UIQ Controls - Floating Point Editor

This guide explains the UIQ control Floating Point Editor (CQikFloatingPointEditor). The Floating Point Editor is used for editing decimal numbers. The Floating Point Editor is based on the Numeric Editor and is normally used in a Container Pop-out.

Besides the functionality inherited from the Numeric Editor, the following functionality can be used by the application developer:

• Set a new floating point value,

• Set a new floating point value range, that is, minimum and maximum accepted values.

By default, the following configuration applies:

• The default value displayed is the initial minimum value of the control.

Examples of Floating Point Editor graphics

Floating Point Editor with cursor Highlighted Floating Point Editor Dimmed Floating Point Editor

See the API documentation for Floating Point Editor (CQikFloatingPointEditor).

Floating Point Editor inherits from Numeric Editor. See the API documentation for Numeric Editor (CQikNumericEditor).

The Floating Point Editor control is pertinent to the Number Editor and the Plain Text Editor. See the How To guides for Plain Text Editor and Number Editor.

See even the API documentation for Plain Text Editor (CEikEdwin) and Number Editor (CQikNumberEditor).

Floating Point Editor inherits from CQikNumericEditor.

This section explains how the control is constructed, used and destroyed. Source code examples are used and explained to illustrate how the Floating Point Editor control is used.

Use the following #include directive:

#include <QikFloatingPointEditor.h>

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

LIBRARY qikctl.lib

Resource files can be used to construct the Floating Point Editor. The resource to use is defined by the QIK_FLOATING_POINT_EDITOR structure, defined in Qikon.rh. The structure looks like this:

STRUCT QIK_FLOATING_POINT_EDITOR
    {
    BYTE version = 0; //cannot be changed
    WORD maxlength = 18;
    DOUBLE min = -9.9e99;
    DOUBLE max = 9.9e99;
    }

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

• version is always zero and cannot be changed,

• maxlength maximum length of displayed number,

• min minimum floating point value accepted in the editor,

• max maximum floating point value accepted in the editor.

The Floating Point Editor has no flags.

This section discusses four different ways of constructing controls. The first three ways describe how to construct and add a control into the view of an application. The view framework is used 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 to 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.

This section covers different ways of constructing a Floating Point Editor.

3.3.1 Construction with View Framework Using Data from a Resource File

The example below describes how to construct a Floating Point Editor 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 Floating Point Editor 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 controls' ID in a *.hrh file for use both in resource and cpp */
enum TMyViewControls
    {
    EMyViewScrollableContainer,
    EMyViewBuildingBlock,
    EMyViewFloatingPointEditor,
    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_floating_point_editor_view_controls
                    {
    items =
        {
        QIK_CONTROL
            {
            unique_handle = EMyViewScrollableContainer;
            type = EQikCtScrollableContainer;
            control = r_my_floating_point_editor_scroll_pane;
            },
        QIK_CONTROL
            {
            unique_handle = EMyViewFloatingPointEditor;
            type = EQikCtFloatingPointEditor;
            control = r_my_floating_point_editor;
            },
        QIK_CONTROL
            {
            unique_handle = EMyViewBuildingBlock;
            type = EQikCtCaptionedTwolineBuildingBlock;
            control = r_my_floating_point_editor_building_block;
            }
        };
    }

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

/* The view */
RESOURCE QIK_VIEW r_my_floating_point_editor_view
    {
    pages = r_my_floating_point_editor_viewpages;
    }
    
/* The view page */
RESOURCE QIK_VIEW_PAGES r_my_floating_point_editor_viewpages
    {
    pages =
        {
        QIK_VIEW_PAGE
            {
            container_unique_handle = EMyViewScrollableContainer;
            page_content = r_my_floating_point_editor_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_floating_point_editor_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_floating_point_editor_view_container_details
    {
    controls =
        {
        QIK_CONTAINER_ITEM
            {
            unique_handle = EMyViewBuildingBlock;
            }
        };
    }

