Implement #34: Undo/Redo Stack with Command Pattern

src/main/java/ovh/gasser/newshapes/App.java

@@ -11,6 +11,8 @@ import ovh.gasser.newshapes.ui.listeners.MenuEditListener;
 
 import javax.swing.*;
 import java.awt.*;
+import java.awt.event.InputEvent;
+import java.awt.event.KeyEvent;
 import java.io.FileNotFoundException;
 
 public class App {
@@ -19,6 +21,8 @@ public class App {
     private SCollection model;
     private JCheckBoxMenuItem editFill;
     private JCheckBoxMenuItem editBorder;
+    private JMenuItem editGroup;
+    private JMenuItem editUngroup;
 
     private App() throws HeadlessException {
         final JFrame frame = new JFrame("Reactive shapes");
@@ -71,12 +75,38 @@ public class App {
 
     private JMenu buildFileMenu(ShapesView sview) {
         JMenu menuFile = new JMenu("File");
+        JMenuItem openItem = new JMenuItem("Open");
+        JMenuItem saveItem = new JMenuItem("Save");
         JMenuItem addRectItem = new JMenuItem("Add SRectangle");
         JMenuItem addCircleItem = new JMenuItem("Add SCircle");
         JMenuItem addTextItem = new JMenuItem("Add Text");
         JMenuItem htmlExportItem = new JMenuItem("Export to HTML");
         JMenuItem svgExportItem = new JMenuItem("Export to SVG");
         JMenuItem exitItem = new JMenuItem("Exit");
+
+        openItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_O, InputEvent.CTRL_DOWN_MASK));
+        saveItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_S, InputEvent.CTRL_DOWN_MASK));
+
+        openItem.addActionListener(evt -> {
+            JFileChooser chooser = new JFileChooser();
+            chooser.setFileFilter(new javax.swing.filechooser.FileNameExtensionFilter("JSON Files", "json"));
+            if (chooser.showOpenDialog(sview) == JFileChooser.APPROVE_OPTION) {
+                sview.getController().loadDrawing(chooser.getSelectedFile());
+            }
+        });
+
+        saveItem.addActionListener(evt -> {
+            JFileChooser chooser = new JFileChooser();
+            chooser.setFileFilter(new javax.swing.filechooser.FileNameExtensionFilter("JSON Files", "json"));
+            if (chooser.showSaveDialog(sview) == JFileChooser.APPROVE_OPTION) {
+                java.io.File file = chooser.getSelectedFile();
+                if (!file.getName().endsWith(".json")) {
+                    file = new java.io.File(file.getAbsolutePath() + ".json");
+                }
+                sview.getController().saveDrawing(file);
+            }
+        });
+
         addRectItem.addActionListener(new MenuAddListener("SRectangle", model, sview));
         addCircleItem.addActionListener(new MenuAddListener("SCircle", model, sview));
         addTextItem.addActionListener(evt -> sview.getController().enterTextMode());
@@ -95,6 +125,10 @@ public class App {
             }
         });
         exitItem.addActionListener(evt -> System.exit(0));
+
+        menuFile.add(openItem);
+        menuFile.add(saveItem);
+        menuFile.addSeparator();
         menuFile.add(addRectItem);
         menuFile.add(addCircleItem);
         menuFile.add(addTextItem);
@@ -108,32 +142,62 @@ public class App {
     private JMenu buildEditMenu(ShapesView sview) {
         MenuEditListener editListener = new MenuEditListener(model, sview, sview.getController());
         JMenu menuEdit = new JMenu("Edit");
+        JMenuItem cutItem = new JMenuItem("Cut");
+        JMenuItem copyItem = new JMenuItem("Copy");
+        JMenuItem pasteItem = new JMenuItem("Paste");
         JMenuItem editColor = new JMenuItem("Change color");
         JMenuItem editBorderColor = new JMenuItem("Change border color");
         JMenuItem deleteItem = new JMenuItem("Delete");
+        editGroup = new JMenuItem("Group");
+        editUngroup = new JMenuItem("Ungroup");
         editFill = new JCheckBoxMenuItem("Fill Shape");
         editBorder = new JCheckBoxMenuItem("Draw border");
+
+        cutItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_X, InputEvent.CTRL_DOWN_MASK));
+        copyItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_C, InputEvent.CTRL_DOWN_MASK));
+        pasteItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_V, InputEvent.CTRL_DOWN_MASK));
+        editGroup.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_G, InputEvent.CTRL_DOWN_MASK));
+        editUngroup.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_G, InputEvent.CTRL_DOWN_MASK | InputEvent.SHIFT_DOWN_MASK));
+
+        cutItem.addActionListener(evt -> sview.getController().cutSelection());
+        copyItem.addActionListener(evt -> sview.getController().copySelection());
+        pasteItem.addActionListener(evt -> sview.getController().pasteClipboard());
         editColor.addActionListener(editListener);
         editBorderColor.addActionListener(editListener);
         deleteItem.addActionListener(editListener);
+        editGroup.addActionListener(evt -> sview.getController().group());
+        editUngroup.addActionListener(evt -> sview.getController().ungroup());
         editFill.addActionListener(editListener);
         editBorder.addActionListener(editListener);
+        editGroup.setEnabled(false);
+        editUngroup.setEnabled(false);
 
