Lists API: Using Lists API

Defining a listbox in resource file

Listbox resources are described with the LISTBOX structure, as defined in the eikon.rh file.

STRUCT LISTBOX
    {
    BYTE version;    // version number
    WORD flags;      // listbox flags
    WORD height;     // in items
    WORD width;      // in chars
    LLINK array_id;  // points to items in ARRAY structure
    }

STRUCT ARRAY
    {
    STRUCT items[];	  // list items
    }

The listbox resource definition describes the application’s listbox properties. The resource contains also information about the type of the listbox.

The listbox items are defined as an array. The array r_listbox_items below defines the listbox item strings for the listbox resource r_listbox above.

The listbox resource is defined in the application resource file (RSS file). The following code describes a selection listbox resource called r_listbox.

RESOURCE LISTBOX r_listbox
    {
    flags = EAknListBoxSelectionList;
    array_id = r_listbox_items;
    }

RESOURCE ARRAY r_listbox_items
    {
    items =
        {
        LBUF { txt = "\tItem1\t\t"; },
        LBUF { txt = "\tItem2\t\t"; },
        LBUF { txt = "\titem3\t\t"; }
        };
    }

The listbox can also be created in a view-only mode, as a viewer listbox, without the highlight indicator. In order to create a viewer listbox, a flag called EAknListBoxViewerFlags must be used in conjunction with the listbox type when defining the flags parameter for the listbox resource. The example listbox resource r_listbox_viewer below demonstrates how to create a selection list in a viewer mode.

RESOURCE LISTBOX r_listbox_viewer
    {
    flags = EAknListBoxSelectionList | EAknListBoxViewerFlags;
    array_id = r_listbox_items;
    }

Once the resources have been defined and a resource file created, the listbox resource can be loaded and used in the application.

Creating a selection listbox from resource

This Section describes how to create lists from resource files and at run time. If lists are created from a resource, a resource file defining the listbox resource must exist and contain a valid listbox resource definition of the listbox structure and listbox items. If the listbox is created at run time, the listbox item array is constructed and initialized in the code.

When creating a listbox, choose a listbox layout that best suits your needs. The chosen layout specifies the class to be used when creating a listbox and the listbox item string format to be used when creating the listbox items.

Lists can be easily created and used from a resource file defining them. The resource file should define the listbox resource and the listbox resource items array. Create a listbox from a resource by following these steps:

1. Create a new listbox instance. Depending on which type of listbox you wish to create, you must select and instantiate an appropriate class.
2. Set the listbox’s container window. Since the listbox is a non window-owning control, its parent control is passed as a parameter, providing a window for the listbox to draw to.
3. Initialize a resource reader that is used to load the resource file describing the listbox resource. The listbox resource ID (name) is passed to the resource reader as a parameter.
4. Load the listbox resource using the resource reader.

First, an instance of the listbox is created and its container control is set. Next, the resource reader is created to prepare the loading of the resource file. Here, the resource reader and listbox resource identifier are passed as parameters. The listbox resource is referred to, using the name given to identify it when defining the resource in the resource file.

Finally, the listbox resource file is loaded by calling the ConstructFromResourceL() method with the resource reader as a parameter. If the resource loading is successful, the listbox is ready for use.

The following example code creates a selection listbox with a single-line item layout loaded from a resource file. This code expects the resource file to define the resource R_LISTBOX.

In this example a listbox is created, and activated. Note that in the example listbox is component of a compound control and it is needed to implement method ComponentControl() and CountComponentControls().

class CMyContainer : public CCoeControl
     {
     CEikTextListBox* iListBox;
     }

void CMyContainer::ConstructL()
     {
     // Create listbox 
     iListBox = new ( ELeave ) CAknSingleStyleListBox(); // markable
     iListBox->SetContainerWindowL( *this );    

