Chapter 1

hellogui's application view is a control whose sole purpose is to draw the text 'Hello
world!' on the screen in a reasonably pleasing manner. It doesn't handle key or pointer
events.
Like all controls, CHelloGuiAppView is derived from CCoeControl, which has virtual
functions that you override to implement a particular control's functionality. In this case, the
only function of interest is Draw(). The definition, from HelloGui_AppView.h is as
follows:
class CHelloGuiAppView : public CCoeControl
{
public:
static CHelloGuiAppView* NewL(const TRect& aRect);
~CHelloGuiAppView();
void ConstructL(const TRect& aRect);
private:
void Draw(const TRect& /* aRect */) const;
private:
HBufC* iHelloText;
};
Let's start with the implementation of the second-phase constructor:
CHelloGuiAppView* CHelloGuiAppView::NewL(const TRect& aRect)
{
CHelloGuiAppView * self = new(ELeave) CHelloGuiAppView;
CleanupStack::PushL(self);
self->ConstructL(aRect);
CleanupStack::Pop();
return self;
}
void CHelloGuiAppView::ConstructL(const TRect& aRect)
{
CreateWindowL();
SetRect(aRect);
ActivateL();
// Fetch the text from the resource file.
iHelloText = iEikonEnv->AllocReadResourceL(R_HELLOGUI_TEXT_HELLO);
}
ConstructL() uses CCoeControl() base-class library functions to create a window, set
it to the rectangle offered, and activate it. It then reads the 'Hello World!' text from a resource
file into an HBufC, which is allocated the appropriate length. This is a common pattern in
application programming. The memory for the HBufC is, of course deleted, in the destructor:
CHelloGuiAppView::~CHelloGuiAppView()