如何在iText中从颜色源获取BaseColor

Question

我正在用ittext解析一个PDF文档，我想知道页面中线条和矩形的颜色。我使用以下代码进行解析:

private PdfDictionary getColorDictionary(PdfDictionary resourcesDic) {
PdfDictionary colorDict = resourcesDic.getAsDict(PdfName.COLORSPACE);
return colorDict;
}
public void decode(File file) throws IOException {
PdfReader reader = new PdfReader(file.toURI().toURL());
int numberOfPages = reader.getNumberOfPages();
ProcessorListener listener = new ProcessorListener ();
PdfContentStreamProcessor processor = new PdfContentStreamProcessor(listener);
for (int pageNumber = 1; pageNumber <= numberOfPages; pageNumber++) {
PdfDictionary pageDic = reader.getPageN(pageNumber);
PdfDictionary resourcesDic = pageDic.getAsDict(PdfName.RESOURCES);
PdfDictionary colorSpaceDic = getColorDictionary(resourcesDic);
listener.setResources(colorSpaceDic);
processor.processContent(ContentByteUtils.getContentBytesForPage(reader, pageNumber), resourcesDic);
} 
}

我的监听器有以下代码，我将其简化为只显示获取每个页面中的图形元素的部分:

public class ProcessorListener implements ExtRenderListener {
private PdfDictionary colorSpaceDic = null;
public void setResources(PdfDictionary colorSpaceDic) {
this.colorSpaceDic = colorSpaceDic;
}
@Override
public void beginTextBlock() {
}
@Override
public void renderText(TextRenderInfo tri) {
}
@Override
public void renderImage(ImageRenderInfo iri) {
}
@Override
public Path renderPath(PathPaintingRenderInfo renderInfo) {
GraphicsState graphicsState;
try {
graphicsState = getGraphicsState(renderInfo);
} catch (NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException e) {
return null;
}
if ((renderInfo.getOperation() & PathPaintingRenderInfo.STROKE) != 0) {
PdfName resource = graphicsState.getColorSpaceStroke();
if (resource != null && colorSpaceDic != null) {
PdfObject obj = colorSpaceDic.get(resource);
System.err.println("STROKE: " + obj);
}
}
if ((renderInfo.getOperation() & PathPaintingRenderInfo.FILL) != 0) {
PdfName resource = graphicsState.getColorSpaceStroke();
if (resource != null && colorSpaceDic != null) {
PdfObject obj = colorSpaceDic.get(resource);
System.err.println("FILL: " + obj);
}
}
}
return null;
}

这段代码执行正确，但是每个与填充或笔画相关的PDFObject都是PRIndirectReference。我如何得到与这个参考相关的BaseColor?

我还尝试使用以下代码(例如填充):

BaseColor fillColor = graphicsState.getFillColor();

但是颜色总是空的。文档中不仅有黑色的形状(我假设这是默认的)，还有绿色或蓝色的线条。

Answer 1

我使用Acrobat Reader(打印选项)或Edge将PDF文档保存到另一个文档中，并且我在结果文档中没有空颜色。