fix: do not hide rows/columns for nonexistent freeze pane splits (#8158)

* fix: Do not hide columns for nonexistent freeze pane splits

Addresses #8136.

* apply spotless

* Use Assert.assertTrue instead of assertTrue in test

* Further fix test

* Add reference screenshots

* test: refactor test to not use screenshot

* test: refactor test to not use screenshot

* test: remove reference screenshots

---------

Co-authored-by: Diego Cardoso <diego@vaadin.com>

Author: thevaadinman

vaadin-spreadsheet-flow-parent/vaadin-spreadsheet-flow-integration-tests/src/main/resources/test_sheets/freeze_and_scroll_test.xlsx

@@ -235,6 +235,24 @@ public void hideRowAndFreeze_shouldScrollCorrectly() {
                 headerRect.getY() + headerRect.getHeight());
     }
 
+    @Test
+    public void frozenAndScrolledSheet_headerColumnsRendered() {
+        loadFile("freeze_and_scroll_test.xlsx");
+
+        var firstColumn = getSpreadsheet().getColumnHeader(1);
+        Assert.assertTrue("Header of column A should have size",
+                firstColumn.getSize().getWidth() > 0);
+    }
+
+    @Test
+    public void frozenAndScrolledSheet_headerRowsRendered() {
+        loadFile("freeze_and_scroll_vertical_test.xlsx");
+
+        var firstRowHeader = getSpreadsheet().getRowHeader(1);
+        Assert.assertTrue("Header of row 1 should have size",
+                firstRowHeader.getSize().getHeight() > 0);
+    }
+
     private int getHeaderCount(String selector) {
         var headers = findElementsInShadowRoot(By.cssSelector(selector));
         return headers.size();

vaadin-spreadsheet-flow-parent/vaadin-spreadsheet-flow-integration-tests/src/main/resources/test_sheets/freeze_and_scroll_vertical_test.xlsx

@@ -1045,6 +1045,7 @@ static void loadMergedRegions(Spreadsheet spreadsheet) {
      *            Target Spreadsheet
      */
     static void loadFreezePane(Spreadsheet spreadsheet) {
+
         final Sheet sheet = spreadsheet.getActiveSheet();
         PaneInformation paneInformation = sheet.getPaneInformation();
 
@@ -1054,34 +1055,52 @@ static void loadFreezePane(Spreadsheet spreadsheet) {
             // With a large sheet, getTopRow could become negative.
             var topRow = Math.max(0, sheet.getTopRow());
             var leftCol = Math.max(0, sheet.getLeftCol());
+            var vSplit = paneInformation.getVerticalSplitPosition();
+            var hSplit = paneInformation.getHorizontalSplitPosition();
 
             /*
              * In POI, HorizontalSplit means rows and VerticalSplit means
              * columns.
              *
              * In Spreadsheet the meaning is the opposite.
-             */
-            spreadsheet.setHorizontalSplitPosition(
-                    paneInformation.getVerticalSplitPosition() + leftCol);
-
-            spreadsheet.setVerticalSplitPosition(
-                    paneInformation.getHorizontalSplitPosition() + topRow);
-
-            /*
+             * 
+             * POI uses a split position of 0 to mean "no split", so we should
+             * not be setting split positions or hiding anything in the case
+             * this position is 0.
+             *
              * If the view was scrolled down / right when panes were frozen, the
              * invisible frozen rows/columns are effectively hidden in Excel. We
-             * mimic this behavior here.
+             * attempt to mimic this behavior here by actually hiding the
+             * rows/columns, but only if there actually was a split.
              */
-            spreadsheet.setColumnsHidden(
-                    IntStream.range(0, leftCol).boxed().collect(Collectors
-                            .toMap(Function.identity(), index -> true)));
-            spreadsheet.setRowsHidden(
-                    IntStream.range(0, topRow).boxed().collect(Collectors
-                            .toMap(Function.identity(), index -> true)));
+            if (vSplit > 0) {
+                spreadsheet.setHorizontalSplitPosition(vSplit + leftCol);
+                if (leftCol > 0) {
+                    spreadsheet.setColumnsHidden(IntStream.range(0, leftCol)
+                            .boxed().collect(Collectors.toMap(
+                                    Function.identity(), index -> true)));
+                }
+            } else if (leftCol > 0) {
+                // TODO: should scroll vertically to restore viewport state
+                // This needs API on the Spreadsheet side
+            }
+
+            if (hSplit > 0) {
+                spreadsheet.setVerticalSplitPosition(hSplit + topRow);
+                if (topRow > 0) {
+                    spreadsheet.setRowsHidden(IntStream.range(0, topRow).boxed()
+                            .collect(Collectors.toMap(Function.identity(),
+                                    index -> true)));
+                }
+            } else if (topRow > 0) {
+                // TODO: should scroll vertically to restore viewport state
+                // This needs API on the Spreadsheet side
+            }
         } else {
             spreadsheet.setVerticalSplitPosition(0);
             spreadsheet.setHorizontalSplitPosition(0);
         }
+
     }
 
     private static Sheet createNewSheet(Workbook workbook) {