     // Initialize resource reader, passing resource id as parameter
     TResourceReader rr;
     iEikonEnv->CreateResourceReaderLC( rr, R_LISTBOX );
     // Load and construct listbox 
     iListBox->ConstructFromResourceL( rr );
     CleanupStack::PopAndDestroy();  // rr       
     // Activate listbox
     iListBox->SetRect( Rect() );	
     iListBox->ActivateL();
     }

Creating a selection listbox runtime

Creating lists without resource file definitions is fairly simple. In this approach, the listbox format and contents are set manually at run time as the resources are not used. To create a listbox at run time, follow these steps:

1. Create a new listbox instance. Depending on which type of listbox you wish to create, you must select and instantiate an appropriate class. This example uses the CAknSingleNumberStyleListBox class.
2. Use flag EAknListBoxSelectionList to create a selection list.
3. Set the listbox’s container window. Since the listbox is a non window-owning control, its parent control is passed as a parameter, providing a window for the listbox to draw to.
4. Create a scrollbar frame to the listbox and set active.
5. Construct the list item array. The listbox item string format must obey the string format specified for the listbox type used. Append the formatted item strings to the listbox item array.
6. Set the listbox item array to list and set the item array ownership to list.

The following example code shows how to create a numbered selection listbox with three items at run time, without using a resource file. Note that the example listbox is a component of a compound control and it is needed to implement method ComponentControl() and CountComponentControls().

class CMyContainer : public CCoeControl
     {
     CEikTextListBox* iListBox;
     CDesCArrayFlat* iListBoxItems;
     }

void CMyContainer::ConstructL()
     {
     …
     CreateWindowL(); // This is a window owning control
     // Create a single numbered style listbox
     iListBox = new (ELeave) CAknSingleNumberStyleListBox(); // markable
     // Construct listbox   
     iListBox->ConstructL( this, EAknListBoxSelectionList | EAknListBoxLoopScrolling );    
     iListBox->SetContainerWindowL( *this );
     // Set scrollbars
     iListBox->CreateScrollBarFrameL( ETrue );
     iListBox->ScrollBarFrame()->SetScrollBarVisibilityL( CEikScrollBarFrame::EOn, CEikScrollBarFrame::EAuto );    
     
     // Create listbox item array
     iListBoxItems = new (ELeave) CDesCArrayFlat(4);
     // Create listbox items
     iListBoxItems->AppendL( _L("1\tItem") );
     iListBoxItems->AppendL( _L("2\tItem") );
     iListBoxItems->AppendL( _L("3\tItem") );
     // Add items to listbox
     iListBox->Model()->SetItemTextArray( iListBoxItems );
     // Listbox deletes the item array
     iListBox->Model()->SetOwnershipType( ELbmOwnsItemArray );
     iListBox->HandleItemAdditionL( );
     // Activate Listbox
     iListBox->SetRect( Rect() );
     iListBox->ActivateL();
     …
     }

Note, that listbox must be informed about size changed events, to display properly.

void CSumoTestContainer::SizeChanged()
    {
    …
    iListBox->SetRect( Rect() );
    …
    }

Creating a selection listbox with a large graphic a primary and a secondary text

The previous code example demonstrated how to create a listbox at run time, without a resource file. The next code example demonstrates how to use a large graphic a primary and secondary text in the listbox. To create a listbox from code, follow these steps:

1. Create a new listbox instance. You must choose an appropriate class to instantiate depending on which type of listbox you wish to create. This example uses the CAknDoubleLargeStyleListBox class.
2. Use flag EAknListBoxSelectionList to create a selection list.
3. Set the listbox’s container window. Since the listbox is a non window-owning control, its parent control is passed as a parameter, providing a window for the listbox to draw to.
4. Create a scrollbar frame to the listbox and set active.
5. Construct a listbox item array. The listbox item string format must obey the string format specified for the listbox type used. Append the formatted item strings to the listbox item array.
6. Set the listbox item array to the listbox and set the item array ownership to the listbox.
7. Construct the listbox icon array. The listbox items are loaded from a AVKON's bitmap file and appended to the icon array. Set the icon array to the listbox.

