examples/Graphics/coverflow/src/ticker.cpp

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Description:� 
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#include "ticker.h"
#include <openfont.h>

CTicker::CTicker(const TRect& aRect, const TDesC& aString):
        iRect(aRect),
        iString(aString)
        {
#ifdef PORTRAIT_MODE
        iPos = TPoint(KFontHeight, 0);
#else
        iPos = TPoint(aRect.iBr.iX, KFontHeight);
#endif
        }

CTicker* CTicker::NewL(const TRect& aRect, const TDesC& aString)
        {
        CTicker* self = new(ELeave) CTicker(aRect, aString);
        CleanupStack::PushL(self);
        self->ConstructL();
        CleanupStack::Pop(self);
        return self;
        }

void CTicker::ConstructL()
        {
        // Connects the client session to the window server.
        User::LeaveIfError(iWs.Connect());
        
        // Constructs a new screen device attached to a particular window server session.
        iScr = new(ELeave) CWsScreenDevice(iWs);
        User::LeaveIfError(iScr->Construct());
        
        // Constructs a graphics context.
        iGc = new(ELeave) CWindowGc(iScr);
        User::LeaveIfError(iGc->Construct());

        // Creates a sessionless, uninitialised window group handle.
        iGrp = RWindowGroup(iWs);
        User::LeaveIfError(iGrp.Construct(0xdeadface, EFalse));
        iGrp.SetOrdinalPositionErr(0, 100);
        
        // Creates a sessionless, uninitialised window handle.
        iWin = RWindow(iWs);
        User::LeaveIfError(iWin.Construct(iGrp, (TInt)this));
        
        // Sets the window to be transparent using the alpha channel.
        iWin.SetTransparencyAlphaChannel();
        
        // Sets the background colour used for clearing in server-initiated redraws.
        iWin.SetBackgroundColor(TRgb(0,0,0,0));
        
        // Sets the size and position of a window.
        iWin.SetExtent(iRect.iTl, iRect.Size());
        
        // Displays the window and enables it to receive events.
        iWin.Activate();
        
        // Sets the ordinal position of a window.
        iWin.SetOrdinalPosition(-1);
        
        // Sets the window's visibility.
        iWin.SetVisible(EFalse);
        
        // Sends all pending commands in the buffer to the window server.
        iWs.Flush();
        
        // Specify the font specification that allows more attributes than TOpenFontSpec.
        TOpenFontSpec openSpec;
        
        // Sets whether the font should be drawn using anti-aliasing
    openSpec.SetBitmapType(EAntiAliasedGlyphBitmap);
    
    // Specify the font specification
        TFontSpec fs;
        
        // Gets the TFontSpec corresponding to this Open Font System font specification.
    openSpec.GetTFontSpec(fs);
    
    // Assign the font specification
    fs.iTypeface.iName = _L("SwissA");
    fs.iHeight = KFontHeight;

        // Gets the font which is the nearest to the given font specification.
        User::LeaveIfError(iScr->GetNearestFontInPixels(iFont, fs));
        iLen = iFont->TextWidthInPixels(iString);
        
        // Allocates and constructs a CPeriodic object. Assign a priority to it.
        iTimer = CPeriodic::NewL(CActive::EPriorityStandard);
        }

CTicker::~CTicker()
        {
        Stop();
        delete iTimer;
        if(iScr)
                {
                // Releases a specified font.
                iScr->ReleaseFont(iFont);
                }
        delete iGc;
        delete iScr;
        
        // Close the nodes.
        iWin.Close();
        iGrp.Close();
        iWs.Close();
        }

void CTicker::Start()
        {
        // Sets the window's visibility.
        iWin.SetVisible(ETrue);
        if (!iTimer->IsActive())
                {
                // Starts generating periodic events. Pass the OnTick() function to call when the CPeriodic is scheduled after a timer event.
                iTimer->Start(0, 20*1000, TCallBack(CTicker::OnTick, this));
                }
        }
        
void CTicker::Stop()
        {
        // Sets the window's visibility.
        iWin.SetVisible(EFalse);
        
        // Sends all pending commands in the buffer to the window server.
        iWs.Flush();
        
        // Cancels the wait for completion of an outstanding request.
        iTimer->Cancel();
        }

TInt CTicker::OnTick(TAny* aArg)
        {
        CTicker* self = (CTicker*)aArg;
        
        // Invalidates the entire window.
        self->iWin.Invalidate();
        
        // Begins redrawing the window's invalid region
        self->iWin.BeginRedraw();
        
        // Activates the context for a given window 
        self->iGc->Activate(self->iWin);
        self->Draw();
        
        // Frees the graphics context to be used with another window.
        self->iGc->Deactivate();
        
        // Ends the current redraw.
        self->iWin.EndRedraw();
        
        // Sends all pending commands in the buffer to the window server.
        self->iWs.Flush();

        return 0;
        }

TBool CTicker::Draw()
        {
#ifdef PORTRAIT_MODE
        ++iPos.iY;

        if (iPos.iY > iLen)
                {
                iPos.iY = 0;
                return ETrue;
                }
#else
        --iPos.iX;

        if (iPos.iX < -iLen)
                {
                iPos.iX = iRect.iBr.iX;
                return ETrue;
                }

#endif
        
        // Sets the line drawing size for the pen.
        iGc->SetPenSize(TSize(1,1));
        
        // Sets the pen colour.
        iGc->SetPenColor(TRgb(255,255,255,255));
        
        // Sets the line drawing style for the pen
        iGc->SetPenStyle(CGraphicsContext::ESolidPen);
        
        // Sets this context's font.
        iGc->UseFont(iFont);

#ifdef PORTRAIT_MODE
        iGc->DrawTextVertical(iString, iPos, ETrue);
#else
        iGc->DrawText(iString, iPos);
#endif
        
        // Discards a font.
        iGc->DiscardFont();

        return EFalse;
        }

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