Fixed primefaces#3032

Author: mertsincan

src/main/java-templates/org/primefaces/component/tree/TreeTemplate.java

@@ -391,6 +391,14 @@ public boolean isTreeNodeDropped() {
         return retValOnDrop;
     }
 
+    public String getScrollState() {
+        Map<String,String> params = getFacesContext().getExternalContext().getRequestParameterMap();
+        String name = this.getClientId() + "_scrollState";
+        String value = params.get(name);
+        
+        return value == null ? "0,0" : value;
+    }
+
     private List<String> filteredRowKeys = new ArrayList<String>();
     public List<String> getFilteredRowKeys() {
         return filteredRowKeys;

src/main/java/org/primefaces/component/tree/TreeRenderer.java

@@ -383,9 +383,11 @@ public void encodeVerticalTree(FacesContext context, Tree tree, TreeNode root) t
         writer.endElement("ul");
 
         if (selectable) {
-            encodeSelectionHolder(context, tree);
+            encodeStateHolder(context, tree, clientId + "_selection", tree.getSelectedRowKeysAsString());
         }
-
+        
+        encodeStateHolder(context, tree, clientId + "_scrollState", tree.getScrollState());
+        
         writer.endElement("div");
     }
 
@@ -435,7 +437,7 @@ protected void encodeHorizontalTree(FacesContext context, Tree tree, TreeNode ro
         }
 
         if (selectionMode != null) {
-            encodeSelectionHolder(context, tree);
+            encodeStateHolder(context, tree, clientId + "_selection", tree.getSelectedRowKeysAsString());
         }
 
         writer.endElement("div");
@@ -806,17 +808,15 @@ protected void encodeIcon(FacesContext context, UITreeNode uiTreeNode, boolean e
         writer.endElement("span");
     }
 
-    protected void encodeSelectionHolder(FacesContext context, Tree tree) throws IOException {
+    protected void encodeStateHolder(FacesContext context, Tree tree, String id, String value) throws IOException {
         ResponseWriter writer = context.getResponseWriter();
 
-        String id = tree.getClientId(context) + "_selection";
-
         writer.startElement("input", null);
         writer.writeAttribute("type", "hidden", null);
         writer.writeAttribute("id", id, null);
         writer.writeAttribute("name", id, null);
-        writer.writeAttribute("value", tree.getSelectedRowKeysAsString(), null);
         writer.writeAttribute("autocomplete", "off", null);
+        writer.writeAttribute("value", value, null);
         writer.endElement("input");
     }
 

src/main/resources/META-INF/resources/primefaces/tree/tree.js

@@ -465,6 +465,8 @@ PrimeFaces.widget.VerticalTree = PrimeFaces.widget.BaseTree.extend({
                 this.initDroppable();
             }
         }
+        
+        this.restoreScrollState();
     },
 
     bindEvents: function() {
@@ -585,6 +587,10 @@ PrimeFaces.widget.VerticalTree = PrimeFaces.widget.BaseTree.extend({
                 }
             });
         }
+        
+        this.jq.on('scroll.tree', function(e) {
+            $this.saveScrollState();
+        });
 
         this.bindKeyEvents();
     },
@@ -1580,6 +1586,24 @@ PrimeFaces.widget.VerticalTree = PrimeFaces.widget.BaseTree.extend({
         };
 
         PrimeFaces.ajax.Request.handle(options);
+    },
+    
+    restoreScrollState: function() {
+        var scrollState = this.scrollStateHolder.val(),
+        scrollValues = scrollState.split(',');
+
+        this.jq.scrollLeft(scrollValues[0]);
+        this.jq.scrollTop(scrollValues[1]);
+    },
+    
+    saveScrollState: function() {
+        var scrollState = this.jq.scrollLeft() + ',' + this.jq.scrollTop();
+        
+        this.scrollStateHolder.val(scrollState);
+    },
+    
+    clearScrollState: function() {
+        this.scrollStateHolder.val('0,0');
     }
 
 });