如何使用 itext 在 PDF 文档上设置边框、边距和内边距 7

Question

I am trying to set border, margin, and padding to a PDF document, is it possible to achieve using itext7

Margin works fine by setting below code

document.setLeftMargin(180);

But the border is not working, below code used to set the border

float width = 1.5f;
Color color = ColorConstants.BLUE;
Border border = new DottedBorder(color,width);
Document document = new Document(pdfDocument);
document.setBorder(border);

Answer 1

Unfortunately it's not possible to specify the document's background and borders just by setting some of the Document 's properties. The good news is that iText7 provides us with an opportunity to override DocumentRenderer (renderers are classes responsible to render corresponding model objects, for example, ParagraphRenderer renders Paragraph and so on).

In the custom DocumentRenderer below updateCurrentArea was overridden to tackle the following two issues:

• shrinking the area which will be used by DocumentRenderer to layout the Document 's children

• adding a background Div , whic will be resposible for border rendering (I've also shown how one could set background, if needed)

   class CustomDocumentRenderer extends DocumentRenderer { public CustomDocumentRenderer(Document document) { super(document); } @Override protected LayoutArea updateCurrentArea(LayoutResult overflowResult) { LayoutArea area = super.updateCurrentArea(overflowResult); // margins are applied on this level Rectangle newBBox = area.getBBox().clone(); // apply border float[] borderWidths = {10, 10, 10, 10}; newBBox.applyMargins(borderWidths[0], borderWidths[1], borderWidths[2], borderWidths[3], false); // this div will be added as a background Div div = new Div().setWidth(newBBox.getWidth()).setHeight(newBBox.getHeight()).setBorder(new SolidBorder(10)).setBackgroundColor(ColorConstants.GREEN); addChild(new DivRenderer(div)); // apply padding float[] paddingWidths = {20, 20, 20, 20}; newBBox.applyMargins(paddingWidths[0], paddingWidths[1], paddingWidths[2], paddingWidths[3], false); return (currentArea = new RootLayoutArea(area.getPageNumber(), newBBox)); }

  }

The last quetions is how to apply it on your document. It could be done as follows:

    PdfDocument pdfDoc = new PdfDocument(new PdfWriter(outFileName));
    Document doc = new Document(pdfDoc);
    doc.setRenderer(new CustomDocumentRenderer(doc));

The resultant PDF: