Java PDFBox在特定pdf文档中获取错误的文本位置

上下文

我一直在开发一个程序，该程序可以获取pdf，突出显示一些单词（通过pdfbox标记注释），并保存新的pdf

为此，我扩展了该类，以覆盖该方法并获取每个单词（框）的坐标，这样我就可以准确地知道文本在PDF文档中的坐标位置（TextPosition对象为我提供每个单词框的坐标）。然后，在此基础上，我画了一个突出显示我想要的单词的图

问题

它适用于我迄今为止尝试过的所有文档，但有一个文档除外，我从TextPosts获得的位置似乎是错误的，导致了错误的突出显示

这是原始文档：

这是writeString（）提供给我的第一个字框中有突出显示的文档，它是MicroRNA:

它应该高亮显示MicroRNA，但它高亮显示了其上方的空白区域（粉色HL矩形）

这是writeString（）提供给我的第一个字框中突出显示的文档，它是原始的：

它应该突出显示原始文档，但它突出显示了PDF文档最开始的空白区域（粉色HL矩形）

我想，这个PDF可能包含PDFBox很难找到正确位置的内容，或者这可能是PDFBox中的一个bug

技术规格：

PDFBox 2.0.17
Java 11.0.6+10，采用OpenJDK
MacOS Catalina 10.15.4、16gb、x86_64

坐标值

例如，对于MicroRNA单词框的开始和结束，writeString（）给我的TextPosition坐标是：

M字母

一封信

它会导致我在上面分享的错误HL注释，而对于所有其他PDF文档，这是非常精确的，我已经测试了许多不同的注释。我在这里毫无头绪，也不是PDF定位方面的专家。我尝试使用PDFbox调试器工具，但无法正确阅读。在此，任何帮助都将不胜感激。如果我能提供更多的证据，请告诉我。谢谢

编辑

请注意，文本提取工作正常

我的代码

首先，我创建了一个坐标数组，其中包含了我要创建的第一个和最后一个字符的TextPosition对象中的一些值：

private void extractHLCoordinates(TextPosition firstPosition, TextPosition lastPosition, int pageNumber) {
    double firstPositionX = firstPosition.getX();
    double firstPositionY = firstPosition.getY();
    double lastPositionEndX = lastPosition.getEndX();
    double lastPositionY = lastPosition.getY();

    double height = firstPosition.getHeight();
    double width = firstPosition.getWidth();
    int rotation = firstPosition.getRotation();

    double[] wordCoordinates = {firstPositionX, firstPositionY, lastPositionEndX, lastPositionY, pageNumber, 
    height, width, rotation};

    
    ...
}

现在是基于提取的坐标绘制时间：

for (int pageIndex = 0; pageIndex < pdDocument.getNumberOfPages(); pageIndex++) {

    DPage page = pdDocument.getPage(pageIndex);
    List<PDAnnotation> annotations = page.getAnnotations();

    int rotation;
    double pageHeight = page.getMediaBox().getHeight();
    double pageWidth  = page.getMediaBox().getWidth();
    
    // each CoordinatePoint obj holds the double array with the 
    // coordinates of each word I want to HL - see the previous method
    for (CoordinatePoint coordinate : coordinates) {
        double[] wordCoordinates = coordinate.getCoordinates();
        
        int pageNumber = (int) wordCoordinates[4];

        // if the current coordinates are not related to the current page, 
        //ignore them
        if ((int) pageNumber == (pageIndex + 1)) {
            // getting rotation of the page: portrait, landscape...
            rotation = (int) wordCoordinates[7];

            firstPositionX = wordCoordinates[0];
            firstPositionY = wordCoordinates[1];
            lastPositionEndX = wordCoordinates[2];
            lastPositionY = wordCoordinates[3];
            height = wordCoordinates[5];

            double height;
            double minX;
            double maxX;
            double minY;
            double maxY;
            
            if (rotation == 90) {

                double width = wordCoordinates[6];
                width = (pageHeight * width) / pageWidth;

                //defining coordinates of a rectangle
                maxX = firstPositionY;
                minX = firstPositionY - height;
                minY = firstPositionX;
                maxY = firstPositionX + width;
            } else {
                minX = firstPositionX;
                maxX = lastPositionEndX;
                minY = pageHeight - firstPositionY;
                maxY = pageHeight - lastPositionY + height;
            }
                    
            // Finally I draw the Rectangle
            PDAnnotationTextMarkup txtMark = new PDAnnotationTextMarkup(PDAnnotationTextMarkup.SUB_TYPE_HIGHLIGHT);

            PDRectangle pdRectangle = new PDRectangle();
            pdRectangle.setLowerLeftX((float) minX);
            pdRectangle.setLowerLeftY((float) minY);
            pdRectangle.setUpperRightX((float) maxX);
            pdRectangle.setUpperRightY((float) ((float) maxY + height));

            txtMark.setRectangle(pdRectangle);

