Difference between revisions of "Development/Tutorials/Akonadi/Application"

Jump to: navigation, search
(Tutorial about usage of Akonadi in applications)
 
 
(21 intermediate revisions by 4 users not shown)
Line 1: Line 1:
 +
 +
 
{{TutorialBrowser|
 
{{TutorialBrowser|
  
series=Akonadi Tutorial|
+
series=[[Development/Tutorials#Personal_Information_Management_.28Akonadi.29|Akonadi Tutorial]]|
  
 
name=Using your own data type with Akonadi|
 
name=Using your own data type with Akonadi|
  
pre=[http://mindview.net/Books/TICPP/ThinkingInCPP2e.html C++], [http://www.trolltech.com/products/qt/ Qt], [[Getting_Started/Build/KDE4|KDE4 development environment]]|
+
pre=[http://mindview.net/Books/TICPP/ThinkingInCPP2e.html C++], [http://www.trolltech.com/products/qt/ Qt], [[Getting_Started/Build|KDE development environment]]|
  
 
next=|
 
next=|
  
reading=[[Development/Tutorials/CMake|CMake]]
+
reading=[[Development/Tutorials/CMake|CMake]], [[Projects/PIM/Akonadi/Development_Tools|Akonadi Development Tools]]
 
}}
 
}}
  
Line 36: Line 38:
  
 
A look at the generated project top level directory shows us the following files:
 
A look at the generated project top level directory shows us the following files:
<code>
+
<syntaxhighlight lang="bash">
 
CMakeLists.txt
 
CMakeLists.txt
 
detacher/
 
detacher/
Line 43: Line 45:
 
README
 
README
 
src/
 
src/
</code>
+
</syntaxhighlight>
 
and the following files in sub directory '''src''':
 
and the following files in sub directory '''src''':
<code>
+
<syntaxhighlight lang="bash">
 
CMakeLists.txt
 
CMakeLists.txt
 
detacher.cpp
 
detacher.cpp
Line 59: Line 61:
 
settings.kcfgc
 
settings.kcfgc
 
prefs_base.ui
 
prefs_base.ui
</code>
+
</syntaxhighlight>
  
 
At this stage it is already possible to compile the application, so we can already check if our development environment is setup correctly by creating the build directory and having CMake either generate Makefiles or a KDevelop project file.
 
At this stage it is already possible to compile the application, so we can already check if our development environment is setup correctly by creating the build directory and having CMake either generate Makefiles or a KDevelop project file.
Line 66: Line 68:
  
 
From within the generated top level directory:
 
From within the generated top level directory:
<code>
+
<syntaxhighlight lang="bash">
 
mkdir build
 
mkdir build
 
cd build
 
cd build
 
cmake -DCMAKE_BUILD_TYPE=debugfull ..
 
cmake -DCMAKE_BUILD_TYPE=debugfull ..
</code>
+
</syntaxhighlight>
 
and run the build using make as usual.
 
and run the build using make as usual.
  
Line 76: Line 78:
  
 
From within the generated top level directory:
 
From within the generated top level directory:
<code>
+
<syntaxhighlight lang="bash">
 
mkdir build
 
mkdir build
 
cd build
 
cd build
 
cmake -DCMAKE_BUILD_TYPE=debugfull -G KDevelop3 ..
 
cmake -DCMAKE_BUILD_TYPE=debugfull -G KDevelop3 ..
</code>
+
</syntaxhighlight>
 
and open the generated project with KDevelop and run the build process from there.
 
and open the generated project with KDevelop and run the build process from there.
  
Line 90: Line 92:
 
Now, from left to right, place two '''Tree Views''' and one '''List Widget''' side-by-side.
 
Now, from left to right, place two '''Tree Views''' and one '''List Widget''' side-by-side.
 
Select all three boxes by holding SHIFT and clicking each box with the left mouse button.
 
Select all three boxes by holding SHIFT and clicking each box with the left mouse button.
Use '''Layout Horizontally in a Splitter''' in the '''Form''' menu and then create a main layout by clicking on their parent widget and using '''Layout Vertically" in the '''Form''' menu.
+
Use '''Layout Horizontally in a Splitter''' in the '''Form''' menu and then create a main layout by clicking on their parent widget and using '''Layout Vertically''' in the '''Form''' menu.
  
 
A preview ('''Form''' -> '''Preview''') should now look like this:
 
A preview ('''Form''' -> '''Preview''') should now look like this:
Line 116: Line 118:
 
This change also requires a change in the '''CMakeLists.txt''' file in the top level directory and in the one from the source directory.
 
This change also requires a change in the '''CMakeLists.txt''' file in the top level directory and in the one from the source directory.
  
