Fix massive memory leak in previews (#679) (#680)

* Fix massve memory leak in lines previews

* Fix memory leak in blobs preview

ui/src/main/java/edu/wpi/grip/ui/preview/BlobsSocketPreviewView.java

@@ -38,6 +38,7 @@ public class BlobsSocketPreviewView extends SocketPreviewView<BlobsReport> {
   private final ImageView imageView = new ImageView();
   private final Label infoLabel = new Label();
   private final Mat tmp = new Mat();
+  private final Point point = new Point();
   private final GripPlatform platform;
   @SuppressWarnings("PMD.ImmutableField")
   @SuppressFBWarnings(value = "IS2_INCONSISTENT_SYNC",
@@ -91,7 +92,8 @@ private void convertImage() {
       if (!blobsReport.getBlobs().isEmpty()) {
         // For each line in the report, draw a line along with the starting and ending points
         for (BlobsReport.Blob blob : blobsReport.getBlobs()) {
-          final Point point = new Point((int) blob.x, (int) blob.y);
+          point.x((int) blob.x);
+          point.y((int) blob.y);
           circle(tmp, point, (int) (blob.size / 2), Scalar.WHITE, 2, LINE_8, 0);
         }
       }

ui/src/main/java/edu/wpi/grip/ui/preview/LinesSocketPreviewView.java

@@ -40,6 +40,8 @@ public class LinesSocketPreviewView extends SocketPreviewView<LinesReport> {
   private final ImageView imageView = new ImageView();
   private final Label infoLabel = new Label();
   private final Mat tmp = new Mat();
+  private final Point startPoint = new Point();
+  private final Point endPoint = new Point();
   private final GripPlatform platform;
   @SuppressWarnings("PMD.ImmutableField")
   @SuppressFBWarnings(value = "IS2_INCONSISTENT_SYNC",
@@ -99,8 +101,10 @@ private void convertImage() {
 
         // For each line in the report, draw a line along with the starting and ending points
         for (LinesReport.Line line : lines) {
-          final Point startPoint = new Point((int) line.x1, (int) line.y1);
-          final Point endPoint = new Point((int) line.x2, (int) line.y2);
+          startPoint.x((int) line.x1);
+          startPoint.y((int) line.y1);
+          endPoint.x((int) line.x2);
+          endPoint.y((int) line.y2);
           line(input, startPoint, endPoint, Scalar.WHITE, 2, LINE_8, 0);
           circle(input, startPoint, 2, Scalar.WHITE, 2, LINE_8, 0);
           circle(input, endPoint, 2, Scalar.WHITE, 2, LINE_8, 0);