对文档添加水印可以有效声明和保护文档，是保护重要文件的方式之一。在PPT文档中同样也可以设置水印，包括文本水印和图片水印，本文将讲述如何通过Spire.Presentation for .NET来对PPT添加水印，下载安装Free Spire.Presentationfor .NET后，添加引用dll文件，参考下面的操作步骤，完成水印添加。
1.添加文本水印
步骤一：初始化Presentation类实例，并加载文档
Presentation ppt = new Presentation();ppt.LoadFromFile(@"C:\Users\Administrator\Desktop\sample.pptx", FileFormat.Pptx);
步骤二：初始化一个Font类实例，并实例化字体格式
Font stringFont = new Font("Arial", 90);Size size = TextRenderer.MeasureText("内部资料", stringFont);
步骤三：绘制一个shape并指定大小、填充颜色、边框颜色和旋转角度
RectangleF rect = new RectangleF((ppt.SlideSize.Size.Width - size.Width) / 2, (ppt.SlideSize.Size.Height - size.Height) / 2, size.Width, size.Height);IAutoShape shape = ppt.Slides[0].Shapes.AppendShape(Spire.Presentation.ShapeType.Rectangle, rect);shape.Fill.FillType = FillFormatType.None;shape.ShapeStyle.LineColor.Color = Color.White;shape.Rotation = -45;
步骤四：设定形状属性为保护属性
shape.Locking.SelectionProtection = true;shape.Line.FillType = FillFormatType.None;
步骤五：设置文本大小、颜色
shape.TextFrame.Text = "内部资料";TextRange textRange = shape.TextFrame.TextRange;textRange.Fill.FillType = Spire.Presentation.Drawing.FillFormatType.Solid;textRange.Fill.SolidColor.Color = Color.FromArgb(120, Color.Gray);textRange.FontHeight = 45;
步骤六：保存文档
ppt.SaveToFile("TextWatermark.pptx", FileFormat.Pptx);
完成以上代码步骤后，调试运行项目程序，生成文件（可在该项目文件中bin>Debug中查看），如下图所示：
全部代码：
using System;using System.Text;using Spire.Presentation;using System.Drawing;using Spire.Presentation.Drawing;using System.Windows.Forms;namespace InsertWatermark_PPT{class Program{static void Main(string[] args){//初始化一个Presentation类实例并加载文档Presentation ppt = new Presentation();ppt.LoadFromFile(@"C:\Users\Administrator\Desktop\sample.pptx", FileFormat.Pptx);//初始化一个Font类字体实例并实例化字体格式Font stringFont = new Font("Arial", 90);Size size = TextRenderer.MeasureText("内部资料", stringFont);//绘制一个Shape并指定大小、填充颜色、边框颜色和旋转度RectangleF rect = new RectangleF((ppt.SlideSize.Size.Width - size.Width) / 2, (ppt.SlideSize.Size.Height - size.Height) / 2, size.Width, size.Height);IAutoShape shape = ppt.Slides[0].Shapes.AppendShape(Spire.Presentation.ShapeType.Rectangle, rect);shape.Fill.FillType = FillFormatType.None;shape.ShapeStyle.LineColor.Color = Color.White;shape.Rotation = -45;//设定形状属性为保护属性shape.Locking.SelectionProtection = true;shape.Line.FillType = FillFormatType.None;//设置文本大小、颜色shape.TextFrame.Text = "内部资料";TextRange textRange = shape.TextFrame.TextRange;textRange.Fill.FillType = Spire.Presentation.Drawing.FillFormatType.Solid;textRange.Fill.SolidColor.Color = Color.FromArgb(150, Color.LightBlue);textRange.FontHeight = 90;//保存文档ppt.SaveToFile("TextWatermark.pptx", FileFormat.Pptx);}}
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2.添加图片水印
步骤一：初始化一个Presentation类实例并加载文档
Presentation ppt = new Presentation();ppt.LoadFromFile(@"C:\Users\Administrator\Desktop\sample.pptx", FileFormat.Pptx);
步骤二: 为第一张幻灯片设置背景图片类型和样式
ppt.Slides[0].SlideBackground.Type = Spire.Presentation.Drawing.BackgroundType.Custom;ppt.Slides[0].SlideBackground.Fill.FillType = FillFormatType.Picture;ppt.Slides[0].SlideBackground.Fill.PictureFill.FillType = PictureFillType.Stretch;
步骤三：加载图片并为第一张幻灯片设置水印
Image img = Image.FromFile(@"C:\Users\Administrator\Desktop\images\1.jpg");IImageData image = ppt.Images.Append(img);ppt.Slides[0].SlideBackground.Fill.PictureFill.Picture.EmbedImage = image;
步骤四：保存文档
ppt.SaveToFile("ImageWatermark1.pptx", FileFormat.Pptx);
全部代码：
using System;using System.Drawing;using Spire.Presentation;using Spire.Presentation.Drawing;namespace ImageWatermark_PPT{class Program{static void Main(string[] args){//初始化一个Presentation类实例并加载文档Presentation ppt = new Presentation();ppt.LoadFromFile(@"C:\Users\Administrator\Desktop\sample.pptx", FileFormat.Pptx);//为第一张幻灯片设置背景图片类型和样式ppt.Slides[0].SlideBackground.Type = Spire.Presentation.Drawing.BackgroundType.Custom;ppt.Slides[0].SlideBackground.Fill.FillType = FillFormatType.Picture;ppt.Slides[0].SlideBackground.Fill.PictureFill.FillType = PictureFillType.Stretch;//加载图片并为第一张幻灯片设置水印效果Image img = Image.FromFile(@"C:\Users\Administrator\Desktop\images\1.jpg");IImageData image = ppt.Images.Append(img);ppt.Slides[0].SlideBackground.Fill.PictureFill.Picture.EmbedImage = image;//保存文档ppt.SaveToFile("ImageWatermark1.pptx", FileFormat.Pptx);}}}
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以上是对PPT添加水印的代码操作，希望该方法能提供帮助，感谢阅读！