Note that the order of the icons in the icon array defines their indexes. In this example, the first icon added to the icon list is ndexed as zero (0), and the next item, as one (1). The first column in the listbox item string defines the index of the icon to be displayed for the specific listbox item.

The following example code shows how to create a listbox with a large graphic, a primary and a secondary text at run time. Note that the example listbox is component of a compound control and it is needed to implement method ComponentControl() and CountComponentControls().

class CMyContainer : public CCoeControl
     {
     CEikFormattedCellListBox* iListBox;
     CDesCArrayFlat* iListBoxItems;
     }

void CMyContainer::ConstructL()
     {
     …
     CreateWindowL(); // This is a window owning control
     // Create listbox
     iListBox = new (ELeave) CAknDoubleLargeStyleListBox();
     // Construct listbox 
     iListBox->ConstructL( this, EAknListBoxSelectionList | EAknListBoxLoopScrolling );
     iListBox->SetContainerWindowL( *this );
     // Set scrollbars
     iListBox->CreateScrollBarFrameL( ETrue );
     iListBox->ScrollBarFrame()->SetScrollBarVisibilityL( CEikScrollBarFrame::EOn, CEikScrollBarFrame::EAuto );    
     
     // Create listbox item array
     iListBoxItems = new (ELeave) CDesCArrayFlat(4);
     // Create listbox items
     iListBoxItems->AppendL( _L("0\tHeading1\tItem1\t") );
     iListBoxItems->AppendL( _L("1\tHeading2\tItem2\t") );
     iListBoxItems->AppendL( _L("2\tHeading3\tItem3\t") );
     // Add items to listbox
     iListBox->Model()->SetItemTextArray( iListBoxItems );
     // Listbox deletes the item array
     iListBox->Model()->SetOwnershipType( ELbmOwnsItemArray );
     iListBox->HandleItemAdditionL( );
     // Add icons to listbox
     AddListboxIconsL();
     // Activate Listbox
     iListBox->SetRect( Rect() );
     iListBox->ActivateL();
     …
     }

// This method adds the icons to iListbox
void CMyContainer::AddListboxIconsL()
    {
    CArrayPtr<CGulIcon>* iconArray = new( ELeave ) CAknIconArray( 1 );
    CleanupStack::PushL( iconArray );
    
    CFbsBitmap* addressIcon = NULL;
    CFbsBitmap* addressIconMask = NULL;
    CFbsBitmap* emailIcon = NULL;
    CFbsBitmap* emailIconMask = NULL;
    CFbsBitmap* faxIcon = NULL;
    CFbsBitmap* faxIconMask = NULL;
    
    AknIconUtils::CreateIconLC( addressIcon,
                               addressIconMask, 
                               KAvkonBitmapFile, 
                               EMbmAvkonQgn_prop_nrtyp_address, 
                               EMbmAvkonQgn_prop_nrtyp_address_mask );
                               
    CGulIcon* addressListIcon = CGulIcon::NewL( addressIcon, addressIconMask );
    CleanupStack::Pop( 2 ); // addressIcon, addressIconMask
    CleanupStack::PushL( addressListIcon );
    iconArray->AppendL( addressListIcon );    			
                               
                               
    AknIconUtils::CreateIconLC( emailIcon, 
                               emailIconMask, 
                               KAvkonBitmapFile, 
                               EMbmAvkonQgn_prop_nrtyp_email, 
                               EMbmAvkonQgn_prop_nrtyp_email_mask );
                               
    CGulIcon* emailListIcon = CGulIcon::NewL( emailIcon, emailIconMask );
    CleanupStack::Pop( 2 ); // emailIcon, emailIconMask
    CleanupStack::PushL( emailListIcon );
    iconArray->AppendL( emailListIcon );
                               
                               
    AknIconUtils::CreateIconLC( faxIcon, 
                               faxIconMask, 
                               KAvkonBitmapFile, 
                               EMbmAvkonQgn_prop_nrtyp_fax, 
                               EMbmAvkonQgn_prop_nrtyp_fax_mask );    
                      
