BoxFitter: throws NotEnoughSpace

pom.xml

@@ -14,6 +14,10 @@
     <version>DEV-SNAPSHOT</version>
 
     <properties>
+        <java.version>11</java.version>
+        <maven.compiler.source>${java.version}</maven.compiler.source>
+        <maven.compiler.target>${java.version}</maven.compiler.target>
+
         <tiles-maven-plugin.version>2.16</tiles-maven-plugin.version>
         <kemitix-maven-tiles.version>2.6.0</kemitix-maven-tiles.version>
         <kemitix-checkstyle.version>5.4.0</kemitix-checkstyle.version>

src/main/java/net/kemitix/text/fit/BoxFitter.java

@@ -2,6 +2,7 @@ package net.kemitix.text.fit;
 
 import java.awt.*;
 import java.awt.geom.Rectangle2D;
+import java.util.List;
 import java.util.function.Function;
 
 public interface BoxFitter {
@@ -11,4 +12,10 @@ public interface BoxFitter {
             Graphics2D graphics2D,
             Rectangle2D box
     );
+    int fit(
+            String text,
+            Function<Integer, Font> fontFactory,
+            Graphics2D graphics2D,
+            List<Rectangle2D> box
+    );
 }

src/main/java/net/kemitix/text/fit/BoxFitterImpl.java

@@ -5,9 +5,12 @@ import lombok.RequiredArgsConstructor;
 import java.awt.*;
 import java.awt.font.FontRenderContext;
 import java.awt.geom.Rectangle2D;
+import java.util.Collections;
 import java.util.List;
+import java.util.function.BiFunction;
 import java.util.function.Function;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 /**
  * Fit the text to a box by finding the best font size and word wrapping to fill
@@ -16,6 +19,7 @@ import java.util.stream.Collectors;
 @RequiredArgsConstructor
 class BoxFitterImpl implements BoxFitter {
 
+    public static final int MAX_FONT_SIZE = 10_000;
     private final WordWrapper wordWrapper;
 
     @Override
@@ -25,10 +29,22 @@ class BoxFitterImpl implements BoxFitter {
             Graphics2D graphics2D,
             Rectangle2D box
     ) {
-        int fit = fitMinMax(0, (int) box.getHeight(),
-                new FitEnvironment(text, fontFactory, graphics2D, box));
+        return fit(text, fontFactory, graphics2D,
+                Collections.singletonList(box));
+    }
+
+    @Override
+    public int fit(
+            String text,
+            Function<Integer, Font> fontFactory,
+            Graphics2D graphics2D,
+            List<Rectangle2D> boxes
+    ) {
+        int fit = fitMinMax(0, MAX_FONT_SIZE,
+                new FitEnvironment(text, fontFactory, graphics2D,
+                        boxes));
         if (fit <= 2) {
-            throw new IllegalArgumentException("The text is too long to fit");
+            throw new NotEnoughSpace(0);
         }
         return fit;
     }
@@ -39,25 +55,39 @@ class BoxFitterImpl implements BoxFitter {
             FitEnvironment e
     ) {
         int mid = (max + min) / 2;
-        if (mid == min){
+        if (mid == min && mid + 1 == max) {
             return mid;
         }
         Font font = e.getFont(mid);
-        List<String> lines = wrapLines(font, e);
-        List<Rectangle2D> lineSizes =
-                lineSizes(font, lines, e.fontRenderContext());
-        if (sumLineHeights(lineSizes) > e.boxHeight() ||
-                maxLineWidth(lineSizes) > e.boxWidth()) {
+        try {
+            List<List<Rectangle2D>> linesPerBox = wrapLines(font, e);
+            if (tooManyLines(linesPerBox, e.boxes)) {
+                return fitMinMax(min, mid, e);
+            }
+        } catch (WordTooLong | NotEnoughSpace err) {
             return fitMinMax(min, mid, e);
         }
         return fitMinMax(mid, max, e);
     }
 
