Adobe 如何在PDF中添加水印并使用；相对于目标页面的比例“；

我正在使用一个基于中TransparentWatermark示例的示例

但我似乎找不到一个方法或选项与Adobe设置中的“相对于目标页面的比例”添加水印相关

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有人能指给我看吗

尝试创建Textwatermark示例的变体，该变体可缩放水印以覆盖总页面面积的百分比。本质上，这是一个线性代数问题，需要找到正确的缩放变换，并确保所有其他平移和旋转都是正确的

package Stackoverflow.ScalingWatermark;

import com.itextpdf.io.IOException;
import com.itextpdf.io.font.FontConstants;
import com.itextpdf.kernel.color.Color;
import com.itextpdf.kernel.color.DeviceCmyk;
import com.itextpdf.kernel.events.Event;
import com.itextpdf.kernel.events.IEventHandler;
import com.itextpdf.kernel.events.PdfDocumentEvent;
import com.itextpdf.kernel.font.PdfFont;
import com.itextpdf.kernel.font.PdfFontFactory;
import com.itextpdf.kernel.geom.AffineTransform;
import com.itextpdf.kernel.geom.Rectangle;
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfPage;
import com.itextpdf.kernel.pdf.PdfWriter;
import com.itextpdf.kernel.pdf.canvas.PdfCanvas;
import com.itextpdf.kernel.pdf.xobject.PdfFormXObject;
import com.itextpdf.layout.Document;
import com.itextpdf.layout.border.SolidBorder;
import com.itextpdf.layout.element.AreaBreak;
import com.itextpdf.layout.element.Div;
import com.itextpdf.layout.element.Paragraph;
import com.itextpdf.layout.property.AreaBreakType;
import com.itextpdf.licensekey.LicenseKey;

import java.io.File;

public class ScalingWatermark {
    public static String DEST = "target/output/Stackoverflow/ScalingWatermark/output.pdf";
    public static String LICENSE = "src/test/resources/skeleton-itextkey.xml";
    public static String[] CONTENT = {"I have seen the face of sorrow", "She looks away in the distance",
            "Across all these bridges", "From whence I came",
            "And those spans, trussed and arched", "Hold up our lives as we go back again",
            "To how we thought then", "To how we thought we thought then",
            "I have seen sorrow's face", "But she is ever turned away",
            "And her words leave me blind", "Her eyes make me mute",
            "I do not understand what she says to me", "I do not know if to obey",
            "Or attempt a flood of tears", "I have seen her face",
            "She does not speak", "She does not weep",
            "She does not know me", "For I am but a stone fitted in place",
            "On the bridge where she walks", "―Lay of the Bridgeburners",
            "Toc the Younger"
    };

    public static void main(String[] args) throws IOException, java.io.IOException {
        LicenseKey.loadLicenseFile(LICENSE);
        File file = new File(DEST);
        file.getParentFile().mkdirs();
        new ScalingWatermark().createPdf(DEST);
    }

    public void createPdf(String dest) throws IOException, java.io.IOException {
        PdfWriter writer = new PdfWriter(dest);
        PdfDocument pdfDoc = new PdfDocument(writer);
        Document doc = new Document(pdfDoc);
        pdfDoc.addEventHandler(PdfDocumentEvent.END_PAGE,
                new TextWatermark());
        addContent(doc);
        doc.add(new AreaBreak(AreaBreakType.NEXT_PAGE));
        addContent(doc);
        doc.close();

    }

    private void addContent(Document doc) {
        Div div = new Div().setBorder(new SolidBorder(1));
        for (String line : CONTENT) {
            Paragraph p = new Paragraph(line).setMarginBottom(0).setMarginTop(0).setMarginLeft(5f);
            div.add(p);
        }
        doc.add(div);
    }


    protected class TextWatermark implements IEventHandler {

        Color lime, blue;
        PdfFont helvetica;

        protected TextWatermark() throws java.io.IOException {
            helvetica = PdfFontFactory.createFont(FontConstants.HELVETICA);
            lime = new DeviceCmyk(0.208f, 0, 0.584f, 0);
            blue = new DeviceCmyk(0.445f, 0.0546f, 0, 0.0667f);
        }

        @Override
        public void handleEvent(Event event) {
            PdfDocumentEvent docEvent = (PdfDocumentEvent) event;
            PdfDocument pdf = docEvent.getDocument();
            PdfPage page = docEvent.getPage();
            int pageNumber = pdf.getPageNumber(page);
            Rectangle pageSize = page.getPageSize();

            //Scale to a percentage of the page area
            float scalingAreaReq = pageNumber % 2 == 0 ? 0.75f : 0.50f;
            //Calculate scaling and x-y positioning
            float scalingFactor = (float) Math.sqrt(scalingAreaReq);
            AffineTransform scaleTf = new AffineTransform();
            //Calculation based on centering the watermark
            float xPos = ((1 - scalingFactor) * pageSize.getWidth()) / 2;
            float yPos = ((1 - scalingFactor) * pageSize.getHeight()) / 2;
            //Add translation to our transformation
            scaleTf.translate(xPos,yPos);
            //Add scaling to our transformation
            scaleTf.scale(scalingFactor, scalingFactor);

            //Use values from calculation
            PdfCanvas pdfCanvas = new PdfCanvas(page.newContentStreamBefore(), page.getResources(), pdf);
            PdfFormXObject watermarkAsXObject = createWatermarkXObject(pageNumber, pageSize, pdf);
            pdfCanvas.saveState()
                    //Apply scaling
                    .concatMatrix(scaleTf)
                    //Insert watermark
                    .addXObject(watermarkAsXObject, 0, 0)
                    .restoreState();

            pdfCanvas.release();
        }


        private PdfFormXObject createWatermarkXObject(int pageNumber, Rectangle bBox, PdfDocument pdfDoc) {
            PdfFormXObject xObject = new PdfFormXObject(bBox);
            PdfCanvas pdfCanvas = new PdfCanvas(xObject, pdfDoc);
            int fontSize = 40;
            float margin = 100;

            //Paint the area that the watermark occupies
            pdfCanvas.saveState()
                    .setFillColor(pageNumber % 2 == 1 ? lime : blue)
                    .rectangle(bBox.getLeft(), bBox.getBottom(),
                            bBox.getWidth(), bBox.getHeight())
                    .fill().restoreState();

            //Translation and rotation to center the watermark text
            AffineTransform rotationAndTranslation = AffineTransform.getTranslateInstance(bBox.getWidth()/2- margin,bBox.getHeight()/2);
            AffineTransform rotation = AffineTransform.getRotateInstance(Math.PI/4);
            rotationAndTranslation.concatenate(rotation);

            //Create the actual text
            pdfCanvas.saveState()
                    .beginText()
                    .setFontAndSize(helvetica, fontSize)
                    .setFillColor(pageNumber % 2 != 1 ? lime : blue)
                    .setTextMatrix(rotationAndTranslation)
                    .showText("Watermark")
                    .endText()
                    .restoreState();

            pdfCanvas.release();

            return xObject;

        }
    }
}

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您可能希望指定所需的行为，而不是指向其他软件产品的功能。我希望将要添加的水印缩放到目标页面的75%。获取页面的尺寸，将图像或XObject缩放到目标页面的75%？我会看看我是否有一个例子。我在做文本而不是图像，如果这在这种情况下有区别的话。确实如此，图像更容易，因为它们有方便的缩放方法，还有，在75%以下你理解什么？水印的边框是否应覆盖原始页面面积的75%，边框的长度是否应为原始页面长度的75%？宽度相同吗？