Constrain image size

gistfile1.cpp

bool ConstrainImageSize(
        int &aWidth,          // in/out - actual image width
        int &aHeight,         // in/out - actual image height
        const int aMaxWidth,  // in - max width
        const int aMaxHeight  // in - max height
        ) const
{
  float ratioNeed = std::max( (float)aWidth / (float)aMaxWidth, (float)aHeight / (float)aMaxHeight );
  if( ratioNeed > 1.0 ) {
    // actually needs downscaling at all
    aWidth = (int)((float)aWidth / ratioNeed + 0.5);
    aHeight = (int)((float)aHeight /ratioNeed + 0.5);
    return true;
  }
  return false;
}