-    private List<String> wrapLines(
+    private boolean tooManyLines(
+            List<List<Rectangle2D>> linesPerBox,
+            List<Rectangle2D> boxes
+    ) {
+        return StreamZipper.zip(linesPerBox, boxes,
+                (stringBounds, box) ->
+                        sumLineHeights(stringBounds) > box.getHeight()
+        ).anyMatch(b -> b);
+    }
+
+    private List<List<Rectangle2D>> wrapLines(
             Font font,
             FitEnvironment e
     ) {
-        return wordWrapper.wrap(e.text, font, e.graphics2D, e.boxWidth());
+        return wordWrapper.wrap(e.text, font, e.graphics2D, e.boxes)
+                .stream()
+                .map(l -> lineSizes(font, l, e.fontRenderContext()))
+                .collect(Collectors.toList());
     }
 
     private List<Rectangle2D> lineSizes(
@@ -71,13 +101,10 @@ class BoxFitterImpl implements BoxFitter {
     }
 
     private int sumLineHeights(List<Rectangle2D> lineSizes) {
-        return lineSizes.stream().map(Rectangle2D::getHeight)
-                .mapToInt(Double::intValue).sum();
-    }
-
-    private int maxLineWidth(List<Rectangle2D> lineSizes) {
-        return lineSizes.stream().map(Rectangle2D::getWidth)
-                .mapToInt(Double::intValue).max().orElse(0);
+        return lineSizes.stream()
+                .map(Rectangle2D::getHeight)
+                .mapToInt(Double::intValue)
+                .sum();
     }
 
     @RequiredArgsConstructor
@@ -85,18 +112,11 @@ class BoxFitterImpl implements BoxFitter {
         private final String text;
         private final Function<Integer, Font> fontFactory;
         private final Graphics2D graphics2D;
-        private final Rectangle2D box;
+        private final List<Rectangle2D> boxes;
 
         public Font getFont(int size) {
             return fontFactory.apply(size);
         }
-        public int boxWidth() {
-            return (int) box.getWidth();
-        }
-
-        public int boxHeight() {
-            return (int) box.getHeight();
-        }
 
         public FontRenderContext fontRenderContext() {
             return graphics2D.getFontRenderContext();

src/main/java/net/kemitix/text/fit/NotEnoughSpace.java

@@ -0,0 +1,10 @@
+package net.kemitix.text.fit;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+@Getter
+@RequiredArgsConstructor
+public class NotEnoughSpace extends RuntimeException {
+    private final int excessWordCount;
+}

src/main/java/net/kemitix/text/fit/StreamZipper.java

@@ -0,0 +1,60 @@
+package net.kemitix.text.fit;
+
+
+import java.util.List;
+import java.util.function.BiFunction;
+import java.util.function.IntFunction;
+import java.util.stream.Stream;
+
+import static java.lang.Math.min;
+import static java.util.stream.IntStream.range;
+
+/**
+ * Utility to zip two {@link Stream}s together.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+public final class StreamZipper {
+
+    private StreamZipper() {
+        throw new UnsupportedOperationException();
+    }
+
+    /**
+     * Zip two {@link Stream}s together.
+     *
+     * <p>The resulting stream will contain only as many items as the shortest of the two lists.</p>
+     *
+     * @param a the first List
+     * @param b the second List
+     * @param zipper the function to zip an item from each list
+     * @param <A> the type of the first list
+     * @param <B> the type of the second list
+     * @param <C> the type of the joined items
+     * @return a Stream of the joined items
+     */
+    public static <A, B, C> Stream<C> zip(
+            final List<A> a,
+            final List<B> b,
+            final BiFunction<A, B, C> zipper
+    ) {
+        return range(0, limit(a, b))
+                .mapToObj(tuple(a, b, zipper));
+    }
+
+    private static <A, B> int limit(
+            final List<A> a,
+            final List<B> b
+    ) {
+        return min(a.size(), b.size());
+    }
+
+    private static <A, B, C> IntFunction<C> tuple(
+            final List<A> a,
+            final List<B> b,
+            final BiFunction<A, B, C> zipper
+    ) {
+        return i -> zipper.apply(a.get(i), b.get(i));
+    }
+
+}

src/main/java/net/kemitix/text/fit/TextLineWrapImpl.java

@@ -1,10 +1,11 @@
 package net.kemitix.text.fit;
 
+import lombok.Getter;
+
 import java.awt.*;
 import java.awt.font.FontRenderContext;
 import java.awt.geom.Rectangle2D;
-import java.util.ArrayList;
-import java.util.Arrays;
+import java.util.*;
 import java.util.List;
 import java.util.stream.Collectors;
 
