为什么这样pageEvent介绍如何使用iText库页面的内容？ [英] Why this pageEvent cover the content of page using iText library?

问题描述

有与边界线PageEvent也适用背景色整页但是当这种PageEvent应用createPDF隐藏的内容。

There is a PageEvent with border-line also apply background color for whole page but when this PageEvent applied the content of "createPDF" hide.

public class BlackBorder extends PdfPageEventHelper {
    @Override
    public void onEndPage(PdfWriter writer, Document document) {
        PdfContentByte canvas = writer.getDirectContent();
        Rectangle rect = document.getPageSize();
        rect.setBackgroundColor(new BaseColor(234,234,234,0));
        rect.setBorder(Rectangle.BOX);  
        rect.setBorderWidth(10);  
        rect.setBorderColor(BaseColor.BLACK); 
        rect.setUseVariableBorders(true);  
        canvas.rectangle(rect);
    }
}


//Method of createPDF.
public void createPdf(String filename) throws IOException, DocumentException {

    Document document = new Document();
    PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream(filename));
    BlackBorder event_border = new BlackBorder();
    writer.setPageEvent(event_border);
    document.open();
    Chunk chunk = new Chunk(String.valueOf(FileCounter)+"No"+String.valueOf(FileCounter));
    chunk.setTextRenderMode(PdfContentByte.TEXT_RENDER_MODE_FILL_STROKE, 0.3f, BaseColor.CYAN);
    document.add(chunk);
    document.close();
}

如果我删除
    rect.setBackgroundColor（新BaseColor（234,234,234,0））

If i remove rect.setBackgroundColor(new BaseColor(234,234,234,0))

块将是可见的。此外，我已经试过背景事件，如：

the Chunk would be visible. Also i've tried Background event like:

public class Background extends PdfPageEventHelper {
    @Override
    public void onEndPage(PdfWriter writer, Document document) {
        PdfContentByte canvas = writer.getDirectContent();
        Rectangle rect = document.getPageSize();
        rect.setBackgroundColor(new BaseColor(234,234,234,0));
        canvas.rectangle(rect);
    }
}

和添加

    Background event = new Background();
    writer.setPageEvent(event);

在createPdf方法，但应用程序无法产生任何PDF文件！

in createPdf method but app couldn't generate any PDF file!

这将非常感激，如果你挂我怎么有多个PageEvent像水印巡航能力，夏理躯，背景等等。我尝试了一些人，但我认为他们互相掩护。

It would be much obliged if you linked me how to have multiple PageEvent like haveing watermark, hearder-footer , background etc. I tried some of them but i think they cover each other.

谢谢..

推荐答案

因为你编程这种方式的矩形覆盖的内容。

The rectangle covers the content because you programmed it this way.

如果你想下添加一个不透明的矩形的 的现有内容，替换：

If you want to add an opaque rectangle under the existing content, replace:

PdfContentByte canvas = writer.getDirectContent();

与

PdfContentByte canvas = writer.getDirectContentUnder();

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