    CGulIcon* faxListIcon = CGulIcon::NewL( faxIcon, faxIconMask );
    CleanupStack::Pop( 2 ); // faxIcon, faxIconMask   
    CleanupStack::PushL( faxListIcon );
    iconArray->AppendL( faxListIcon );

    iListBox->ItemDrawer()->ColumnData()->SetIconArray( iconArray );
    // faxListIcon, emailListIcon, addressListIcon, iconArray    
    CleanupStack::Pop( 4 );
    iListBox->HandleItemAdditionL();
    }

Getting the selected item of a selection listbox

The menu and selection lists allow selection of one item on the list. The listbox instance contains the index of its currently selected item. The index of the currently selected item on the menu and selection lists can be retrieved by the following code:

TInt currentIndex = iListBox->CurrentItemIndex();

Creating a multiselection listbox

In a multiselection list, different list items can be selected at the same time, to perform some operation on them. A listbox consists of a checkbox icon, and a text. Because of the type of the listbox items, the CAknSingleGraphicStyleListBox class is used, so a checkbox can be used on the left side on the list item. To create a listbox from code, follow these steps:

1. Create a new listbox instance. You must choose an appropriate class to instantiate depending on which type of listbox you wish to create This example uses the CAknSingleGraphicStyleListBox class.
2. Use flag EAknListBoxMultiselectionList to create a multiselection list.
3. Set the listbox’s container window. Since the listbox is a non window-owning control, its parent control is passed as a parameter, providing a window for the listbox to draw to.
4. Create a scrollbar frame to the listbox and set active.
5. Construct a listbox item array. The listbox item string format must obey the string format specified for the listbox type used. Append the formatted item strings to the listbox item array.
6. Set the listbox item array to the listbox and set the item array ownership to the listbox.
7. Construct the list icon array, that contains the checkbox icons The checkbox icons are loaded from a AVKON's bitmap file and appended to the icon array. Set the icon array to the listbox. In the example the checkbox icons are gotten from the current active skin, so if the skin changes, the checkbox icons change as well, according to the new skin.

Note that the order of the icons in the icon array defines their indexes. In this example, the first icon is indexed as zero (0), and the next is indexed as one (1). The first column in the listbox item string defines the index of the icon to be displayed for the specific listbox item.

The example listbox is a component of a compound control and it is needed to implement the method ComponentControl() and CountComponentControls().

class CMyContainer : public CCoeControl
     {
     CAknColumnListBox* iListBox;
     CDesCArrayFlat* iListBoxItems;
     }

void CMyContainer::ConstructL()
     {
     …
     CreateWindowL(); // This is a window owning control
     // Create listbox
     iListBox = new (ELeave) CAknSingleGraphicStyleListBox(); // markable
     // Construct listbox   
     iListBox->ConstructL( this, EAknListBoxMultiselectionList| EAknListBoxLoopScrolling );    
     iListBox->SetContainerWindowL( *this );
     // Set scrollbars
     iListBox->CreateScrollBarFrameL( ETrue );
     iListBox->ScrollBarFrame()->SetScrollBarVisibilityL( CEikScrollBarFrame::EOn, CEikScrollBarFrame::EAuto );    
     
     // Create listbox item array
     iListBoxItems = new (ELeave) CDesCArrayFlat(4);
     // Create listbox items
    iListBoxItems->AppendL( _L("1\tItem1") );
    iListBoxItems->AppendL( _L("1\tItem2") );
    iListBoxItems->AppendL( _L("1\tItem3") );
     // Add items to listbox
     iListBox->Model()->SetItemTextArray( iListBoxItems );
     // Listbox deletes the item array
     iListBox->Model()->SetOwnershipType( ELbmOwnsItemArray );
     iListBox->HandleItemAdditionL( );
     // Add icons to listbox
     AddCheckboxIconsL();
     // Activate Listbox
     iListBox->SetRect( Rect() );
     iListBox->ActivateL();
     …
     }

void CMyContainer::AddCheckboxIconsL()
    {
    CAknIconArray* iconArray = new( ELeave ) CAknIconArray( 1 );
    CleanupStack::PushL( iconArray );
    CFbsBitmap* checkboxOnBitmap = NULL;
    CFbsBitmap* checkboxOnBitmapMask = NULL;
    CFbsBitmap* checkboxOffBitmap = NULL;
    CFbsBitmap* checkboxOffBitmapMask = NULL;
    