@@ -17,30 +18,77 @@ class TextLineWrapImpl implements WordWrapper {
             Graphics2D graphics2D,
             int width
     ) {
-        String source = String.join(" ", text.split("\n"));
-        List<Word> words = wordLengths(source.split(" "), font, graphics2D);
-        return wrapWords(words, width);
+        return wrap(text, font, graphics2D,
+                Collections.singletonList(
+                        new Rectangle(width, Integer.MAX_VALUE)))
+                .get(0);
     }
 
-    private List<String> wrapWords(List<Word> words, int width) {
-        List<String> lines = new ArrayList<>();
-        int end = 0;
-        List<String> line = new ArrayList<>();
-        for (Word word : words) {
-            if ((end + word.width) > width) {
-                lines.add(String.join(" ", line));
-                line.clear();
-                end = 0;
+    @Override
+    public List<List<String>> wrap(
+            String text,
+            Font font,
+            Graphics2D graphics2D,
+            List<Rectangle2D> boxes
+    ) {
+        String source = String.join(" ", text.split("\n"));
+        List<Word> words = wordLengths(source.split(" "), font, graphics2D);
+        return wrapWords(words, boxes);
     }
-            line.add(word.word);
+
+    private List<List<String>> wrapWords(
+            List<Word> words,
+            List<Rectangle2D> boxes
+    ) {
+        Deque<Word> wordQ = new ArrayDeque<>(words);
+        List<List<String>> wrappings = boxes.stream()
+                .map(rectangle2D -> {
+                    double width = rectangle2D.getWidth();
+                    double height = rectangle2D.getHeight();
+                    List<String> lines = new ArrayList<>();
+                    int bottom = 0;
+                    int end = 0;
+                    Deque<Word> lineQ = new ArrayDeque<>();
+                    while (!wordQ.isEmpty()) {
+                        Word word = wordQ.pop();
+                        if ((bottom + word.height) > height) {
+                            wordQ.add(word);
+                            lineQ.forEach(wordQ::push);
+                            return removeBlankLines(lines);
+                        }
+                        if (end == 0 && word.width > width) {
+                            throw new WordTooLong(word.word);
+                        }
+                        if ((end + word.width) > width) {
+                            lines.add(wordsAsString((Deque<Word>) lineQ));
+                            lineQ.clear();
+                            end = 0;
+                            bottom += word.height;
+                        }
+                        lineQ.add(word);
                         end += word.width;
                     }
-        lines.add(String.join(" ", line));
+                    lines.add(wordsAsString(lineQ));
+                    return removeBlankLines(lines);
+                }).collect(Collectors.toList());
+        if (wordQ.isEmpty()) {
+            return wrappings;
+        }
+        throw new NotEnoughSpace(wordQ.size());
+    }
+
+    private List<String> removeBlankLines(List<String> lines) {
         return lines.stream()
                 .filter(l -> l.length() > 0)
                 .collect(Collectors.toList());
     }
 
+    private String wordsAsString(Deque<Word> lineQ) {
+        return lineQ.stream()
+                .map(Word::getWord)
+                .collect(Collectors.joining(" "));
+    }
+
     private List<Word> wordLengths(String[] words, Font font, Graphics2D graphics2D) {
         FontRenderContext fontRenderContext = graphics2D.getFontRenderContext();
         return Arrays.stream(words)
@@ -49,13 +97,16 @@ class TextLineWrapImpl implements WordWrapper {
     }
 
     private static class Word {
+        @Getter
         private final String word;
         private final int width;
+        private final int height;
 
         public Word(String word, Font font, FontRenderContext fontRenderContext) {
             this.word = word;
             Rectangle2D stringBounds = font.getStringBounds(word + " ", fontRenderContext);
             this.width = Double.valueOf(stringBounds.getWidth()).intValue();
+            this.height = Double.valueOf(stringBounds.getHeight()).intValue();
         }
     }
 

src/main/java/net/kemitix/text/fit/Tuple.java

@@ -0,0 +1,24 @@
+package net.kemitix.text.fit;
+
+public class Tuple<A, B> {
+
+    private final A partA;
+    private final B partB;
+
+    private Tuple(final A partA, final B partB) {
+        this.partA = partA;
+        this.partB = partB;
+    }
+
+    public static <A, B> Tuple<A, B> of(final A a, final B b) {
+        return new Tuple<>(a, b);
+    }
+
+    public A get1() {
+        return partA;
+    }
+
+    public B get2() {
+        return partB;
+    }
+}