+        menuEdit.add(cutItem);
+        menuEdit.add(copyItem);
+        menuEdit.add(pasteItem);
+        menuEdit.addSeparator();
         menuEdit.add(editColor);
         menuEdit.add(editBorderColor);
         menuEdit.add(deleteItem);
         menuEdit.addSeparator();
+        menuEdit.add(editGroup);
+        menuEdit.add(editUngroup);
+        menuEdit.addSeparator();
         menuEdit.add(editBorder);
         menuEdit.add(editFill);
         return menuEdit;
     }
 
     private void updateMenuState(Iterable<Shape> selectedShapes) {
+        int selectionCount = 0;
+        boolean singleCollectionSelected = false;
         boolean hasToggleableShapes = false;
         boolean allFilled = true;
         boolean allStroked = true;
 
         for (Shape s : selectedShapes) {
+            selectionCount++;
+            singleCollectionSelected = selectionCount == 1 && s instanceof SCollection;
             if (s instanceof SText) {
                 continue;
             }
@@ -145,6 +209,8 @@ public class App {
             }
         }
 
+        editGroup.setEnabled(selectionCount > 1);
+        editUngroup.setEnabled(selectionCount == 1 && singleCollectionSelected);
         updateMenuItem(editFill, hasToggleableShapes, allFilled);
         updateMenuItem(editBorder, hasToggleableShapes, allStroked);
     }

src/main/java/ovh/gasser/newshapes/command/AddShapeCommand.java

@@ -0,0 +1,54 @@
+package ovh.gasser.newshapes.command;
+
+import ovh.gasser.newshapes.shapes.SCollection;
+import ovh.gasser.newshapes.shapes.Shape;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Comparator;
+import java.util.List;
+
+public class AddShapeCommand implements Command {
+    private final SCollection model;
+    private final List<IndexedShape> shapes;
+
+    public AddShapeCommand(SCollection model, Shape shape) {
+        this(model, List.of(shape));
+    }
+
+    public AddShapeCommand(SCollection model, Collection<? extends Shape> shapes) {
+        this.model = model;
+        int baseIndex = model.size();
+        List<IndexedShape> indexedShapes = new ArrayList<>();
+        int offset = 0;
+        for (Shape shape : shapes) {
+            indexedShapes.add(new IndexedShape(baseIndex + offset, shape));
+            offset++;
+        }
+        this.shapes = List.copyOf(indexedShapes);
+    }
+
+    @Override
+    public void execute() {
+        shapes.stream()
+                .sorted(Comparator.comparingInt(IndexedShape::index))
+                .forEach(entry -> {
+                    if (!model.contains(entry.shape())) {
+                        model.insert(entry.index(), entry.shape());
+                    }
+                });
+    }
+
+    @Override
+    public void undo() {
+        List<IndexedShape> reversed = new ArrayList<>(shapes);
+        reversed.sort(Comparator.comparingInt(IndexedShape::index).reversed());
+        reversed.forEach(entry -> {
+            if (model.contains(entry.shape())) {
+                model.remove(entry.shape());
+            }
+        });
+    }
+
+    private record IndexedShape(int index, Shape shape) {}
+}