    
    //CListItemDrawer is using this logical color as default for its marked icons
    TRgb defaultColor;
    defaultColor = CEikonEnv::Static()->Color( EColorControlText );

    AknsUtils::CreateColorIconLC( AknsUtils::SkinInstance(),
    			KAknsIIDQgnPropCheckboxOff,
    			KAknsIIDQsnIconColors,
    			EAknsCIQsnIconColorsCG13,
    			checkboxOnBitmap,
    			checkboxOnBitmapMask,
    			KAvkonBitmapFile,
    			EMbmAvkonQgn_indi_checkbox_on,
    			EMbmAvkonQgn_indi_checkbox_on_mask,
    			defaultColor
    			);
    			
    CGulIcon* checkboxOnIcon = CGulIcon::NewL( checkboxOnBitmap, checkboxOnBitmapMask );
    CleanupStack::Pop( 2 ); // checkboxOnBitmap, checkboxOnBitmapMask
    CleanupStack::PushL( checkboxOnIcon );
    iconArray->AppendL( checkboxOnIcon );

    AknsUtils::CreateColorIconLC( AknsUtils::SkinInstance(),
    			KAknsIIDQgnPropCheckboxOff,
    			KAknsIIDQsnIconColors,
    			EAknsCIQsnIconColorsCG13,
    			checkboxOffBitmap,
    			checkboxOffBitmapMask,
    			KAvkonBitmapFile,
    			EMbmAvkonQgn_indi_checkbox_off,
    			EMbmAvkonQgn_indi_checkbox_off_mask,
    			defaultColor
    			);
    			    
    CGulIcon* checkboxOffIcon = CGulIcon::NewL( checkboxOffBitmap, checkboxOffBitmapMask );
    CleanupStack::Pop( 2 ); // checkboxOffBitmap, checkboxOffBitmapMask    
    CleanupStack::PushL( checkboxOffIcon );
    iconArray->AppendL( checkboxOffIcon );
        
    iListBox->ItemDrawer()->ColumnData()->SetIconArray( iconArray );
    
    // checkboxOffIcon, checkboxOnIcon, iconArray
    CleanupStack::Pop( 3 );
    }

Select and deselect an item in a multiselection listbox

This example shows how to change the checkbox states of a multiselection list item.

// Checks the second item in the list
iListBox->View()->SelectItemL( 1 ); 
// Unchecks the first item in the list
iListBox->View()->DeselectItem( 0 );

Creating a markable listbox

A markable listbox is essentially a selection listbox with an added feature that allows list items to be marked. Any number of items can be marked on the list. A command can be applied to all of the marked items. A listbox consists of a mark icon, if the item is marked and a text. Because of the type of the listbox items, the CAknSingleGraphicStyleListBox class is used, so a mark icon can be used on the right side on the list item. To create a listbox from code, follow these steps:

1. Create a new listbox instance. You must choose an appropriate class to instantiate depending on which type of listbox you wish to create This example uses the CAknSingleGraphicStyleListBox class.
2. Use flag EAknListBoxMarkableList to create a markable list.
3. Set the listbox’s container window. Since the listbox is a non window-owning control, its parent control is passed as a parameter, providing a window for the listbox to draw to.
4. Create a scrollbar frame to the listbox and set active.
5. Construct a listbox item array. The listbox item string format must obey the string format specified for the listbox type used. Append the formatted item strings to the listbox item array.
6. Set the listbox item array to the listbox and set the item array ownership to the listbox.
7. Construct the list icon array, that contains the mark icons The mark icons are loaded from a AVKON's bitmap file and appended to the icon array. Set the icon array to the listbox. In the example the mark icons are gotten from the current active skin, so if the skin changes, the mark icons change as well, according to the new skin.