src/main/java/net/kemitix/text/fit/WordTooLong.java

@@ -0,0 +1,10 @@
+package net.kemitix.text.fit;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+@Getter
+@RequiredArgsConstructor
+public class WordTooLong extends RuntimeException {
+    private final String longWord;
+}

src/main/java/net/kemitix/text/fit/WordWrapper.java

@@ -1,13 +1,49 @@
 package net.kemitix.text.fit;
 
 import java.awt.*;
+import java.awt.geom.Rectangle2D;
 import java.util.List;
 
 public interface WordWrapper {
+    /**
+     * Wraps the text using the font in the graphics context to fit within the
+     * width.
+     *
+     * @param text the text to be line wrapped
+     * @param font the font to calculate character widths from
+     * @param graphics2D the context into which the font would be rendered
+     * @param width the maximum width of each line in pixels
+     * @return a list of the each line of text
+     * @throws NotEnoughSpace if there are more than {@link Integer#MAX_VALUE}
+     * lines - so not likely.
+     * @throws WordTooLong if there is a word that is too long to fit on a line
+     * by itself.
+     */
     List<String> wrap(
             String text,
             Font font,
             Graphics2D graphics2D,
             int width
     );
+
+    /**
+     * Wraps the text using the font in the graphics context to fit within the
+     * boxes, filling them in order.
+     *
+     * @param text the text to be line wrapped
+     * @param font the font to calculate character widths from
+     * @param graphics2D the context into which the font would be rendered
+     * @param boxes the list of rectangles to fit each line within.
+     * @return a list of the each line of text
+     * @throws NotEnoughSpace if there are more lines than can be fitted in the
+     * boxes provided.
+     * @throws WordTooLong if there is a word that is too long to fit on a line
+     * by itself. Not likely as this would simply force smaller fonts.
+     */
+    List<List<String>> wrap(
+            String text,
+            Font font,
+            Graphics2D graphics2D,
+            List<Rectangle2D> boxes
+    );
 }

src/test/java/net/kemitix/text/fit/BoxFitterTest.java

@@ -2,6 +2,7 @@ package net.kemitix.text.fit;
 
 import org.assertj.core.api.WithAssertions;
 import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 
 import java.awt.*;
@@ -11,9 +12,10 @@ import java.io.File;
 import java.io.IOException;
 import java.net.URISyntaxException;
 import java.net.URL;
+import java.util.Arrays;
 import java.util.Collections;
+import java.util.List;
 import java.util.Map;
-import java.util.function.BiConsumer;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
@@ -22,44 +24,57 @@ public class BoxFitterTest
         implements WithAssertions {
 
     private final BoxFitter boxFitter = TextFit.fitter();
-    private final int imageSize = 300;
-    private final int fontSize = 20;
-    private final Graphics2D graphics2D = graphics(imageSize, imageSize);
     private final Font font;
     private Function<Integer, Font> fontFactory;
+    private final int imageSize = 300;
+    private final Graphics2D graphics2D = graphics(imageSize, imageSize);
     private Rectangle2D box = new Rectangle(imageSize, imageSize);
 
     public BoxFitterTest() throws URISyntaxException, IOException, FontFormatException {
         URL resource = this.getClass().getResource("alice/Alice-Regular.ttf");
+        int initialFontSize = 20;
         font = Font.createFont(Font.TRUETYPE_FONT, new File(resource.toURI()))
-                .deriveFont(Font.PLAIN, fontSize);
+                .deriveFont(Font.PLAIN, initialFontSize);
         fontFactory = size -> font.deriveFont(Font.PLAIN, size);
     }
 
+    interface FitTests {
+        int fit(String text);
+    }
+
+    @Nested
+    @DisplayName("Single Box API")
+    public class SingleBoxAPI implements FitTests {
+
+        @Override
+        public int fit(String longText) {
+            return boxFitter.fit(longText, fontFactory, graphics2D, box);
+        }
+
         @Test
         @DisplayName("Fit single words")
         public void fitSingleWord() {
             Map<String, Integer> wordMap = Map.of(
                     ".", 263,
                     "a", 263,
-                "Word", 121,
-                "longer", 104,
-                "extralongword", 44
+                    "Word", 110,
+                    "longer", 96,
+                    "extralongword", 43
             );
             wordMap.forEach((word, expectedSize) ->
-                assertThat(invoke(word))
+                    assertThat(fit(word))
                             .as(word)
                             .isEqualTo(expectedSize));
         }
 
