UI scroll position can be given programmatically (#9952)

Change-Id: Icef0858ee495abcacab7823f7f8fc6044abd64dc

2 files changed, 42 insertions, 43 deletions

diff --git a/client/src/com/vaadin/client/ui/VUI.java b/client/src/com/vaadin/client/ui/VUI.java
index 688c60bca1..cbfbda813e 100644
--- a/client/src/com/vaadin/client/ui/VUI.java
+++ b/client/src/com/vaadin/client/ui/VUI.java
@@ -20,6 +20,9 @@ import java.util.ArrayList;
 
 import com.google.gwt.core.client.Scheduler.ScheduledCommand;
 import com.google.gwt.dom.client.Element;
+import com.google.gwt.event.dom.client.HasScrollHandlers;
+import com.google.gwt.event.dom.client.ScrollEvent;
+import com.google.gwt.event.dom.client.ScrollHandler;
 import com.google.gwt.event.logical.shared.HasResizeHandlers;
 import com.google.gwt.event.logical.shared.ResizeEvent;
 import com.google.gwt.event.logical.shared.ResizeHandler;
@@ -49,7 +52,7 @@ import com.vaadin.shared.ui.ui.UIConstants;
  */
 public class VUI extends SimplePanel implements ResizeHandler,
         Window.ClosingHandler, ShortcutActionHandlerOwner, Focusable,
-        HasResizeHandlers {
+        HasResizeHandlers, HasScrollHandlers {
 
     private static int MONITOR_PARENT_TIMER_INTERVAL = 1000;
 
@@ -95,18 +98,9 @@ public class VUI extends SimplePanel implements ResizeHandler,
     private int parentHeight;
 
     /** For internal use only. May be removed or replaced in the future. */
-    public int scrollTop;
-
-    /** For internal use only. May be removed or replaced in the future. */
-    public int scrollLeft;
-
-    /** For internal use only. May be removed or replaced in the future. */
     public boolean rendering;
 
     /** For internal use only. May be removed or replaced in the future. */
-    public boolean scrollable;
-
-    /** For internal use only. May be removed or replaced in the future. */
     public boolean immediate;
 
     /** For internal use only. May be removed or replaced in the future. */
@@ -350,26 +344,6 @@ public class VUI extends SimplePanel implements ResizeHandler,
         if (type == Event.ONKEYDOWN && actionHandler != null) {
             actionHandler.handleKeyboardEvent(event);
             return;
-        } else if (scrollable && type == Event.ONSCROLL) {
-            updateScrollPosition();
-        }
-    }
-
-    /**
-     * Updates scroll position from DOM and saves variables to server.
-     */
-    private void updateScrollPosition() {
-        int oldTop = scrollTop;
-        int oldLeft = scrollLeft;
-        scrollTop = DOM.getElementPropertyInt(getElement(), "scrollTop");
-        scrollLeft = DOM.getElementPropertyInt(getElement(), "scrollLeft");
-        if (connection != null && !rendering) {
-            if (oldTop != scrollTop) {
-                connection.updateVariable(id, "scrollTop", scrollTop, false);
-            }
-            if (oldLeft != scrollLeft) {
-                connection.updateVariable(id, "scrollLeft", scrollLeft, false);
-            }
         }
     }
 
@@ -478,4 +452,9 @@ public class VUI extends SimplePanel implements ResizeHandler,
         return addHandler(resizeHandler, ResizeEvent.getType());
     }
 
