UIQ Controls - Color Selector

This guide explains the UIQ control Color Selector (CQikColorSelector). The Color Selector allows the user to select a color from a preset set of colors available in a pop-out palette called the Color Picker. The order of the colors in the Color Picker range from the top left to the bottom right. When the Color Picker is launched, the currently selected color is highlighted and the background is dimmed.

The following functionality can be used by the application developer:

• Use of a 4-color gray-scale palette,

• Use of a 16-color gray-scale palette,

• Use of a 16-color color palette,

• Use of a custom palette which has been created from a resource file,

• Use of custom color names for a custom palette which has been created from a resource file,

• Hide the name of the selected color,

• Change the selected color,

• Toggle between dimmed state and normal state,

• Change border properties of the Color Selector.

By default, the following configuration applies:

• The name of the selected color is visible,

• A 4-color gray-scale palette is used,

• The first color in the color range is selected,

• The control is not dimmed.

Examples of Color Selector graphics

Color Selector Color Selector with the name of the selected color visible Dimmed Color Selector Color Picker with a 4-color palette Color Picker with a 16-colored color palette Color Picker with the Color Selector in the background

See the API documentation for Color Selector CQikColorSelector.

Color Selector inherits from CEikChoiceListBase and contains a CQikColorPicker and a CPalette.

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

Use the following #include directive:

#include <QikColorSelector.h>

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

LIBRARY qikctl.lib

Use the following control identifier when specifying the control in resource data files. It is used by the framework when constructing the control from resource data:

EQikCtColorSelector

Resource files can be used to construct the Color Selector. The resource to use is defined by the QIK_COLOR_SEL structure, defined in Qikon.rh. The structure looks like this:

STRUCT QIK_COLOR_SEL
    {
    WORD flags=0;
    LLINK palette_colors=0; //assign with resource array of COLOR items if using a custom palette.
    LLINK palette_names=0;
    }

The values given in the structure definition are default values. To make a customized Color Selector, an array of COLOR items needs to be assigned to palette_colors; see the example in the section on how to create a Color Selector with customized colors, using data from resource file.

The structure contains the following:

• flags is used to customize the control.

• palette_colors is set to 0 when the standard palette is used. If a custom palette is used, assign a resource array of COLOR items.

• palette_names is set to 0 when the standard palette is used. If custom color names are used, assign an array with the custom color names.

The Color Selector can have the following flags :

Color Selector - Resource flags EQikColorSelDisplayNoText Show no text. EQikColorSelStandardColor Use standard color palette. EQikColorSelStandard16 Use 16-color palette rather than 4-color palette. EQikColorSelCustomPalette Use custom palette, supplied in palette_colors.

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 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 Color Selector.

3.3.1 Construction with View Framework Using Data from a Resource File

The example below describes how to construct a Color Selector 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 Color Selector 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,
    EMyViewColorSelector,
    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_color_selector_view_controls
    {
    items =
        {
        QIK_CONTROL
            {
            unique_handle = EMyViewScrollableContainer;
            type = EQikCtScrollableContainer;
            control = r_my_color_selector_scroll_pane;
            },
        QIK_CONTROL
            {
            unique_handle = EMyViewColorSelector;
            type = EQikCtColorSelector;
            control = r_my_color_selector;
            },
        QIK_CONTROL
            {
            unique_handle = EMyViewBuildingBlock;
            type = EQikCtCaptionedTwolineBuildingBlock;
            control = r_my_color_selector_building_block;
            }
        };
    }

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

/* The view */
RESOURCE QIK_VIEW r_my_color_selector_view
    {
    pages = r_my_color_selector_viewpages;
    }
                
/* The view page */
RESOURCE QIK_VIEW_PAGES r_my_color_selector_viewpages
    {
    pages =
        {
        QIK_VIEW_PAGE
            {
            container_unique_handle = EMyViewScrollableContainer;
            page_content = r_my_color_selector_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_color_selector_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_color_selector_view_container_details
    {
    controls =
        {
        QIK_CONTAINER_ITEM
            {
            unique_handle = EMyViewBuildingBlock;
            }
        };
    }

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

/* The Color Selector used in the view */
RESOURCE QIK_COLOR_SEL r_my_color_selector
    {
    flags = EQikColorSelStandardColor | EQikColorSelStandard16;
    palette_colors = 0;
    palette_names = 0;
    }

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

/* Settings for the EQikCtCaptionedTwolineBuildingBlock containing the Color Selector */
RESOURCE QIK_SYSTEM_BUILDING_BLOCK r_my_color_selector_building_block
    {
    content =
        {
        QIK_SLOT_CONTENT
            {
            slot_id = EQikItemSlot1;
            caption = "Choose:";
            },
        QIK_SLOT_CONTENT
            {
            slot_id = EQikItemSlot2;
            unique_handle = EMyViewColorSelector;
            }
        };
    }

8) The configurations of the view:

RESOURCE QIK_VIEW_CONFIGURATIONS r_my_color_selector_ui_configurations
    {
    configurations=
        {
        QIK_VIEW_CONFIGURATION
            {
            ui_config_mode = KQikSoftkeyStylePortrait;
            view = r_my_color_selector_view;
            command_list = r_my_color_selector_commands;
            },
        QIK_VIEW_CONFIGURATION
            {
            ui_config_mode = KQikPenStyleTouchPortrait;
            view = r_my_color_selector_view;
            command_list = r_my_color_selector_commands;
            }   
        };
    }

9) The command list for the view:

RESOURCE QIK_COMMAND_LIST r_my_color_selector_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_COLOR_SELECTOR_UI_CONFIGURATIONS, R_MY_COLOR_SELECTOR_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 Color Selector 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 Color Selector in a Building Block.

