[merge from 6.7] #8805 fix flickering of partial first row in table, related manual test

svn changeset:23762/svn branch:6.8

src/com/vaadin/ui/Table.java

@@ -1458,6 +1458,13 @@ public class Table extends AbstractSelect implements Action.Container,
             }
         } else {
             // initial load
+
+            // #8805 send one extra row in the beginning in case a partial
+            // row is shown on the UI
+            if (firstIndex > 0) {
+                firstIndex = firstIndex - 1;
+                rows = rows + 1;
+            }
             firstToBeRenderedInClient = firstIndex;
         }
         if (totalRows > 0) {

tests/testbench/com/vaadin/tests/components/table/TableFirstRowFlicker.java

@@ -0,0 +1,85 @@
+package com.vaadin.tests.components.table;
+
+import com.vaadin.Application;
+import com.vaadin.data.Container;
+import com.vaadin.data.util.IndexedContainer;
+import com.vaadin.ui.Label;
+import com.vaadin.ui.ProgressIndicator;
+import com.vaadin.ui.Table;
+import com.vaadin.ui.VerticalLayout;
+import com.vaadin.ui.Window;
+
+public class TableFirstRowFlicker extends Application {
+
+    Table t;
+
+    @Override
+    public void init() {
+        Window mainWindow = new Window("Table Row Flicker");
+        mainWindow.getContent().setSizeFull();
+        setMainWindow(mainWindow);
+
+        t = new Table();
+        t.setSizeFull();
+        t.setSelectable(true);
+        t.setContainerDataSource(buildContainer());
+        mainWindow.addComponent(t);
+        ((VerticalLayout) mainWindow.getContent()).setExpandRatio(t, 1);
+
+        // Button button = new Button("Refresh");
+        // button.addListener(new Button.ClickListener() {
+        // public void buttonClick(ClickEvent event) {
+        // t.refreshRowCache();
+        // }
+        // });
+        // mainWindow.addComponent(button);
+
+        ProgressIndicator pi = new ProgressIndicator();
+        pi.setPollingInterval(1000);
+        pi.setIndeterminate(true);
+        mainWindow.addComponent(pi);
+
+        Thread r = new Thread() {
+            @Override
+            public void run() {
+                while (t != null) {
+                    synchronized (t.getApplication()) {
+                        int firstId = t.getCurrentPageFirstItemIndex();
+                        Object selected = t.getValue();
+                        t.setContainerDataSource(buildContainer());
+                        t.setValue(selected);
+                        t.setCurrentPageFirstItemIndex(firstId);
+                        // lighter alternative for all of above
+                        // t.refreshRowCache();
+                    }
+                    try {
+                        Thread.sleep(500);
+                    } catch (InterruptedException e) {
+                        e.printStackTrace();
+                    }
+                }
+                System.out.println("Table update thread stopped");
+            }
+        };
+        r.start();
+    }
+
+    @Override
+    public void close() {
+        t = null;
+        super.close();
+    }
+
+    private Container buildContainer() {
+        IndexedContainer cont = new IndexedContainer();
+        cont.addContainerProperty("name", Label.class, null);
+        for (int i = 0; i < 10000; i++) {
+            cont.addItem(i);
+            Label l = new Label("Item " + i);
+            l.setHeight("50px");
+            cont.getContainerProperty(i, "name").setValue(l);
+        }
+        return cont;
+    }
+
+}