UIQ Controls - Labeled Check Box

This guide explains the UIQ control Labeled Check Box (CEikLabeledCheckBox). A Labeled Check Box is a compound control consisting of a Check Box control and a Label control. Labeled Check Box offers a Check Box, which the user can check and uncheck, together with a descriptive text displayed in a Label. The text cannot be changed by the user. The Labeled Check Box is a multiline control that can display from one to three lines of text. If the text does not fit within those lines, the text is truncated. The control configuration for this control is, however, a subset of the configuration options available for the Check Box and Label controls.

The following functionality can be set by the application developer:

• Enable tri-state mode. This adds the third control state, filled state. By enabling tri-state mode the current state is changed to filled state,

• Toggle Checked, Unchecked and Filled states, if tri-state mode enabled, for Labeled Check Box,

• Set the text displayed in Labeled Check Box. The text can be set when constructing the control and changed afterwards,

• Set whether the text should be to the right or left of the check box,

• Toggle dimmed state.

Example of Labeled Check Box control graphics

Bitmaps Normal Dimmed Pressed Unchecked Checked Filled

The label can hold one, two or three rows of text.

See the API-documentation for Labeled Check Box CEikLabeledCheckBox.

Labeled Check Box (CEikLabeledCheckBox) is built on Check Box and Label. See the How To guides for Check Box and Label.

See even the API-documentation for Check Box CEikCheckBox and Label CEikLabel.

Labeled Check Box inherits from CCoeControl and consists of a Check Box and a Label.

This section explains how the control is constructed, used and destroyed.

Source code examples are used and explained to illustrate how Labeled Check Box is used.

Use the following #include directive:

#include <eikchkbx.h>

Use the following LIBRARY directive in the project's mmp-file:

LIBRARY eikctl.lib

Resource files can be used to construct Labeled Check Box. The resource to use is defined by the LABELEDCHECKBOX structure, defined in Eikon.rh. The structure looks like this:

STRUCT LABELEDCHECKBOX
    {
    LTEXT labeltext="";
    BYTE textonright=1;
    }

The values given in the structure definition are default values. The structure contains the following:

• labeltext contains the text of the Labeled Check Box, specified in the Label,

• textonright states whether the label text is placed to the left or to the right of the Check Box, default is to the right.

The Labeled Check Box has no flags, however, its Label and the base class of Check Box have flags. For more information concerning these flags please see the How To guides for these controls.

This section discusses four different ways of constructing controls. The first three ways describe how to construct and add a control to the view of an application. The view framework is used in all three cases but in three different ways. The fourth way describes how to construct and launch a dialog from an application. The dialog framework constructs the control and adds it into the dialog.

A common way to construct controls is to specify them in the resource files and let the framework construct them from there. Specifying the controls in resource files is the preferred way of constructing controls since it allows for easier modifications compared to creating them entirely from source code.

3.3.1 Construction with View Framework Using Data from a Resource File

The example below describes how to construct a Labeled Check Box using the view framework.

The reason the example seems to be rather complex is because it demonstrates how to construct a complete view containing a Scrollable Container and a Layout Manager. It also encapsulates the Labeled Check Box in a Building Block. The view supports both pen and softkey styles. Support of both styles in a view is optional.

1) Declare an enumeration for the controls to be used in the view in a *.hrh file. Hrh files are files to be included both in resource files (*.rss) and C++ files:

/* Declare the control ID in *.hrh file for use both in resource and cpp */
enum TMyViewControls
    {   
    EMyViewScrollableContainer,
    EMyViewBuildingBlock,
    EMyViewLabeledCheckBox,
    EMyViewNumberOfControls
    };

2) Declare the controls to be used in the view in your resource (*.rss) file:

/* Declare the set of controls to be used in the view */
RESOURCE QIK_CONTROL_COLLECTION r_my_labeled_check_box_view_controls
    {
    items =
        {
        QIK_CONTROL
            {
            unique_handle = EMyViewScrollableContainer;
            type = EQikCtScrollableContainer;
            control = r_my_labeled_check_box_scroll_pane;
            },
        QIK_CONTROL
            {
            unique_handle = EMyViewBuildingBlock;
            type = EQikCtCaptionedTwolineBuildingBlock;
            control = r_my_labeled_check_box_building_block;
            },
        QIK_CONTROL
            {
            unique_handle = EMyViewLabeledCheckBox;
            type = EEikCtLabeledCheckBox;
            control = r_my_labeled_check_box;
            }
        };
    }

3) Define the view and its contents in your resource file:

/* The view */
RESOURCE QIK_VIEW r_my_labeled_check_box_view
    {
    pages = r_my_labeled_check_box_viewpages;
    }
                
/* The view page */
RESOURCE QIK_VIEW_PAGES r_my_labeled_check_box_viewpages
    {
    pages =
        {
        QIK_VIEW_PAGE
            {
            container_unique_handle = EMyViewScrollableContainer;
            page_content = r_my_labeled_check_box_view_container_details;
            }           
        };
    }

4) Define the resource for the Scrollable Container used in the view:

/* The scrollable container used in the view */
RESOURCE QIK_SCROLLABLE_CONTAINER r_my_labeled_check_box_scroll_pane
    {
    }

5) Declare the contents and properties for the Scrollable Container used in the view:

/* Contents of the scrollable container used in the view */
RESOURCE QIK_SCROLLABLE_CONTAINER_SETTINGS r_my_labeled_check_box_view_container_details
    {
    controls =
        {
        QIK_CONTAINER_ITEM
            {
            unique_handle = EMyViewBuildingBlock;
            }
        };
    }

6) Define the control resource structure used in the view:

/* The labeled check box used in the view */   
RESOURCE LABELEDCHECKBOX r_my_labeled_check_box
    {
    labeltext = "LabeledCheckBox";
    }

7) Define settings for the Building Block containing the control:

/* Settings for the EQikCtCaptionedTwolineBuildingBlock containing the labeled check box */ 
RESOURCE QIK_SYSTEM_BUILDING_BLOCK r_my_labeled_check_box_building_block
    {
    content =
        {
        QIK_SLOT_CONTENT
            {
            slot_id = EQikItemSlot1;
            caption = "Choose:";
            },
        QIK_SLOT_CONTENT
            {
            slot_id = EQikItemSlot2;
            unique_handle = EMyViewLabeledCheckBox;
            }
        };
    }

8) The configurations of the view:

RESOURCE QIK_VIEW_CONFIGURATIONS r_my_labeled_check_box_ui_configurations
    {
    configurations=
        {
        QIK_VIEW_CONFIGURATION
            {
            ui_config_mode = KQikSoftkeyStylePortrait;
            view = r_my_labeled_check_box_view;
            command_list = r_my_labeled_check_box_commands;
            },
        QIK_VIEW_CONFIGURATION
            {
            ui_config_mode = KQikPenStyleTouchPortrait;
            view = r_my_labeled_check_box_view;
            command_list = r_my_labeled_check_box_commands;
            }                       
        };
    }

9) The command list for the view:

RESOURCE QIK_COMMAND_LIST r_my_labeled_check_box_commands
    {
    items =
        {
        // This command shall only be visible in debug mode because it is only
        // used to find memory leaks during development of the application.
        QIK_COMMAND
            {
            id = EEikCmdExit;
            type = EQikCommandTypeScreen;
            // Indicate that this command will only be visible in debug
            stateFlags = EQikCmdFlagDebugOnly;
            text = "Close (debug)";
            }
        };
    }

9) The view framework constructs the view described in this example with this code:

void CMySinglePageView::ViewConstructL()
    {
    ViewConstructFromResourceL(R_MY_LABELED_CHECK_BOX_UI_CONFIGURATIONS, R_MY_LABELED_CHECK_BOX_VIEW_CONTROLS);
    }

10) The result should look something like this:

3.3.2 Construction with Your Own C++ Code Using Data from a Resource File

The example below describes how to construct a Labeled Check Box from resource with your own C++ code.