This example uses the resource structures from the previous example. The following code creates the Color Selector:

#include <QikColorSelector.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_COLOR_SELECTOR_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 Color Selector) and
    // add it to the container
    CQikBuildingBlock* block = CQikBuildingBlock::CreateSystemBuildingBlockL(EQikCtCaptionedTwolineBuildingBlock);
    container->AddControlLC(block, EMyViewBuildingBlock);
    TResourceReader blockReader;
    iCoeEnv->CreateResourceReaderLC(blockReader,R_MY_COLOR_SELECTOR_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 that the created control 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 Color Selector from the resource R_MY_BUILDING_BLOCK. Adds the Building Block to the container.

The Color Selector 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, QikColorSelector.h needs to be included in the cpp-file and qikctl.lib in the mmp-file.

// Create the Color Selector and add it into the container
TResourceReader reader;
iEikonEnv->CreateResourceReaderLC(reader, R_MY_COLOR_SELECTOR);
CQikColorSelector* colSel = new (ELeave) CQikColorSelector();
container->AddControlLC(colSel, EMyViewColorSelector);
colSel->ConstructFromResourceL(reader);
colSel->SetUniqueHandle(EMyViewColorSelector);
CleanupStack::Pop(colSel);
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 Color Selector 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 Color Selector:

#include <QikColorSelector.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 Color Selector and add it to the container
    CQikColorSelector* colSel = new (ELeave) CQikColorSelector();
    container->AddControlLC(colSel, EMyViewColorSelector);
    colSel->ConstructL(0 /*flags*/);
    colSel->SetUniqueHandle(EMyViewColorSelector);
    colSel->SetObserver(this);
    CleanupStack::Pop(colSel);
    }

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

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

The Color Selector 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 Color Selector control:

RESOURCE DIALOG r_my_color_selector_dialog
    {
    title = "Color Selector Test";
    flags = EEikDialogFlagWait; 
    items =
        {
        DLG_LINE
            {
            type = EQikCtColorSelector;
            prompt = "Color Selector";
            control = QIK_COLOR_SEL
                {
                flags = EQikColorSelStandardColor | EQikColorSelStandard16;
                palette_colors = 0;
                palette_names = 0;
                };
            }
        };
    }

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_COLOR_SELECTOR_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
colSel>SetUniqueHandle(EMyViewColorSelector);
            
// Get a pointer to the Color Selector control
CQikColorSelector* colSel = LocateControlByUniqueHandle<CQikColorSelector>(EMyViewColorSelector); 

3.4.1 How to Create a Color Selector with Customized Colors Using Data from a Resource File

This example shows what needs to be specified in the project's resource file to be able to create a Color Selector with an array of customized colors. It also shows how to set customized names of the colors in the color array.

RESOURCE QIK_COLOR_SEL my_color_selector
    {
    flags = EQikColorSelCustomPalette;
    palette_colors = my_custom_palette;
    palette_names = my_palette_names;
    }
            
RESOURCE ARRAY my_custom_palette
    {
    items =
        {
        COLOR { red = 0xFF; green = 0x00; blue = 0xAA; },
        COLOR { red = 0x00; green = 0x00; blue = 0xFF; }
        };
    }
                
RESOURCE ARRAY my_palette_names
    {
    items =
        {
        LBUF { txt = "Purple"; },
        LBUF { txt = "Blue"; }
        };
    }

3.4.2 How to Get the Selected Color

This example shows how to get the color that has been selected in the control.

TRgb theColor;
                    
// Get the control by its unique handle, EMyViewColorSelector.
CQikColorSelector* colSel = LocateControlByUniqueHandle<CQikColorSelector>(EMyViewColorSelector);
    
theColor = colSel->SelectedColor();

3.4.3 How to be Notified with Control Events

In order to be notified when the Color Selector changes state, you must add an observer to the Color Selector. 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 Color Selector 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 Color Selector:

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

void CMySinglePageView::HandleControlEventL(CCoeControl* aControl, TCoeEvent aEventType)
    {
    // Call base class to handle focus management
    CQikViewBase::HandleControlEventL(aControl, aEventType);
    
    CQikColorSelector* colSel = LocateControlByUniqueHandle<CQikColorSelector>(EMyViewColorSelector);             
    
    if(aControl == colSel)
        {
        switch(aEventType)
            {
            case EEventStateChanged:
                // The internal state of the Color Selector 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.

Destroying the control is just a matter of invoking operator delete on the Color Selector object. The only thing to think about is whether or not the Color Selector owns the item array. If it does, the Color Selector will delete the array, and its objects, in its destructor. If it does not, someone else must take care of it.

Subclassing Color Selector is not recommended.