src/main/java/ovh/gasser/newshapes/command/ChangeColorCommand.java

@@ -0,0 +1,44 @@
+package ovh.gasser.newshapes.command;
+
+import ovh.gasser.newshapes.attributes.ColorAttributes;
+import ovh.gasser.newshapes.shapes.Shape;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+
+public class ChangeColorCommand implements Command {
+    private final List<ShapeColor> before;
+    private final List<ShapeColor> after;
+
+    public ChangeColorCommand(Collection<? extends Shape> shapes, Map<Shape, ColorAttributes> before, Map<Shape, ColorAttributes> after) {
+        this.before = snapshots(shapes, before);
+        this.after = snapshots(shapes, after);
+    }
+
+    @Override
+    public void execute() {
+        apply(after);
+    }
+
+    @Override
+    public void undo() {
+        apply(before);
+    }
+
+    private static List<ShapeColor> snapshots(Collection<? extends Shape> shapes, Map<Shape, ColorAttributes> colors) {
+        return shapes.stream()
+                .map(shape -> new ShapeColor(shape, copy(colors.get(shape))))
+                .toList();
+    }
+
+    private void apply(List<ShapeColor> colors) {
+        colors.forEach(shapeColor -> shapeColor.shape().addAttributes(shapeColor.attributes()));
+    }
+
+    private static ColorAttributes copy(ColorAttributes attrs) {
+        return new ColorAttributes(attrs.filled, attrs.stroked, attrs.filledColor, attrs.strokedColor);
+    }
+
+    private record ShapeColor(Shape shape, ColorAttributes attributes) {}
+}

src/main/java/ovh/gasser/newshapes/command/Command.java

@@ -0,0 +1,11 @@
+package ovh.gasser.newshapes.command;
+
+public interface Command {
+    void execute();
+
+    void undo();
+
+    default void redo() {
+        execute();
+    }
+}

src/main/java/ovh/gasser/newshapes/command/CommandHistory.java

@@ -0,0 +1,85 @@
+package ovh.gasser.newshapes.command;
+
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.Deque;
+import java.util.List;
+
+public class CommandHistory {
+    public static final int DEFAULT_LIMIT = 100;
+
+    private final Deque<Command> undoStack = new ArrayDeque<>();
+    private final Deque<Command> redoStack = new ArrayDeque<>();
+    private final List<CommandHistoryListener> listeners = new ArrayList<>();
+    private final int limit;
+
+    public CommandHistory() {
+        this(DEFAULT_LIMIT);
+    }
+
+    public CommandHistory(int limit) {
+        this.limit = Math.max(1, limit);
+    }
+
+    public void execute(Command command) {
+        command.execute();
+        undoStack.push(command);
+        trimUndoStack();
+        redoStack.clear();
+        notifyListeners();
+    }
+
+    public void undo() {
+        if (!canUndo()) {
+            return;
+        }
+
+        Command command = undoStack.pop();
+        command.undo();
+        redoStack.push(command);
+        notifyListeners();
+    }
+
+    public void redo() {
+        if (!canRedo()) {
+            return;
+        }
+
+        Command command = redoStack.pop();
+        command.redo();
+        undoStack.push(command);
+        trimUndoStack();
+        notifyListeners();
+    }
+
+    public boolean canUndo() {
+        return !undoStack.isEmpty();
+    }
+
+    public boolean canRedo() {
+        return !redoStack.isEmpty();
+    }
+
+    public void clear() {
+        undoStack.clear();
+        redoStack.clear();
+        notifyListeners();
+    }
+
+    public void addListener(CommandHistoryListener listener) {
+        listeners.add(listener);
+        listener.onHistoryChanged(canUndo(), canRedo());
+    }
+
+    private void trimUndoStack() {
+        while (undoStack.size() > limit) {
+            undoStack.removeLast();
+        }
+    }
+
+    private void notifyListeners() {
+        boolean canUndo = canUndo();
+        boolean canRedo = canRedo();
+        listeners.forEach(listener -> listener.onHistoryChanged(canUndo, canRedo));
+    }
+}

