如何在VC中更改PPT的背景色,字体颜色,字体

_Application app;
Presentations presentations;
_Presentation presentation;
Slides slides;
_Slide slide;
ShapeRange shaperange;
Shapes shapes;
Shape shape;
TextFrame textframe;
TextRange textrange;
Font font;
FillFormat fillformat;
ColorFormat colorformat;
ShadowFormat shadow;

if(!app.CreateDispatch("Powerpoint.Application", &e))
{
CString str;
str.Format("CreateDispatch() failed w/err 0x%08lx", e.m_sc),
AfxMessageBox(str, MB_SETFOREGROUND);
return;
}
app.SetVisible(TRUE); Presentations presSet(app.GetPresentations());
_Presentation pres(presSet.Add(TRUE));

Slides slideSet(pres.GetSlides());
_Slide slide1(slideSet.Add(1, 2));

// Add text to slide, by navigating the slide as follows:
// slide1.shapes(#).TextFrame.TextRange.Text
{
Shapes shapes(slide1.GetShapes());
Shape shape(shapes.Item(COleVariant((long)1)));
TextFrame textFrame(shape.GetTextFrame());
TextRange textRange(textFrame.GetTextRange());
textRange.SetText("My first slide");
}
{
Shapes shapes(slide1.GetShapes());
Shape shape(shapes.Item(COleVariant((long)2)));
TextFrame textFrame(shape.GetTextFrame());
TextRange textRange(textFrame.GetTextRange());
textRange.SetText("Automating PowerPoint is easy\r\n"
"Using Visual C++ is powerful!我是中国人");
font = textrange.GetFont();
font.SetName("华文行楷"); //Set the font name.
font.SetSize((float)48);
}
现在字体的大小、加粗，斜体属性都可以改，但就是字体的颜色改不了，还有，写的东西英文是华文行楷，汉语就不是，是默认的宋体，不知为什么！ 请高手赐教！！