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In this step, we will attempt to increase the usability of p5, in order to learn how to use a few other standard KDE classes that should be used in nearly every application.
require 'Korundum'
class Browser < KDE::MainWindow
k_dcop 'void setURL(QString)'
slots 'fileSetDefaultPage()',
'changeLocation()',
'bookLocation()',
'gotoPreviousPage()',
'openURLRequest(const KURL&, const KParts::URLArgs&)'
TOOLBAR_ID_ADDBOOKMARK = 1
TOOLBAR_ID_BACK = 2
TOOLBAR_ID_QUIT = 3
def initialize( name )
super(nil, name)
setCaption("KDE Tutorial - p7")
@history = []
filemenu = Qt::PopupMenu.new
filemenu.insertItem( i18n( "&Set default page" ),
self, SLOT( 'fileSetDefaultPage()' ) )
filemenu.insertItem(i18n( "&Quit" ), $kapp, SLOT( 'quit()' ))
about =
i18n("p7 1.0\n\n" +
"(C) 1999-2002 Antonio Larrosa Jimenez\n" +
"larrosa@kde.org\t\tantlarr@supercable.es\n" +
"Malaga (Spain)\n\n" +
"Simple KDE Tutorial\n" +
"This tutorial comes with ABSOLUTELY NO WARRANTY \n" +
"This is free software, and you are welcome to redistribute it\n" +
"under certain conditions\n")
helpmenu = helpMenu(about)
menu = menuBar()
menu.insertItem( i18n( "&File" ), filemenu)
menu.insertSeparator()
menu.insertItem(i18n("&Help"), helpmenu)
toolbar = KDE::ToolBar.new(self)
icons = KDE::IconLoader.new()
toolbar.insertButton(icons.loadIcon("reload", KDE::Icon::Toolbar), TOOLBAR_ID_ADDBOOKMARK,
SIGNAL('clicked(int)'),self,SLOT('bookLocation()'),true,
i18n("Add to Bookmarks"))
toolbar.insertButton(icons.loadIcon("back", KDE::Icon::Toolbar), TOOLBAR_ID_BACK,
SIGNAL('clicked(int)'),self,SLOT('gotoPreviousPage()'),
false, i18n("Back to previous page"))
toolbar.insertButton(icons.loadIcon("exit", KDE::Icon::Toolbar), TOOLBAR_ID_QUIT,
SIGNAL('clicked(int)'),$kapp,SLOT('quit()'),true,
i18n("Quit the application"))
addToolBar(toolbar)
vbox = Qt::VBox.new( self )
@location = Qt::LineEdit.new( vbox )
config = $kapp.config()
config.setGroup("Settings")
@location.text = config.readEntry( "defaultPage", "http://localhost")
connect( @location , SIGNAL( 'returnPressed()' ),
self, SLOT( 'changeLocation()' ) )
split = Qt::Splitter.new( vbox )
split.setOpaqueResize()
@browser = KDE::HTMLPart.new( split )
@browser.openURL( KDE::URL.new(@location.text()) )
connect( @browser.browserExtension(),
SIGNAL( 'openURLRequest( const KURL&, const KParts::URLArgs& )' ),
self, SLOT( 'openURLRequest(const KURL&, const KParts::URLArgs& )' ) )
setCentralWidget(vbox)
end
def changeLocation()
@history.push( @browser.url().url() );
toolBar().setItemEnabled( TOOLBAR_ID_BACK, true)
@browser.openURL( KDE::URL.new(@location.text()) )
end
def setURL( url )
@location.text = url
changeLocation()
end
def openURLRequest(url, part)
setURL( url.url() )
end
def gotoPreviousPage()
@location.text = @history.pop()
if @history.empty?
toolBar().setItemEnabled(TOOLBAR_ID_BACK, false)
end
@browser.openURL( KDE::URL.new(@location.text()) )
end
def bookLocation()
dcopRef = KDE::DCOPRef.new("p8", "BookMarkList")
if ! dcopRef.add(@location.text())
Qt.qWarning("Error with DCOP\n")
end
end
def fileSetDefaultPage()
config = $kapp.config()
config.group = "Settings"
config.writeEntry( "defaultPage", @browser.url().url() )
end
end
about = KDE::AboutData.new("p7", "Tutorial - p7", "0.1")
KDE::CmdLineArgs.init(ARGV, about)
a = KDE::UniqueApplication.new()
window = Browser.new( "Tutorial - p7" )
window.resize( 300, 200 )
a.mainWidget = window
window.show
a.exec
The first thing we do is to add a DCOP interface to p7 for p8 (the next generation on bookmark lists :-) ) to use. It's very similar to the one in p6, so I won't comment on it.
a = KDE::UniqueApplication.new()
Here we create a KDE::UniqueApplication, rather than a KDE::Application as before. This means that only a single instance of the app will ever be started, and it will always be known to DCOP as 'p7'. If we had created a KDE::Application it would be given a name 'p7-process id', such as 'p7-2469'.
TOOLBAR_ID_ADDBOOKMARK = 1
TOOLBAR_ID_BACK = 2
TOOLBAR_ID_QUIT = 3
Ok, we're now looking at the beginning of p7.rb. Here we define some identifiers to identify the toolbar buttons. This isn't always needed and you may create toolbars letting the toolbar class assign default identifiers. But as we're going to enable/disable toolbar buttons, it's more clear to do it this way.
def initialize( name )
super(nil, name)
setCaption("KDE Tutorial - p7")
@history = []
filemenu = Qt::PopupMenu.new
filemenu.insertItem( i18n( "&Set default page" ),
self, SLOT( 'fileSetDefaultPage()' ) )
We're going to name this object Browser.
