OP的示例PDF中的不可见文本通常通过定义剪辑路径(文本的边界之外)和填充路径(隐藏下面的文本)而变得不可见.因此,我们必须在文本提取期间考虑与路径相关的指令以忽略该不可见文本.

不幸的是,为这些指令设计的回调未在PDFTextStripper或其父类LegacyPDFStreamEngine和PDFStreamEngine中声明.

但是它们在另一个主要的PDFStreamEngine子类PDFGraphicsStreamEngine中声明,并且它们在PageDrawer中明智地实现.

因此,为了利用这一点,我们可以复制&粘贴&将PageDrawer实现调整为PDFTextStripper的子类,例如喜欢这个：

public class PDFVisibleTextStripper extends PDFTextStripper {

public PDFVisibleTextStripper() throws IOException {

addOperator(new AppendRectangleToPath());

addOperator(new ClipEvenOddRule());

addOperator(new ClipNonZeroRule());

addOperator(new ClosePath());

addOperator(new CurveTo());

addOperator(new CurveToReplicateFinalPoint());

addOperator(new CurveToReplicateInitialPoint());

addOperator(new EndPath());

addOperator(new FillEvenOddAndStrokePath());

addOperator(new FillEvenOddRule());

addOperator(new FillNonZeroAndStrokePath());

addOperator(new FillNonZeroRule());

addOperator(new LineTo());

addOperator(new MoveTo());

addOperator(new StrokePath());

}

@Override

protected void processTextPosition(TextPosition text) {

Matrix textMatrix = text.getTextMatrix();

Vector start = textMatrix.transform(new Vector(0, 0));

Vector end = new Vector(start.getX() + text.getWidth(), start.getY());

PDGraphicsState gs = getGraphicsState();

Area area = gs.getCurrentClippingPath();

if (area == null || (area.contains(start.getX(), start.getY()) && area.contains(end.getX(), end.getY())))

super.processTextPosition(text);

}

private GeneralPath linePath = new GeneralPath();

void deleteCharsInPath() {

for (List list : charactersByArticle) {

List toRemove = new ArrayList<>();

for (TextPosition text : list) {

Matrix textMatrix = text.getTextMatrix();

Vector start = textMatrix.transform(new Vector(0, 0));

Vector end = new Vector(start.getX() + text.getWidth(), start.getY());

if (linePath.contains(start.getX(), start.getY()) || linePath.contains(end.getX(), end.getY())) {

toRemove.add(text);

}

}

if (toRemove.size() != 0) {

System.out.println(toRemove.size());

list.removeAll(toRemove);

}

}

}

public final class AppendRectangleToPath extends OperatorProcessor {

@Override

public void process(Operator operator, List operands) throws IOException {

if (operands.size() < 4) {

throw new MissingOperandException(operator, operands);

}

if (!checkArrayTypesClass(operands, COSNumber.class)) {

return;

}

COSNumber x = (COSNumber) operands.get(0);

COSNumber y = (COSNumber) operands.get(1);

COSNumber w = (COSNumber) operands.get(2);

COSNumber h = (COSNumber) operands.get(3);

float x1 = x.floatValue();

float y1 = y.floatValue();

// create a pair of coordinates for the transformation

float x2 = w.floatValue() + x1;

float y2 = h.floatValue() + y1;

Point2D p0 = context.transformedPoint(x1, y1);

Point2D p1 = context.transformedPoint(x2, y1);

Point2D p2 = context.transformedPoint(x2, y2);

Point2D p3 = context.transformedPoint(x1, y2);

// to ensure that the path is created in the right direction, we have to create

// it by combining single lines instead of creating a simple rectangle

linePath.moveTo((float) p0.getX(), (float) p0.getY());

linePath.lineTo((float) p1.getX(), (float) p1.getY());

linePath.lineTo((float) p2.getX(), (float) p2.getY());

linePath.lineTo((float) p3.getX(), (float) p3.getY());

// close the subpath instead of adding the last line so that a possible set line

// cap style isn't taken into account at the "beginning" of the rectangle

linePath.closePath();

}

@Override

public String getName() {

return "re";

}

}

public final class StrokePath extends OperatorProcessor {

@Override

public void process(Operator operator, List operands) throws IOException {

linePath.reset();

}

@Override

public String getName() {

return "S";