The reason the example seems to be rather complex is because it demonstrates how to construct a complete view containing a Scrollable Container and a Layout Manager. It also encapsulates the Labeled Check Box in a Building Block.

This example uses the resource structs from the previous example. The following code creates the Labeled Check Box:

#include <eikchkbx.h>
#include <QikBuildingBlock.h>
#include <QikRowLayoutManager.h>
#include <QikGridLayoutManager.h>
                
void CMySinglePageView::ViewConstructL()
    {
    // Give a layout manager to the view
    CQikGridLayoutManager* gl = CQikGridLayoutManager::NewLC();
    SetLayoutManagerL(gl);
    CleanupStack::Pop(gl);
    
    // Create a container and give it to the view
    ControlProvider()->ControlInfos().AddFromResourceL(R_MY_LABELED_CHECK_BOX_VIEW_CONTROLS);
    CQikContainerBase* container = static_cast<CQikContainerBase*>(ControlProvider()->ControlConstructIfNeededL(EMyViewScrollableContainer, *this));
    ASSERT(container);
    Controls().AppendLC(container);
    CleanupStack::Pop(container);
    
    // Create a layout manager to be used inside the container
    CQikRowLayoutManager* rowlayout = CQikRowLayoutManager::NewLC();
    container->SetLayoutManagerL(rowlayout);
    CleanupStack::Pop(rowlayout);
    
    // Create the building block (containing a labeled check box) and add it to the container
    CQikBuildingBlock* block = CQikBuildingBlock::CreateSystemBuildingBlockL(EQikCtCaptionedTwolineBuildingBlock);
    container->AddControlLC(block, EMyViewBuildingBlock);
    TResourceReader blockReader;
    iCoeEnv->CreateResourceReaderLC(blockReader,R_MY_LABELED_CHECK_BOX_BUILDING_BLOCK);
    block->ConstructFromResourceL(blockReader, *ControlProvider());
    CleanupStack::PopAndDestroy(); //blockReader
    CleanupStack::Pop(block);
    }

What the code does

1) Initializes a Command Manager with an empty Command List. The controls placed in the view add their commands to the Command List when they receive focus.

2) Creates a Layout Manager for the view. The Grid Layout Manager fills the view with its only control in this example, the Scrollable Container.

3) Loads the control collection R_MY_VIEW_CONTROLS into the Control Provider. Then the Control Provider is asked to create the Scrollable Container.

4) Uses the MopGetObjectNoChaining function to determine whether the control that was created really is a class of the type CQikContainerBase before it is added to the view.

5) Creates a Layout Manager to control the layout inside the container. Adds the Layout Manager to the container.

6) Constructs the Building Block containing the Labeled Check Box from the resource R_MY_BUILDING_BLOCK. Adds the Building Block to the container.

The Labeled Check Box can also be created without a Building Block. In that case, replace the last section in the code above, from the "Create building block..." comment, with this code example:

Since a pointer to the control is declared here, eikchkbx.h needs to be included in the cpp-file and eikctl.lib in the mmp-file.

// Create the labeled check box and add it to the container
TResourceReader reader;
iEikonEnv->CreateResourceReaderLC(reader, R_MY_LABELED_CHECK_BOX);
CEikLabeledCheckBox* lchbx = new (ELeave) CEikLabeledCheckBox();
container->AddControlLC(lchbx, EMyViewLabeledCheckBox);
lchbx->ConstructFromResourceL(reader);   
lchbx->SetUniqueHandle(EMyViewLabeledCheckBox);
CleanupStack::Pop(lchbx);
CleanupStack::PopAndDestroy(); //reader

Use AddControlLC to add controls to a Scrollable Container. Add the controls as soon as they are created. Do not push them onto the Cleanup Stack before they are added. Do not pop them from the Cleanup Stack until they are fully constructed. A TCleanupItem created in AddControlLC will make sure that the control is both cleaned up and removed from the Components Array if a leave occurs before the control is fully constructed.