There's now another item on the File menu, it will be used to
set the actual page to be the default one that will be downloaded when running
the application. This will show us how to store a configuration variable.
toolbar = KDE::ToolBar.new(self)
KDE::ToolBar is the class that implements a tool bar in KDE. By using
it you automatically get the standard look of tool bars, a little handle to
move it in and out of the window, etc.
icons = KDE::IconLoader.new()
toolbar.insertButton(icons.loadIcon("reload", KDE::Icon::Toolbar), TOOLBAR_ID_ADDBOOKMARK,
SIGNAL('clicked(int)'),self,SLOT('bookLocation()'),true,
i18n("Add to Bookmarks"))
toolbar.insertButton(icons.loadIcon("back", KDE::Icon::Toolbar), TOOLBAR_ID_BACK,
SIGNAL('clicked(int)'),self,SLOT('gotoPreviousPage()'),
false, i18n("Back to previous page"))
toolbar.insertButton(icons.loadIcon("exit", KDE::Icon::Toolbar), TOOLBAR_ID_QUIT,
SIGNAL('clicked(int)'),$kapp,SLOT('quit()'),true,
i18n("Quit the application"))
We are going to add three buttons, the first one will be used instead of the big (and if you allow me, ugly) button that we used on p5. The second button will be used to go back to the previous visited page, so we are going to need a way to handle the history of visited pages. Finally, the third button will be used to quit the application (note: The user interface authorities recommend not to put a button on the toolbar to quit the application, anyway, as this is not a real application, we are going to omit this serious advice).
icons.loadIcon("reload", KDE::Icon::Toolbar) is a method that automatically searches the
reload icon (wherever it may be, given that it's on a standard
place for toolbar icons, like $KDEDIR/share/toolbar or $KDEDIR/share/apps/<appname>/toolbar ) and returns a valid QPixmap object that stores it.
The next parameter is the identifier we are going to use later to refer to this
button, then comes the signal we are going to connect and the object that will
receive it, followed by the slot that will be called. Note that most times,
you won't need to worry about toolbar buttons, so you can just use 0 as the
identifier for every button as you don't need to assign an unique indentifier to
each one. An exception to this is when you want to enable/disable a button, as
we want to do with the back button.
addToolBar(toolbar)
We have finished constructing the toolbar, so we add it to the main widget with
addToolBar. addToolBar doesn't follow the same
naming style as setMenu because you're not restricted to just use a toolbar
(as you are with menus), so you're not setting it, but adding it.
config = $kapp.config()
config.setGroup("Settings")
@location.text = config.readEntry( "defaultPage", "http://localhost")
We already know what $kapp is, but we haven't used the config()
method before. This method returns the active KDE::Config object of this application.
KDE::Config is used to store the configuration variables of an application. It
automatically stores the keys on the application configuration file and restores
them when running the application again.
Once we have the config object, we set the active group to Settings
to work on it. Groups are used to better structure the configuration file.
Finally, instead of using the "http://localhost" string as the
default location, we read the application configuration. defaultPage
is the name of the key we want to read, and "http://localhost" is
the default value that is returned in case the config file doesn't store any
value for defaultPage
You can also read integer values with KDE::Config.readNumEntry, boolean
values with KDE::Config.readBoolEntry, etc.
def setURL( url )
@location.text = url
changeLocation()
end
This method is now used to generically set a given url. Currently this function
can be called by the DCOP interface or when the user clicks on a link.
We first set the location text to display the url, and then call the
changeLocation method.
def changeLocation()
@history.push( @browser.url().url() );
toolBar().setItemEnabled( TOOLBAR_ID_BACK, true)
@browser.openURL( KDE::URL.new(@location.text()) )
end
changeLocation (which is also connected to the
enterPressed() signal in the location object)
is used as the central place to load a new page once the url is already on the
location bar. It is done this way to implement history capabilities into p7.
We note now that we defined a @history array in the constructor.
Now we get the default toolbar (if there were more, we could get the other
ones by using an identifier as a parameter to toolBar), and
enable the back button to let the user click on it.
Finally, we open the new url in the @browser widget by getting the
url from the location bar.
def gotoPreviousPage()
@location.text = @history.pop()
When the user wants to go back to the previous page we just take out the last inserted element from the history stack (with pop as it's a stack after all :-) ) and put it on the location bar. The string is removed from the stack, so the next time we call pop, we take the previous url, and so on until the stack is empty.
if @history.empty?
toolBar().setItemEnabled(TOOLBAR_ID_BACK, false)
end
@browser.openURL( KDE::URL.new(@location.text()) )
end
If the stack is empty, we better disable the back button, once we
add another element, the button is enabled again in
changeLocation(). Then, we open the popped url in the
browser.
def fileSetDefaultPage()
config = $kapp.config()
config.group = "Settings"
config.writeEntry( "defaultPage", @browser.url().url() )
end
Finally, we implement the method that is connected to the Set default
page menu item. This method stores the current url in the configuration
file of this application.
First we get the KDE::Config object and set the Settings group as we
did in the constructor. Then, we write a new entry with writeEntry.
The first parameter is the name of the key and the second one is the value we set it to. We can use writeEntry with different data type variables in the second parameter (Integer, Boolean, Float, String, Array of Strings, Qt::Font, etc).
We are now reaching the end of the tutorial, but first, we have to make a little change to p8 so that it communicates with p7 in order to set the current page when you click on a url in the bookmark list (in other case, there's not much point in having a bookmark list :-) )
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