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

/* The Floating Point Editor used in the view */
RESOURCE QIK_FLOATING_POINT_EDITOR r_my_floating_point_editor
    {
    maxlength = 18;
    min = -9.9e99;
    max = 9.9e99;
    }

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

/* Settings for the EQikCtCaptionedTwolineBuildingBlock containing the Floating Point Editor */ 
RESOURCE QIK_SYSTEM_BUILDING_BLOCK r_my_floating_point_editor_building_block
    {
    content =
        {
        QIK_SLOT_CONTENT
            {
            slot_id = EQikItemSlot1;
            caption = "Choose:";
            },
        QIK_SLOT_CONTENT
            {
            slot_id = EQikItemSlot2;
            unique_handle = EMyViewFloatingPointEditor;
            }
        };
    }

8) The configurations of the view:

RESOURCE QIK_VIEW_CONFIGURATIONS r_my_floating_point_editor_ui_configurations
    {
    configurations=
        {
        QIK_VIEW_CONFIGURATION
            {
            ui_config_mode = KQikSoftkeyStylePortrait;
            view = r_my_floating_point_editor_view;
            command_list = r_my_floating_point_editor_commands;
            },
        QIK_VIEW_CONFIGURATION
            {
            ui_config_mode = KQikPenStyleTouchPortrait;
            view = r_my_floating_point_editor_view;
            command_list = r_my_floating_point_editor_commands;
            }
        };
    }

9) The command list for the view:

RESOURCE QIK_COMMAND_LIST r_my_floating_point_editor_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)";
            }
        };
    }

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

void CMySinglePageView::ViewConstructL()
    {
    ViewConstructFromResourceL(R_MY_FLOATING_POINT_EDITOR_UI_CONFIGURATIONS, R_MY_FLOATING_POINT_EDITOR_VIEW_CONTROLS);
    }

11) 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 Floating Point Editor 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 Floating Point Editor in a Building Block.

This example uses the resource structures from the previous example. The following code creates the Floating Point Editor:

#include <QikFloatingPointEditor.h>
#include <QikRowLayoutManager.h>
#include <QikGridLayoutManager.h>
#include <QikBuildingBlock.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_FLOATING_POINT_EDITOR_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 Floating Point Editor) and
    // add it to the container
    CQikBuildingBlock* block = CQikBuildingBlock::CreateSystemBuildingBlockL(EQikCtCaptionedTwolineBuildingBlock);
    container->AddControlLC(block, EMyViewBuildingBlock);
    TResourceReader blockReader;
    iCoeEnv->CreateResourceReaderLC(blockReader,R_MY_FLOATING_POINT_EDITOR_BUILDING_BLOCK);
    block->ConstructFromResourceL(blockReader, *ControlProvider());
    CleanupStack::PopAndDestroy(); //blockReader
    CleanupStack::Pop(block);
    }

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) 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 Floating Point Editor from the resource R_MY_BUILDING_BLOCK. Adds the Building Block to the container.

The Floating Point Editor 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 the following code.

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

// Create the Floating Point Editor and add it into the container
TResourceReader reader;
iEikonEnv->CreateResourceReaderLC(reader, R_MY_FLOATING_POINT_EDITOR);
CQikFloatingPointEditor* flped = new (ELeave) CQikFloatingPointEditor();
container->AddControlLC(flped, EMyViewFloatingPointEditor);
flped->ConstructFromResourceL(reader);
flped->SetUniqueHandle(EMyViewFloatingPointEditor);
CleanupStack::Pop(flped);
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 Floating Point Editor 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 Floating Point Editor:

#include <QikFloatingPointEditor.h>
#include <QikScrollableContainer.h>
#include <QikRowLayoutManager.h>
#include <QikGridLayoutManager.h>
#include <QikBuildingBlock.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 Floating Point Editor and add it to the container
    CQikFloatingPointEditor* flped = new (ELeave) CQikFloatingPointEditor();
    container->AddControlLC(flped, EMyViewFloatingPointEditor);
    flped->ConstructL(-9.9e99/*aMinimumValue*/, 9.9e99/*aMaximumValue*/, 18/*aTextLimit*/);
    flped->SetUniqueHandle(EMyViewFloatingPointEditor);
    flped->SetObserver(this);
    CleanupStack::Pop(flped);
    }

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 Floating Point Editor control from C++ code. Sets the view, this, to be observer of the Floating Point Editor. The view's base class, CQikViewBase, handles focus changes in its method HandleControlEventL. For more details see the section on how to be notified with Control Events.

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

The Floating Point Editor 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 Floating Point Editor control:

RESOURCE DIALOG r_my_floating_point_editor_dialog
    {
    title = "Floating Point Editor";
    flags = EEikDialogFlagWait;
    items =
        {
        DLG_LINE
            {
            type = EQikCtFloatingPointEditor;
            prompt = "Floating Point Editor";
            control = QIK_FLOATING_POINT_EDITOR
                {
                maxlength = 18;
                min = -9.9e99;
                max = 9.9e99;
                };
            }
        };
    }

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_FLOATING_POINT_EDITOR_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 will return NULL if the control could not be found. Always check the pointer before using it!

// Set the unique handle
flped->SetUniqueHandle(EMyViewFloatingPointEditor);
            
// Get a pointer to the Floating Point Editor control
CQikFloatingPointEditor* flped = LocateControlByUniqueHandle<CQikFloatingPointEditor>(EMyViewFloatingPointEditor)

3.4.1 How to be Notified with Control Events

In order to be notified when the Floating Point Editor changes state you must add an observer to the Floating Point Editor. An observer is an object of the type MCoeControlObserver. The observer will then receive a function call to its function HandleControlEventL(CCoeControl* aControl, TCoeEvent aEventType) when the Floating Point Editor 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 Floating Point Editor:

void CMySinglePageView::ViewConstructL()
    {
    // Construction code
    …
    // Adding this object as an observer
    flped->SetObserver(this);
    }

void CMySinglePageView::HandleControlEventL(CCoeControl* aControl, TCoeEvent aEventType)
    {
    // Call base class to handle focus management
    CQikViewBase::HandleControlEventL(aControl, aEventType);
    
    CQikFloatingPointEditor* flped = LocateControlByUniqueHandle<CQikFloatingPointEditor>(EMyViewFloatingPointEditor);    
    if(aControl == flped)
        {
        switch(aEventType)
            {
            case EEventStateChanged:
                // The internal state of the Floating Point Editor was changed,
                // for example, due to another item being selected. 
                break;
                                    
            case EEventRequestExit:
                break;
                                
            case EEventRequestCancel:
                                break;
                                    
            case EEventRequestFocus:
                // The control received a pointer down event
                break;
                                    
            case EEventPrepareFocusTransition:
                // A focus change is about to appear
                break;
                        
            case EEventInteractionRefused:
                // The control 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 control's 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.

3.4.2 How to Get the Current Value

To get the current value of the Floating Point Editor, use the code below:

TReal currValue = flped->Value();

3.4.3 How to Set the Current Value

To set the current value of the Floating Point Editor, use the code below:

TReal newValue = 777.77
flped->SetValueL(newValue);

3.4.4 How to Get Minimum and Maximum Value

To get the minimum and maximum values of the Floating Point Editor, use the code below. On return, the variables will contain the minimum and maximum values of the control:

TReal min;
TReal max;
flped->GetMinimumAndMaximum(min, max);

3.4.5 How to Set Minimum and Maximum Value

To set the minimum and maximum values of the Floating Point Editor, use the code below:

TReal min = -10.99
TReal max = 10.99
flped->SetMinimumAndMaximum(min, max);

Destroying the control is just a matter of invoking operator delete on the Floating Point Editor object.

Subclassing Floating Point Editor is not recommended.