In the file from the top level directory the following line
+
In the file from the top level directory add the following line
<code>
+
<syntaxhighlight lang="cmake">
include (FindKdepimLibs)
+
find_package (KdepimLibs REQUIRED)
</code>
+
</syntaxhighlight>
 +
 
 +
and change
 +
 
 +
<syntaxhighlight lang="cmake">
 +
include_directories( ${KDE4_INCLUDES} ${QT_INCLUDES} )
 +
</syntaxhighlight>
 +
 
 +
into
 +
 
 +
<syntaxhighlight lang="cmake">
 +
include_directories( ${KDE4_INCLUDES} ${KDEPIMLIBS_INCLUDE_DIRS} ${QT_INCLUDES} )
 +
</syntaxhighlight>
  
 
In the file from the source directory the line
 
In the file from the source directory the line
<code>
+
<syntaxhighlight lang="cmake">
 
target_link_libraries(detacher ${KDE4_KDEUI_LIBS})
 
target_link_libraries(detacher ${KDE4_KDEUI_LIBS})
</code>
+
</syntaxhighlight>
  
 
has to be changed to
 
has to be changed to
  
<code>
+
<syntaxhighlight lang="cmake">
target_link_libraries(detacher ${KDE4_KDEUI_LIBS} ${KDE4_AKONADI_LIBS})
+
target_link_libraries(detacher ${KDE4_KDEUI_LIBS} ${KDEPIMLIBS_AKONADI_LIBS})
</code>
+
</syntaxhighlight>
  
 
== Initialization ==
 
== Initialization ==
Line 140: Line 154:
 
A slot so we can delay its executing using a single shot timer, a technique called "Delayed Initialization", i.e. letting the application create and show its GUI as fast as possible and do any probably time consuming initialization after that.
 
A slot so we can delay its executing using a single shot timer, a technique called "Delayed Initialization", i.e. letting the application create and show its GUI as fast as possible and do any probably time consuming initialization after that.
  
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
private slots:
 
private slots:
 
     void fileNew();
 
     void fileNew();
 
     void optionsPreferences();
 
     void optionsPreferences();
 
     void delayedInit();
 
     void delayedInit();
</code>
+
</syntaxhighlight>
  
 
In '''detacher.cpp''' we need two new include directives:
 
In '''detacher.cpp''' we need two new include directives:
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
#include <QtCore/QTimer>
 
#include <QtCore/QTimer>
  
 
#include <akonadi/control.h>
 
#include <akonadi/control.h>
</code>
+
</syntaxhighlight>
  
 
and the slot's implementation
 
and the slot's implementation
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
void Detacher::delayedInit()
 
void Detacher::delayedInit()
 
{
 
{
Line 163: Line 177:
 
     }
 
     }
 
}
 
}
</code>
+
</syntaxhighlight>
  
 
If the application fails to start Akonadi, it simply quits. A real application should probably tell the user about that though.
 
If the application fails to start Akonadi, it simply quits. A real application should probably tell the user about that though.
Line 169: Line 183:
 
Since we want the slot to be executed delayed, add the following line at the end of the class' constructor
 
Since we want the slot to be executed delayed, add the following line at the end of the class' constructor
  
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
QTimer::singleShot( 0, this, SLOT( delayedInit() ) );
 
QTimer::singleShot( 0, this, SLOT( delayedInit() ) );
</code>
+
</syntaxhighlight>
  
 
Lets add a new public method to the view class. In '''detacherview.h''' add
 
Lets add a new public method to the view class. In '''detacherview.h''' add
  
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
void createModels();
 
void createModels();
</code>
+
</syntaxhighlight>
  
 
and for now with an empty body in '''detacherview.cpp''' (we will get to the implementation shortly)
 
and for now with an empty body in '''detacherview.cpp''' (we will get to the implementation shortly)
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
void DetacherView::createModels()
 
void DetacherView::createModels()
 
{
 
{
 
}
 
}
</code>
+
</syntaxhighlight>
  
 
and call it from '''Detacher::delayedInit()''' after the Akonadi start succeeded
 
and call it from '''Detacher::delayedInit()''' after the Akonadi start succeeded
  
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
void Detacher::delayedInit()
 
void Detacher::delayedInit()
 
{
 
{
Line 198: Line 212:
 
     m_view->createModels();
 
     m_view->createModels();
 
}
 
}
</code>
+
</syntaxhighlight>
  
 
== Connecting Views to Akonadi ==
 
== Connecting Views to Akonadi ==
Line 206: Line 220:
 
Actually, the data type the application will be working on, MIME messages, has an even further specialized model in a type specific sub library.
 
Actually, the data type the application will be working on, MIME messages, has an even further specialized model in a type specific sub library.
  