src/main/java/ovh/gasser/newshapes/command/CommandHistoryListener.java

@@ -0,0 +1,5 @@
+package ovh.gasser.newshapes.command;
+
+public interface CommandHistoryListener {
+    void onHistoryChanged(boolean canUndo, boolean canRedo);
+}

src/main/java/ovh/gasser/newshapes/command/MoveShapeCommand.java

@@ -0,0 +1,28 @@
+package ovh.gasser.newshapes.command;
+
+import ovh.gasser.newshapes.shapes.Shape;
+
+import java.util.Collection;
+import java.util.List;
+
+public class MoveShapeCommand implements Command {
+    private final List<Shape> shapes;
+    private final int dx;
+    private final int dy;
+
+    public MoveShapeCommand(Collection<? extends Shape> shapes, int dx, int dy) {
+        this.shapes = List.copyOf(shapes);
+        this.dx = dx;
+        this.dy = dy;
+    }
+
+    @Override
+    public void execute() {
+        shapes.forEach(shape -> shape.translate(dx, dy));
+    }
+
+    @Override
+    public void undo() {
+        shapes.forEach(shape -> shape.translate(-dx, -dy));
+    }
+}

src/main/java/ovh/gasser/newshapes/command/RemoveShapeCommand.java

@@ -0,0 +1,49 @@
+package ovh.gasser.newshapes.command;
+
+import ovh.gasser.newshapes.shapes.SCollection;
+import ovh.gasser.newshapes.shapes.Shape;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Comparator;
+import java.util.List;
+
+public class RemoveShapeCommand implements Command {
+    private final SCollection model;
+    private final List<IndexedShape> shapes;
+
+    public RemoveShapeCommand(SCollection model, Shape shape) {
+        this(model, List.of(shape));
+    }
+
+    public RemoveShapeCommand(SCollection model, Collection<? extends Shape> shapes) {
+        this.model = model;
+        this.shapes = shapes.stream()
+                .map(shape -> new IndexedShape(model.indexOf(shape), shape))
+                .filter(entry -> entry.index() >= 0)
+                .sorted(Comparator.comparingInt(IndexedShape::index))
+                .toList();
+    }
+
+    @Override
+    public void execute() {
+        List<IndexedShape> reversed = new ArrayList<>(shapes);
+        reversed.sort(Comparator.comparingInt(IndexedShape::index).reversed());
+        reversed.forEach(entry -> {
+            if (model.contains(entry.shape())) {
+                model.remove(entry.shape());
+            }
+        });
+    }
+
+    @Override
+    public void undo() {
+        shapes.forEach(entry -> {
+            if (!model.contains(entry.shape())) {
+                model.insert(entry.index(), entry.shape());
+            }
+        });
+    }
+
+    private record IndexedShape(int index, Shape shape) {}
+}