         @Test
-    @DisplayName("Fit two words")
-    public void fitTwoWords() {
+        @DisplayName("Fit various lengths")
+        public void fitVariousLengths() {
             Map<String, Integer> wordMap = Map.of(
                     ". .", 263,
                     "a a", 208,
-                "Another Word", 81,
-                longStringGenerator(1), 100,
+                    "Another Word", 76,
+                    longStringGenerator(1), 93,
                     longStringGenerator(2), 36,
                     longStringGenerator(3), 27,
                     longStringGenerator(4), 22,
@@ -68,30 +83,96 @@ public class BoxFitterTest
                     longStringGenerator(196), 3
             );
             wordMap.forEach((word, expectedSize) ->
-                assertThat(invoke(word))
+                    assertThat(fit(word))
                             .as(word)
                             .isEqualTo(expectedSize));
         }
 
         @Test
-    @DisplayName("Text too long to fit throws and exception")
+        @DisplayName("Text too long to fit throws")
         // too long to fit means it would need to be rendered at a font size of <2
         public void tooLongThrows() {
             String longText = longStringGenerator(197);
-        assertThatExceptionOfType(IllegalArgumentException.class)
-                .isThrownBy(() -> invoke(longText));
+            assertThatExceptionOfType(NotEnoughSpace.class)
+                    .isThrownBy(() -> fit(longText));
         }
 
         @Test
         @DisplayName("Long text can be fitted down to a font size of 3")
         public void veryLongFits() {
             String longText = longStringGenerator(196);
-        assertThatCode(() -> invoke(longText))
+            assertThatCode(() -> fit(longText))
+                    .doesNotThrowAnyException();
+        }
+    }
+
+    @Nested
+    @DisplayName("List of Boxes API")
+    public class BoxListAPI {
+
+        @Nested
+        @DisplayName("Single Box")
+        // different API, but should have same behaviour as using single box API
+        public class SingleBox implements FitTests {
+
+            private final List<Rectangle2D> boxes = Collections.singletonList(box);
+
+            @Override
+            public int fit(String longText) {
+                return boxFitter.fit(longText, fontFactory, graphics2D, boxes);
+            }
+
+            @Test
+            @DisplayName("Fit various lengths")
+            public void fitVariousLengths() {
+                Map<String, Integer> wordMap = Map.of(
+                        ". .", 263,
+                        "a a", 208,
+                        "Another Word", 76,
+                        longStringGenerator(1), 93,
+                        longStringGenerator(2), 36,
+                        longStringGenerator(3), 27,
+                        longStringGenerator(4), 22,
+                        longStringGenerator(5), 20,
+                        longStringGenerator(100), 4,
+                        longStringGenerator(196), 3
+                );
+                wordMap.forEach((word, expectedSize) ->
+                        assertThat(fit(word))
+                                .as(word)
+                                .isEqualTo(expectedSize));
+            }
+
+            @Test
+            @DisplayName("Excess text for one box - throws")
+            public void tooMuchForOneBox() {
+                assertThatExceptionOfType(NotEnoughSpace.class)
+                        .isThrownBy(() ->
+                                fit(longStringGenerator(197)));
+            }
+        }
+
+        @Nested
+        @DisplayName("Two Boxes")
+        public class TwoBoxes implements FitTests{
+
+            private final List<Rectangle2D> boxes = Arrays.asList(box, box);
+
+            @Override
+            public int fit(String longText) {
+                return boxFitter.fit(longText, fontFactory, graphics2D, boxes);
+            }
+
+            @Test
+            @DisplayName("Excess text for one box - fits into two")
+            public void tooLongThrows() {
+                assertThatCode(() ->
+                        fit(longStringGenerator(197)))
                         .doesNotThrowAnyException();
             }
 