}

}

public final class FillEvenOddRule extends OperatorProcessor {

@Override

public void process(Operator operator, List operands) throws IOException {

linePath.setWindingRule(GeneralPath.WIND_EVEN_ODD);

deleteCharsInPath();

linePath.reset();

}

@Override

public String getName() {

return "f*";

}

}

public class FillNonZeroRule extends OperatorProcessor {

@Override

public final void process(Operator operator, List operands) throws IOException {

linePath.setWindingRule(GeneralPath.WIND_NON_ZERO);

deleteCharsInPath();

linePath.reset();

}

@Override

public String getName() {

return "f";

}

}

public final class FillEvenOddAndStrokePath extends OperatorProcessor {

@Override

public void process(Operator operator, List operands) throws IOException {

linePath.setWindingRule(GeneralPath.WIND_EVEN_ODD);

deleteCharsInPath();

linePath.reset();

}

@Override

public String getName() {

return "B*";

}

}

public class FillNonZeroAndStrokePath extends OperatorProcessor {

@Override

public void process(Operator operator, List operands) throws IOException {

linePath.setWindingRule(GeneralPath.WIND_NON_ZERO);

deleteCharsInPath();

linePath.reset();

}

@Override

public String getName() {

return "B";

}

}

public final class ClipEvenOddRule extends OperatorProcessor {

@Override

public void process(Operator operator, List operands) throws IOException {

linePath.setWindingRule(GeneralPath.WIND_EVEN_ODD);

getGraphicsState().intersectClippingPath(linePath);

}

@Override

public String getName() {

return "W*";

}

}

public class ClipNonZeroRule extends OperatorProcessor {

@Override

public void process(Operator operator, List operands) throws IOException {

linePath.setWindingRule(GeneralPath.WIND_NON_ZERO);

getGraphicsState().intersectClippingPath(linePath);

}

@Override

public String getName() {

return "W";

}

}

public final class MoveTo extends OperatorProcessor {

@Override

public void process(Operator operator, List operands) throws IOException {

if (operands.size() < 2) {

throw new MissingOperandException(operator, operands);

}

COSBase base0 = operands.get(0);

if (!(base0 instanceof COSNumber)) {

return;

}

COSBase base1 = operands.get(1);

if (!(base1 instanceof COSNumber)) {

return;

}

COSNumber x = (COSNumber) base0;

COSNumber y = (COSNumber) base1;

Point2D.Float pos = context.transformedPoint(x.floatValue(), y.floatValue());

linePath.moveTo(pos.x, pos.y);

}

@Override

public String getName() {

return "m";

}

}

public class LineTo extends OperatorProcessor {

@Override

public void process(Operator operator, List operands) throws IOException {

if (operands.size() < 2) {

throw new MissingOperandException(operator, operands);

}

COSBase base0 = operands.get(0);

if (!(base0 instanceof COSNumber)) {

return;

}

COSBase base1 = operands.get(1);

if (!(base1 instanceof COSNumber)) {

return;

}

// append straight line segment from the current point to the point

COSNumber x = (COSNumber) base0;

COSNumber y = (COSNumber) base1;

Point2D.Float pos = context.transformedPoint(x.floatValue(), y.floatValue());

linePath.lineTo(pos.x, pos.y);

}

@Override

public String getName() {

return "l";

}

}

public class CurveTo extends OperatorProcessor {

@Override

public void process(Operator operator, List operands) throws IOException {

if (operands.size() < 6) {

throw new MissingOperandException(operator, operands);

}

if (!checkArrayTypesClass(operands, COSNumber.class)) {

return;

}

COSNumber x1 = (COSNumber) operands.get(0);

COSNumber y1 = (COSNumber) operands.get(1);

COSNumber x2 = (COSNumber) operands.get(2);

COSNumber y2 = (COSNumber) operands.get(3);

COSNumber x3 = (COSNumber) operands.get(4);

COSNumber y3 = (COSNumber) operands.get(5);

Point2D.Float point1 = context.transformedPoint(x1.floatValue(), y1.floatValue());

Point2D.Float point2 = context.transformedPoint(x2.floatValue(), y2.floatValue());

Point2D.Float point3 = context.transformedPoint(x3.floatValue(), y3.floatValue());

linePath.curveTo(point1.x, point1.y, point2.x, point2.y, point3.x, point3.y);

}

@Override

public String getName() {

return "c";

}

}

public final class CurveToReplicateFinalPoint extends OperatorProcessor {

@Override

public void process(Operator operator, List operands) throws IOException {

if (operands.size() < 4) {

throw new MissingOperandException(operator, operands);