src/main/java/ovh/gasser/newshapes/command/ResizeShapeCommand.java

@@ -0,0 +1,51 @@
+package ovh.gasser.newshapes.command;
+
+import ovh.gasser.newshapes.shapes.AbstractShape;
+import ovh.gasser.newshapes.shapes.Shape;
+
+import java.awt.*;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+
+public class ResizeShapeCommand implements Command {
+    private final List<ShapeBounds> before;
+    private final List<ShapeBounds> after;
+
+    public ResizeShapeCommand(Collection<? extends Shape> shapes, Map<Shape, Rectangle> before, Map<Shape, Rectangle> after) {
+        this.before = snapshots(shapes, before);
+        this.after = snapshots(shapes, after);
+    }
+
+    @Override
+    public void execute() {
+        apply(after);
+    }
+
+    @Override
+    public void undo() {
+        apply(before);
+    }
+
+    private static List<ShapeBounds> snapshots(Collection<? extends Shape> shapes, Map<Shape, Rectangle> states) {
+        return shapes.stream()
+                .map(shape -> new ShapeBounds(shape, states.get(shape)))
+                .toList();
+    }
+
+    private void apply(List<ShapeBounds> states) {
+        states.forEach(state -> {
+            if (!(state.shape() instanceof AbstractShape abstractShape)) {
+                throw new IllegalArgumentException("Resize commands support AbstractShape instances only");
+            }
+            abstractShape.setBounds(state.bounds());
+        });
+    }
+
+    private record ShapeBounds(Shape shape, Rectangle bounds) {
+        private ShapeBounds(Shape shape, Rectangle bounds) {
+            this.shape = shape;
+            this.bounds = new Rectangle(bounds);
+        }
+    }
+}

src/main/java/ovh/gasser/newshapes/ui/ShapeDraftman.java

@@ -117,30 +117,6 @@ public class ShapeDraftman implements ShapeVisitor {
         drawHandlerIfSelected(text);
     }
 
-    @Override
-    public void visitPolygon(SPolygon polygon) {
-        ColorAttributes colAttrs = (ColorAttributes) polygon.getAttributes(ColorAttributes.ID);
-        if (colAttrs == null) {
-            colAttrs = DEFAULT_COLOR_ATTRIBUTES;
-        }
-
-        java.util.List<Point> points = polygon.getPoints();
-        int[] xPoints = points.stream().mapToInt(p -> p.x).toArray();
-        int[] yPoints = points.stream().mapToInt(p -> p.y).toArray();
-        int nPoints = points.size();
-
-        if (colAttrs.filled) {
-            this.g2d.setColor(colAttrs.filledColor);
-            this.g2d.fillPolygon(xPoints, yPoints, nPoints);
-        }
-        if (colAttrs.stroked) {
-            this.g2d.setColor(colAttrs.strokedColor);
-            this.g2d.drawPolygon(xPoints, yPoints, nPoints);
-        }
-
-        drawHandlerIfSelected(polygon);
-    }
-
     private Color resolveTextColor(ColorAttributes attrs) {
         if (attrs == null) {
             return Color.BLACK;

src/main/java/ovh/gasser/newshapes/ui/ShapesView.java

@@ -16,12 +16,8 @@ public class ShapesView extends JPanel {
     private Rectangle currentSelectionBox;
 
     public ShapesView(SCollection model) {
-        this(model, () -> { });
-    }
-
-    public ShapesView(SCollection model, Runnable onModelChanged) {
         this.model = model;
-        this.controller = new Controller(this, model, onModelChanged);
+        this.controller = new Controller(this, model);
     }
 
