Optimize layout performance of Table (#17947)

Adds functions for skipping child component layout measuring.
Removes unnecessary code from VScrollTable.

1. case: no components

- render time without the fix: ~105ms 
- render time with fix: ~105ms 

2. case: 2 button and 2 textfield cols

- render time without the fix: ~279ms 
- render time with fix: ~240ms (~17% faster) 

3. case: 3 button and 3 textfield cols

- render time without the fix: ~350ms 
- render time with fix: ~281ms (~20% faster) 

Change-Id: I6025f8ee2fd438d228ff3b65f43535961cf12c0b

6 files changed, 190 insertions, 10 deletions

diff --git a/client/src/com/vaadin/client/HasChildMeasurementHintConnector.java b/client/src/com/vaadin/client/HasChildMeasurementHintConnector.java
new file mode 100644
index 0000000000..5ca6317b9b
--- /dev/null
+++ b/client/src/com/vaadin/client/HasChildMeasurementHintConnector.java
@@ -0,0 +1,72 @@
+/*
+ * Copyright 2000-2014 Vaadin Ltd.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ * 
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.client;
+
+import com.vaadin.client.ui.ManagedLayout;
+import com.vaadin.client.ui.layout.ElementResizeListener;
+
+/**
+ * Connector with layout measuring hint. Used to improve granularity of control
+ * over child component measurements.
+ * 
+ * @since
+ * @author Vaadin Ltd
+ */
+public interface HasChildMeasurementHintConnector extends
+        HasComponentsConnector {
+
+    /**
+     * Specifies how you would like child components measurements to be handled.
+     * Since this is a hint, it can be ignored when deemed necessary.
+     */
+    public enum ChildMeasurementHint {
+
+        /**
+         * Always measure all child components (default).
+         */
+        MEASURE_ALWAYS,
+
+        /**
+         * Measure child component only if child component is a {@link Layout}
+         * or implements either {@link ManagedLayout} or
+         * {@link ElementResizeListener}.
+         */
+        MEASURE_IF_NEEDED,
+
+        /**
+         * Never measure child components. This can improve rendering speed of
+         * components with lots of children (e.g. Table), but can cause some
+         * child components to be rendered incorrectly (e.g. ComboBox).
+         */
+        MEASURE_NEVER
+    }
+
+    /**
+     * Sets the child measurement hint for this component.
+     * 
+     * @param hint
+     *            the value to set
+     */
+    void setChildMeasurementHint(ChildMeasurementHint hint);
+
+    /**
+     * Returns the current child measurement hint value.
+     * 
+     * @return a ChildLayoutMeasureMode value
+     */
+    ChildMeasurementHint getChildMeasurementHint();
+
+}
diff --git a/client/src/com/vaadin/client/LayoutManager.java b/client/src/com/vaadin/client/LayoutManager.java
index d39e604aaf..ed83e195d7 100644
--- a/client/src/com/vaadin/client/LayoutManager.java
+++ b/client/src/com/vaadin/client/LayoutManager.java
@@ -712,7 +712,8 @@ public class LayoutManager {
                     .createArray().cast();
             for (int i = 0; i < size; i++) {
                 ComponentConnector candidate = allConnectors.get(i);
-                if (needsMeasure(candidate.getWidget().getElement())) {
+                if (!Util.shouldSkipMeasurementOfConnector(candidate)
+                        && needsMeasure(candidate.getWidget().getElement())) {
                     connectors.add(candidate);
                 }
             }
diff --git a/client/src/com/vaadin/client/Util.java b/client/src/com/vaadin/client/Util.java
index ab7d344877..8b5caa6051 100644
--- a/client/src/com/vaadin/client/Util.java
+++ b/client/src/com/vaadin/client/Util.java
@@ -33,8 +33,12 @@ import com.google.gwt.user.client.DOM;
 import com.google.gwt.user.client.Event;
 import com.google.gwt.user.client.ui.HasWidgets;
 import com.google.gwt.user.client.ui.Widget;
+import com.vaadin.client.HasChildMeasurementHintConnector.ChildMeasurementHint;
 import com.vaadin.client.RenderInformation.FloatSize;
+import com.vaadin.client.ui.AbstractLayoutConnector;
+import com.vaadin.client.ui.ManagedLayout;
 import com.vaadin.client.ui.VOverlay;
+import com.vaadin.client.ui.layout.ElementResizeListener;
 import com.vaadin.shared.AbstractComponentState;
 import com.vaadin.shared.ApplicationConstants;
 import com.vaadin.shared.communication.MethodInvocation;
@@ -1186,6 +1190,83 @@ public class Util {
         return +(Math.round(num + "e+" + exp)  + "e-" + exp);
     }-*/;
 
