Constructing a Symbian container control

Template:KBCS

ID	CS000861	Creation date	March 25, 2008
Platform	S60 3rd Edition, FP1	Tested on devices	Nokia N95
Category	Symbian C++	Subcategory	UI

Keywords (APIs, classes, methods, functions): CCoeControl, TResourceReader, CCoeControlArray

Overview

This code snippet shows how to create a container control that owns custom controls. The example shows how to focus the first component with a rectangle and how to change focus.

The example extends the existing code snippet CS000859 - Custom control.

Container controls store their controls into CCoeControlArray.

Header

class CMyContainerControl : public CCoeControl
{
public:
    static CMyContainerControl* NewL(const TRect& aRect);
    static CMyContainerControl* NewLC(const TRect& aRect);
    virtual ~CMyContainerControl();
 
private: // from CCoeControl
    void Draw(const TRect& aRect) const;
    void SizeChanged();
 
public: // own methods
    // NOTE: Transfer ownership to CMyContainerControl
    void AddControlL(CCoeControl* aControl,TInt aControlId);
    void UpdateControls();
 
private: // own methods
    CMyContainerControl();
    void ConstructL(const TRect& aRect);
};

Source

CMyContainerControl* CMyContainerControl::NewL(const TRect& aRect)
    {
    CMyContainerControl* self = CMyContainerControl::NewLC(aRect);
    CleanupStack::Pop(self);
    return self;
    }
 
CMyContainerControl* CMyContainerControl::NewLC(const TRect& aRect)
    {
    CMyContainerControl* self = new(ELeave) CMyContainerControl();
    CleanupStack::PushL(self);
    self->ConstructL(aRect);
    return self;
    }
 
CMyContainerControl::CMyContainerControl()
    {
    }
 
CMyContainerControl::~CMyContainerControl()
    {
    }
 
void CMyContainerControl::ConstructL(const TRect& aRect)
    {
    // No parent owner, so create an own window
    CreateWindowL();
 
    // Initialize component array
    InitComponentArrayL();
 
    SetRect(aRect);
 
    ActivateL(); 
    }
 
void CMyContainerControl::SizeChanged()
    {
    UpdateControls();
    }
 
void CMyContainerControl::UpdateControls()
    {
    TPoint position;
 
    // Goes through all components of this container control
    CCoeControlArray::TCursor cursor = Components().Begin();
    CCoeControl* ctrl = NULL;
    while ((ctrl = cursor.Control<CCoeControl>()) != NULL)
        {
        // If control is not visible does not handle it
        if (!ctrl->IsVisible())
            {
            cursor.Next();
            continue;
            }
 
        // Set position
        ctrl->SetPosition(position);
 
        // Set size
        TSize size = ctrl->MinimumSize();
        size.SetSize(Rect().Width(),size.iHeight);
        ctrl->SetSize(size);
 
        // Store position of last component
        position.iY += size.iHeight;
 
        // Does control fit to view?
        if (position.iY >= Rect().iBr.iY)
            {
            ctrl->MakeVisible(EFalse);
            }
        else
            {
            ctrl->MakeVisible(ETrue);
            }
 
        cursor.Next();
        }
    }
 
void CMyContainerControl::Draw(const TRect& /*aRect*/) const
    {
    CWindowGc& gc = SystemGc();
    gc.SetBrushColor(KRgbBlack);
    gc.Clear(Rect());
    }
 
void CMyContainerControl::AddControlL(CCoeControl* aControl,TInt aControlId)
    {
    // NOTE: Transfer ownership of CCoeControl to CMyContainerControl
    // Add control into container control
    Components().AppendLC(aControl,aControlId);
    CleanupStack::Pop(aControl);
 
    // Focus first component
    if (Components().Count()==1)
        {
        aControl->SetFocus(ETrue);
        }
 
    // Update control's position
    UpdateControls();
    }

SizeChanged

When CMyContainerControl's size changes (when, for example, SetRect() is called), components' positions have to be calculated again.

void CMyContainerControl::SizeChanged()
    {
    // Sets new position of the components
    UpdateControls();
    }

Focusing component

Make the following changes to the CMyControl component.

• CMyControl::Draw() must call DrawFocusFrame() for drawing the focus rectangle
• CMyControl::DrawFocusFrame() is a new method where focus rectangle is drawn

void CMyControl::Draw(const TRect& aRect) const
    {
    CWindowGc& gc = SystemGc();
    gc.SetBrushColor(KRgbBlue);
    gc.Clear(Rect());
 
    DrawFocusFrame(aRect);
    }
 
void CMyControl::DrawFocusFrame(const TRect& aRect) const
    {
    // Nothing to draw if not focused
    if ( IsFocused() == EFalse )
        return;
 
    // Prep for draw
    CWindowGc& gc = SystemGc();
    gc.SetPenStyle( CGraphicsContext::ESolidPen );
    gc.SetPenSize( TSize(KFocusFrameWidth,KFocusFrameWidth) );
    gc.SetBrushStyle( CGraphicsContext::ENullBrush );
    gc.SetPenColor( KRgbDarkGray );
 
    // Draw the rounded rectangle
    gc.DrawRoundRect( aRect, TSize( KFrameRoundRadius, KFrameRoundRadius ) );
    }

Postconditions

CMyContainerControl container has some CMyControlcustom controls in a list.

See also

Custom Control Series:

• CS000859 - Custom_control Defining a custom control
• CS000860 - Custom control: Construct from resource Creating a control from a resource
• Custom control - focusing Handling key events and changing active custom control focus
• Custom control - scrollbars Adding scroll bar to custom control
• Custom control - in dialog Adding a custom control into CAknDialog
• File:CustomControl.zip Example code patch