Made image zoomable and movable

src/com/imegumii/ui/GraphImagePanel.java

@@ -3,6 +3,10 @@ package com.imegumii.ui;
 import javax.imageio.ImageIO;
 import javax.swing.*;
 import java.awt.*;
+import java.awt.event.*;
+import java.awt.geom.AffineTransform;
+import java.awt.geom.NoninvertibleTransformException;
+import java.awt.geom.Point2D;
 import java.awt.image.BufferedImage;
 import java.io.IOException;
 import java.io.*;
@@ -14,6 +18,11 @@ public class GraphImagePanel extends JPanel {
 
     private BufferedImage image;
 
+    private float scale = 1f;
+    private float x = 0f, y = 0f;
+    private Point dragStartScreen;
+    private Point dragEndScreen;
+
     public GraphImagePanel(File f)
     {
         super();
@@ -22,10 +31,71 @@ public class GraphImagePanel extends JPanel {
 
         try {
             image = ImageIO.read(f);
+//            x = image.getWidth() / 2;
+//            y = image.getHeight() / 2;
         } catch (IOException e) {
             e.printStackTrace();
         }
 
+        addMouseWheelListener(new MouseAdapter() {
+
+            @Override
+            public void mouseWheelMoved(MouseWheelEvent e) {
+//                System.out.println("Scrolled" + scale);
+                double delta = 0.05f * e.getPreciseWheelRotation();
+                scale += delta;
+                revalidate();
+                repaint();
+            }
+
+        });
+
+        addMouseMotionListener(new MouseMotionListener() {
+            @Override
+            public void mouseDragged(MouseEvent e) {
+                dragEndScreen = e.getPoint();
+                double dx = dragEndScreen.getX() - dragStartScreen.getX();
+                double dy = dragEndScreen.getY() - dragStartScreen.getY();
+                x += dx;
+                y += dy;
+                dragStartScreen = dragEndScreen;
+                dragEndScreen = null;
+                repaint();
+            }
+
+            @Override
+            public void mouseMoved(MouseEvent e) {
+            }
+        });
+
+        addMouseListener(new MouseListener() {
+            @Override
+            public void mouseClicked(MouseEvent e) {
+
+            }
+
+            @Override
+            public void mousePressed(MouseEvent e) {
+                dragStartScreen = e.getPoint();
+                dragEndScreen = null;
+            }
+
+            @Override
+            public void mouseReleased(MouseEvent e) {
+
+            }
+
+            @Override
+            public void mouseEntered(MouseEvent e) {
+
+            }
+
+            @Override
+            public void mouseExited(MouseEvent e) {
+
+            }
+        });
+
         repaint();
     }
 
@@ -38,17 +108,23 @@ public class GraphImagePanel extends JPanel {
 
         if(image != null){
 
-            int width = this.getWidth();
-            int height = this.getHeight();
-
-            if(image.getWidth() > image.getHeight()) {
-                height = (int)((width * image.getHeight()) / image.getWidth());
-            }
-            else {
-                width = (int) ((height * image.getWidth()) / image.getHeight());
-            }
-
-            g2d.drawImage(image, 0,0, width, height, this);
+//            int width = this.getWidth();
+//            int height = this.getHeight();
+//
+//            if(image.getWidth() > image.getHeight()) {
+//                height = (int)((width * image.getHeight()) / image.getWidth());
+//            }
+//            else {
+//                width = (int) ((height * image.getWidth()) / image.getHeight());
+//            }
+            AffineTransform at = new AffineTransform();
+            g.drawLine(-1000, 0, 1000, 0);
+            g.drawLine(0, -1000, 0, 1000);
+            at.scale(1, -1);
+            at.setToTranslation(x, y);
+            at.scale(scale, scale);
+            g2d.drawImage(image, at, this);
+//            g2d.drawImage(image, 0,0, width, height, this);
         }
     }
 }