Chapter 1

TInt baseline=aDeviceRect.Height()/2 + font-
>AscentInPixels()/2;
}
aGc.DrawText(*iText, aDeviceRect, baseline,
CGraphicsContext::ECenter);
aGc.DiscardFont();
//Draw a surrounding box
This uses the version of DrawText() that specifies a rectangle and guarantees that
drawing will be clipped within that rectangle.
However, the DrawText() function will only white out the background before drawing, if
iFullRedraw is set. When it is set, the brush setting is solid and white, which will cause the
background to be whited; when it is not set, there is effectively no brush and the text is
drawn straight over whatever was there before. This is the reason for the messy display in
the upper rectangle in the screen shot of our application. In a real program, the whiting out of
the background would not be conditional.
15.1.2 Using the View
CExampleHelloControl has a CExampleHelloView, which it uses for drawing its
model. Here's CExampleHelloControl::Draw():
void CExampleHelloControl::Draw(const TRect& /*aRect*/) const
{
CWindowGc& gc = SystemGc();//CWindowGc is derived from
CGraphicsContext
TRect rect = Rect();
rect.Shrink(10,10);
gc.SetPenStyle(CGraphicsContext::ENullPen);
gc.SetBrushStyle(CGraphicsContext::ESolidBrush);
gc.SetBrushColor(KRgbWhite);
DrawUtils::DrawBetweenRects(gc, Rect(), rect);//whitens the
border
gc.SetPenStyle(CGraphicsContext::ESolidPen);
gc.SetPenColor(KRgbBlack);
gc.SetBrushStyle(CGraphicsContext::ENullBrush);
gc.DrawRect(rect);
rect.Shrink(1,1);
iView->DrawInRect(iZoomFactor, gc, rect, iFont);
}
First, CExampleHelloControl draws a surrounding 10-pixel border. This code is
guaranteed to be on the screen, and the 10-pixel border is chosen independently of the
zoom state (as it would look silly if the border were to scale to honor the zoom state).