-    private int invoke(String longText) {
-        return boxFitter.fit(longText, fontFactory, graphics2D, box);
+        }
+
     }
 
     private String longStringGenerator(int cycles) {

src/test/java/net/kemitix/text/fit/StreamZipperTest.java

@@ -0,0 +1,40 @@
+package net.kemitix.text.fit;
+
+import org.assertj.core.api.WithAssertions;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import java.lang.reflect.Constructor;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+class StreamZipperTest implements WithAssertions {
+
+    @Test
+    void privateUtilityConstructor() throws NoSuchMethodException {
+        //given
+        final Constructor<StreamZipper> constructor = StreamZipper.class.getDeclaredConstructor();
+        constructor.setAccessible(true);
+        //then
+        assertThatCode(constructor::newInstance)
+                .hasCauseInstanceOf(UnsupportedOperationException.class);
+    }
+
+    @Test
+    @DisplayName("Pair two lists together")
+    void pairItems() {
+        //when
+        final List<String> strings = Arrays.asList("One", "Two", "Three");
+        final List<Integer> integers = Arrays.asList(3, 2, 1);
+        final List<Tuple<String, Integer>> zipped =
+                StreamZipper.zip(strings, integers, Tuple::of).collect(Collectors.toList());
+        //then
+        assertThat(zipped)
+                .extracting(Tuple::get1)
+                .containsExactlyElementsOf(strings.subList(0, zipped.size()));
+        assertThat(zipped)
+                .extracting(Tuple::get2)
+                .containsExactlyElementsOf(integers.subList(0, zipped.size()));
+    }
+}

src/test/java/net/kemitix/text/fit/TextLineWrapTest.java

@@ -1,25 +1,41 @@
 package net.kemitix.text.fit;
 
 import org.assertj.core.api.WithAssertions;
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Nested;
 
 import java.awt.*;
+import java.awt.geom.Rectangle2D;
 import java.awt.image.BufferedImage;
 import java.io.File;
 import java.io.IOException;
 import java.net.URISyntaxException;
 import java.net.URL;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
 
 public class TextLineWrapTest
         implements WithAssertions {
 
+    private static final String WORD = "word";
+    private static final String SPACE = " ";
+
     private final WordWrapper textLineWrap = TextFit.wrapper();
     private final int imageSize = 300;
     private final int fontSize = 20;
     private final Graphics2D graphics2D = graphics(imageSize, imageSize);
     private final Font font;
+    private final int spaceWidth;
+    private final int wordWidth;
+    private final int wordsPerLine;
+    private final int wordHeight;
+    private final int linesPerBox;
 
     public TextLineWrapTest()
             throws FontFormatException,
@@ -28,8 +44,27 @@ public class TextLineWrapTest
         URL resource = this.getClass().getResource("alice/Alice-Regular.ttf");
         font = Font.createFont(Font.TRUETYPE_FONT, new File(resource.toURI()))
                 .deriveFont(Font.PLAIN, fontSize);
+        Rectangle2D spaceBounds = stringBounds(SPACE, font, graphics2D);
+        Rectangle2D wordBounds = stringBounds(WORD, font, graphics2D);
+        spaceWidth = (int) spaceBounds.getWidth();
+        wordWidth = (int) wordBounds.getWidth();
+        wordHeight = (int) wordBounds.getHeight();
+        wordsPerLine = imageSize / (wordWidth + spaceWidth);
+        linesPerBox = imageSize / wordHeight;
     }
 
+    private Rectangle2D stringBounds(
+            String string,
+            Font font,
+            Graphics2D graphics2D
+    ) {
+        return font.getStringBounds(string, graphics2D.getFontRenderContext());
+    }
+
+    @Nested
+    @DisplayName("Single box")
+    public class SingleBox {
+
         private List<String> invoke(String in) {
             return textLineWrap.wrap(in, font, graphics2D, imageSize);
         }
@@ -47,27 +82,49 @@ public class TextLineWrapTest
         }
 
         @Test
-    @DisplayName("Longer string fits on two lines")
-    public void longerStringOnTwoLines() {
-        assertThat(invoke(
-                "xxxxxxxxxxx xxxxxxxxxxxx " +
-                        "xxxxxxxxxxx xxxxxxxxxxxx"))
-                .containsExactly(
-                        "xxxxxxxxxxx xxxxxxxxxxxx",
-                        "xxxxxxxxxxx xxxxxxxxxxxx");
+        @DisplayName("Fits max 'words' per line on one line")
+        public void fitMaxWordsOneLine() {
+            String input = words(wordsPerLine, WORD);
+            assertThat(invoke(input)).containsExactly(input);
         }
 
