Added an image viewing widget.

sensor-plotting/src/main/java/org/orangepalantir/ImageFileMonitor.java

@@ -0,0 +1,80 @@
+package org.orangepalantir;
+
+import javax.imageio.ImageIO;
+import java.awt.*;
+import java.awt.image.BufferedImage;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.attribute.FileTime;
+
+public class ImageFileMonitor extends Widget {
+    BufferedImage img;
+    Path path;
+    FileTime last;
+    public ImageFileMonitor(Path monitoring) throws IOException {
+        super(monitoring.getFileName().toString());
+        img = ImageIO.read(monitoring.toFile());
+        last = Files.getLastModifiedTime(monitoring);
+        int w = 480;
+        int h = 360;
+        double sx = (w*1.0 - 2*padding)/img.getWidth();
+        double sy = (h*1.0 - 2*padding)/img.getHeight();
+
+        if(sx > sy){
+            w = (int)(sy*img.getWidth()) + 2*padding;
+        } else{
+            h = (int)(sx*img.getHeight()) + 2*padding;
+        }
+
+
+        panel.setSize(w, h);
+        path = monitoring;
+    }
+    public void paintWidget(Graphics2D g2d){
+        if(img != null){
+            int x2 = panel.getWidth() - padding;
+            int y2 = panel.getHeight() - padding;
+            g2d.drawImage(img, padding, padding, x2, y2, 0, 0, img.getWidth(), img.getHeight(), panel);
+        }
+    }
+
+    public void monitor(){
+        Thread t = new Thread(()->{
+            while(true){
+                try {
+                    FileTime mod = Files.getLastModifiedTime(path);
+
+                    if(mod.compareTo(last)>0){
+                        img = ImageIO.read(path.toFile());
+                        last = mod;
+                    } else{
+                        Thread.sleep(500);
+                    }
+
+                } catch (IOException | InterruptedException e) {
+                    e.printStackTrace();
+                    break;
+                }
+
+            }
+        });
+        t.setDaemon(true);
+        t.start();
+    }
+
+    public void setImage(BufferedImage img){
+        this.img = img;
+        panel.repaint();
+    }
+
+    public static void main(String[] args) throws Exception{
+        ImageFileMonitor ifm = new ImageFileMonitor(Paths.get(args[0]));
+        ifm.show();
+        ifm.addCloseListener((w)->{
+            System.exit(0);
+        });
+        ifm.monitor();
+    }
+}