To properly link this additional library change the source directory's '''CMakeLists.txt''' to this
+
To properly link this additional libraries change the source directory's '''CMakeLists.txt''' to this
<code>
+
<syntaxhighlight lang="cmake">
target_link_libraries(detacher ${KDE4_KDEUI_LIBS} ${KDE4_AKONADI_LIBS} ${KDE4_AKONADI_KMIME_LIBS})
+
target_link_libraries(detacher ${KDE4_KDEUI_LIBS} ${KDEPIMLIBS_AKONADI_LIBS} ${KDEPIMLIBS_AKONADI_KMIME_LIBS} ${KDEPIMLIBS_KMIME_LIBS})
</code>
+
</syntaxhighlight>
  
 
In '''detacherview.cpp'' add the following include directives
 
In '''detacherview.cpp'' add the following include directives
  
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
#include <akonadi/collectionfilterproxymodel.h>
 
#include <akonadi/collectionfilterproxymodel.h>
 
#include <akonadi/collectionmodel.h>
 
#include <akonadi/collectionmodel.h>
 
#include <akonadi/kmime/messagemodel.h>
 
#include <akonadi/kmime/messagemodel.h>
</code>
+
</syntaxhighlight>
  
 
With that we can now properly implement the '''createModels()''' method:
 
With that we can now properly implement the '''createModels()''' method:
  
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
void DetacherView::createModels()
 
void DetacherView::createModels()
 
{
 
{
Line 238: Line 252:
 
             itemModel, SLOT( setCollection( Akonadi::Collection ) ) );
 
             itemModel, SLOT( setCollection( Akonadi::Collection ) ) );
 
}
 
}
</code>
+
</syntaxhighlight>
  
 
The first line creates a [http://api.kde.org/4.x-api/kdepimlibs-apidocs/akonadi/html/classAkonadi_1_1CollectionModel.html CollectionModel] which will get all "folders" from Akonadi and keep this data updated as long as the application is running.
 
The first line creates a [http://api.kde.org/4.x-api/kdepimlibs-apidocs/akonadi/html/classAkonadi_1_1CollectionModel.html CollectionModel] which will get all "folders" from Akonadi and keep this data updated as long as the application is running.
Line 266: Line 280:
 
Using this is quite simple. First we add a new include and a class forward declaration for '''detacherview.h'''
 
Using this is quite simple. First we add a new include and a class forward declaration for '''detacherview.h'''
  
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
#include <akonadi/item.h>
 
#include <akonadi/item.h>
 
class KJob;
 
class KJob;
</code>
+
</syntaxhighlight>
  
 
In the private member section add an [http://api.kde.org/4.x-api/kdepimlibs-apidocs/akonadi/html/classAkonadi_1_1Item.html Item] member:
 
In the private member section add an [http://api.kde.org/4.x-api/kdepimlibs-apidocs/akonadi/html/classAkonadi_1_1Item.html Item] member:
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
private:
 
private:
 
     Ui::detacherview_base ui_detacherview_base;
 
     Ui::detacherview_base ui_detacherview_base;
  
 
     Akonadi::Item mItem;
 
     Akonadi::Item mItem;
</code>
+
</syntaxhighlight>
  
 
and two new slots in the private slots section:
 
and two new slots in the private slots section:
  
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
private slots:
 
private slots:
 
     void switchColors();
 
     void switchColors();
Line 288: Line 302:
 
     void itemChanged( const Akonadi::Item &item );
 
     void itemChanged( const Akonadi::Item &item );
 
     void itemFetchDone( KJob *job );
 
     void itemFetchDone( KJob *job );
</code>
+
</syntaxhighlight>
  
 
In the source file '''detacherview.cpp''' two new includes are required
 
In the source file '''detacherview.cpp''' two new includes are required
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
#include <akonadi/itemfetchjob.h>
 
#include <akonadi/itemfetchjob.h>
 
#include <akonadi/itemfetchscope.h>
 
#include <akonadi/itemfetchscope.h>
</code>
+
</syntaxhighlight>
  
 
for the implementation of the two new slots
 
for the implementation of the two new slots
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
void DetacherView::itemChanged( const Akonadi::Item &item )
 
void DetacherView::itemChanged( const Akonadi::Item &item )
 
{
 
{
Line 332: Line 346:
 
     }
 
     }
 
}
 
}
</code>
+
</syntaxhighlight>
  
 
To trigger the item fetching we connect the first new slot to a signal of the MessageView. In '''DetacherView::createModels()''' add another '''connect''' statement:
 
To trigger the item fetching we connect the first new slot to a signal of the MessageView. In '''DetacherView::createModels()''' add another '''connect''' statement:
  
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
connect( ui_detacherview_base.messageView, SIGNAL( currentChanged( Akonadi::Item ) ),
 
connect( ui_detacherview_base.messageView, SIGNAL( currentChanged( Akonadi::Item ) ),
 
         SLOT( itemChanged( Akonadi::Item ) ) );
 
