Remember previous row height to maintain table size when all rows are removed (#9132)

svn changeset:24041/svn branch:6.8

1 files changed, 30 insertions, 2 deletions

diff --git a/src/com/vaadin/terminal/gwt/client/ui/VScrollTable.java b/src/com/vaadin/terminal/gwt/client/ui/VScrollTable.java
index fa7621e512..c1f90b0157 100644
--- a/src/com/vaadin/terminal/gwt/client/ui/VScrollTable.java
+++ b/src/com/vaadin/terminal/gwt/client/ui/VScrollTable.java
@@ -217,6 +217,19 @@ public class VScrollTable extends FlowPanel implements Table, ScrollHandler,
     private Set<String> noncollapsibleColumns;
 
     /**
+     * The last known row height used to preserve the height of a table with
+     * custom row heights and a fixed page length after removing the last row
+     * from the table.
+     * 
+     * A new VScrollTableBody instance is created every time the number of rows
+     * changes causing {@link VScrollTableBody#rowHeight} to be discarded and
+     * the height recalculated by {@link VScrollTableBody#getRowHeight(boolean)}
+     * to avoid some rounding problems, e.g. round(2 * 19.8) / 2 = 20 but
+     * round(3 * 19.8) / 3 = 19.66.
+     */
+    private double lastKnownRowHeight = Double.NaN;
+
+    /**
      * Represents a select range of rows
      */
     private class SelectionRange {
@@ -4455,13 +4468,27 @@ public class VScrollTable extends FlowPanel implements Table, ScrollHandler,
             if (tBodyMeasurementsDone && !forceUpdate) {
                 return rowHeight;
             } else {
-
                 if (tBodyElement.getRows().getLength() > 0) {
                     int tableHeight = getTableHeight();
                     int rowCount = tBodyElement.getRows().getLength();
                     rowHeight = tableHeight / (double) rowCount;
                 } else {
-                    if (isAttached()) {
+                    // Special cases if we can't just measure the current rows
+                    if (!Double.isNaN(lastKnownRowHeight)) {
+                        // Use previous value if available
+                        if (BrowserInfo.get().isIE()) {
+                            /*
+                             * IE needs to reflow the table element at this
+                             * point to work correctly (e.g.
+                             * com.vaadin.tests.components.table.
+                             * ContainerSizeChange) - the other code paths
+                             * already trigger reflows, but here it must be done
+                             * explicitly.
+                             */
+                            getTableHeight();
+                        }
+                        rowHeight = lastKnownRowHeight;
+                    } else if (isAttached()) {
                         // measure row height by adding a dummy row
                         VScrollTableRow scrollTableRow = new VScrollTableRow();
                         tBodyElement.appendChild(scrollTableRow.getElement());
@@ -4472,6 +4499,7 @@ public class VScrollTable extends FlowPanel implements Table, ScrollHandler,
                         return DEFAULT_ROW_HEIGHT;
                     }
                 }
+                lastKnownRowHeight = rowHeight;
                 tBodyMeasurementsDone = true;
                 return rowHeight;
             }