         @Test
-    @DisplayName("Longer string fits on three lines")
-    public void longerStringOnThreeLines() {
-        assertThat(invoke(
-                "xxxxxxxxxxx xxxxxxxxxxxx " +
-                        "xxxxxxxxxxx xxxxxxxxxxxx " +
-                        "xxxxxxxxxxx xxxxxxxxxxxx"))
+        @DisplayName("Wraps just over max 'words' per line onto two lines")
+        public void wrapOneWordTooManyOntoTwoLines() {
+            assertThat(invoke(words(wordsPerLine + 1, WORD)))
                     .containsExactly(
-                        "xxxxxxxxxxx xxxxxxxxxxxx",
-                        "xxxxxxxxxxx xxxxxxxxxxxx",
-                        "xxxxxxxxxxx xxxxxxxxxxxx");
+                            words(wordsPerLine, WORD),
+                            WORD);
+        }
+
+        @Test
+        @DisplayName("Wraps onto three lines")
+        public void longerStringOnThreeLines() {
+            String oneLinesWorthOfWords = words(wordsPerLine, WORD);
+            assertThat(invoke(words(wordsPerLine + wordsPerLine + 1, WORD)))
+                    .containsExactly(
+                            oneLinesWorthOfWords,
+                            oneLinesWorthOfWords,
+                            WORD);
+        }
+
+        @Test
+        @DisplayName("A word that can't fit on a line by itself throws")
+        public void overLongWordThrows() {
+            String longWord = words(wordsPerLine * 2, WORD)
+                    .replace(" ", "");
+            assertThatExceptionOfType(WordTooLong.class)
+                    .isThrownBy(() -> invoke(longWord))
+                    .satisfies(error ->
+                            assertThat(error.getLongWord())
+                                    .isEqualTo(longWord));
+        }
+    }
+
+    private String words(int number, String word) {
+        return IntStream.range(0, number)
+                .mapToObj(i -> word + SPACE)
+                .collect(Collectors.joining()).trim();
     }
 
