Add zoom controls to basic drawing.

src/main/org/insa/graphics/drawing/components/MapZoomControls.java

@@ -0,0 +1,173 @@
+package org.insa.graphics.drawing.components;
+
+import java.awt.Color;
+import java.awt.Component;
+import java.awt.Graphics2D;
+import java.awt.Image;
+import java.awt.Rectangle;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import java.awt.event.MouseAdapter;
+import java.awt.event.MouseEvent;
+import java.awt.image.ImageObserver;
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+import javax.imageio.ImageIO;
+
+public class MapZoomControls {
+
+    // Default ID for action events
+    private static final int ZOOM_IN_ACTION_ID = 0x1;
+    private static final String ZOOM_IN_ACTION_NAME = "ZoomIn";
+
+    private static final int ZOOM_OUT_ACTION_ID = 0x2;
+    private static final String ZOOM_OUT_ACTION_NAME = "ZoomOut";
+
+    // Height
+    private static final int DEFAULT_HEIGHT = 18;
+
+    // Default spacing between mark
+    private static final int DEFAULT_SPACING = 3;
+
+    // Zoom ticks ratio from height (not the current one)
+    private static final double ZOOM_TICK_HEIGHT_RATIO = 0.3;
+
+    // Zoom ticks color
+    private static final Color ZOOM_TICK_COLOR = Color.GRAY;
+
+    // Current zoom ticks ratio from height
+    private static final double CURRENT_ZOOM_TICK_HEIGHT_RATIO = 0.8;
+
+    // Zoom ticks color
+    private static final Color CURRENT_ZOOM_TICK_COLOR = new Color(25, 25, 25);
+
+    // Use half mark or not
+    private boolean halfMark = true;
+
+    private int currentLevel = 0;
+    private final int minLevel, maxLevel;
+
+    // Zoom in/out image and their rectangles.
+    private final Image zoomIn, zoomOut;
+    private final Rectangle zoomInRect = new Rectangle(0, 0, 0, 0), zoomOutRect = new Rectangle(0, 0, 0, 0);
+
+    // List of listeners
+    private final List<ActionListener> zoomInListeners = new ArrayList<>();
+    private final List<ActionListener> zoomOutListeners = new ArrayList<>();
+
+    public MapZoomControls(Component component, final int defaultZoom, final int minZoom, final int maxZoom)
+            throws IOException {
+
+        zoomIn = ImageIO.read(new File("zoomIn.png")).getScaledInstance(DEFAULT_HEIGHT, DEFAULT_HEIGHT,
+                Image.SCALE_SMOOTH);
+        zoomOut = ImageIO.read(new File("zoomOut.png")).getScaledInstance(DEFAULT_HEIGHT, DEFAULT_HEIGHT,
+                Image.SCALE_SMOOTH);
+
+        this.currentLevel = defaultZoom;
+        this.minLevel = minZoom;
+        this.maxLevel = maxZoom;
+
+        component.addMouseListener(new MouseAdapter() {
+            @Override
+            public void mouseClicked(MouseEvent e) {
+                if (zoomInRect.contains(e.getPoint()) && currentLevel < maxLevel) {
+                    currentLevel += 1;
+                    for (ActionListener al: zoomInListeners) {
+                        al.actionPerformed(new ActionEvent(this, ZOOM_IN_ACTION_ID, ZOOM_IN_ACTION_NAME));
+                    }
+                }
+                else if (zoomOutRect.contains(e.getPoint()) && currentLevel > minLevel) {
+                    currentLevel -= 1;
+                    for (ActionListener al: zoomOutListeners) {
+                        al.actionPerformed(new ActionEvent(this, ZOOM_OUT_ACTION_ID, ZOOM_OUT_ACTION_NAME));
+                    }
+                }
+                component.repaint();
+            }
+        });
+    }
+
+    /**
+     * Add a zoom-in listener.
+     * 
+     * @param listener
+     */
+    public void addZoomInListener(ActionListener listener) {
+        this.zoomInListeners.add(listener);
+    }
+
+    /**
+     * Add a zoom-out listener.
+     * 
+     * @param listener
+     */
+    public void addZoomOutListener(ActionListener listener) {
+        this.zoomOutListeners.add(listener);
+    }
+
+    /**
+     * @return the current zoom level.
+     */
+    public int getZoomLevel() {
+        return this.currentLevel;
+    }
+
+    /**
+     * Set the current zoom level.
+     * 
+     * @param level
+     */
+    public void setZoomLevel(int level) {
+        this.currentLevel = level;
+    }
+
+    /**
+     * @return Height of this "component" when drawn.
+     */
+    public int getHeight() {
+        return DEFAULT_HEIGHT;
+    }
+
+    /**
+     * @return Width of this "component" when drawn.
+     */
+    public int getWidth() {
+        return DEFAULT_HEIGHT + 2 + (this.maxLevel - this.minLevel) * DEFAULT_SPACING + 1 + 2 + DEFAULT_HEIGHT;
+    }
+
+    protected void draw(Graphics2D g, int xoffset, int yoffset, ImageObserver observer) {
+
+        int height = getHeight();
+
+        // Draw icon
+        g.drawImage(zoomOut, xoffset, yoffset, observer);
+        zoomOutRect.setBounds(xoffset, yoffset, DEFAULT_HEIGHT, DEFAULT_HEIGHT);
+
+        // Draw ticks
+        xoffset += DEFAULT_HEIGHT + 2;
+        g.setColor(ZOOM_TICK_COLOR);
+        g.drawLine(xoffset, yoffset + height / 2, xoffset + (this.maxLevel - this.minLevel) * DEFAULT_SPACING + 1,
+                yoffset + height / 2);
+        for (int i = 0; i <= (this.maxLevel - this.minLevel); i += halfMark ? 2 : 1) {
+            g.drawLine(xoffset + i * DEFAULT_SPACING, yoffset + (int) (height * (1 - ZOOM_TICK_HEIGHT_RATIO) / 2),
+                    xoffset + i * DEFAULT_SPACING, yoffset + (int) (height * (1 + ZOOM_TICK_HEIGHT_RATIO) / 2));
+        }
+
+        // Draw current ticks
+        g.setColor(CURRENT_ZOOM_TICK_COLOR);
+        g.drawLine(xoffset + (currentLevel - this.minLevel) * DEFAULT_SPACING,
+                yoffset + (int) (height * (1 - CURRENT_ZOOM_TICK_HEIGHT_RATIO) / 2),
+                xoffset + (currentLevel - this.minLevel) * DEFAULT_SPACING,
+                yoffset + (int) (height * (1 + CURRENT_ZOOM_TICK_HEIGHT_RATIO) / 2));
+
+        xoffset += (this.maxLevel - this.minLevel) * DEFAULT_SPACING + 1 + 2;
+
+        g.drawImage(zoomIn, xoffset, yoffset, observer);
+        zoomInRect.setBounds(xoffset, yoffset, DEFAULT_HEIGHT, DEFAULT_HEIGHT);
+
+    }
+
+}