controlled bu menu_on_map_click
   * radius - Distance in meters for searching point name. Default is 10
   * pitch - Initial pitch for 3D view. Default is 20
   * lazy - "1"-Gui should be lazy and keep it state between calls,"0"-Gui is always reset to main page when called
   * width #height - Width and height for gui window. Default values are 800 and 600
   * source - Directory with qml skins. Default value is NAVIT_SHAREDIR/gui/qml/skins
   * skin - Skin for gui. Default skin is navit
   * icon_src - Directory with icons for gui.Default value is NAVIT_SHAREDIR/xpm/

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 LEFT 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

RIGHT click on map (or loooong tap on touch screen) turns on the gui with special point screen.

Redesigning in

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

   * main.qml
   * point.qml

main.qml will be instantiated when calling a gui for the first time (or every time when "lazy" set to "0") and point.qml used for a special point screen mentioned above. Every other aspect of gui structure and desing 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)
   * returnSource - Tree of visited pages (see below)

gui object also have some slots:

   * setPage
   * backToMap
   * backToPrevPage

All of those slots and returnSource property are related to 'page switch helper'. The idea behind them is to encapsulate every dialog into different qml file and switch them programatically directly from qml. So you may define a button for maps and call gui.setPage("maps.qml") when it is clicked. Every setPage call modifies returnSource property, storing the history of your setPage calls, so when you done with your maps.qml from the example aboe, you could just call gui.backToPrevPage() in it (in maps.qml) and it will work like a back button. gui.backToMap() switch from gui to map, it's obvious. But what if you want to return to your starting point? You could use the following code:

    gui.returnSource=""; gui.setPage("main.qml");

in you qml application. Even more - you could use returnSource any way you like - for returning to the every odd page for exmaple or inserting some new pages into history on some even. You may also not use this functionality at all and implement everything right in the QML app.

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 directo 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 "faluse" in attr_string variable to "1" and "0". It's not a bug :-)

NGQProxy inherited by the following classes:

NGQProxySearch

not yet ready

NGQProxyGui

Object of this class is injected into qml namespace as a gui

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 in space (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 and call a function, that processes it. Right now current point object is set in two cases:

  * Right click on map
  * bookmarks.setPoint call

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 :-)

to be continued