         SLOT( itemChanged( Akonadi::Item ) ) );
</code>
+
</syntaxhighlight>
  
 
=== Getting the attachments from the message ===
 
=== Getting the attachments from the message ===
Line 349: Line 363:
 
For the application this means two more includes and a typedef:
 
For the application this means two more includes and a typedef:
  
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
#include <kmime/kmime_message.h>
 
#include <kmime/kmime_message.h>
 
#include <boost/shared_ptr.hpp>
 
#include <boost/shared_ptr.hpp>
 
typedef boost::shared_ptr<KMime::Message> MessagePtr;
 
typedef boost::shared_ptr<KMime::Message> MessagePtr;
</code>
+
</syntaxhighlight>
  
 
[http://api.kde.org/4.x-api/kdepimlibs-apidocs/kmime/html/classKMime_1_1Message.html KMime::Message] is the data type and we need the [http://www.boost.org/doc/libs/1_37_0/libs/smart_ptr/shared_ptr.htm boost::shared_ptr] to provide us with the value based behavior required by the item's payload methods.
 
[http://api.kde.org/4.x-api/kdepimlibs-apidocs/kmime/html/classKMime_1_1Message.html KMime::Message] is the data type and we need the [http://www.boost.org/doc/libs/1_37_0/libs/smart_ptr/shared_ptr.htm boost::shared_ptr] to provide us with the value based behavior required by the item's payload methods.
Line 359: Line 373:
 
Equipped with this new tools we can extend '''DetacherView::itemFetchDone()''' by adding the following code at its end:
 
Equipped with this new tools we can extend '''DetacherView::itemFetchDone()''' by adding the following code at its end:
  
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
if ( !mItem.hasPayload<MessagePtr>() ) {
 
if ( !mItem.hasPayload<MessagePtr>() ) {
 
     kWarning() << "Item does not have message payload";
 
     kWarning() << "Item does not have message payload";
Line 375: Line 389:
 
     ui_detacherview_base.attachmentList->addItem( fileName );
 
     ui_detacherview_base.attachmentList->addItem( fileName );
 
}
 
}
</code>
+
</syntaxhighlight>
  
 
{{tip|'''Exercise:''' Instead of using a QListView and simple strings, a model working on the single item would make the application a lot cleaner.}}
 
{{tip|'''Exercise:''' Instead of using a QListView and simple strings, a model working on the single item would make the application a lot cleaner.}}
Line 389: Line 403:
 
First we need a new slot in the private slots section of '''detacherview.h'''
 
First we need a new slot in the private slots section of '''detacherview.h'''
  
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
void detachAttachment();
 
void detachAttachment();
</code>
+
</syntaxhighlight>
  
 
To implement the first sub task, saving the selected attachment into a file, the following new includes are needed in '''detacherview.cpp'''
 
To implement the first sub task, saving the selected attachment into a file, the following new includes are needed in '''detacherview.cpp'''
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
#include <kaction.h>
 
#include <kaction.h>
 
#include <kfiledialog.h>
 
#include <kfiledialog.h>
 
#include <kstandardaction.h>
 
#include <kstandardaction.h>
</code>
+
</syntaxhighlight>
  
 
In the class' constructor create and connect an action and make it available as the attachment list widget's context menu:
 
In the class' constructor create and connect an action and make it available as the attachment list widget's context menu:
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
KAction *detachAction = KStandardAction::cut( this, SLOT( detachAttachment() ), this );
 
KAction *detachAction = KStandardAction::cut( this, SLOT( detachAttachment() ), this );
 
detachAction->setText( i18nc( "@action:button remove an attachment from an email",
 
detachAction->setText( i18nc( "@action:button remove an attachment from an email",
Line 408: Line 422:
 
ui_detacherview_base.attachmentList->addAction( detachAction );
 
ui_detacherview_base.attachmentList->addAction( detachAction );
 
ui_detacherview_base.attachmentList->setContextMenuPolicy( Qt::ActionsContextMenu );
 
ui_detacherview_base.attachmentList->setContextMenuPolicy( Qt::ActionsContextMenu );
</code>
+
</syntaxhighlight>
  
 
{{note|Abusing a KDE standard action like this is not recommendable for real applications. For the scope of this tutorial we overlook this as it provides a quick way to setup an action.}}
 
{{note|Abusing a KDE standard action like this is not recommendable for real applications. For the scope of this tutorial we overlook this as it provides a quick way to setup an action.}}
  
In case the '''i18nc''' function or the text used in it are unexpected, see the [[http://techbase.kde.org/Development/Tutorials/Localization/i18n_Semantics Semantic Markup Tutorial]].
+
To properly link the additional library for file dialog, change the source directory's '''CMakeLists.txt''' to this
 +
<syntaxhighlight lang="cmake">
 +
target_link_libraries(detacher ${KDE4_KDEUI_LIBS} ${KDEPIMLIBS_AKONADI_LIBS} ${KDEPIMLIBS_AKONADI_KMIME_LIBS} ${KDEPIMLIBS_KMIME_LIBS} ${KDE4_KIO_LIBS})
 +
</syntaxhighlight>
 +
 
 +
In case the [http://api.kde.org/4.x-api/kdelibs-apidocs/kdecore/html/klocalizedstring_8h.html#c3e33b6ced4f356d040e165094a5c3d5 i18nc] function or the text used in it are unexpected, see the [[Development/Tutorials/Localization/i18n_Semantics|Semantic Markup Tutorial]].
  