+    /**
+     * Test if we can can skip measuring this connector. We can skip the
+     * measurement if its parent is a ChildMeasureHintConnector and has an
+     * appropriate mode set.
+     *
+     * For internal use only. May be removed or replaced in the future.
+     */
+    public static boolean shouldSkipMeasurementOfConnector(
+            ComponentConnector candidate, ComponentConnector parent) {
+        Profiler.enter("skipMeasureDueLayoutHint");
+        boolean skip = false;
+
+        if (parent instanceof HasChildMeasurementHintConnector) {
+            ChildMeasurementHint measureMode = ((HasChildMeasurementHintConnector) parent)
+                    .getChildMeasurementHint();
+
+            if (measureMode == ChildMeasurementHint.MEASURE_NEVER) {
+                skip = true;
+            } else if (measureMode == ChildMeasurementHint.MEASURE_IF_NEEDED) {
+                skip = canWeSkipChildMeasurement(candidate);
+            }
+        }
+        Profiler.leave("skipMeasureDueLayoutHint");
+        return skip;
+    }
+
+    /**
+     * Test if we can can skip measuring this connector. We can skip the
+     * measurement if its parent is a ChildMeasureHintConnector and has an
+     * appropriate mode set.
+     *
+     * This version of the method tries to recursively locate such a parent.
+     * 
+     * For internal use only. May be removed or replaced in the future.
+     */
+    public static boolean shouldSkipMeasurementOfConnector(
+            ComponentConnector candidate) {
+        Profiler.enter("skipMeasureDueLayoutHint");
+        boolean skip = false;
+
+        HasChildMeasurementHintConnector parent = getPossibleChildMeasurementHintParentConnector(candidate);
+
+        if (parent != null) {
+            ChildMeasurementHint measureMode = parent.getChildMeasurementHint();
+
+            if (measureMode == ChildMeasurementHint.MEASURE_NEVER) {
+                skip = true;
+            } else if (measureMode == ChildMeasurementHint.MEASURE_IF_NEEDED) {
+                skip = canWeSkipChildMeasurement(candidate);
+            }
+        }
+        Profiler.leave("skipMeasureDueLayoutHint");
+        return skip;
+    }
+
+    /** For internal use only. May be removed or replaced in the future. */
+    private static boolean canWeSkipChildMeasurement(ComponentConnector child) {
+        // common cases when child measuring is possibly needed
+        if (child instanceof ElementResizeListener
+                || child instanceof ManagedLayout
+                || child instanceof AbstractLayoutConnector) {
+            return false;
+        }
+        return true;
+    }
+
+    /** For internal use only. May be removed or replaced in the future. */
+    private static HasChildMeasurementHintConnector getPossibleChildMeasurementHintParentConnector(
+            ComponentConnector candidate) {
+        ServerConnector parent = candidate.getParent();
+        if (parent != null
+                && parent instanceof HasChildMeasurementHintConnector) {
+            return (HasChildMeasurementHintConnector) parent;
+        }
+        return null;
+    }
+
     private static Logger getLogger() {
         return Logger.getLogger(Util.class.getName());
     }
diff --git a/client/src/com/vaadin/client/ui/VScrollTable.java b/client/src/com/vaadin/client/ui/VScrollTable.java
index 6bb8f063a6..3b85356f86 100644
--- a/client/src/com/vaadin/client/ui/VScrollTable.java
+++ b/client/src/com/vaadin/client/ui/VScrollTable.java
@@ -84,6 +84,7 @@ import com.vaadin.client.ComponentConnector;
 import com.vaadin.client.ConnectorMap;
 import com.vaadin.client.DeferredWorker;
 import com.vaadin.client.Focusable;
+import com.vaadin.client.HasChildMeasurementHintConnector.ChildMeasurementHint;
 import com.vaadin.client.MouseEventDetailsBuilder;
 import com.vaadin.client.StyleConstants;
 import com.vaadin.client.TooltipInfo;
@@ -699,6 +700,11 @@ public class VScrollTable extends FlowPanel implements HasWidgets,
 
     private int multiselectmode;
 
+    /**
+     * Hint for how to handle measurement of child components
+     */
+    private ChildMeasurementHint childMeasurementHint = ChildMeasurementHint.MEASURE_ALWAYS;
+
     /** For internal use only. May be removed or replaced in the future. */
     public int tabIndex;
 
@@ -1238,11 +1244,6 @@ public class VScrollTable extends FlowPanel implements HasWidgets,
                 uidl.getIntAttribute("rows"));
         scrollBodyPanel.add(scrollBody);
 
