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Png Device类允许将PDF页转换为Png图像。这个类提供了一个叫Process方法用来实现这一转换过程。您首先需要创建一个文档类对象,用于获取需要转换成PNG格式的指定PDF页。之后,调用Process方法将页面转换为PNG图像。

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下面是具体示例代码

C#

//open document
Document pdfDocument = new Document("input.pdf");


using (FileStream imageStream = new FileStream("image.png", FileMode.Create))
{
//create PNG device with specified attributes
//Width, Height, Resolution, Quality
//Quality [0-100], 100 is Maximum
//create Resolution object
Resolution resolution = new Resolution(300);
PngDevice pngDevice = new PngDevice(resolution);


//convert a particular page and save the image to stream
pngDevice.Process(pdfDocument.Pages[1], imageStream);

//close stream
imageStream.Close();
 

'open document
Dim pdfDocument As New Document("input.pdf")


Using imageStream As New FileStream("image.png", FileMode.Create)
'create PNG device with specified attributes
'Width, Height, Resolution, Quality
'Quality [0-100], 100 is Maximum
'create Resolution object
Dim resolution As New Resolution(300)
Dim pngDevice As New PngDevice(resolution)


'convert a particular page and save the image to stream
pngDevice.Process(pdfDocument.Pages(1), imageStream)

'close stream
imageStream.Close()