How to create and draw to an off-screen bitmap

This phase of the example shows the creation of a bitmap, the creation of an off-screen graphics device and graphics context for it, and the use of that graphics context to draw to the bitmap. Once a graphics context has been established for the bitmap, any of the GDI drawing functions can be used on the bitmap, as if it were the more common graphics context the screen.

// create a bitmap to be used off-screen
CFbsBitmap* offScreenBitmap = new (ELeave) CFbsBitmap();
User::LeaveIfError(offScreenBitmap->Create(TSize(100,100),EColor256));
CleanupStack::PushL(offScreenBitmap);

// create an off-screen device and context
CGraphicsContext* bitmapContext=NULL;
CFbsBitmapDevice* bitmapDevice = CFbsBitmapDevice::NewL(offScreenBitmap);
CleanupStack::PushL(bitmapDevice);
User::LeaveIfError(bitmapDevice->CreateContext(bitmapContext));
CleanupStack::PushL(bitmapContext);

// draw something on the bitmap
TRect rect(0,0,100,100);
bitmapContext->SetBrushColor(KRgbRed);
bitmapContext->SetBrushStyle(CGraphicsContext::ESolidBrush);
bitmapContext->DrawRect(rect); // a filled red rectangle

// now do what you want with it, such as blitting to the screen
gc.BitBlt(TPoint(20,20),offScreenBitmap);

// cleanup
CleanupStack::PopAndDestroy(3);
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