Note that the order of the icons in the icon array defines their indexes. In this example, the first icon is indexed as zero (0), and the next is indexed as one (1). The first column in the listbox item string defines the index of the icon to be displayed for the specific listbox item.

The example listbox is a component of a compound control and it is needed to implement the method ComponentControl() and CountComponentControls().

class CMyContainer : public CCoeControl
     {
     CAknColumnListBox* iListBox;
     CDesCArrayFlat* iListBoxItems;
     }

void CMyContainer::ConstructL()
     {
     …
     CreateWindowL(); // This is a window owning control
     // Create a single numbered style listbox
     iListBox = new (ELeave) CAknSingleGraphicStyleListBox(); // markable
     // Construct listbox   
     iListBox->ConstructL( this, EAknListBoxMarkableList | EAknListBoxLoopScrolling );    
     iListBox->SetContainerWindowL( *this );
     // Set scrollbars
     iListBox->CreateScrollBarFrameL( ETrue );
     iListBox->ScrollBarFrame()->SetScrollBarVisibilityL( CEikScrollBarFrame::EOn, CEikScrollBarFrame::EAuto );    
     
     // Create listbox item array
     iListBoxItems = new (ELeave) CDesCArrayFlat(4);
     // Create listbox items
     iListBoxItems->AppendL( _L("\tItem1\t\t") );
     iListBoxItems->AppendL( _L("\tItem2\t\t") );
     iListBoxItems->AppendL( _L("\tItem3\t\t") );
     // Add items to listbox
     iListBox->Model()->SetItemTextArray( iListBoxItems );
     // Listbox deletes the item array
     iListBox->Model()->SetOwnershipType( ELbmOwnsItemArray );
     iListBox->HandleItemAdditionL( );
     // Add icons to listbox
     AddMarkIconsL();
     // Activate Listbox
     iListBox->SetRect( Rect() );
     iListBox->ActivateL();
     …
     }

void CMyContainer::AddMarkIconsL()
    {
    CAknIconArray* iconArray = new(ELeave) CAknIconArray(1);
    CleanupStack::PushL(iconArray);
    CFbsBitmap* markBitmap = NULL;
    CFbsBitmap* markBitmapMask = NULL;
    
    //CListItemDrawer is using this logical color as default for its marked icons
    TRgb defaultColor;
    defaultColor = CEikonEnv::Static()->Color(EColorControlText);

    AknsUtils::CreateColorIconLC(AknsUtils::SkinInstance(),
    			KAknsIIDQgnIndiMarkedAdd,
    			KAknsIIDQsnIconColors,
    			EAknsCIQsnIconColorsCG13,
    			markBitmap,
    			markBitmapMask,
    			KAvkonBitmapFile,
    			EMbmAvkonQgn_indi_marked_add,
    			EMbmAvkonQgn_indi_marked_add_mask,
    			defaultColor
    			);
    
    CGulIcon* markIcon = CGulIcon::NewL( markBitmap,markBitmapMask );
    CleanupStack::Pop( 2 ); // markBitmap, markBitmapMask
    CleanupStack::PushL( markIcon );      
    iconArray->AppendL( markIcon );

    iListBox->ItemDrawer()->ColumnData()->SetIconArray( iconArray );
    
    // markIcon, iconArray
    CleanupStack::Pop( 2 );
    }

Mark and unmark an item in a markable listbox

This example shows how to change the mark states of a markable list item.