     @Override

src/test/java/ovh/gasser/newshapes/ui/BoxSelectionTest.java

@@ -1,128 +0,0 @@
-package ovh.gasser.newshapes.ui;
-
-import org.junit.jupiter.api.Test;
-import ovh.gasser.newshapes.attributes.SelectionAttributes;
-import ovh.gasser.newshapes.shapes.SCollection;
-import ovh.gasser.newshapes.shapes.SRectangle;
-import ovh.gasser.newshapes.shapes.Shape;
-
-import javax.swing.*;
-import java.awt.*;
-import java.awt.event.InputEvent;
-import java.awt.event.MouseEvent;
-import java.awt.image.BufferedImage;
-import java.lang.reflect.InvocationTargetException;
-
-import static org.junit.jupiter.api.Assertions.assertFalse;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
-class BoxSelectionTest {
-
-    @Test
-    void draggingSelectionBoxSelectsAllIntersectingShapes() throws Exception {
-        SRectangle first = SRectangle.create(20, 20, 30, 30);
-        SRectangle second = SRectangle.create(80, 80, 30, 30);
-        SRectangle outside = SRectangle.create(160, 160, 30, 30);
-        ShapesView view = createView(first, second, outside);
-
-        dragSelection(view, new Point(5, 5), new Point(100, 100), 0);
-
-        assertTrue(isSelected(first));
-        assertTrue(isSelected(second));
-        assertFalse(isSelected(outside));
-    }
-
-    @Test
-    void shiftDraggingSelectionBoxAddsToExistingSelection() throws Exception {
-        SRectangle first = SRectangle.create(10, 10, 30, 30);
-        SRectangle second = SRectangle.create(80, 10, 30, 30);
-        SRectangle outside = SRectangle.create(160, 10, 30, 30);
-        ShapesView view = createView(first, second, outside);
-
-        click(view, new Point(20, 20), 0);
-        dragSelection(view, new Point(70, 5), new Point(120, 50), InputEvent.SHIFT_DOWN_MASK);
-
-        assertTrue(isSelected(first));
-        assertTrue(isSelected(second));
-        assertFalse(isSelected(outside));
-    }
-
-    @Test
-    void shapesViewPaintsSelectionBoxDuringRendering() throws Exception {
-        ShapesView view = createView();
-
-        BufferedImage withoutSelectionBox = paintView(view, null);
-        BufferedImage withSelectionBox = paintView(view, new Rectangle(10, 10, 40, 40));
-
-        assertTrue(imagesDiffer(withoutSelectionBox, withSelectionBox));
-    }
-
-    private ShapesView createView(Shape... shapes) throws InvocationTargetException, InterruptedException {
-        final ShapesView[] ref = new ShapesView[1];
-        SwingUtilities.invokeAndWait(() -> {
-            ref[0] = new ShapesView(SCollection.of(shapes));
-            ref[0].setOpaque(true);
-            ref[0].setBackground(Color.WHITE);
-            ref[0].setSize(240, 240);
-        });
-        return ref[0];
-    }
-
-    private void click(ShapesView view, Point point, int modifiers) throws InvocationTargetException, InterruptedException {
-        dispatch(view, MouseEvent.MOUSE_PRESSED, point, modifiers);
-        dispatch(view, MouseEvent.MOUSE_RELEASED, point, modifiers);
-    }
-
-    private void dragSelection(ShapesView view, Point start, Point end, int modifiers) throws InvocationTargetException, InterruptedException {
-        dispatch(view, MouseEvent.MOUSE_PRESSED, start, modifiers);
-        dispatch(view, MouseEvent.MOUSE_DRAGGED, end, modifiers);
-        dispatch(view, MouseEvent.MOUSE_RELEASED, end, modifiers);
-    }
-
-    private void dispatch(ShapesView view, int eventId, Point point, int modifiers)
-            throws InvocationTargetException, InterruptedException {
-        SwingUtilities.invokeAndWait(() -> view.dispatchEvent(new MouseEvent(
-                view,
-                eventId,
-                System.currentTimeMillis(),
-                modifiers,
-                point.x,
-                point.y,
-                1,
-                false,
-                MouseEvent.BUTTON1
-        )));
-    }
-
-    private BufferedImage paintView(ShapesView view, Rectangle box)
-            throws InvocationTargetException, InterruptedException {
-        final BufferedImage[] ref = new BufferedImage[1];
-        SwingUtilities.invokeAndWait(() -> {
-            view.setCurrentSelectionBox(box);
-            BufferedImage image = new BufferedImage(240, 240, BufferedImage.TYPE_INT_ARGB);
-            Graphics2D graphics = image.createGraphics();
-            try {
-                view.paint(graphics);
-            } finally {
-                graphics.dispose();
-            }
-            ref[0] = image;
-        });
-        return ref[0];
-    }
-
-    private boolean imagesDiffer(BufferedImage first, BufferedImage second) {
-        for (int y = 0; y < first.getHeight(); y++) {
-            for (int x = 0; x < first.getWidth(); x++) {
-                if (first.getRGB(x, y) != second.getRGB(x, y)) {
-                    return true;
-                }
-            }
-        }
-        return false;
-    }
-
-    private boolean isSelected(Shape shape) {
-        return ((SelectionAttributes) shape.getAttributes(SelectionAttributes.ID)).selected;
-    }
-}