     private Graphics2D graphics(int width, int height) {
@@ -78,4 +135,181 @@ public class TextLineWrapTest
     private BufferedImage image(int width, int height) {
         return new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
     }
+
+    @Nested
+    @DisplayName("Overflowing Boxes")
+    public class OverflowingBoxes {
+
+        private List<Rectangle2D> boxes = new ArrayList<>();
+
+        private List<List<String>> wrap(String in) {
+            return textLineWrap.wrap(in, font, graphics2D, boxes);
+        }
+
+        @Nested
+        @DisplayName("Single box")
+        public class SingleBox {
+
+            @BeforeEach
+            public void setUp() {
+                boxes.add(new Rectangle(imageSize, imageSize));
+            }
+
+            @Test
+            @DisplayName("Empty String give empty List")
+            public void emptyStringEmptyList() {
+                assertThat(wrap("")).containsExactly(Collections.emptyList());
+            }
+
+            @Test
+            @DisplayName("Short string fits on one line")
+            public void shortStringOnOneLine() {
+                assertThat(wrap("x"))
+                        .containsExactly(Collections.singletonList("x"));
+            }
+
+            @Test
+            @DisplayName("Fits max 'words' per line on one line")
+            public void fitMaxWordsOneLine() {
+                String input = words(wordsPerLine, WORD);
+                assertThat(wrap(input))
+                        .containsExactly(Collections.singletonList(input));
+            }
+
+            @Test
+            @DisplayName("Wraps just over max 'words' per line onto two lines")
+            public void wrapOneWordTooManyOntoTwoLines() {
+                String input = words(wordsPerLine + 1, WORD);
+                assertThat(wrap(input)).containsExactly(Arrays.asList(
+                        words(wordsPerLine, WORD),
+                        WORD));
+            }
+
+            @Test
+            @DisplayName("Wraps onto three lines")
+            public void longerStringOnThreeLines() {
+                String input = words(wordsPerLine + wordsPerLine + 1, WORD);
+                String oneLinesWorthOfWords = words(wordsPerLine, WORD);
+                assertThat(wrap(input)).containsExactly(Arrays.asList(
+                        oneLinesWorthOfWords,
+                        oneLinesWorthOfWords,
+                        WORD));
+            }
+
+            @Test
+            @DisplayName("Text fills the box")
+            public void textFillsBox() {
+                String lineOfWords = words(wordsPerLine, WORD);
+                String words = words(linesPerBox, lineOfWords);
+                assertThat(wrap(words).get(0))
+                        .hasSize(linesPerBox)
+                        .allSatisfy(line ->
+                                assertThat(line).isEqualTo(lineOfWords));
+            }
+
+            @Test
+            @DisplayName("Text overflows the box")
+            public void tooManyLinesForBox() {
+                String lineOfWords = words(wordsPerLine, WORD);
+                String input = words(linesPerBox + 1, lineOfWords);
+                assertThatExceptionOfType(NotEnoughSpace.class)
+                        .isThrownBy(() -> wrap(input))
+                        .satisfies(error ->
+                                assertThat(error.getExcessWordCount())
+                                        .isEqualTo(wordsPerLine));
+            }
+        }
+
+        @Nested
+        @DisplayName("Two boxes of equal width")
+        public class TwoEqualWidthBoxes {
+
+            @BeforeEach
+            public void setUp() {
+                Rectangle box = new Rectangle(imageSize, imageSize);
+                boxes.add(box);
+                boxes.add(box);
+            }
+
+            // Check that even with two boxes the shorted strings are unaffected
+            @Test
+            @DisplayName("Empty String give empty List")
+            public void emptyStringEmptyList() {
+                assertThat(wrap("")).containsExactly(
+                        Collections.emptyList(),
+                        Collections.emptyList());
+            }
+
+            @Test
+            @DisplayName("Short string fits on one line")
+            public void shortStringOnOneLine() {
+                assertThat(wrap("x"))
+                        .containsExactly(
+                                Collections.singletonList("x"),
+                                Collections.emptyList());
+            }
+
+            @Test
+            @DisplayName("Fits max 'words' per line on one line")
+            public void fitMaxWordsOneLine() {
+                String input = words(wordsPerLine, WORD);
+                assertThat(wrap(input))
+                        .containsExactly(
+                                Collections.singletonList(input),
+                                Collections.emptyList()                         );
+            }
+
+            @Test
+            @DisplayName("Wraps just over max 'words' per line onto two lines")
+            public void wrapOneWordTooManyOntoTwoLines() {
+                String input = words(wordsPerLine + 1, WORD);
+                assertThat(wrap(input)).containsExactly(Arrays.asList(
+                        words(wordsPerLine, WORD),
+                        WORD),
+                        Collections.emptyList());
+            }
+
+            @Test
+            @DisplayName("Wraps onto three lines")
+            public void longerStringOnThreeLines() {
+                String input = words(wordsPerLine + wordsPerLine + 1, WORD);
+                String oneLinesWorthOfWords = words(wordsPerLine, WORD);
+                assertThat(wrap(input)).containsExactly(Arrays.asList(
+                        oneLinesWorthOfWords,
+                        oneLinesWorthOfWords,
+                        WORD),
+                        Collections.emptyList());
+            }
+
+            @Test
+            @DisplayName("Fit max lines into the first box")
+            public void fitMaxLinesInFirstBox() {
+                String oneLinesWorthOfWords = words(wordsPerLine, WORD);
+                String input = words(linesPerBox, oneLinesWorthOfWords);
+                List<List<String>> result = wrap(input);
+                List<String> linesBoxOne = result.get(0);
+                assertThat(linesBoxOne)
+                        .hasSize(linesPerBox)
+                        .allSatisfy(line ->
+                                assertThat(line)
+                                        .isEqualTo(oneLinesWorthOfWords));
+            }
+
+            @Test
+            @DisplayName("Overflow just over max lines into the second box")
+            public void overflowMaxPlusOneLinesIntoSecondBox() {
+                String oneLinesWorthOfWords = words(wordsPerLine, WORD);
+                String input = words(linesPerBox + 1, oneLinesWorthOfWords);
+                List<List<String>> result = wrap(input);
+                List<String> linesBoxOne = result.get(0);
+                assertThat(linesBoxOne)
+                        .hasSize(linesPerBox)
+                        .allSatisfy(line ->
+                                assertThat(line)
+                                        .isEqualTo(oneLinesWorthOfWords));
+                assertThat(result.get(1))
+                        .containsExactly(oneLinesWorthOfWords);
+            }
+        }
+    }
 }