            // And the QuadPoints
            float[] quads = new float[8];
            quads[0] = pdRectangle.getLowerLeftX();  // x1
            quads[1] = pdRectangle.getUpperRightY() - 2; // y1
            quads[2] = pdRectangle.getUpperRightX(); // x2
            quads[3] = quads[1]; // y2
            quads[4] = quads[0];  // x3
            quads[5] = pdRectangle.getLowerLeftY() - 2; // y3
            quads[6] = quads[2]; // x4
            quads[7] = quads[5]; // y5

            txtMark.setQuadPoints(quads);
            ...
        }
    }

for（int pageIndex=0；pageIndex

您的四点坐标是相对于CropBox计算的，但它们需要相对于MediaBox。对于本文档，CropBox比MediaBox小，因此高光不在正确的位置。使用CropBox.LLX-MediaBox.LLY调整x，使用MediaBox.URY-CropBox.URY调整y，高光将位于正确的位置打开。
上面的调整适用于Rotate=0的页面。如果Rotate！=0，则可能需要根据PDFBox返回坐标的方式进行进一步调整（我对PDFB不太熟悉）

private void extractHLCoordinates(TextPosition firstPosition, TextPosition lastPosition, int pageNumber) {
    double firstPositionX = firstPosition.getX();
    double firstPositionY = firstPosition.getY();
    double lastPositionEndX = lastPosition.getEndX();
    double lastPositionY = lastPosition.getY();

    double height = firstPosition.getHeight();
    double width = firstPosition.getWidth();
    int rotation = firstPosition.getRotation();

    double[] wordCoordinates = {firstPositionX, firstPositionY, lastPositionEndX, lastPositionY, pageNumber, 
    height, width, rotation};

    
    ...
}

for (int pageIndex = 0; pageIndex < pdDocument.getNumberOfPages(); pageIndex++) {

    DPage page = pdDocument.getPage(pageIndex);
    List<PDAnnotation> annotations = page.getAnnotations();

    int rotation;
    double pageHeight = page.getMediaBox().getHeight();
    double pageWidth  = page.getMediaBox().getWidth();
    
    // each CoordinatePoint obj holds the double array with the 
    // coordinates of each word I want to HL - see the previous method
    for (CoordinatePoint coordinate : coordinates) {
        double[] wordCoordinates = coordinate.getCoordinates();
        
        int pageNumber = (int) wordCoordinates[4];

        // if the current coordinates are not related to the current page, 
        //ignore them
        if ((int) pageNumber == (pageIndex + 1)) {
            // getting rotation of the page: portrait, landscape...
            rotation = (int) wordCoordinates[7];

            firstPositionX = wordCoordinates[0];
            firstPositionY = wordCoordinates[1];
            lastPositionEndX = wordCoordinates[2];
            lastPositionY = wordCoordinates[3];
            height = wordCoordinates[5];

            double height;
            double minX;
            double maxX;
            double minY;
            double maxY;
            
            if (rotation == 90) {

                double width = wordCoordinates[6];
                width = (pageHeight * width) / pageWidth;

                //defining coordinates of a rectangle
                maxX = firstPositionY;
                minX = firstPositionY - height;
                minY = firstPositionX;
                maxY = firstPositionX + width;
            } else {
                minX = firstPositionX;
                maxX = lastPositionEndX;
                minY = pageHeight - firstPositionY;
                maxY = pageHeight - lastPositionY + height;
            }
                    
            // Finally I draw the Rectangle
            PDAnnotationTextMarkup txtMark = new PDAnnotationTextMarkup(PDAnnotationTextMarkup.SUB_TYPE_HIGHLIGHT);

            PDRectangle pdRectangle = new PDRectangle();
            pdRectangle.setLowerLeftX((float) minX);
            pdRectangle.setLowerLeftY((float) minY);
            pdRectangle.setUpperRightX((float) maxX);
            pdRectangle.setUpperRightY((float) ((float) maxY + height));

            txtMark.setRectangle(pdRectangle);

            // And the QuadPoints
            float[] quads = new float[8];
            quads[0] = pdRectangle.getLowerLeftX();  // x1
            quads[1] = pdRectangle.getUpperRightY() - 2; // y1
            quads[2] = pdRectangle.getUpperRightX(); // x2
            quads[3] = quads[1]; // y2
            quads[4] = quads[0];  // x3
            quads[5] = pdRectangle.getLowerLeftY() - 2; // y3
            quads[6] = quads[2]; // x4
            quads[7] = quads[5]; // y5

            txtMark.setQuadPoints(quads);
            ...
        }
    }

...
if (rotation == 90) {

    double width = wordCoordinates[6];
    width = (pageHeight * width) / pageWidth;

    //defining coordinates of a rectangle
    maxX = firstPositionY;
    minX = firstPositionY - height;
    minY = firstPositionX;
    maxY = firstPositionX + width;
} else {
    minX = firstPositionX;
    maxX = lastPositionEndX;
    minY = pageHeight - firstPositionY;
    maxY = pageHeight - lastPositionY + height;
}
...

...

PDRectangle mediaBox = page.getMediaBox();
PDRectangle cropBox = page.getCropBox();

if (rotation == 90) {

    double width = wordCoordinates[6];
    width = (pageHeight * width) / pageWidth;

    //defining coordinates of a rectangle
    maxX = firstPositionY;
    minX = firstPositionY - height;
    minY = firstPositionX;
    maxY = firstPositionX + width;
} else {
    minX = firstPositionX + cropBox.getLowerLeftX() - mediaBox.getLowerLeftY();
    maxX = lastPositionEndX + cropBox.getLowerLeftX() - mediaBox.getLowerLeftY();
    minY = pageHeight - firstPositionY - (mediaBox.getUpperRightY() - cropBox.getUpperRightY());
    maxY = pageHeight - lastPositionY + height - (mediaBox.getUpperRightY() - cropBox.getUpperRightY());
}
...