Add more comments, clean code, due to PR

src/main/java/featurecat/lizzie/gui/VariationTree.java

@@ -117,7 +117,7 @@ public void draw(Graphics2D g, int posx, int posy, int width, int height) {
         YSPACING = (Lizzie.config.showLargeSubBoard() ? 20 : 30);
         XSPACING = YSPACING;
 
-		posx1=posx;posy1=posy;width1=width;height1=height;  //backup for mouse click event
+	    posx1=posx;posy1=posy;width1=width;height1=height;  //backup for mouse click event
 
         // Draw background
         g.setColor(new Color(0, 0, 0, 60));
@@ -149,7 +149,7 @@ public void draw(Graphics2D g, int posx, int posy, int width, int height) {
     }
 
 
-	//clone from drawTree() method but draw nothing, just caculate (x,y)->BoardNode
+    //Clone from drawTree() method but draw nothing, just caculate (x,y)->BoardNode
 	public BoardHistoryNode inSubtree(int posx, int posy, int mouseX, int mouseY, int startLane, int maxposy, BoardHistoryNode startNode, int variationNumber)
 	{
         // Finds depth on leftmost variation of this tree
@@ -205,13 +205,14 @@ public BoardHistoryNode inSubtree(int posx, int posy, int mouseX, int mouseY, in
             posy -= YSPACING;
         }
 		return null;
-	}
-
+    }
+
+    //Clone from draw() method but draw nothing, just caculate (x,y)->BoardNode
 	public BoardHistoryNode inVariationTree(int mouseX, int mouseY) {
 
-		//check if (x,y) is in the variation window
-		if (mouseX < posx1 || mouseX > posx1+width1 || mouseY < posy1 || mouseY > posy1+height1)
-			return null;
+	    //check if (x,y) is in the variation window
+	    if (mouseX < posx1 || mouseX > posx1+width1 || mouseY < posy1 || mouseY > posy1+height1)
+		    return null;
 
         // Use dense tree for saving space if large-subboard
         YSPACING = (Lizzie.config.showLargeSubBoard() ? 20 : 30);
@@ -235,13 +236,13 @@ public BoardHistoryNode inVariationTree(int mouseX, int mouseY) {
         }
         return inSubtree(posx1 + xoffset, curposy, mouseX, mouseY,0, posy1 + height1, node, 0);
 
-		}
+    }
 
 	public int jumpVariationTree(int mouseX, int mouseY){
 		BoardHistoryNode node;
 		node = inVariationTree(mouseX, mouseY);    //check if (x,y) hit proper branch node
-		if (node!=null)
-			Lizzie.board.jumpToAnyPosition(node);  
-		return 0;
+        if (node==null) return -1;  //check if any error occur
+        Lizzie.board.jumpToAnyPosition(node);  
+        return 0;
 	}
 }

src/main/java/featurecat/lizzie/rules/Board.java

@@ -489,20 +489,27 @@ public boolean nextVariation(int idx) {
     }
 
 
-	// jump anywhere in the board history tree.  Written for mouse click navigation 
+	// Jump anywhere in the board history tree.  Written for mouse click navigation
 	public void jumpToAnyPosition(BoardHistoryNode targetNode) {
-		BoardHistoryNode  srcNode, tarNode=targetNode, prevNode;
-
-		int[] tar = new int[512], src = new int[512]; int i=0 ,j=0, k=0;
-
+		BoardHistoryNode  srcNode, tarNode, prevNode;
+
+        //tar[] to track path from target node to root node
+        //src[] to track path from source node to root node
+        int[] tar = new int[512], src = new int[512];
+
+        int i=0 ,j=0, k=0;  //i is index for target node, j for source node, k is working variable
+
+        //find path from target node to root node
+        tarNode=targetNode;
 		prevNode=tarNode.previous();
 		while(prevNode != null){
 			for(k=0;k<prevNode.numberOfChildren();k++)
 				if (prevNode.getVariation(k) == tarNode) 
 					tar[i++]=k;		
 			tarNode = prevNode; prevNode=prevNode.previous(); 
 		}
-
+
+        //find path from source node to root node
 		srcNode=history.getCurrentHistoryNode();
 		prevNode=srcNode.previous();
 		while(prevNode != null){
@@ -512,32 +519,31 @@ public void jumpToAnyPosition(BoardHistoryNode targetNode) {
 			srcNode = prevNode; prevNode=prevNode.previous(); 
 		}
 
-		//compare tar[]  with src[] , and try to find nearest branch
+		//Compare tar[]  with src[] , and try to find nearest branch
 		for(k=0; k<Math.min(i,j);k++) {
 			if(tar[i-k-1] == src[j-k-1]) continue;
 			break;
 		}
-
-		if (k==i)
-			{
-			//target node is shorter, just move back
-			for (int m=0; m<j-k; m++) previousMove();
-			}
-		else if (k==j){
+
+        //Move to the target node from source node
+		if (k==i) {
+            //target node is shorter, just move back
+            for (int m=0; m<j-k; m++)
+                 previousMove();
+
+        } else if (k==j) {
 			//source node is shorter, move forward
 			for (int m=i-k; m>0;m--)
-				nextVariation(tar[m-1]);		
-			}
-
-		else {
-			// in the different branchs, must move back first, then move forword
-			for (int m=0; m<j-k; m++) 
-				previousMove();
-			for (int m=i-k; m>0;m--){
-				nextVariation(tar[m-1]);
-			}
-		}
-	}
+                nextVariation(tar[m-1]);
+
+        } else {
+            // in the different branchs, must move back first, then move forword
+            for (int m=0; m<j-k; m++)
+                previousMove();
+            for (int m=i-k; m>0;m--)
+                nextVariation(tar[m-1]);
+        }
+    }
 
 
     /*