向PDF添加水印

在将Excel文件转换为PDF时,可能需要在PDF文件中添加水印。以下示例展示了在呈现PDF时如何向PDF添加文本和图像水印。

向PDF添加文本水印

您可以通过指定文本和对应的字体轻松地向PDF添加文本水印。还可以在RenderingWatermark中设置对齐、偏移、旋转、不透明度、前景/背景和页面缩放。

//prepare a workbook with 3 pages.
Workbook wb = new Workbook();
wb.getWorksheets().get(0).getCells().get("A1").putValue("Page1");
int index = wb.getWorksheets().add();
wb.getWorksheets().get(index).getCells().get("A1").putValue("Page2");
index = wb.getWorksheets().add();
wb.getWorksheets().get(index).getCells().get("A1").putValue("Page3");
wb.getWorksheets().get(index).getPageSetup().setPaperSize(PaperSizeType.PAPER_A_3);
//create a font for watermark, and specify bold, italic, color.
RenderingFont font = new RenderingFont("Calibri", 68);
font.setItalic(true);
font.setBold(true);
font.setColor(Color.getBlue());
//create a watermark from text and the specified font.
RenderingWatermark watermark = new RenderingWatermark("Watermark", font);
//specify horizontal and vertical alignment
watermark.setHAlignment(TextAlignmentType.CENTER);
watermark.setVAlignment(TextAlignmentType.CENTER);
//specify rotation
watermark.setRotation(30);
//specify opacity
watermark.setOpacity(0.6f);
//specify the scale to page(e.g. 100, 50) in percent.
watermark.setScaleToPagePercent(50);
//spcify watermark for rendering to pdf.
PdfSaveOptions options = new PdfSaveOptions();
options.setWatermark(watermark);
wb.save("output_text_watermark.pdf", options);

向PDF添加图像水印

您可以通过指定图像的图像字节轻松地向PDF添加图像水印。还可以在RenderingWatermark中设置对齐、偏移、旋转、不透明度、前景/背景和页面缩放。

//prepare a workbook with 3 pages.
Workbook wb = new Workbook();
wb.getWorksheets().get(0).getCells().get("A1").putValue("Page1");
int index = wb.getWorksheets().add();
wb.getWorksheets().get(index).getCells().get("A1").putValue("Page2");
index = wb.getWorksheets().add();
wb.getWorksheets().get(index).getCells().get("A1").putValue("Page3");
wb.getWorksheets().get(index).getPageSetup().setPaperSize(PaperSizeType.PAPER_A_3);
//create a watermark from image(you need to prepare image bytes).
RenderingWatermark watermark = new RenderingWatermark(imageBytes);
//specify offset to alignment.
watermark.setOffsetX(100);
watermark.setOffsetY(200);
//specify rotation
watermark.setRotation(30);
//specify watermark to background.
watermark.setBackground(true);
//specify opacity
watermark.setOpacity(0.6f);
//specify the scale to page(e.g. 100, 50) in percent.
watermark.setScaleToPagePercent(50);
//spcify watermark for rendering to pdf.
PdfSaveOptions options = new PdfSaveOptions();
options.setWatermark(watermark);
wb.save("oputput_image_watermark.pdf", options);