提取和打印文本位置
Extracting and Printing text positions
我一直在 pdfbox 上做一些实验，目前我遇到了一个问题，我怀疑它与坐标系有关。
我正在扩展 PDFTextStripper 以获取 pdf 页面中每个字符的 X 和 Y。
最初我正在创建一个图像，ImageIO 在我收到的位置打印文本，并在我想要的每个参考的底部放一个小标记（不同颜色的矩形），一切看起来都很好。
但是现在为了避免丢失 pdf 的样式，我只想覆盖 pdf 并添加之前所说的标记，但是我得到的坐标在 PDPageContentStream 中不匹配。
关于匹配 pdf 坐标的任何帮助，我从 PDFTextStripper -> processTextPosition 获得视觉坐标
使用版本 1.8.11
正如评论中所讨论的，这是 DrawPrintTextLocations 工具的 1.8 版本，它是 2.0 版本示例集合的一部分，并且基于更为人所知的 PrintTextLocations 示例。与 2.0 版本不同，这个版本不显示字体边界框，只显示文本提取大小，大约是一个小字形（a、e 等）的高度。它用作文本提取的启发式工具。这就是这里 "the textpositions i'm getting are halfed" 效果的原因。如果您需要边界框，最好使用 2.0（可能太大）。要获得精确的大小，您必须计算每个字形的路径并获得该字形的边界，同样，您需要该字形的 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;
}
}
我一直在 pdfbox 上做一些实验，目前我遇到了一个问题，我怀疑它与坐标系有关。
我正在扩展 PDFTextStripper 以获取 pdf 页面中每个字符的 X 和 Y。
最初我正在创建一个图像，ImageIO 在我收到的位置打印文本，并在我想要的每个参考的底部放一个小标记（不同颜色的矩形），一切看起来都很好。
但是现在为了避免丢失 pdf 的样式，我只想覆盖 pdf 并添加之前所说的标记，但是我得到的坐标在 PDPageContentStream 中不匹配。
关于匹配 pdf 坐标的任何帮助，我从 PDFTextStripper -> processTextPosition 获得视觉坐标
使用版本 1.8.11
正如评论中所讨论的，这是 DrawPrintTextLocations 工具的 1.8 版本，它是 2.0 版本示例集合的一部分，并且基于更为人所知的 PrintTextLocations 示例。与 2.0 版本不同，这个版本不显示字体边界框，只显示文本提取大小，大约是一个小字形（a、e 等）的高度。它用作文本提取的启发式工具。这就是这里 "the textpositions i'm getting are halfed" 效果的原因。如果您需要边界框，最好使用 2.0（可能太大）。要获得精确的大小，您必须计算每个字形的路径并获得该字形的边界，同样，您需要该字形的 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;
}
}