// Marks the second item in the list
iListBox->View()->SelectItemL( 1 ); 
// Unmarks the first item in the list
iListBox->View()->DeselectItem( 0 );

Getting the selected items of a markable or multiselection list

Markable and multiselection lists allow multiple items to be selected, as well as one item or none at all. An array of the indexes of the selected items can be requested from these lists. The indexes are returned by the listbox as an array of type CSelectionIndexArray, which is essentially just a typedef of CArrayFix. The following code example demonstrates how to retrieve the array of selected items from markable and multiselection lists:

// Get the selected item indexes an array
const CArrayFix<TInt> *selectedIndexes = iListBox ->SelectionIndexes();

// Make sure the array is not null (no items)
if ( selectedIndexes != NULL ) 
    {
    // Loop through the selected item indexes
    for ( TInt index=0; index < selectedIndexes->Count(); index++ )
        {
        // Get the index of the selected item
        TInt selectedItemIndex = (*aIndexArray)[index];
        // now do something with the index…
        }
    }

Creating a settings style listbox

A setting style listbox is essentially a selection listbox with an added feature that allows to change the items according to a setting. A listbox consists of a name and a value. Because of the type of the listbox items, the CAknSettingStyleListBox class is used. It is also possible to create a settings lists using class CAknSettingItemList. For details please see Setting Lists API documentation.

To create a listbox from code, follow these steps:

1. Create a new listbox instance. You must choose an appropriate class to instantiate depending on which type of listbox you wish to create This example uses the CAknSettingStyleListBox class.
2. Use flag EAknListBoxSelectionList to create a markable list.
3. Set the listbox’s container window. Since the listbox is a non window-owning control, its parent control is passed as a parameter, providing a window for the listbox to draw to.
4. Create a scrollbar frame to the listbox and set active.
5. Construct a listbox item array. The listbox item string format must obey the string format specified for the listbox type used. Append the formatted item strings to the listbox item array.
6. Set the listbox item array to the listbox and set the item array ownership to the listbox.

The example listbox is a component of a compound control and it is needed to implement the method ComponentControl() and CountComponentControls().

class CMyContainer : public CCoeControl
     {
     CAknSettingStyleListBox * iListBox;
     CDesCArrayFlat* iListBoxItems;
     }

void CMyContainer::ConstructL()
     {
     …
     CreateWindowL(); // This is a window owning control
     // Create listbox
     iListBox = new (ELeave) CAknSettingStyleListBox(); // markable
     // Construct listbox   
     iListBox->ConstructL( this, EAknListBoxSelectionList | EAknListBoxLoopScrolling );    
     iListBox->SetContainerWindowL( *this );
     // Set scrollbars
     iListBox->CreateScrollBarFrameL( ETrue );
     iListBox->ScrollBarFrame()->SetScrollBarVisibilityL( CEikScrollBarFrame::EOn, CEikScrollBarFrame::EAuto );    
     
     // Create listbox item array
     iListBoxItems = new (ELeave) CDesCArrayFlat(4);
     // Create listbox items
    iListBoxItems->AppendL( _L("\tUpdates\t\tOff") );
    iListBoxItems->AppendL( _L("\tLanguage\t\tEnglish") );
    iListBoxItems->AppendL( _L("\tSounds\t\tOn") );
     // Add items to listbox
     iListBox->Model()->SetItemTextArray( iListBoxItems );
     // Listbox deletes the item array
     iListBox->Model()->SetOwnershipType( ELbmOwnsItemArray );
     iListBox->HandleItemAdditionL( );
     // Activate Listbox
     iListBox->SetRect( Rect() );
     iListBox->ActivateL();
     …
     }

Adding an item to listbox

New items are added to the listbox by appending a new entry to the listbox item array. First, the listbox item array is retrieved from the listbox. A new listbox item is then appended to the existing listbox item array and the listbox is requested to handle the addition of a new item. The HandleItemAdditionL() method handles the listbox redrawing and repositions the selection in a sensible state.

The following example code adds a new entry to a selection listbox:

// Get listbox item array
MDesC16Array* textArray = iListBox->Model()->ItemTextArray();
// Add new item to item array
static_cast<CDesC16Array*>( textArray )->AppendL( _L( "\tNewItem\t\t" ) );
// Update listbox
iListBox->HandleItemAdditionL();

Removing an item from listbox

To remove items from the listbox, you must first get the listbox item array from the listbox. Items are deleted from the item list array by specifying the index of the item to be deleted and the number of items to be deleted. The listbox is requested to handle the item deletion and redraw itself to show the changes.