 
Saving the attachment means we need to ask for a saving location, probably including a filename override and get the data from the message.
 
Saving the attachment means we need to ask for a saving location, probably including a filename override and get the data from the message.
  
 
This can be implemented like this
 
This can be implemented like this
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
void DetacherView::detachAttachment()
 
void DetacherView::detachAttachment()
 
{
 
{
Line 480: Line 499:
 
     file.close();
 
     file.close();
 
}
 
}
</code>
+
</syntaxhighlight>
  
{{note|Ideally we would have a direct mapping of file name to attachment pointer, e.g. when using a model working on the Akonadi item.}
+
{{note|Ideally we would have a direct mapping of file name to attachment pointer, e.g. when using a model working on the Akonadi item.}}
  
 
=== Removing the Attachment ===
 
=== Removing the Attachment ===
Line 489: Line 508:
  
 
For the last step another job class is needed: [http://api.kde.org/4.x-api/kdepimlibs-apidocs/akonadi/html/classAkonadi_1_1ItemModifyJob.html ItemModifyJob]
 
For the last step another job class is needed: [http://api.kde.org/4.x-api/kdepimlibs-apidocs/akonadi/html/classAkonadi_1_1ItemModifyJob.html ItemModifyJob]
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
#include <akonadi/itemmodifyjob.h>
 
#include <akonadi/itemmodifyjob.h>
</code>
+
</syntaxhighlight>
  
 
and can be implemented by appending the following code to '''DetacherView::detachAttachment()'''
 
and can be implemented by appending the following code to '''DetacherView::detachAttachment()'''
  
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
// remove attachment from message
 
// remove attachment from message
 
message->removeContent( selectedAttachment, true );
 
message->removeContent( selectedAttachment, true );
Line 511: Line 530:
 
     return;
 
     return;
 
}
 
}
</code>
+
</syntaxhighlight>
  
 
[[Category:Tutorial]]
 
[[Category:Tutorial]]

Latest revision as of 19:38, 15 July 2012


Using your own data type with Akonadi
Tutorial Series   Akonadi Tutorial
Previous   C++, Qt, KDE development environment
What's Next  
Further Reading   CMake, Akonadi Development Tools

This tutorial will guide you through the steps of creating an Akonadi application, an end user program which displays and manipulates PIM data provided by Akonadi.

If you are looking for a tutorial on how to provide data for Akonadi see the Akonadi Resource Tutorial

Contents

[edit] Prerequisites

noframe
 
This section needs improvements: Please help us to

cleanup confusing sections and fix sections which contain a todo


Describe required versions and build setup

[edit] Tutorial Example

The goal of the tutorial is to create a simple application allowing a user to "detach" attachments from e-mails, i.e. save them to disk and remove them from the message.

To stay concentrated on Akonadi related steps, all general application or GUI related steps will done in a minimal fashion.

[edit] Preparation

We can kick-start the application by using KAppTemplate, which can be found as KDE template generator in the development section of the K-menu, or by running kapptemplate in a terminal window.

First, we select the KDE4 GUI Application in the C++ section of the program, give our project a name and continue through the following pages to complete the template creation.

TutorialAkonadiDetacherTemplate.png

A look at the generated project top level directory shows us the following files:

CMakeLists.txt
detacher/
doc/
icons/
README
src/

and the following files in sub directory src:

CMakeLists.txt
detacher.cpp
detacher.desktop
detacher.h
detacher.kcfg
detacherui.rc
detacherview_base.ui
detacherview.cpp
detacherview.h
main.cpp
Messages.sh
settings.kcfgc
prefs_base.ui

At this stage it is already possible to compile the application, so we can already check if our development environment is setup correctly by creating the build directory and having CMake either generate Makefiles or a KDevelop project file.

[edit] Generating Makefiles

From within the generated top level directory:

mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=debugfull ..

and run the build using make as usual.

[edit] Generating a KDevelop project file

From within the generated top level directory:

mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=debugfull -G KDevelop3 ..

and open the generated project with KDevelop and run the build process from there.

