8276167: VirtualFlow.scrollToTop doesn't scroll to the top of the last element

Reviewed-by: aghaisas, jvos

Author: eduardsdv

modules/javafx.controls/src/main/java/javafx/scene/control/skin/VirtualFlow.java

@@ -1581,7 +1581,7 @@ private boolean tryScrollOneCell(int targetIndex, boolean downOrRight) {
     public void scrollToTop(int index) {
         boolean posSet = false;
 
-        if (index >= getCellCount() - 1) {
+        if (index > getCellCount() - 1) {
             setPosition(1);
             posSet = true;
         } else if (index < 0) {

modules/javafx.controls/src/test/java/test/javafx/scene/control/ListViewKeyInputTest.java

@@ -1861,11 +1861,11 @@ private boolean isAnchor(int index) {
         final int diff = 99 - leadSelectedIndex;
         assertEquals(99 - diff, leadSelectedIndex);
         assertEquals(99 - diff, fm.getFocusedIndex());
-        assertEquals(7, selectedIndicesCount);
+        assertEquals(8, selectedIndicesCount);
 
         keyboard.doKeyPress(KeyCode.PAGE_UP, KeyModifier.SHIFT);
-        assertEquals(99 - diff * 2, sm.getSelectedIndex());
-        assertEquals(selectedIndicesCount * 2 - 1, sm.getSelectedIndices().size());
+        assertEquals(99 - diff * 2 + 1, sm.getSelectedIndex());
+        assertEquals(selectedIndicesCount * 2 - 2, sm.getSelectedIndices().size());
 
         keyboard.doKeyPress(KeyCode.PAGE_DOWN, KeyModifier.SHIFT);
         assertEquals(leadSelectedIndex, sm.getSelectedIndex());

modules/javafx.controls/src/test/java/test/javafx/scene/control/TreeTableViewTest.java

@@ -3660,7 +3660,7 @@ protected <T> void assert_rt35857(ObservableList<T> items, MultipleSelectionMode
         // However, for now, we'll test on the assumption that across all
         // platforms we only get one extra cell created, and we can loosen this
         // up if necessary.
-        assertEquals(cellCountAtStart + 13, rt36452_instanceCount);
+        assertEquals(cellCountAtStart + 14, rt36452_instanceCount);
 
         sl.dispose();
     }

modules/javafx.controls/src/test/java/test/javafx/scene/control/skin/VirtualFlowTest.java

@@ -1143,6 +1143,43 @@ private void assertLastCellInsideViewport(boolean vertical) {
         assertEquals("Last cell must end on viewport size", viewportLength, (cellPosition + cellLength), 0.1);
     }
 
+    @Test
+    public void testScrollToTopOfLastLargeCell() {
+        double flowHeight = 150;
+        int cellCount = 2;
+
+        flow = new VirtualFlowShim<>();
+        flow.setCellFactory(p -> new CellStub(flow) {
+            @Override
+            protected double computePrefHeight(double width) {
+                return getIndex() == cellCount -1 ? 200 : 100;
+            }
+
+            @Override
+            protected double computeMinHeight(double width) {
+                return computePrefHeight(width);
+            }
+
+            @Override
+            protected double computeMaxHeight(double width) {
+                return computePrefHeight(width);
+            }
+        });
+        flow.setVertical(true);
+
+        flow.resize(50,flowHeight);
+        flow.setCellCount(cellCount);
+        pulse();
+
+        flow.scrollToTop(cellCount - 1);
+        pulse();
+
+        IndexedCell<?> cell = flow.getCell(cellCount - 1);
+        double cellPosition = flow.getCellPosition(cell);
+
+        assertEquals("Last cell must be aligned to top of the viewport", 0, cellPosition, 0.1);
+    }
+
     @Test
     public void testImmediateScrollTo() {
         flow.setCellCount(100);