# PDLinkAppearanceHandler.java

    /*
     * Licensed to the Apache Software Foundation (ASF) under one or more
     * contributor license agreements.  See the NOTICE file distributed with
     * this work for additional information regarding copyright ownership.
     * The ASF licenses this file to You 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 org.apache.pdfbox.pdmodel.interactive.annotation.handlers;

    import java.io.IOException;
    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;

    import org.apache.pdfbox.cos.COSArray;
    import org.apache.pdfbox.cos.COSBase;
    import org.apache.pdfbox.cos.COSNumber;
    import org.apache.pdfbox.pdmodel.common.PDRectangle;
    import org.apache.pdfbox.pdmodel.graphics.color.PDColor;
    import org.apache.pdfbox.pdmodel.graphics.color.PDDeviceGray;
    import org.apache.pdfbox.pdmodel.interactive.annotation.PDAnnotation;
    import org.apache.pdfbox.pdmodel.interactive.annotation.PDAnnotationLink;
    import org.apache.pdfbox.pdmodel.PDAppearanceContentStream;
    import org.apache.pdfbox.pdmodel.PDDocument;
    import org.apache.pdfbox.pdmodel.interactive.annotation.PDBorderStyleDictionary;

    /**
     * Handler to generate the link annotations appearance.
     *
     */
    public class PDLinkAppearanceHandler extends PDAbstractAppearanceHandler
    {
        private static final Log LOG = LogFactory.getLog(PDLinkAppearanceHandler.class);

        public PDLinkAppearanceHandler(PDAnnotation annotation)
        {
            super(annotation);
        }

        public PDLinkAppearanceHandler(PDAnnotation annotation, PDDocument document)
        {
            super(annotation, document);
        }

        @Override
        public void generateNormalAppearance()
        {
            PDAnnotationLink annotation = (PDAnnotationLink) getAnnotation();
            PDRectangle rect = annotation.getRectangle();
            if (rect == null)
            {
                // 660402-p1-AnnotationEmptyRect.pdf has /Rect entry with 0 elements
                return;
            }

            // Adobe doesn't generate an appearance for a link annotation
            float lineWidth = getLineWidth();
            try (PDAppearanceContentStream contentStream = getNormalAppearanceAsContentStream())
            {
                PDColor color = annotation.getColor();
                if (color == null)
                {
                    // spec is unclear, but black is what Adobe does
                    color = new PDColor(new float[] { 0 }, PDDeviceGray.INSTANCE);
                }
                boolean hasStroke = contentStream.setStrokingColorOnDemand(color);

                contentStream.setBorderLine(lineWidth, annotation.getBorderStyle(), annotation.getBorder());

                // Acrobat applies a padding to each side of the bbox so the line is completely within
                // the bbox.
                PDRectangle borderEdge = getPaddedRectangle(getRectangle(),lineWidth/2);

                float[] pathsArray = annotation.getQuadPoints();

                if (pathsArray != null)
                {
                    // QuadPoints shall be ignored if any coordinate in the array lies outside
                    // the region specified by Rect.
                    for (int i = 0; i < pathsArray.length / 2; ++i)
                    {
                        if (!rect.contains(pathsArray[i * 2], pathsArray[i * 2 + 1]))
                        {
                            LOG.warn("At least one /QuadPoints entry (" +
                                    pathsArray[i * 2] + ";" + pathsArray[i * 2 + 1] +
                                    ") is outside of rectangle, " + rect +
                                    ", /QuadPoints are ignored and /Rect is used instead");
                            pathsArray = null;
                            break;
                        }
                    }
                }

                if (pathsArray == null)
                {
                    // Convert rectangle coordinates as if it was a /QuadPoints entry
                    pathsArray = new float[8];
                    pathsArray[0] = borderEdge.getLowerLeftX();
                    pathsArray[1] = borderEdge.getLowerLeftY();
                    pathsArray[2] = borderEdge.getUpperRightX();
                    pathsArray[3] = borderEdge.getLowerLeftY();
                    pathsArray[4] = borderEdge.getUpperRightX();
                    pathsArray[5] = borderEdge.getUpperRightY();
                    pathsArray[6] = borderEdge.getLowerLeftX();
                    pathsArray[7] = borderEdge.getUpperRightY();
                }

                boolean underlined = false;
                if (pathsArray.length >= 8)
                {
                    PDBorderStyleDictionary borderStyleDic = annotation.getBorderStyle();
                    if (borderStyleDic != null)
                    {
                        underlined = PDBorderStyleDictionary.STYLE_UNDERLINE.equals(borderStyleDic.getStyle());
                    }
                }
                int of = 0;
                while (of + 7 < pathsArray.length)
                {
                    contentStream.moveTo(pathsArray[of], pathsArray[of + 1]);
                    contentStream.lineTo(pathsArray[of + 2], pathsArray[of + 3]);
                    if (!underlined)
                    {
                        contentStream.lineTo(pathsArray[of + 4], pathsArray[of + 5]);
                        contentStream.lineTo(pathsArray[of + 6], pathsArray[of + 7]);
                        contentStream.closePath();
                    }
                    of += 8;
                }

                contentStream.drawShape(lineWidth, hasStroke, false);
            }
            catch (IOException e)
            {
                LOG.error(e);
            }
        }

        @Override
        public void generateRolloverAppearance()
        {
            // No rollover appearance generated for a link annotation
        }

        @Override
        public void generateDownAppearance()
        {
         // No down appearance generated for a link annotation
        }

        /**
         * Get the line with of the border.
         *
         * Get the width of the line used to draw a border around the annotation.
         * This may either be specified by the annotation dictionaries Border
         * setting or by the W entry in the BS border style dictionary. If both are
         * missing the default width is 1.
         *
         * @return the line width
         */
        // TODO: according to the PDF spec the use of the BS entry is annotation
        // specific
        // so we will leave that to be implemented by individual handlers.
        // If at the end all annotations support the BS entry this can be handled
        // here and removed from the individual handlers.
        float getLineWidth()
        {
            PDAnnotationLink annotation = (PDAnnotationLink) getAnnotation();

            PDBorderStyleDictionary bs = annotation.getBorderStyle();

            if (bs != null)
            {
                return bs.getWidth();
            }

            COSArray borderCharacteristics = annotation.getBorder();
            if (borderCharacteristics.size() >= 3)
            {
                COSBase base = borderCharacteristics.getObject(2);
                if (base instanceof COSNumber)
                {
                    return ((COSNumber) base).floatValue();
                }
            }

            return 1;
        }
    }