-        // New body starts scrolled to the left, make sure the header and footer
-        // are also scrolled to the left
-        tHead.setHorizontalScrollPosition(0);
-        tFoot.setHorizontalScrollPosition(0);
-
         initialContentReceived = true;
         sizeNeedsInit = true;
         scrollBody.restoreRowVisibility();
@@ -2620,8 +2621,7 @@ public class VScrollTable extends FlowPanel implements HasWidgets,
         @Override
         public void run() {
 
-            if (client.getMessageSender().hasActiveRequest()
-                    || navKeyDown) {
+            if (client.getMessageSender().hasActiveRequest() || navKeyDown) {
                 // if client connection is busy, don't bother loading it more
                 VConsole.log("Postponed rowfetch");
                 schedule(250);
@@ -8332,4 +8332,12 @@ public class VScrollTable extends FlowPanel implements HasWidgets,
     private static Logger getLogger() {
         return Logger.getLogger(VScrollTable.class.getName());
     }
+
+    public ChildMeasurementHint getChildMeasurementHint() {
+        return childMeasurementHint;
+    }
+
+    public void setChildMeasurementHint(ChildMeasurementHint hint) {
+        childMeasurementHint = hint;
+    }
 }
diff --git a/client/src/com/vaadin/client/ui/layout/LayoutDependencyTree.java b/client/src/com/vaadin/client/ui/layout/LayoutDependencyTree.java
index a4c5668948..27733bfbe3 100644
--- a/client/src/com/vaadin/client/ui/layout/LayoutDependencyTree.java
+++ b/client/src/com/vaadin/client/ui/layout/LayoutDependencyTree.java
@@ -248,7 +248,8 @@ public class LayoutDependencyTree {
             if (connector instanceof HasComponentsConnector) {
                 HasComponentsConnector container = (HasComponentsConnector) connector;
                 for (ComponentConnector child : container.getChildComponents()) {
-                    if (isRelativeInDirection(child, direction)) {
+                    if (!Util.shouldSkipMeasurementOfConnector(child, connector)
+                            && isRelativeInDirection(child, direction)) {
                         resized.push(child.getConnectorId());
                     }
                 }
diff --git a/client/src/com/vaadin/client/ui/table/TableConnector.java b/client/src/com/vaadin/client/ui/table/TableConnector.java
index 0cce611191..7e7995b5e1 100644
--- a/client/src/com/vaadin/client/ui/table/TableConnector.java
+++ b/client/src/com/vaadin/client/ui/table/TableConnector.java
@@ -28,6 +28,7 @@ import com.google.gwt.event.shared.HandlerRegistration;
 import com.google.gwt.user.client.ui.Widget;
 import com.vaadin.client.ApplicationConnection;
 import com.vaadin.client.BrowserInfo;
+import com.vaadin.client.HasChildMeasurementHintConnector;
 import com.vaadin.client.ComponentConnector;
 import com.vaadin.client.ConnectorHierarchyChangeEvent;
 import com.vaadin.client.ConnectorHierarchyChangeEvent.ConnectorHierarchyChangeHandler;
@@ -55,7 +56,7 @@ import com.vaadin.shared.ui.table.TableState;
 @Connect(com.vaadin.ui.Table.class)
 public class TableConnector extends AbstractFieldConnector implements
         HasComponentsConnector, ConnectorHierarchyChangeHandler, Paintable,
-        DirectionalManagedLayout, PostLayoutListener {
+        DirectionalManagedLayout, PostLayoutListener, HasChildMeasurementHintConnector {
 
     private List<ComponentConnector> childComponents;
 
@@ -199,6 +200,12 @@ public class TableConnector extends AbstractFieldConnector implements
 
         getWidget().updateDragMode(uidl);
 
+        // Update child measure hint
+        int childMeasureHint = uidl.hasAttribute("measurehint") ? uidl
+                .getIntAttribute("measurehint") : 0;
+        getWidget().setChildMeasurementHint(
+                ChildMeasurementHint.values()[childMeasureHint]);
+
         getWidget().updateSelectionProperties(uidl, getState(), isReadOnly());
 
         if (uidl.hasAttribute("alb")) {
@@ -532,4 +539,14 @@ public class TableConnector extends AbstractFieldConnector implements
                 ConnectorHierarchyChangeEvent.TYPE, handler);
     }
 
+    @Override
+    public void setChildMeasurementHint(ChildMeasurementHint hint) {
+        getWidget().setChildMeasurementHint(hint);
+    }
+
+    @Override
+    public ChildMeasurementHint getChildMeasurementHint() {
+        return getWidget().getChildMeasurementHint();
+    }
+
 }