First version of the library.

.gitignore

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+.idea
+.gradle
+.DS_Store
+build
+out
+*.iml

README.md

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+# Simple PDF Library
+
+A library ,akes easier to manually create a simple PDF document with [Apache PDFBox](https://pdfbox.apache.org) library.
+
+## Features
+
+* HTML-like element model.
+* Reversed Y-axis so a point (0, 0) is at the top-left corner of the page.
+* Few basic elements for drawing boxes, texts, tables and arrows.
+
+## Getting started
+
+1. Include the library into your project.
+
+    ```kotlin
+    // build.gradle.kts
+    repositories {
+        maven("https://jitpack.id")
+    }
+
+    dependencies {
+        compile("com.github.vkuzel:Simple-PDF-Layout:1.0.0")
+    }
+    ```
+
+2. Use it
+
+    ```java
+    try (PDDocument document = new PDDocument()) {
+        PDPage page = new PDPage(PDRectangle.A4);
+        document.addPage(page);
+
+        try (PDPageContentStream contentStream = new PDPageContentStream(document, page)) {
+            // Create a text somewhere at the page and align it to the right in a box of width 100.
+            Text text = new Text<>().setTopLeft(100, 100).setWidth(100).setText("Hello World!").setAlignment(Text.Alignment.RIGHT);
+            // Add an arrow pointing to text.
+            Arrow arrow = new Arrow().setStartElement(text);
+            // Create parent element, add text and arrow to it and draw it.
+            new Page<>().addChild(text).addChild(arrow).draw(document, contentStream);
+        }
+
+        document.save("hello-world.pdf");
+    }
+    ```
+
+## Box model
+
+Following image was drawn by `BoxModelDocumentTest.generateBoxModelDocumentTest()` method in this project.
+
+![Document box model](document-box-model.png)

build.gradle

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+plugins {
+    id 'java'
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    compile("org.apache.pdfbox:pdfbox:2.0.4")
+    testCompile("junit:junit:4.12")
+}
+

