使用pdfbox将透明图像插入pdf

Question

我通过以下方式将图像加载到 pdf 中：

PDImageXObject image= PDImageXObject.createFromFile(<image_path>, doc);
contentStream.drawImage(image, 15, pdfData.getPageHeight() - 80,
image.getWidth(), image.getHeight());

我试图使图像看起来透明，就像它在文档（谷歌文档，word 等）的标题中看起来一样，有没有一种简单的方法可以做到这一点？

Answer 1

使用扩展图形状态：

stream.saveGraphicsState();
PDExtendedGraphicsState pdExtGfxState = new PDExtendedGraphicsState();
pdExtGfxState.getCOSObject().setItem(COSName.BM, COSName.MULTIPLY); // pdExtGfxState.setBlendMode(BlendMode.MULTIPLY) doesn't work yet, maybe in later version 
pdExtGfxState.setNonStrokingAlphaConstant(0.5f);
contentStream.setGraphicsStateParameters(pdExtGfxState);
// do your stuff
stream.restoreGraphicsState();