每个PowerPoint演示文稿都有一个幻灯片母版，它包含幻灯片的所有样式。通过选择幻灯片母版，然后采用主题，添加背景图片或更改配色方案，可以快速改变整个演示文稿的外观。

在本文中，您将学习如何获取和修改现有演示文稿中的幻灯片母版。

测试文档：

//加载PDF文档
Presentation ppt = new Presentation();
ppt.LoadFromFile("sample.pptx");

//获取文档中的母版
IMasterSlide masterSlide = ppt.Masters[0];

//在母版上添加背景图片
string backgroundPic = "background.png";           
RectangleF rect = new RectangleF(0, 0, ppt.SlideSize.Size.Width, ppt.SlideSize.Size.Height);
masterSlide.SlideBackground.Fill.FillType = FillFormatType.Picture;
IEmbedImage image = masterSlide.Shapes.AppendEmbedImage(ShapeType.Rectangle, backgroundPic, rect);
masterSlide.SlideBackground.Fill.PictureFill.Picture.EmbedImage = image as IImageData;

//更改母版主题颜色
masterSlide.Theme.ColorScheme.Accent1.Color = Color.Red;
masterSlide.Theme.ColorScheme.Accent2.Color = Color.RosyBrown;
masterSlide.Theme.ColorScheme.Accent3.Color = Color.Ivory;
masterSlide.Theme.ColorScheme.Accent4.Color = Color.Lavender;
masterSlide.Theme.ColorScheme.Accent5.Color = Color.Black;

//在母版上添加图片
string logo = "logo.png";
IEmbedImage imageShape = masterSlide.Shapes.AppendEmbedImage(ShapeType.Rectangle, logo, new RectangleF(40, 40, 240, 65));
imageShape.Line.FillFormat.FillType = FillFormatType.None;

//保存文档
ppt.SaveToFile("result.pptx", FileFormat.Pptx2013);

'加载PDF文档
Dim ppt As New Presentation()
ppt.LoadFromFile("sample.pptx")

'获取文档中的母版
Dim masterSlide As IMasterSlide = ppt.Masters(0)

'在母版上添加背景图片
Dim backgroundPic As String = "background.png"
Dim rect As New RectangleF(0, 0, ppt.SlideSize.Size.Width, ppt.SlideSize.Size.Height)
masterSlide.SlideBackground.Fill.FillType = FillFormatType.Picture
Dim image As IEmbedImage = masterSlide.Shapes.AppendEmbedImage(ShapeType.Rectangle, backgroundPic, rect)
masterSlide.SlideBackground.Fill.PictureFill.Picture.EmbedImage = TryCast(image, IImageData)

'更改母版主题颜色
masterSlide.Theme.ColorScheme.Accent1.Color = Color.Red
masterSlide.Theme.ColorScheme.Accent2.Color = Color.RosyBrown
masterSlide.Theme.ColorScheme.Accent3.Color = Color.Ivory
masterSlide.Theme.ColorScheme.Accent4.Color = Color.Lavender
masterSlide.Theme.ColorScheme.Accent5.Color = Color.Black

'在母版上添加图片
Dim logo As String = "logo.png"
Dim imageShape As IEmbedImage = masterSlide.Shapes.AppendEmbedImage(ShapeType.Rectangle, logo, New RectangleF(40, 40, 240, 65))
imageShape.Line.FillFormat.FillType = FillFormatType.None

'保存文档
ppt.SaveToFile("result.pptx", FileFormat.Pptx2013)

结果文档：