implement translation mode

src/main/java/com/github/creme332/controller/canvas/CanvasController.java

@@ -35,6 +35,7 @@
 import com.github.creme332.controller.canvas.drawing.DrawIrregularPolygon;
 import com.github.creme332.controller.canvas.drawing.DrawLine;
 import com.github.creme332.controller.canvas.drawing.DrawRegularPolygon;
+import com.github.creme332.controller.canvas.transform.Translator;
 import com.github.creme332.model.AppState;
 import com.github.creme332.model.CanvasModel;
 import com.github.creme332.model.Mode;
@@ -75,6 +76,9 @@ public CanvasController(AppState app, Canvas canvas) {
         drawControllers.add(new DrawRegularPolygon(app, canvas));
         drawControllers.add(new DrawIrregularPolygon(app, canvas));
 
+        // initialize other canvas sub-controllers
+        new Translator(app, canvas);
+
         // when canvas is resized, update dimensions and reset zoom
         canvas.addComponentListener(new ComponentAdapter() {
             @Override

src/main/java/com/github/creme332/controller/canvas/transform/AbstractTransformer.java

@@ -0,0 +1,87 @@
+package com.github.creme332.controller.canvas.transform;
+
+import java.awt.event.MouseAdapter;
+import java.awt.event.MouseEvent;
+import java.awt.geom.Point2D;
+import java.util.List;
+
+import com.github.creme332.model.AppState;
+import com.github.creme332.model.CanvasModel;
+import com.github.creme332.model.Mode;
+import com.github.creme332.model.ShapeWrapper;
+import com.github.creme332.view.Canvas;
+
+public abstract class AbstractTransformer {
+    protected Canvas canvas;
+    protected CanvasModel canvasModel;
+    private AppState app;
+
+    protected AbstractTransformer(AppState app, Canvas canvas) {
+        this.app = app;
+        this.canvas = canvas;
+        this.canvasModel = app.getCanvasModel();
+
+        canvas.addMouseListener(new MouseAdapter() {
+            @Override
+            public void mousePressed(MouseEvent e) {
+                if (!shouldDraw())
+                    return;
+                Point2D polyspaceMousePosition = canvasModel.toPolySpace(e.getPoint());
+                int selectedShapeIndex = getSelectedShapeIndex(polyspaceMousePosition);
+                if (selectedShapeIndex < 0)
+                    return;
+                handleShapeSelection(selectedShapeIndex);
+            }
+        });
+    }
+
+    /**
+     * 
+     * @param polyspaceMousePosition Coordinate of point lying inside shape
+     * @return Index of first shape that contains polyspaceMousePosition. -1 if no
+     *         such shape found.
+     */
+    private int getSelectedShapeIndex(Point2D polyspaceMousePosition) {
+        List<ShapeWrapper> shapes = canvasModel.getShapeManager().getShapes();
+        for (int i = 0; i < shapes.size(); i++) {
+            ShapeWrapper wrapper = shapes.get(i);
+            if (wrapper.getShape().contains(polyspaceMousePosition)) {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+    /**
+     * 
+     * @return Current canvas mode
+     */
+    public Mode getCanvasMode() {
+        return app.getMode();
+    }
+
+    /**
+     * This method only gets called when shouldDraw() returns true and mouse
+     * clicked.
+     * 
+     * @param shapeIndex A valid index representing selected shape
+     */
+    public abstract void handleShapeSelection(int shapeIndex);
+
+    /**
+     * Determines whether current controller should be allowed to handle event or
+     * not.
+     * 
+     * @return
+     */
+    public abstract boolean shouldDraw();
+
+    /**
+     * Reset current controller to its initial state. For example, this method will
+     * be invoked when mode changes while drawing was ongoing.
+     */
+    public void disposePreview() {
+        // delete any preview shape
+        canvasModel.getShapeManager().setShapePreview(null);
+    }
+}

src/main/java/com/github/creme332/controller/canvas/transform/Translator.java

@@ -0,0 +1,95 @@
+package com.github.creme332.controller.canvas.transform;
+
+import java.awt.Shape;
+import java.awt.geom.AffineTransform;
+import java.awt.geom.Point2D;
+import java.util.List;
+
+import javax.swing.JLabel;
+import javax.swing.JOptionPane;
+import javax.swing.JPanel;
+import javax.swing.JTextField;
+
+import com.github.creme332.model.AppState;
+import com.github.creme332.model.Mode;
+import com.github.creme332.model.ShapeWrapper;
+import com.github.creme332.view.Canvas;
+
+public class Translator extends AbstractTransformer {
+
+    public Translator(AppState app, Canvas canvas) {
+        super(app, canvas);
+    }
+
+    @Override
+    public void handleShapeSelection(int shapeIndex) {
+        /**
+         * A copy of the shape selected
+         */
+        final ShapeWrapper selectedWrapperCopy = canvasModel.getShapeManager().getShapes().get(shapeIndex);
+
+        // request user for translation vector
+        final Point2D translationVector = requestTranslationVector();
+
+        // apply transformation on shape
+        final AffineTransform transform = new AffineTransform();
+        transform.translate(translationVector.getX(), translationVector.getY());
+        final Shape transformedShape = transform.createTransformedShape(selectedWrapperCopy.getShape());
+
+        // save transformed shape
+        selectedWrapperCopy.setShape(transformedShape);
+        canvasModel.getShapeManager().editShape(shapeIndex, selectedWrapperCopy);
+
+        // translate plotted points
+        final List<Point2D> originalPlottedPoints = selectedWrapperCopy.getPlottedPoints();
+        for (int i = 0; i < originalPlottedPoints.size(); i++) {
+            Point2D oldPoint = originalPlottedPoints.get(i);
+            originalPlottedPoints.set(i,
+                    new Point2D.Double(oldPoint.getX() + translationVector.getX(),
+                            oldPoint.getY() + translationVector.getY()));
+        }
+
+        // repaint canvas
+        canvas.repaint();
+    }
+
+    @Override
+    public boolean shouldDraw() {
+        return getCanvasMode() == Mode.TRANSLATION;
+    }
+
+    /**
+     * Asks user to enter the radii for the ellipse. If input values are invalid
+     * or if the operation is cancelled, null is returned.
+     * 
+     * @return array with radii [rx, ry]
+     */
+    private Point2D requestTranslationVector() {
+        final Point2D zeroVector = new Point2D.Double(0, 0);
+
+        JTextField rxField = new JTextField(5);
+        JTextField ryField = new JTextField(5);
+        JPanel panel = new JPanel();
+        panel.add(new JLabel("X:"));
+        panel.add(rxField);
+        panel.add(new JLabel("Y:"));
+        panel.add(ryField);
+
+        int result = JOptionPane.showConfirmDialog(null, panel, "Enter translation vector",
+                JOptionPane.OK_CANCEL_OPTION,
+                JOptionPane.PLAIN_MESSAGE);
+
+        // Request focus again otherwise keyboard shortcuts will not work
+        canvas.getTopLevelAncestor().requestFocus();
+
+        if (result == JOptionPane.OK_OPTION) {
+            try {
+                return new Point2D.Double(Integer.parseInt(rxField.getText()), Integer.parseInt(ryField.getText()));
+            } catch (NumberFormatException e) {
+                return zeroVector;
+            }
+        }
+        return zeroVector;
+    }
+
+}