The following example code removes the second item from a listbox:

// Get listbox item array
MDesCArray* textArray = iListBox->Model()->ItemTextArray();
// Delete second item from item array
static_cast<CDesCArray*>( textArray )->Delete( 1 );
// Handle deletion
iListBox->HandleItemRemovalL();
iListBox->DrawNow();

Multiple contiguous items can also be deleted by specifying the count of the contiguous items to be deleted as the second parameter of the Delete() method. In the example above, only the selected item is deleted by specifying the count as one (1).

Getting the number of items in listbox

This example shows how to get the number of listbox items.

TInt listboxItems = iListBox->Model()->NumberOfItems();

Offering key events to listbox

If the listbox is a component of a compound control, it is needed to inform the listbox about key events. It is simply forwarding the event to the listbox from the components OfferKeyEventL() method.

TKeyResponse CMyContainer::OfferKeyEventL(const TKeyEvent& aKeyEvent, TEventCode aType)
    {
    return iListBox->OfferKeyEventL( aKeyEvent, aType );
    }

Handling listbox events

To observe events if a listbox item is selected, a listbox observer is needed. The observer class must be inherited from class MEikListBoxObserver and must implement the method HandleListBoxEventL().

Listbox can set an observer to which it can send other events, usually from a component to its container control. The control observer interface is MCoeControlObserver. For example the EEventStateChanged event can be used by a control to report that some piece of internal data has changed, and hence that any observer should be notified accordingly.

If a custom listbox is created or it is needed to handle situations where the theme is changed and listbox needs to display different icons, HandleResourceChange() must be implemented.

In this example, the class CMyContainer observes if a listbox item is selected, by pressing the Enter key.

class CMyContainer : public CCoeControl, MEikListBoxObserver
    {
    …
    /**
    * From MEikListBoxObserver
    */    
    void HandleListBoxEventL( CEikListBox* aListBox, TListBoxEvent aEventType ); 
    CAknColumnListBox* iListBox;
    …
    };

void CMyContainer::HandleListBoxEventL( CEikListBox* /*aListBox*/, TListBoxEvent aEventType )
	{
	if ( aEventType == EEventEnterKeyPressed )
	     {
	     switch ( iListBox->CurrentItemIndex() )
	          {
                    case 1: 
                         // Handle keypress event here…
                    break;

                    default:
                         // Do default handling here…
                    break;
                    }
               }
	}

Creating animated highlight

If the current skin supports animated highlight, it is only visible on the list if the focus is set to list. This example shows how to set the focus on the list. iListBox can be a pointer to any type of AVKON list. For example: CAknSingleGraphicStyleListBox.

void MyContainer::FocusChanged( TDrawNow aDrawNow )
    {
    CCoeControl::FocusChanged( aDrawNow );
        if( iListBox )
        {
        iListBox->SetFocus( IsFocused(), aDrawNow );
        }
    }

Common problems in the listbox usage

This section describes what are the common problems when using a listbox.

• Listbox crashes if no icon array has been set.
• Listbox crashes if list items have non-numeric indexes or indexes outside of the icon array.
• Layout is not correct, listbox flags has not been set in ConstructL() or in resource file.
• Listbox size and position are not correct, the height in the LISTBOX resource inside of the dialogs needs to be correct.
• Listbox item layout not correct, payload strings may contain extra tab characters.

Error handling

Listbox uses standard Symbian OS error reporting mechanism. Possible panic circumstances and panic codes are indicated in class or method descriptions.

Leaves and system wide error codes as function return values are used if the error is recoverable. A client application can handle these errors similarly as a normal Symbian platform application.

Exception handling is not needed, except when setting up a layout in the SizeChanged() method, which needs to allocate memory.

Memory overhead

The amount of reserved memory for listbox depend on the application, but despite the application the amount of reserved memory is relatively small.

Limitations of the API

None.