PDFBox - PDF 页面坐标系、PDF 页面尺寸获取、PDF 页面位置计算

一、PDF 页面坐标系

• PDF 页面的原点 (0, 0) 位于页面的左下角，X 轴向右为正，Y 轴向上为正

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二、PDF 页面尺寸获取

PDPage page = new PDPage();PDRectangle mediaBox = page.getMediaBox();float width = mediaBox.getWidth();
float height = mediaBox.getHeight();System.out.println("mediaBox: " + mediaBox);
System.out.println("width: " + width);
System.out.println("height: " + height);

# 输出结果mediaBox: [0.0,0.0,612.0,792.0]
width: 612.0
height: 792.0

try (PDDocument document = PDDocument.load(new File("pdf/example.pdf"))) {PDPage page = document.getPage(0);PDRectangle mediaBox = page.getMediaBox();float width = mediaBox.getWidth();float height = mediaBox.getHeight();System.out.println("mediaBox: " + mediaBox);System.out.println("width: " + width);System.out.println("height: " + height);
} catch (Exception e) {e.printStackTrace();
}

# 输出结果mediaBox: [0.0,0.0,612.0,792.0]
width: 612.0
height: 792.0

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三、PDF 页面位置计算

1、使图片位于 PDF 页面的左上角

try (PDDocument document = new PDDocument()) {PDPage page = new PDPage();document.addPage(page);PDImageXObject pdImage = PDImageXObject.createFromFile("pdf/dzs.jpeg", document);try (PDPageContentStream contentStream = new PDPageContentStream(document, page)) {// 获取 PDF 页面的尺寸PDRectangle mediaBox = page.getMediaBox();float pdfWidth = mediaBox.getWidth();float pdfHeight = mediaBox.getHeight();// 获取图片的尺寸float imgWidth = pdImage.getWidth() * 0.25f;float imgHeight = pdImage.getHeight() * 0.25f;float x = 0;float y = pdfHeight - imgHeight;contentStream.drawImage(pdImage, x, y, imgWidth, imgHeight);} catch (IOException e) {e.printStackTrace();}document.save("pdf/image_position_example.pdf");
} catch (IOException e) {e.printStackTrace();
}

2、使图片位于 PDF 页面的左下角

...float x = 0;
float y = 0;...

3、使图片位于 PDF 页面的右上角

...float x = pdfWidth - imgWidth;
float y = pdfHeight - imgHeight;...

4、使图片位于 PDF 页面的右下角

...float x = pdfWidth - imgWidth;
float y = 0;...

5、使图片靠左垂直居中

...float x = 0;
float y = (pdfHeight - imgHeight) / 2;...

6、使图片靠右垂直居中

...float x = pdfWidth - imgWidth;
float y = (pdfHeight - imgHeight) / 2;...

7、使图片靠上水平居中

...float x = (pdfWidth - imgWidth) / 2;
float y = pdfHeight - imgHeight;...

8、使图片靠下水平居中

...float x = (pdfWidth - imgWidth) / 2;
float y = 0;...

9、使图片居中

...float x = (pdfWidth - imgWidth) / 2;
float y = (pdfHeight - imgHeight) / 2;...