Fix ScrollbarBundle to not round down pixel values (#19421)

Since Escalator now uses subpixels in most cases, scrollbar calculation
fails when ScrollbarBundle calls Math.floor for the offset size. Removed
rounding, added a pixel epsilon check that we don't make a scrollbar
when it's not really needed.

Change-Id: I228fd7dd48d4506e5b2b7bb799291c9a122ea3fe

3 files changed, 80 insertions, 12 deletions

diff --git a/client/src/com/vaadin/client/widget/escalator/ScrollbarBundle.java b/client/src/com/vaadin/client/widget/escalator/ScrollbarBundle.java
index 2b33d7103f..958029889d 100644
--- a/client/src/com/vaadin/client/widget/escalator/ScrollbarBundle.java
+++ b/client/src/com/vaadin/client/widget/escalator/ScrollbarBundle.java
@@ -402,11 +402,6 @@ public abstract class ScrollbarBundle implements DeferredWorker {
 
     /**
      * Sets the length of the scrollbar.
-     * <p>
-     * <em>Note:</em> Even though {@code double} values are used, they are
-     * currently only used as integers as large {@code int} (or small but fast
-     * {@code long}). This means, all values are truncated to zero decimal
-     * places.
      * 
      * @param px
      *            the length of the scrollbar in pixels
@@ -437,7 +432,7 @@ public abstract class ScrollbarBundle implements DeferredWorker {
     }
 
     private void setOffsetSizeNow(double px) {
-        internalSetOffsetSize(Math.max(0, truncate(px)));
+        internalSetOffsetSize(Math.max(0, px));
         recalculateMaxScrollPos();
         forceScrollbar(showsScrollHandle());
         fireVisibilityChangeIfNeeded();
@@ -595,11 +590,6 @@ public abstract class ScrollbarBundle implements DeferredWorker {
     /**
      * Sets the amount of pixels the scrollbar needs to be able to scroll
      * through.
-     * <p>
-     * <em>Note:</em> Even though {@code double} values are used, they are
-     * currently only used as integers as large {@code int} (or small but fast
-     * {@code long}). This means, all values are truncated to zero decimal
-     * places.
      * 
      * @param px
      *            the number of pixels the scrollbar should be able to scroll
@@ -727,7 +717,7 @@ public abstract class ScrollbarBundle implements DeferredWorker {
      * @return <code>true</code> iff the scrollbar's handle is visible
      */
     public boolean showsScrollHandle() {
-        return getOffsetSize() < getScrollSize();
+        return getScrollSize() - getOffsetSize() > WidgetUtil.PIXEL_EPSILON;
     }
 
     public void recalculateMaxScrollPos() {
diff --git a/uitest/src/com/vaadin/tests/components/grid/GridMultiSelectionScrollBar.java b/uitest/src/com/vaadin/tests/components/grid/GridMultiSelectionScrollBar.java
new file mode 100644
index 0000000000..be1f32164c
--- /dev/null
+++ b/uitest/src/com/vaadin/tests/components/grid/GridMultiSelectionScrollBar.java
@@ -0,0 +1,34 @@
+/*
+ * 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.tests.components.grid;
+
+import com.vaadin.server.VaadinRequest;
+import com.vaadin.tests.components.AbstractTestUI;
+import com.vaadin.ui.Grid;
+
+public class GridMultiSelectionScrollBar extends AbstractTestUI {
+
+    @Override
+    protected void setup(VaadinRequest request) {
+        Grid grid = new Grid();
+        grid.addColumn("X").setWidth(39.25d);
+        grid.addColumn("Hello");
+        grid.addColumn("World");
+        grid.setFrozenColumnCount(1);
+        addComponent(grid);
+    }
+
+}
diff --git a/uitest/src/com/vaadin/tests/components/grid/GridMultiSelectionScrollBarTest.java b/uitest/src/com/vaadin/tests/components/grid/GridMultiSelectionScrollBarTest.java
new file mode 100644
index 0000000000..cf85f4eecd
--- /dev/null
+++ b/uitest/src/com/vaadin/tests/components/grid/GridMultiSelectionScrollBarTest.java
@@ -0,0 +1,44 @@
+/*
+ * 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.tests.components.grid;
+
+import static org.junit.Assert.assertTrue;
+
+import java.io.IOException;
+
+import org.junit.Test;
+
+import com.vaadin.testbench.elements.GridElement;
+import com.vaadin.tests.tb3.MultiBrowserTest;
+
+public class GridMultiSelectionScrollBarTest extends MultiBrowserTest {
+
+    @Test
+    public void testNoVisibleScrollBar() throws IOException {
+        setDebug(true);
+        openTestURL();
+
+        assertTrue(
+                "Horizontal scrollbar should not be visible.",
+                $(GridElement.class).first().getHorizontalScroller()
+                        .getAttribute("style").toLowerCase()
+                        .contains("display: none;"));
+
+        // Just to make sure nothing odd happened.
+        assertNoErrorNotifications();
+    }
+
+}