代码：
private void button4_Click(object sender, EventArgs e)
{
PowerPoint1.Application pptApplication = Globals.ThisAddIn.Application.ActivePresentation.Application;//获得正在运行的PowerPoint应用程序
PowerPoint1.Presentation presentation = pptApplication.ActivePresentation;//获得当前活动的演示文稿对象
presentation.PageSetup.SlideOrientation = Office.MsoOrientation.msoOrientationVertical;//幻灯片方向设置为垂直
}
private void button5_Click(object sender, EventArgs e)
{
PowerPoint1.Application pptApplication = Globals.ThisAddIn.Application.ActivePresentation.Application;//获得正在运行的PowerPoint应用程序
PowerPoint1.Presentation presentation = pptApplication.ActivePresentation;//获得当前活动的演示文稿对象
presentation.PageSetup.SlideOrientation = Office.MsoOrientation.msoOrientationHorizontal;//幻灯片方向设置为水平
}
private void button6_Click(object sender, EventArgs e)
{
PowerPoint1.Application pptApplication = Globals.ThisAddIn.Application.ActivePresentation.Application;//获得正在运行的PowerPoint应用程序
PowerPoint1.Presentation presentation = pptApplication.ActivePresentation;//获得当前活动的演示文稿对象
presentation.PageSetup.SlideOrientation = Office.MsoOrientation.msoOrientationMixed;//幻灯片方向设置为垂直与水平切换
}
}
}