[edit] Adjusting the main Qt Designer file

Open the file detacherview_base.ui in Qt Designer and remove the example label. Remove the widget's main layout by clicking on the now empty widget and use the Break Layout menu entry in the Form menu.

Now, from left to right, place two Tree Views and one List Widget side-by-side. Select all three boxes by holding SHIFT and clicking each box with the left mouse button. Use Layout Horizontally in a Splitter in the Form menu and then create a main layout by clicking on their parent widget and using Layout Vertically in the Form menu.

A preview (Form -> Preview) should now look like this: TutorialAkonadiDetacherPreview.png

Finally, change the object names for the three widgets by right clicking it and choosing Change objectName. The left widget should be named folderView, the middle one messageView and the right one attachmentList.

In order to make it build again, edit the file detacherview.cpp and remove the code from the settingsChanged method. The application should now build again and be able to run.

noframe
 
Note
A lot of other code of this generated files is not necessary either, feel free to do more cleanup yourself.

[edit] Promoting Views

The KDE client library for Akonadi has a couple of convenience classes which make our life as application developers more pleasant. Two of these classes are specialized view widgets, one for displaying collections and one for displaying items.

In order to use these widgets instead of ones from Qt we need to use a Qt Designer feature called "promoting". Right click the left widget and choose Promote to. Then fill the form like shown in the next screenshot.

TutorialAkonadiDetacherPromote.png

Click add and promote. Repeat the same for the middle widget, this time using Akonadi::ItemView as the class name and akonadi/itemview.h for the header file.

This change also requires a change in the CMakeLists.txt file in the top level directory and in the one from the source directory.

In the file from the top level directory add the following line

find_package (KdepimLibs REQUIRED)

and change

include_directories( ${KDE4_INCLUDES} ${QT_INCLUDES} )

into

include_directories( ${KDE4_INCLUDES} ${KDEPIMLIBS_INCLUDE_DIRS} ${QT_INCLUDES} )

In the file from the source directory the line

target_link_libraries(detacher ${KDE4_KDEUI_LIBS})

has to be changed to

target_link_libraries(detacher ${KDE4_KDEUI_LIBS} ${KDEPIMLIBS_AKONADI_LIBS})

[edit] Initialization

Since the application will depend on Akonadi running, we can ensure this by starting it if it is not. This is handled by the Akonadi::Control class.

In detacher.h we add another slot called delayedInit() which will perform this initialization. A slot so we can delay its executing using a single shot timer, a technique called "Delayed Initialization", i.e. letting the application create and show its GUI as fast as possible and do any probably time consuming initialization after that.

private slots:
    void fileNew();
    void optionsPreferences();
    void delayedInit();

In detacher.cpp we need two new include directives:

#include <QtCore/QTimer>
 
#include <akonadi/control.h>

and the slot's implementation

void Detacher::delayedInit()
{
    if ( !Akonadi::Control::start( this ) ) {
        qApp->exit( -1 );
        return;
    }
}

If the application fails to start Akonadi, it simply quits. A real application should probably tell the user about that though.

Since we want the slot to be executed delayed, add the following line at the end of the class' constructor

QTimer::singleShot( 0, this, SLOT( delayedInit() ) );

Lets add a new public method to the view class. In detacherview.h add

void createModels();

and for now with an empty body in detacherview.cpp (we will get to the implementation shortly)

void DetacherView::createModels()
{
}

and call it from Detacher::delayedInit() after the Akonadi start succeeded

void Detacher::delayedInit()
{
    if ( !Akonadi::Control::start( this ) ) {
        qApp->exit( -1 );
        return;
    }
 
    m_view->createModels();
}

[edit] Connecting Views to Akonadi

The actual data connection between our views and Akonadi is conveniently handled by specialized models which are also provided by the KDE client library for Akonadi.

Actually, the data type the application will be working on, MIME messages, has an even further specialized model in a type specific sub library.

To properly link this additional libraries change the source directory's CMakeLists.txt to this

target_link_libraries(detacher ${KDE4_KDEUI_LIBS} ${KDEPIMLIBS_AKONADI_LIBS} ${KDEPIMLIBS_AKONADI_KMIME_LIBS} ${KDEPIMLIBS_KMIME_LIBS})

In 'detacherview.cpp add the following include directives

#include <akonadi/collectionfilterproxymodel.h>
#include <akonadi/collectionmodel.h>
#include <akonadi/kmime/messagemodel.h>

With that we can now properly implement the createModels() method:

void DetacherView::createModels()
{
    Akonadi::CollectionModel *collectionModel = new Akonadi::CollectionModel( this );
 
    Akonadi::CollectionFilterProxyModel *filterModel = new Akonadi::CollectionFilterProxyModel( this );
    filterModel->setSourceModel( collectionModel );
    filterModel->addMimeTypeFilter( QLatin1String( "message/rfc822" ) );
 
    Akonadi::ItemModel *itemModel = new Akonadi::MessageModel( this );
 
    ui_detacherview_base.folderView->setModel( filterModel );
    ui_detacherview_base.messageView->setModel( itemModel );
 
    connect( ui_detacherview_base.folderView, SIGNAL( currentChanged( Akonadi::Collection ) ),
             itemModel, SLOT( setCollection( Akonadi::Collection ) ) );
}

The first line creates a CollectionModel which will get all "folders" from Akonadi and keep this data updated as long as the application is running.

