void RRotateDialog::RotateDisplay( int iPos )
{
if ( iPos == m_iPrevPos )
return;
// We need to use the RBitmap::Rotate() function, so to do that, convert to
// Renaissance types.
CClientDC clientDC( &m_staticDisplay );
HDC hClientDC = clientDC.GetSafeHdc();
RDcDrawingSurface drawSurface;
drawSurface.Initialize( hClientDC, hClientDC );
R2dTransform transform;
// Prepare the image on an offscreen DC
RAutoDrawingSurface drawSurfaceOffscreen;
RRealRect rRealStaticRect(m_rectStaticDisplay);
BOOLEAN fPrepared = drawSurfaceOffscreen.Prepare( &drawSurface, transform, rRealStaticRect );
RDrawingSurface* pSurface = ( (fPrepared)? &drawSurfaceOffscreen : &drawSurface );
// Paint the offscreen DC white
RColor rColor = RSolidColor( kWhite );
pSurface->SetFillColor( rColor );
pSurface->SetPenColor( rColor );
pSurface->FillRectangle( m_rectStaticDisplay );
YAngle flRadiansRotation = ::DegreesToRadians( YFloatType( iPos ) );
// The rotation leaves a black background, so blit with a mask. The mask
// has to be created the same size as the original (not rotated) bitmap
// size, so create it and then rotate it.
RBitmapImage bmpRotated;
RBitmapImage bmpMaskRotated;
RImageLibrary rLibrary;
rLibrary.Rotate( m_rBitmapImage, bmpRotated, bmpMaskRotated, flRadiansRotation );
RIntSize sizeBmpRotated;
sizeBmpRotated.m_dx = bmpRotated.GetWidthInPixels();
sizeBmpRotated.m_dy = bmpRotated.GetHeightInPixels();
RIntRect rectSource;
RIntRect rectDest;
DeriveSourceAndDestinationRects( sizeBmpRotated, rectSource, rectDest );
bmpRotated.RenderWithMask( *pSurface, bmpMaskRotated, rectSource, rectDest );
if ( fPrepared )
drawSurfaceOffscreen.Release();
drawSurface.DetachDCs();
m_iPrevPos = iPos;
}
