[英]Extracting and Printing text positions
我已經在pdfbox上進行了一些實驗,但目前仍停留在一個我懷疑與坐標系有關的問題上。
我正在擴展PDFTextStripper以獲取pdf頁面中每個字符的X和Y。
最初,我是用ImageIO創建一個Image的,它在接收到的位置打印文本,並在我想要的每個參考的底部都打上一個小標記(帶有不同顏色的矩形),一切似乎都很好。 但是現在為了避免從pdf中丟失樣式,我只想覆蓋pdf並添加以前的口語標記,但是我得到的坐標在PDPageContentStream中不匹配。
從PDFTextStripper-> processTextPosition到視覺坐標的匹配pdf坐標的任何幫助
使用版本1.8.11
正如評論中所討論的,這是DrawPrintTextLocations工具的1.8版本,它是2.0版本的示例集合的一部分,並且基於更知名的PrintTextLocations示例。 與2.0版本不同,此版本不顯示字體邊界框,僅顯示文本提取大小,大約是一個小的字形(a,e等)的高度。 它用作文本提取的啟發式工具。 這就是“我得到的文本位置被弄成一半”效果的原因。 如果需要邊框,最好使用2.0(可能太大)。 要獲得准確的大小,您必須計算每個字形的路徑並獲取該字形的邊界,同樣,您需要該字形的2.0版本。
public class DrawPrintTextLocations extends PDFTextStripper
{
private BufferedImage image;
private final String filename;
static final int SCALE = 4;
private Graphics2D g2d;
private final PDDocument document;
/**
* Instantiate a new PDFTextStripper object.
*
* @param document
* @param filename
* @throws IOException If there is an error loading the properties.
*/
public DrawPrintTextLocations(PDDocument document, String filename) throws IOException
{
this.document = document;
this.filename = filename;
}
/**
* This will print the documents data.
*
* @param args The command line arguments.
*
* @throws IOException If there is an error parsing the document.
*/
public static void main(String[] args) throws IOException
{
if (args.length != 1)
{
usage();
}
else
{
PDDocument document = null;
try
{
document = PDDocument.load(new File(args[0]));
DrawPrintTextLocations stripper = new DrawPrintTextLocations(document, args[0]);
stripper.setSortByPosition(true);
for (int page = 0; page < document.getNumberOfPages(); ++page)
{
stripper.stripPage(page);
}
}
finally
{
if (document != null)
{
document.close();
}
}
}
}
private void stripPage(int page) throws IOException
{
PDPage pdPage = (PDPage) document.getDocumentCatalog().getAllPages().get(page);
image = pdPage.convertToImage(BufferedImage.TYPE_INT_RGB, 72 * SCALE);
PDRectangle cropBox = pdPage.getCropBox();
g2d = image.createGraphics();
g2d.setStroke(new BasicStroke(0.1f));
g2d.scale(SCALE, SCALE);
setStartPage(page + 1);
setEndPage(page + 1);
Writer dummy = new OutputStreamWriter(new ByteArrayOutputStream());
writeText(document, dummy);
// beads in green
g2d.setStroke(new BasicStroke(0.4f));
List<PDThreadBead> pageArticles = pdPage.getThreadBeads();
for (PDThreadBead bead : pageArticles)
{
PDRectangle r = bead.getRectangle();
GeneralPath p = transform(r, Matrix.getTranslatingInstance(-cropBox.getLowerLeftX(), cropBox.getLowerLeftY()));
AffineTransform flip = new AffineTransform();
flip.translate(0, pdPage.findCropBox().getHeight());
flip.scale(1, -1);
Shape s = flip.createTransformedShape(p);
g2d.setColor(Color.green);
g2d.draw(s);
}
g2d.dispose();
String imageFilename = filename;
int pt = imageFilename.lastIndexOf('.');
imageFilename = imageFilename.substring(0, pt) + "-marked-" + (page + 1) + ".png";
ImageIO.write(image, "png", new File(imageFilename));
}
/**
* Override the default functionality of PDFTextStripper.
*/
@Override
protected void writeString(String string, List<TextPosition> textPositions) throws IOException
{
for (TextPosition text : textPositions)
{
System.out.println("String[" + text.getXDirAdj() + ","
+ text.getYDirAdj() + " fs=" + text.getFontSize() + " xscale="
+ text.getXScale() + " height=" + text.getHeightDir() + " space="
+ text.getWidthOfSpace() + " width="
+ text.getWidthDirAdj() + "]" + text.getCharacter());
// in red:
// show rectangles with the "height" (not a real height, but used for text extraction
// heuristics, it is 1/2 of the bounding box height and starts at y=0)
Rectangle2D.Float rect = new Rectangle2D.Float(
text.getXDirAdj(),
(text.getYDirAdj() - text.getHeightDir()),
text.getWidthDirAdj(),
text.getHeightDir());
g2d.setColor(Color.red);
g2d.draw(rect);
}
}
/**
* This will print the usage for this document.
*/
private static void usage()
{
System.err.println("Usage: java " + DrawPrintTextLocations.class.getName() + " <input-pdf>");
}
/**
* Transforms the given point by this matrix.
*
* @param x x-coordinate
* @param y y-coordinate
*/
private Point2D.Float transformPoint(Matrix m, float x, float y)
{
float[][] values = m.getValues();
float a = values[0][0];
float b = values[0][1];
float c = values[1][0];
float d = values[1][1];
float e = values[2][0];
float f = values[2][2];
return new Point2D.Float(x * a + y * c + e, x * b + y * d + f);
}
/**
* Returns a path which represents this rectangle having been transformed by the given matrix.
* Note that the resulting path need not be rectangular.
*/
private GeneralPath transform(PDRectangle r, Matrix matrix)
{
float x1 = r.getLowerLeftX();
float y1 = r.getLowerLeftY();
float x2 = r.getUpperRightX();
float y2 = r.getUpperRightY();
Point2D.Float p0 = transformPoint(matrix, x1, y1);
Point2D.Float p1 = transformPoint(matrix, x2, y1);
Point2D.Float p2 = transformPoint(matrix, x2, y2);
Point2D.Float p3 = transformPoint(matrix, x1, y2);
GeneralPath path = new GeneralPath();
path.moveTo((float) p0.getX(), (float) p0.getY());
path.lineTo((float) p1.getX(), (float) p1.getY());
path.lineTo((float) p2.getX(), (float) p2.getY());
path.lineTo((float) p3.getX(), (float) p3.getY());
path.closePath();
return path;
}
}
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