src/main/java/com/github/vkuzel/simplepdflayout/Arrow.java

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+package com.github.vkuzel.simplepdflayout;
+
+import com.github.vkuzel.simplepdflayout.geometry.Dimension;
+import com.github.vkuzel.simplepdflayout.geometry.Point;
+import com.github.vkuzel.simplepdflayout.geometry.Vector;
+import org.apache.pdfbox.pdmodel.PDDocument;
+import org.apache.pdfbox.pdmodel.PDPageContentStream;
+
+import java.awt.*;
+import java.io.IOException;
+
+public class Arrow<T extends Arrow> implements ChildElement<Arrow> {
+
+    protected ParentElement parent;
+    protected float startX = 0;
+    protected float startY = 0;
+    protected Float endX;
+    protected Float endY;
+    protected Box startElement;
+    protected boolean startArrow = true;
+    protected boolean endArrow = false;
+    protected Line line = new Line().setWidth(3).setColor(Color.RED);
+
+    @SuppressWarnings("unchecked")
+    protected T getThis() {
+        return (T) this;
+    }
+
+    @Override
+    public Arrow setParent(ParentElement parent) {
+        this.parent = parent;
+        return this;
+    }
+
+    @Override
+    public ParentElement getParent() {
+        return parent;
+    }
+
+    public T setStartPoint(Point point) {
+        return setStartPosition(point.getX(), point.getY());
+    }
+
+    public T setStartPosition(float x, float y) {
+        this.startX = x;
+        this.startY = y;
+        return getThis();
+    }
+
+    public T setEndPoint(Point point) {
+        return setEndPosition(point.getX(), point.getY());
+    }
+
+    public T setEndPosition(float x, float y) {
+        this.endX = x;
+        this.endY = y;
+        return getThis();
+    }
+
+    public T setStartElement(Box startElement) {
+        this.startElement = startElement;
+        return getThis();
+    }
+
+    public T setStartArrow(boolean startArrow) {
+        this.startArrow = startArrow;
+        return getThis();
+    }
+
+    public T setEndArrow(boolean endArrow) {
+        this.endArrow = endArrow;
+        return getThis();
+    }
+
+    public T setLine(Line line) {
+        this.line = line;
+        return getThis();
+    }
+
+    @Override
+    public void draw(PDDocument document, PDPageContentStream contentStream) {
+        try {
+            Point pdfStart = parent.convertPointToPdfCoordinates(calculateStart());
+            Point pdfEnd = parent.convertPointToPdfCoordinates(calculateEnd());
+            float arrowSize = line.getWidth() * 5.5f;
+
+            if (startArrow) {
+                Vector v = Vector.ofLineSegment(pdfStart, pdfEnd).normalize();
+                Point p = new Point(pdfStart.getX() + v.getX() * arrowSize, pdfStart.getY() + v.getY() * arrowSize);
+
+                contentStream.setNonStrokingColor(line.getColor());
+                contentStream.moveTo(pdfStart.getX(), pdfStart.getY());
+                contentStream.lineTo(p.getX() + v.getY() * arrowSize / 2, p.getY() - v.getX() * arrowSize / 2);
+                contentStream.lineTo(p.getX() - v.getY() * arrowSize / 2, p.getY() + v.getX() * arrowSize / 2);
+                contentStream.closePath();
+                contentStream.fill();
+
+                pdfStart = p;
+            }
+
+            if (endArrow) {
+                Vector v = Vector.ofLineSegment(pdfEnd, pdfStart).normalize();
+                Point p = new Point(pdfEnd.getX() + v.getX() * arrowSize, pdfEnd.getY() + v.getY() * arrowSize);
+
+                contentStream.setNonStrokingColor(line.getColor());
+                contentStream.moveTo(pdfEnd.getX(), pdfEnd.getY());
+                contentStream.lineTo(p.getX() + v.getY() * arrowSize / 2, p.getY() - v.getX() * arrowSize / 2);
+                contentStream.lineTo(p.getX() - v.getY() * arrowSize / 2, p.getY() + v.getX() * arrowSize / 2);
+                contentStream.closePath();
+                contentStream.fill();
+
+                pdfEnd = p;
+            }
+
+            contentStream.setLineWidth(line.getWidth());
+            contentStream.setStrokingColor(line.getColor());
+            contentStream.setLineDashPattern(line.calculatePattern(), 0);
+            contentStream.moveTo(pdfStart.getX(), pdfStart.getY());
+            contentStream.lineTo(pdfEnd.getX(), pdfEnd.getY());
+            contentStream.stroke();
+        } catch (IOException e) {
+            throw new IllegalStateException(e);
+        }
+    }
+
+    protected Point calculateStart() {
+        if (startElement != null) {
+            Point topLeft = startElement.calculateTopLeft();
+            Dimension dimension = startElement.calculateDimension();
+            return new Point(topLeft.getX() + dimension.getWidth(), topLeft.getY() + dimension.getHeight());
+        } else {
+            return new Point(startX, startY);
+        }
+    }
+
+    protected Point calculateEnd() {
+        Point start = calculateStart();
+
+        Dimension pageDimension = null;
+        Float length = null;
+        if (endX == null || endY == null) {
+            pageDimension = getRootElement().calculateContentDimension();
+            length = line.getWidth() * 20;
+        }
+
+        float rx, ry;
+
+        if (endX == null) {
+            rx = start.getX() + length;
+            if (rx > pageDimension.getWidth()) {
+                rx = start.getX() - length;
+            }
+        } else {
+            rx = endX;
+        }
+
+        if (endY == null) {
+            ry = start.getY() + length;
+            if (ry > pageDimension.getHeight()) {
+                ry = start.getY() - length;
+            }
+        } else {
+            ry = endY;
+        }
+
+        return new Point(rx, ry);
+    }
+
+    protected ParentElement getRootElement() {
+        ParentElement parent = this.getParent();
+        while (parent instanceof ChildElement) {
+            parent = ((ChildElement) parent).getParent();
+        }
+        return parent;
+    }
+
+    public String toStringCoordinates() {
+        Point start = calculateStart();
+        Point end = calculateEnd();
+        return "[startX, startY], [endX, endY] = " + start + ", " + end +
+                ", [pdfStartX, pdfStartY], [pdfEndX, pdfEndY] = " + parent.convertPointToPdfCoordinates(start) + ", " + parent.convertPointToPdfCoordinates(end);
+    }
+}