Add DPI setter

Signed-off-by: Rahul Rudragoudar <rr83019@gmail.com>

src/main/java/lc/misc/DPISetter.java

@@ -0,0 +1,69 @@
+package lc.misc;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.util.Iterator;
+
+import javax.imageio.IIOImage;
+import javax.imageio.ImageIO;
+import javax.imageio.ImageTypeSpecifier;
+import javax.imageio.ImageWriteParam;
+import javax.imageio.ImageWriter;
+import javax.imageio.metadata.IIOInvalidTreeException;
+import javax.imageio.metadata.IIOMetadata;
+import javax.imageio.metadata.IIOMetadataNode;
+import javax.imageio.stream.ImageOutputStream;
+import java.awt.image.BufferedImage;
+
+public class DPISetter {
+
+  final int DPI = 245;
+  final double INCH_2_CM = 2.54;
+
+  public void setDPI(ByteArrayOutputStream boas, BufferedImage gridImage) throws IOException {
+    final String formatName = "png";
+    for (Iterator<ImageWriter> iw = ImageIO.getImageWritersByFormatName(formatName);
+        iw.hasNext(); ) {
+      ImageWriter writer = iw.next();
+      ImageWriteParam writeParam = writer.getDefaultWriteParam();
+      ImageTypeSpecifier typeSpecifier = ImageTypeSpecifier.createFromBufferedImageType(BufferedImage.TYPE_INT_RGB);
+      IIOMetadata metadata = writer.getDefaultImageMetadata(typeSpecifier, writeParam);
+      if (metadata.isReadOnly() || !metadata.isStandardMetadataFormatSupported()) {
+        continue;
+      }
+
+      setDPIMeta(metadata);
+
+      final ImageOutputStream stream = ImageIO.createImageOutputStream(boas);
+      try {
+        writer.setOutput(stream);
+        writer.write(metadata, new IIOImage(gridImage, null, metadata), writeParam);
+      } finally {
+        stream.close();
+      }
+      break;
+    }
+  }
+
+  public void setDPIMeta(IIOMetadata metadata) throws IIOInvalidTreeException {
+
+    // for PNG, it's dots per millimeter
+    double dotsPerMilli = 1.0 * DPI / 10 / INCH_2_CM;
+    System.out.println(dotsPerMilli);
+
+    IIOMetadataNode horiz = new IIOMetadataNode("HorizontalPixelSize");
+    horiz.setAttribute("value", Double.toString(dotsPerMilli));
+
+    IIOMetadataNode vert = new IIOMetadataNode("VerticalPixelSize");
+    vert.setAttribute("value", Double.toString(dotsPerMilli));
+
+    IIOMetadataNode dim = new IIOMetadataNode("Dimension");
+    dim.appendChild(horiz);
+    dim.appendChild(vert);
+
+    IIOMetadataNode root = new IIOMetadataNode("javax_imageio_1.0");
+    root.appendChild(dim);
+
+    metadata.mergeTree("javax_imageio_1.0", root);
+  }
+}

src/main/java/lc/misc/HelperFunctions.java

@@ -7,7 +7,7 @@ public class HelperFunctions {
 
   private static Random random = new Random();
 
-  synchronized public static void setSeed(long seed){
+  public static synchronized void setSeed(long seed) {
     random.setSeed(seed);
   }
 
@@ -38,12 +38,11 @@ public class HelperFunctions {
     return stringBuilder.toString();
   }
 
-  synchronized public static int randomNumber(int min, int max) {
+  public static synchronized int randomNumber(int min, int max) {
     return random.nextInt((max - min) + 1) + min;
   }
 
-  synchronized public static int randomNumber(int bound) {
+  public static synchronized int randomNumber(int bound) {
     return random.nextInt(bound);
   }
-  
 }