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Revision as of 07:33, 30 May 2013 by hamishwillee (Talk | contribs)

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How to create a custom control in Symbian C++

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Article Metadata
Code ExampleTested with
Devices(s): Nokia N95
Compatibility
Platform(s): S60 3rd Edition, FP1
S60 3rd Edition FP1
Article
Keywords: CCoeControl
Created: tepaa (29 Feb 2008)
Last edited: hamishwillee (30 May 2013)

Contents

Overview

Symbian OS provides a large set of ready-made controls but sometimes that is not enough. You can build your own UI control by deriving CCoeControl base class for controls. This example shows how to define your own simple custom control that has the CEikLabel.

Start by deriving CCoeControl and implement basic methods

  • construction
  • layout
  • size
  • drawing the control
  • contained controls (if any)


MMP file

The following libraries are needed:

LIBRARY euser.lib
LIBRARY apparc.lib
LIBRARY cone.lib
LIBRARY eikcore.lib
LIBRARY avkon.lib
LIBRARY commonengine.lib
LIBRARY eikcoctl.lib
LIBRARY gdi.lib

Header

#include <coecntrl.h>
#include <eiklabel.h>
 
class CMyControl : public CCoeControl
{
public:
static CMyControl* NewL(const TRect& aRect,const CCoeControl* aParent=NULL);
static CMyControl* NewLC(const TRect& aRect,const CCoeControl* aParent=NULL);
virtual ~CMyControl();
 
public: // from CCoeControl
TSize MinimumSize();
 
private: // from CCoeControl
void Draw(const TRect& aRect) const;
void SizeChanged();
 
private: // own methods
CMyControl();
void ConstructL(const TRect& aRect,const CCoeControl* aParent = NULL);
 
private: // data
CEikLabel* iStatusText;
};

Source

CMyControl* CMyControl::NewL(const TRect& aRect,const CCoeControl* aParent)
{
CMyControl* self = CMyControl::NewLC(aRect,aParent);
CleanupStack::Pop(self);
return self;
}
 
CMyControl* CMyControl::NewLC(const TRect& aRect,const CCoeControl* aParent)
{
CMyControl* self = new(ELeave) CMyControl();
CleanupStack::PushL(self);
self->ConstructL(aRect,aParent);
return self;
}
 
CMyControl::CMyControl()
{
}
 
CMyControl::~CMyControl()
{
// NOTE: Does not delete iStatusText because we do not own it
}
 
void CMyControl::ConstructL(const TRect& aRect,const CCoeControl* aParent)
{
// No owner, so create an own window
if(aParent == NULL)
{
CreateWindowL();
}
// Use Parent's window
else
{
// This is component in a compound control
SetContainerWindowL(*aParent);
}
 
// Initialize component array
InitComponentArrayL();
 
// Create contained controls
iStatusText = new (ELeave) CEikLabel;
iStatusText->SetContainerWindowL(*this);
iStatusText->SetTextL(_L("HelloWorld"));
 
// Store component to component array
Components().AppendLC(iStatusText);
CleanupStack::Pop(iStatusText);
 
SetRect(aRect); // or
//SetExtentToWholeScreen(); //NOTE: Can not see CBA buttons
 
// The application should call this function on
// all controls that are not components in a compound control
if(aParent == NULL)
{
ActivateL();
}
}
 
TSize CMyControl::MinimumSize()
{
// Get CEikLabel minium size and grow it
// that is this control MinimumSize.
// Custom control also needs a few other methods so it can be laid out
// and drawn. For example, custom controls usually implement MinimumSize(),
// SizeChanged() and Draw() methods.
 
// When using control in container control, set the minium size very small
TRect rect = iStatusText->MinimumSize();
rect.Grow(TSize(2,2));
return rect.Size();
 
// When using the control in a dialog, set the control size large
//return Rect().Size();
}
 
void CMyControl::SizeChanged()
{
// Responds to size changes to set the size and position of the contents
// of this control. For a simple control this might include text or
// graphics. For a compound control this sets the size and position of the
// component. It has an empty default implementation and should be
// implemented by the CCoeControl-derived class.
// The function is called whenever SetExtent(), SetSize(), SetRect(),
// SetCornerAndSize(), or SetExtentToWholeScreen() are called on
// the control.
if (iStatusText)
{
TRect labelRect(Rect());
labelRect.Shrink(TSize(5,2));
iStatusText->SetRect(labelRect);
}
}
 
void CMyControl::Draw(const TRect& /*aRect*/) const
{
CWindowGc& gc = SystemGc();
gc.SetBrushColor(KRgbBlue);
gc.Clear(Rect());
}


Using CCoeControl

The CMyControl custom control was added to the (S60 3rd FP1) MultiViews example and these are the changes in .cpp.

void CMultiViewsView1::DoActivateL( const TVwsViewId& /*aPrevViewId*/,
TUid /*aCustomMessageId*/,
const TDesC8& /*aCustomMessage*/)
{
iControl = CMyControl::NewL(ClientRect());
}
 
void CMultiViewsView1::DoDeactivate()
{
if (iControl)
{
AppUi()->RemoveFromStack(iControl);
delete iControl;
iControl = NULL;
}
}
 
void CMultiViewsView1::HandleSizeChange( TInt aType )
{
if( iControl )
{
iControl->HandleResourceChange( aType );
if ( aType==KEikDynamicLayoutVariantSwitch )
{
TRect rect;
AknLayoutUtils::LayoutMetricsRect(AknLayoutUtils::EMainPane, rect);
iControl->SetRect(rect);
}
}
}


Postconditions

CMyControl can be inside another CCoeControl (compound control) or be as a single control without a parent.


See also

Custom Control Series:

Other useful articles:

This page was last modified on 30 May 2013, at 07:33.
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