However, since this includes collections for other data types as well, we need to filter for the data type we are interested in, MIME messages or in terms of MIME type message/rfc822. This kind of filtering is conveniently supplied in the form of a proxy model called CollectionFilterProxyModel.

The next model, MessageModel is an ItemModel specialized in dealing with our data type, messages.

Setting the models on the respective view almost completes the setup process, the only thing left is to connect the CollectionView to the MessageModel so it changes its data depending on which folder gets selected.

At this stage the application is already capable of showing all your mail folders and headers of all your e-mails!

[edit] Getting at the Attachments

This task can be split into two steps:

  • Getting the message from Akonadi
  • Getting the attachments from the message

[edit] Getting the message from Akonadi

While we could have instructed the MessageModel to get all data for each of its entries, the proper way is to retrieve it only for the items that get selected. Moreover we want to do this asynchronously because we don't want to block the application even is a message is really huge.

The KDE client library for Akonadi offers this kind of functionality through a job-based API, in this case ItemFetchJob.

Using this is quite simple. First we add a new include and a class forward declaration for detacherview.h

#include <akonadi/item.h>
class KJob;

In the private member section add an Item member:

private:
    Ui::detacherview_base ui_detacherview_base;
 
    Akonadi::Item mItem;

and two new slots in the private slots section:

private slots:
    void switchColors();
    void settingsChanged();
 
    void itemChanged( const Akonadi::Item &item );
    void itemFetchDone( KJob *job );

In the source file detacherview.cpp two new includes are required

#include <akonadi/itemfetchjob.h>
#include <akonadi/itemfetchscope.h>

for the implementation of the two new slots

void DetacherView::itemChanged( const Akonadi::Item &item )
{
    // clear attachment list
    ui_detacherview_base.attachmentList->clear();
 
    // re-initialize the member we use for referencing the current item
    mItem = Akonadi::Item();
 
    // create fetch job and let it get the whole message
    Akonadi::ItemFetchJob *fetchJob = new Akonadi::ItemFetchJob( item, this );
    fetchJob->fetchScope().fetchFullPayload();
 
    connect( fetchJob, SIGNAL( result( KJob* ) ), SLOT( itemFetchDone( KJob* ) ) );
}
 
void DetacherView::itemFetchDone( KJob *job )
{
    Akonadi::ItemFetchJob *fetchJob = static_cast<Akonadi::ItemFetchJob*>( job );
    if ( job->error() ) {
        kError() << job->errorString();
        return;
    }
 
    if ( fetchJob->items().isEmpty() ) {
        kWarning() << "Job did not retrieve any items";
        return;
    }
 
    mItem = fetchJob->items().first();
    if ( !mItem.isValid() ) {
        kWarning() << "Item not valid";
        return;
    }
}

To trigger the item fetching we connect the first new slot to a signal of the MessageView. In DetacherView::createModels() add another connect statement:

connect( ui_detacherview_base.messageView, SIGNAL( currentChanged( Akonadi::Item ) ),
         SLOT( itemChanged( Akonadi::Item ) ) );

[edit] Getting the attachments from the message

With the item now fully available, we can proceed to check whether the message has any attachments and if it has display them in the right most widget of our GUI.

MIME messages in KDE are handled by the kmime library.

For the application this means two more includes and a typedef:

#include <kmime/kmime_message.h>
#include <boost/shared_ptr.hpp>
typedef boost::shared_ptr<KMime::Message> MessagePtr;

KMime::Message is the data type and we need the boost::shared_ptr to provide us with the value based behavior required by the item's payload methods.

Equipped with this new tools we can extend DetacherView::itemFetchDone() by adding the following code at its end:

if ( !mItem.hasPayload<MessagePtr>() ) {
    kWarning() << "Item does not have message payload";
    return;
}
 
const MessagePtr message = mItem.payload<MessagePtr>();
const KMime::Content::List attachments = message->attachments();
 
foreach ( KMime::Content *attachment, attachments ) {
    const QString fileName = attachment->contentDisposition()->filename();
    if ( fileName.isEmpty() )
        continue;
 
    ui_detacherview_base.attachmentList->addItem( fileName );
}
Ktip.png
 
Tip
Exercise: Instead of using a QListView and simple strings, a model working on the single item would make the application a lot cleaner.