}

if (!checkArrayTypesClass(operands, COSNumber.class)) {

return;

}

COSNumber x1 = (COSNumber) operands.get(0);

COSNumber y1 = (COSNumber) operands.get(1);

COSNumber x3 = (COSNumber) operands.get(2);

COSNumber y3 = (COSNumber) operands.get(3);

Point2D.Float point1 = context.transformedPoint(x1.floatValue(), y1.floatValue());

Point2D.Float point3 = context.transformedPoint(x3.floatValue(), y3.floatValue());

linePath.curveTo(point1.x, point1.y, point3.x, point3.y, point3.x, point3.y);

}

@Override

public String getName() {

return "y";

}

}

public class CurveToReplicateInitialPoint extends OperatorProcessor {

@Override

public void process(Operator operator, List operands) throws IOException {

if (operands.size() < 4) {

throw new MissingOperandException(operator, operands);

}

if (!checkArrayTypesClass(operands, COSNumber.class)) {

return;

}

COSNumber x2 = (COSNumber) operands.get(0);

COSNumber y2 = (COSNumber) operands.get(1);

COSNumber x3 = (COSNumber) operands.get(2);

COSNumber y3 = (COSNumber) operands.get(3);

Point2D currentPoint = linePath.getCurrentPoint();

Point2D.Float point2 = context.transformedPoint(x2.floatValue(), y2.floatValue());

Point2D.Float point3 = context.transformedPoint(x3.floatValue(), y3.floatValue());

linePath.curveTo((float) currentPoint.getX(), (float) currentPoint.getY(), point2.x, point2.y, point3.x, point3.y);

}

@Override

public String getName() {

return "v";

}

}

public final class ClosePath extends OperatorProcessor {

@Override

public void process(Operator operator, List operands) throws IOException {

linePath.closePath();

}

@Override

public String getName() {

return "h";

}

}

public final class EndPath extends OperatorProcessor {

@Override

public void process(Operator operator, List operands) throws IOException {

linePath.reset();

}

@Override

public String getName() {

return "n";

}

}

}

请确保使用PDFVisibleTextStripper构造函数中的内部运算符类,而不是PageDrawer使用的具有相同名称的类.要确保只需按照代码下的链接.

这会减少输出

REVERSE tEaSER caRd

500

elections

er of Teams

t Bet

1,000

MARK BOX AS SHOWN 

DENOTES HOME TEAM

PRO FOOTBALL - THURSDAY, SEPTEMBER 8, 2016

1 PANTHERS nbc - 10½ 8:30p 2 BRONCOS  - 3½

PRO FOOTBALL - SUNDAY, SEPTEMBER 11, 2016

3 FALCONS  - 9½ 1:00p 4 BUCCANEERS - 4½

5 VIKINGS - 9½ 1:00p 6 TITANS  - 4½

7 EAGLES  - 10½ 1:00p 8 BROWNS - 3½

9 BENGALS - 9½ 1:00p 10 JETS  - 4½

11 SAINTS  - 7½ 1:00p 12 RAIDERS - 6½

13 CHIEFS  - 14½ 1:00p 14 CHARGERS + ½

15 RAVENS  - 10½ 1:00p 16 BILLS - 3½

17 TEXANS  - 14½ 1:00p 18 BEARS + ½

19 PACKERS - 12½ 1:00p 20 JAGUARS  - 1½

21 SEAHAWKS  - 17½ 4:05p 22 DOLPHINS + 3½

23 COWBOYS  - 7½ 4:25p 24 GIANTS - 6½

25 COLTS  - 10½ 4:25p 26 LIONS - 3½

27 CARDINALS  nbc - 14½ 8:30p 28 PATRIOTS + ½

PRO FOOTBALL - MONDAY, SEPTEMBER 12, 2016

29 STEELERS espn - 10½ 7:10p 30 REDSKINS  - 3½

31 RAMS espn - 9½ 10:20p 32 49ERS  - 4½

这会丢弃大部分不需要的数据.

在this question的上下文中,很明显,processTextPosition和deleteCharsInPath计算字符基线结束的方式隐含地假定水平文本没有页面旋转.但是,如果放松一个人的“可见性”标准,如果其基线的开始可见,则可以假定一个角色是可见的.在这种情况下,不再需要计算出的Vector结束,并且代码也适用于旋转页面.

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