3.3.3 Construction Solely from C++ Code

The example below describes how to construct a Labeled Check Box solely from C++ code.

The reason the example seems to be rather complex is because it demonstrates how to construct a complete view containing a Scrollable Container and a Layout Manager.

The following source code constructs a Labeled Check Box:

#include <QikScrollableContainer.h>
#include <QikRowLayoutManager.h>
#include <QikGridLayoutManager.h>
#include <QikBuildingBlock.h>
#include <eikchkbx.h>

void CMySinglePageView::ViewConstructL()
    {                   
                    
    // Give a layout manager to the view
    CQikGridLayoutManager* gridlayout = CQikGridLayoutManager::NewLC();
    SetLayoutManagerL(gridlayout);
    CleanupStack::Pop(gridlayout);      
                        
    // Create a container and add it to the view
    CQikScrollableContainer* container = new (ELeave) CQikScrollableContainer();
    Controls().AppendLC(container);
    container->ConstructL(EFalse);
    CleanupStack::Pop(container);
                        
    // Create a layout manager to be used inside the container
    CQikRowLayoutManager* rowlayout = CQikRowLayoutManager::NewLC();
    container->SetLayoutManagerL(rowlayout);
    CleanupStack::Pop(rowlayout);
                    
    // Create the labeled check box and add it to the container
    CEikLabeledCheckBox* lchbx = new (ELeave) CEikLabeledCheckBox();
    container->AddControlLC(lchbx, EMyViewLabeledCheckBox);
    _LIT(KLabeledCheckBoxText, "LabeledCheckBox");
    lchbx->ConstructL(KLabeledCheckBoxText); 
    lchbx->SetObserver(this);
    lchbx->SetUniqueHandle(EMyViewLabeledCheckBox);
    CleanupStack::Pop(lchbx);
    }

What the code does

1) Initializes the Command Manager with an empty Command List. The controls placed in the view add their commands to the Command List when they receive focus.

2) Creates a Layout Manager for the view. The Grid Layout Manager fills the view with its only control in this example, the Scrollable Container.

3) Instantiates a container and adds it to the view.

4) Creates a Layout Manager and adds it to the container.

5) Creates the Labeled Check Box control from C++ code. Sets the view, this, to be observer of the Labeled Check Box. The view's base class CQikViewBase handles focus changes in its method HandleControlEventL. For more details see the section How to be notified with Control Events below.

3.3.4 Construction with the Dialog Framework Using Data from a Resource File

Labeled Check Box can be constructed from resource files in dialogs as well. To construct a dialog from resource, a valid resource definition of that dialog must be in one of the project's resource files.

An example of a dialog resource containing the control is given below. For more information about the dialog class and its resource structure see CEikDialog and DIALOG in the API documentation.

1) Declare a dialog resource containing the Labeled Check Box control:

RESOURCE DIALOG r_my_labeled_check_box_dialog
    {
    title = "Labeled Check Box Test";
    flags = EEikDialogFlagWait;
    items =
        {
        DLG_LINE
            {
            prompt = "Labeled Check Box:";
            type = EEikCtLabeledCheckBox;
            control = LABELEDCHECKBOX
                {
                labeltext = "Test LabeledCheckBox";
                textonright = 1;
                };
            }
        };
    }

The resource properties inside the Control Block are the same as the ones described in the previous section.