[edit] Detaching an Attachment

This task can again be split into sub tasks:

  • Saving the selected attachment into a file
  • Removing the selected attachment from the message

[edit] Saving Attachment into File

First we need a new slot in the private slots section of detacherview.h

void detachAttachment();

To implement the first sub task, saving the selected attachment into a file, the following new includes are needed in detacherview.cpp

#include <kaction.h>
#include <kfiledialog.h>
#include <kstandardaction.h>

In the class' constructor create and connect an action and make it available as the attachment list widget's context menu:

KAction *detachAction = KStandardAction::cut( this, SLOT( detachAttachment() ), this );
detachAction->setText( i18nc( "@action:button remove an attachment from an email",
                              "Detach..." ) );
 
ui_detacherview_base.attachmentList->addAction( detachAction );
ui_detacherview_base.attachmentList->setContextMenuPolicy( Qt::ActionsContextMenu );
noframe
 
Note
Abusing a KDE standard action like this is not recommendable for real applications. For the scope of this tutorial we overlook this as it provides a quick way to setup an action.

To properly link the additional library for file dialog, change the source directory's CMakeLists.txt to this

target_link_libraries(detacher ${KDE4_KDEUI_LIBS} ${KDEPIMLIBS_AKONADI_LIBS} ${KDEPIMLIBS_AKONADI_KMIME_LIBS} ${KDEPIMLIBS_KMIME_LIBS} ${KDE4_KIO_LIBS})

In case the i18nc function or the text used in it are unexpected, see the Semantic Markup Tutorial.

Saving the attachment means we need to ask for a saving location, probably including a filename override and get the data from the message.

This can be implemented like this

void DetacherView::detachAttachment()
{
    const QList<QListWidgetItem*> items = ui_detacherview_base.attachmentList->selectedItems();
 
    if ( items.isEmpty() ) {
        kDebug() << "No attachment selected";
        return;
    }
 
    if ( !mItem.hasPayload<MessagePtr>() ) {
        kWarning() << "Item no longer has a payload";
        return;
    }
 
    // get the selected list item's text. it is the attachment's filename
    const QString fileName = items.first()->text();
 
    // ask for a saving location, using the attachment's filename as a
    // suggestion
    KFileDialog dialog( KUrl(), QString(), this );
    dialog.setMode( KFile::Files | KFile::LocalOnly );
    dialog.setOperationMode( KFileDialog::Saving );
    dialog.setConfirmOverwrite( true );
    dialog.setSelection( fileName );
 
    if ( dialog.exec() != QDialog::Accepted ) {
        kDebug() << "Saving cancelled. Aborting detaching";
        return;
    }
 
    const QString saveFileName = dialog.selectedFile();
    if ( saveFileName.isEmpty() ) {
        kDebug() << "Empty target file name. Aborting detaching";
        return;
    }
 
    // find the corresponding attachment data structure
    const MessagePtr message = mItem.payload<MessagePtr>();
    const KMime::Content::List attachments = message->attachments();
 
    KMime::Content *selectedAttachment = 0;
    foreach ( KMime::Content *attachment, attachments ) {
        if ( fileName == attachment->contentDisposition()->filename() ) {
            selectedAttachment = attachment;
            break;
        }
    }
 
    if ( selectedAttachment == 0 ) {
        kWarning() << "Selected attachment file name no longer available in message. Aborting detaching";
        return;
    }
 
    QFile file( saveFileName );
    if ( !file.open( QIODevice::WriteOnly ) ) {
        kError() << "Cannot open target file for writing. Aborting detaching.";
        return;
    }
 
    file.write( selectedAttachment->decodedContent() );
    file.close();
}
noframe
 
Note
Ideally we would have a direct mapping of file name to attachment pointer, e.g. when using a model working on the Akonadi item.

[edit] Removing the Attachment

After successfully saving the attachment we can proceed with removing the attachment from the message data and finally update the item in Akonadi to make it a permanent change.

For the last step another job class is needed: ItemModifyJob

#include <akonadi/itemmodifyjob.h>

and can be implemented by appending the following code to DetacherView::detachAttachment()

// remove attachment from message
message->removeContent( selectedAttachment, true );
 
// and from the listwidget
delete items.first();
 
// prepare Akonadi update
Akonadi::Item item( mItem );
item.setPayload<MessagePtr>( message );
 
Akonadi::ItemModifyJob *modifyJob = new Akonadi::ItemModifyJob( item, this );
if ( !modifyJob->exec() ) {
    kError() << modifyJob->errorString();
    return;
}

This page was last modified on 15 July 2012, at 19:38. This page has been accessed 14,326 times. Content is available under Creative Commons License SA 3.0 as well as the GNU Free Documentation License 1.2.
KDE® and the K Desktop Environment® logo are registered trademarks of KDE e.V.Legal