+    @Override
+    public HandlerRegistration addScrollHandler(ScrollHandler scrollHandler) {
+        return addHandler(scrollHandler, ScrollEvent.getType());
+    }
+
 }
diff --git a/client/src/com/vaadin/client/ui/ui/UIConnector.java b/client/src/com/vaadin/client/ui/ui/UIConnector.java
index 1d2c830ea6..a297a89b8e 100644
--- a/client/src/com/vaadin/client/ui/ui/UIConnector.java
+++ b/client/src/com/vaadin/client/ui/ui/UIConnector.java
@@ -23,10 +23,13 @@ import com.google.gwt.core.client.Scheduler;
 import com.google.gwt.dom.client.NativeEvent;
 import com.google.gwt.dom.client.Style;
 import com.google.gwt.dom.client.Style.Position;
+import com.google.gwt.event.dom.client.ScrollEvent;
+import com.google.gwt.event.dom.client.ScrollHandler;
 import com.google.gwt.event.logical.shared.ResizeEvent;
 import com.google.gwt.event.logical.shared.ResizeHandler;
 import com.google.gwt.user.client.Command;
 import com.google.gwt.user.client.DOM;
+import com.google.gwt.user.client.Element;
 import com.google.gwt.user.client.Event;
 import com.google.gwt.user.client.History;
 import com.google.gwt.user.client.Window;
@@ -56,6 +59,7 @@ import com.vaadin.shared.ui.ComponentStateUtil;
 import com.vaadin.shared.ui.Connect;
 import com.vaadin.shared.ui.Connect.LoadStyle;
 import com.vaadin.shared.ui.ui.PageClientRpc;
+import com.vaadin.shared.ui.ui.ScrollClientRpc;
 import com.vaadin.shared.ui.ui.UIConstants;
 import com.vaadin.shared.ui.ui.UIServerRpc;
 import com.vaadin.shared.ui.ui.UIState;
@@ -85,6 +89,17 @@ public class UIConnector extends AbstractSingleComponentContainerConnector
                 com.google.gwt.user.client.Window.setTitle(title);
             }
         });
+        registerRpc(ScrollClientRpc.class, new ScrollClientRpc() {
+            @Override
+            public void setScrollTop(int scrollTop) {
+                getWidget().getElement().setScrollTop(scrollTop);
+            }
+
+            @Override
+            public void setScrollLeft(int scrollLeft) {
+                getWidget().getElement().setScrollLeft(scrollLeft);
+            }
+        });
         getWidget().addResizeHandler(new ResizeHandler() {
             @Override
             public void onResize(ResizeEvent event) {
@@ -96,6 +111,24 @@ public class UIConnector extends AbstractSingleComponentContainerConnector
                 }
             }
         });
+        getWidget().addScrollHandler(new ScrollHandler() {
+            private int lastSentScrollTop = Integer.MAX_VALUE;
+            private int lastSentScrollLeft = Integer.MAX_VALUE;
+
+            @Override
+            public void onScroll(ScrollEvent event) {
+                Element element = getWidget().getElement();
+                int newScrollTop = element.getScrollTop();
+                int newScrollLeft = element.getScrollLeft();
+                if (newScrollTop != lastSentScrollTop
+                        || newScrollLeft != lastSentScrollLeft) {
+                    lastSentScrollTop = newScrollTop;
+                    lastSentScrollLeft = newScrollLeft;
+                    getRpcProxy(UIServerRpc.class).scroll(newScrollTop,
+                            newScrollLeft);
+                }
+            }
+        });
     }
 
     @Override
@@ -244,19 +277,6 @@ public class UIConnector extends AbstractSingleComponentContainerConnector
             Window.addResizeHandler(getWidget());
         }
 
-        // finally set scroll position from UIDL
-        if (uidl.hasVariable("scrollTop")) {
-            getWidget().scrollable = true;
-            getWidget().scrollTop = uidl.getIntVariable("scrollTop");
-            DOM.setElementPropertyInt(getWidget().getElement(), "scrollTop",
-                    getWidget().scrollTop);
-            getWidget().scrollLeft = uidl.getIntVariable("scrollLeft");
-            DOM.setElementPropertyInt(getWidget().getElement(), "scrollLeft",
-                    getWidget().scrollLeft);
-        } else {
-            getWidget().scrollable = false;
-        }
-
         if (uidl.hasAttribute("scrollTo")) {
             final ComponentConnector connector = (ComponentConnector) uidl
                     .getPaintableAttribute("scrollTo", getConnection());