2) Launch the dialog using the following source code. The dialog resource ID is passed as an argument:

CEikDialog* dlg = new (ELeave) CEikDialog();
dlg->ExecuteLD(R_MY_LABELED_CHECK_BOX_DIALOG);

The function returns immediately if EEikDialogFlagWait has not been specified in the dialog resource. If EEikDialogFlagWait is specified, it returns when the dialog exits. The dialog framework will in both situations delete the dialog appropriately as indicated by the D suffix of the ExcecuteLD function name.

This section covers the most common functions used for interacting with the control.

When constructing the control with resource data, no reference to the control is available in the view class. When constructing the control with code, the preferred way might be to not save a reference to the control. In both these cases, the LocateControlByUniqueHandle function is used to get a pointer to the control by supplying the control's unique handle. When constructing the view and the control from code, you must explicitly set this unique handle by calling the method SetUniqueHandle. See the code examples below.

Note that the function returns NULL if the control could not be found. Always check the pointer before using it!

// Set the unique handle
lchkbx->SetUniqueHandle(EMyViewLabeledCheckbox);
    
// Get a pointer to the labeled check box control
CEikLabeledCheckBox* lchkbx = LocateControlByUniqueHandle<CEikLabeledCheckBox>(EMyViewLabeledCheckbox);

3.4.1 How to Get the State of the Control's Check Box

To obtain the state of the Control's Check Box, extract the value as follows:

// Get the state of the control's Check Box and assign it to a data member
iState = lchkbx->State();

// or to a local variable
CEikCheckBox::TState state = lchkbx->State();

3.4.2 How to Get the Text of the Control's Label

To get hold of the text of the Controls Label use the code below:

TPtrC labelText = lchkbx->Text();

3.4.3 How to be Notified with Control Events

In order to be notified when the Labeled Check Box changes state, you must add an observer to the Labeled Check Box. An observer is an object of the type MCoeControlObserver. The observer receives a function call to its function HandleControlEventL(CCoeControl* aControl, TCoeEvent aEventType) when the Labeled Check Box changes state.

The view base class, CQikViewBase, implements the MCoeControlObserver. The HandleControlEventL function must be overloaded in the view class, because the view inherits from CQikViewBase.

The following source code example shows how to add an object as an observer and how to receive events from the Labeled Check Box:

void CMySinglePageView::ViewConstructL()
    {
    // Construction code
    …
    // Adding this object as an observer
    lchkbx->SetObserver(this);
    }
                            
void CMySinglePageView::HandleControlEventL(CCoeControl* aControl, TCoeEvent aEventType)
    {
    // Call base class to get focus navigation right
    CQikViewBase::HandleControlEventL(aControl, aEventType);
    
    CEikLabeledCheckBox* lchkbx = LocateControlByUniqueHandle<CEikLabeledCheckBox>(EMyViewLabeledCheckbox);

    if (aControl == lchkbx)
        {
        switch(aEventType)
            {
            case EEventStateChanged:
                // The internal state of the Labeled Check Box was changed,
                // for example, due to another item being selected. 
                break;
                                        
            case EEventRequestExit:
                break;
                                        
            case EEventRequestCancel:
                break;
                                        
            case EEventRequestFocus:
                // The labeled check box received a pointer down event
                break;
                                        
            case EEventPrepareFocusTransition:
                // A focus change is about to appear
                break;
                                    
            case EEventInteractionRefused:
                // The labeled check box is dimmed and received a
                // pointer down event.
                break;
                                    
            default:
                break;
            }
        }
    }

The reason for calling the base class's HandleControlEventL function is that the view base class CQikViewBase handles focus management between controls in the view. If the Labeled Check Box observer is not a class which derives from CQikViewBase, focus management must be resolved by the observer itself. If a control requests focus and does not get it from the observer, it will generate a panic in some cases if the observer does not leave.

For more details on the TCoeEvent type, see class MCoeControlObserver in the API documentation.

Destroying the control is just a matter of invoking operator delete on the Labeled Check Box object.

Subclassing Labeled Check Box is not recommended.