com.formkiq.vision.pdf.parser.PDRectangleIntersectionTransformer Maven / Gradle / Ivy

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/*
 * Copyright (C) 2018 FormKiQ Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.formkiq.vision.pdf.parser;

import static com.formkiq.vision.pdf.PDRectangleUtil.isIntersect;
import static com.formkiq.vision.pdf.PDRectangleUtil.isIntersectionAtPoint;
import static com.formkiq.vision.pdf.PDRectangleUtil.mergeInto;
import static com.formkiq.vision.pdf.PDRectangleUtil.removeDuplicates;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.function.Function;
import java.util.stream.Collectors;

import org.apache.pdfbox.pdmodel.common.PDRectangle;

import com.formkiq.vision.pdf.comparator.PDRectangleLowerYXComparator;
import com.formkiq.vision.pdf.comparator.PDRectangleXYComparator;
import com.formkiq.vision.pdf.predicate.PDRectangleHorizontalLinePredicate;
import com.formkiq.vision.pdf.predicate.PDRectangleVerticalLinePredicate;

/**
 * Merges intersecting horizontal / vertical {@link PDRectangle}.
 *
 */
public class PDRectangleIntersectionTransformer
        implements Function, List> {

	@Override
	public List apply(final List list) {

		List re = new ArrayList<>(removeDuplicates(list, 0));

        mergeHorizontal(re);
        mergeVertical(re);

        return re;
	}

	/**
     * Merge Horizontal lines together.
     *
     * @param re
     *            {@link List} {@link PDRectangle}
     */
    private void mergeHorizontal(final List re) {

        List lines = re.stream()
                .filter(new PDRectangleHorizontalLinePredicate())
                .collect(Collectors.toList());

        re.removeAll(lines);

        Collections.sort(lines, new PDRectangleLowerYXComparator());
        mergeIntersecting(lines);

        re.addAll(lines);
    }

    /**
     * Merge intersecting {@link PDRectangle} together.
     *
     * @param lines {@link List} {@link PDRectangle}
     */
    private void mergeIntersecting(final List lines) {

        PDRectangle last = null;

        for (Iterator i = lines.iterator(); i.hasNext();) {

            PDRectangle rect = i.next();

            if (last != null && isIntersect(rect, last)) {

                mergeInto(last, rect);
                i.remove();

            } else {
                last = rect;
            }
        }
    }

    /**
     * Merge intersecting {@link PDRectangle} together.
     *
     * @param lines {@link List} {@link PDRectangle}
     */
    private void mergeIntersectingVertical(final List lines) {

        PDRectangle last = null;

        for (Iterator i = lines.iterator(); i.hasNext();) {

            PDRectangle rect = i.next();

            if (last != null && (isIntersectionAtPoint(rect,
                    last.getLowerLeftX(), last.getLowerLeftY())
                    || isIntersectionAtPoint(rect, last.getUpperRightX(),
                            last.getUpperRightY()))) {

                mergeInto(last, rect);
                i.remove();

            } else {
                last = rect;
            }
        }
    }

    /**
     * Merge Vertical lines together.
     *
     * @param re {@link List} {@link PDRectangle}
     */
    private void mergeVertical(final List re) {

        List lines = re.stream()
                .filter(new PDRectangleVerticalLinePredicate())
                .collect(Collectors.toList());

        re.removeAll(lines);

        Collections.sort(lines, new PDRectangleXYComparator());

        mergeIntersectingVertical(lines);

        re.addAll(lines);
    }
}