PR: Fix issues with scrolling in dataframe editor (Variable Explorer)

spyder/plugins/variableexplorer/widgets/dataframeeditor.py

@@ -658,6 +658,10 @@ def __init__(self, parent, model, header, hscroll, vscroll,
         self.resize_action = None
         self.resize_columns_action = None
 
+        self.menu = self.setup_menu()
+        self.menu_header_h = self.setup_menu_header()
+        self.config_shortcut(self.copy, 'copy', self)
+
         self.setModel(model)
         self.setHorizontalScrollBar(hscroll)
         self.setVerticalScrollBar(vscroll)
@@ -671,14 +675,9 @@ def __init__(self, parent, model, header, hscroll, vscroll,
             self.show_header_menu)
         self.header_class.sectionClicked.connect(self.sortByColumn)
         self.data_function = data_function
-        self.menu = self.setup_menu()
-        self.menu_header_h = self.setup_menu_header()
-        self.config_shortcut(self.copy, 'copy', self)
         self.horizontalScrollBar().valueChanged.connect(
             self._load_more_columns)
         self.verticalScrollBar().valueChanged.connect(self._load_more_rows)
-        self.selectionModel().selectionChanged.connect(self.refresh_menu)
-        self.refresh_menu()
 
     def _load_more_columns(self, value):
         """Load more columns to display."""
@@ -713,6 +712,17 @@ def load_more_data(self, value, rows=False, columns=False):
             # See spyder-ide/spyder#7880.
             pass
 
+    def setModel(self, model: DataFrameModel) -> None:
+        """
+        Set the model for the view to present.
+
+        This overrides the function in QTableView so that we can enable or
+        disable actions when appropriate if the selection changes.
+        """
+        super().setModel(model)
+        self.selectionModel().selectionChanged.connect(self.refresh_menu)
+        self.refresh_menu()
+
     def sortByColumn(self, index):
         """Implement a column sort."""
         if self.sort_old == [None]:
@@ -1417,22 +1427,8 @@ def __init__(self, model, axis, use_monospace_font=False):
 
         self.total_rows = self.model.shape[0]
         self.total_cols = self.model.shape[1]
-        size = self.total_rows * self.total_cols
-
-        # Use paging when the total size, number of rows or number of
-        # columns is too large
-        if size > LARGE_SIZE:
-            self.rows_loaded = ROWS_TO_LOAD
-            self.cols_loaded = COLS_TO_LOAD
-        else:
-            if self.total_cols > LARGE_COLS:
-                self.cols_loaded = COLS_TO_LOAD
-            else:
-                self.cols_loaded = self.total_cols
-            if self.total_rows > LARGE_NROWS:
-                self.rows_loaded = ROWS_TO_LOAD
-            else:
-                self.rows_loaded = self.total_rows
+        self.cols_loaded = self.model.cols_loaded
+        self.rows_loaded = self.model.rows_loaded
 
         if self.axis == 0:
             self.total_cols = self.model.shape[1]
@@ -1687,6 +1683,10 @@ def data(self, index, role):
         return None
 
 
+class EmptyDataFrame:
+    shape = (0, 0)
+
+
 class DataFrameEditor(BaseDialog, SpyderWidgetMixin):
     """
     Dialog for displaying and editing DataFrame and related objects.
@@ -1790,9 +1790,23 @@ def setup_ui(self, title: str) -> None:
         # Create menu to allow edit index
         self.menu_header_v = self.setup_menu_header(self.table_index)
 
+        # Create the model and view of the data
+        empty_data = EmptyDataFrame()
+        self.dataModel = DataFrameModel(empty_data, parent=self)
+        self.dataModel.dataChanged.connect(self.save_and_close_enable)
+        self.create_data_table()
+
         self.glayout.addWidget(self.hscroll, 2, 0, 1, 2)
         self.glayout.addWidget(self.vscroll, 0, 2, 2, 1)
 
+        # autosize columns on-demand
+        self._autosized_cols = set()
+
+        # Set limit time to calculate column sizeHint to 300ms,
+        # See spyder-ide/spyder#11060
+        self._max_autosize_ms = 300
+        self.dataTable.installEventFilter(self)
+
         avg_width = self.fontMetrics().averageCharWidth()
         self.min_trunc = avg_width * 12  # Minimum size for columns
         self.max_width = avg_width * 64  # Maximum size for columns
@@ -1853,7 +1867,7 @@ def set_data_and_check(self, data) -> bool:
         # Create the model and view of the data
         self.dataModel = DataFrameModel(data, parent=self)
         self.dataModel.dataChanged.connect(self.save_and_close_enable)
-        self.create_data_table()
+        self.dataTable.setModel(self.dataModel)
 
         # autosize columns on-demand
         self._autosized_cols = set()
@@ -2034,11 +2048,6 @@ def create_table_index(self):
 
     def create_data_table(self):
         """Create the QTableView that will hold the data model."""
-        if self.dataTable:
-            self.layout.removeWidget(self.dataTable)
-            self.dataTable.deleteLater()
-            self.dataTable = None
-
         self.dataTable = DataFrameView(self, self.dataModel,
                                        self.table_header.horizontalHeader(),
                                        self.hscroll, self.vscroll,

spyder/plugins/variableexplorer/widgets/tests/test_dataframeeditor.py

@@ -34,7 +34,7 @@
 from spyder.utils.test import close_message_box
 from spyder.plugins.variableexplorer.widgets import dataframeeditor
 from spyder.plugins.variableexplorer.widgets.dataframeeditor import (
-    DataFrameEditor, DataFrameModel)
+    DataFrameEditor, DataFrameModel, COLS_TO_LOAD, LARGE_COLS)
 
 
 # =============================================================================
@@ -150,6 +150,77 @@ def test_dataframe_to_type(qtbot):
     assert editor.btn_save_and_close.isEnabled()
 
 
+def test_dataframe_editor_shows_scrollbar(qtbot):
+    """
+    Test the dataframe editor shows a scrollbar when opening a large dataframe.
+    Regression test for spyder-ide/spyder#21627 .
+    """
+    df = DataFrame(numpy.zeros((100, 100)))
+    editor = DataFrameEditor()
+    editor.setup_and_check(df)
+    with qtbot.waitExposed(editor):
+        editor.show()
+
+    assert editor.dataTable.horizontalScrollBar().isVisible()
+
+
+def test_dataframe_editor_scroll(qtbot):
+    """
+    Test that when opening a "large" dataframe, only a part of it is initially
+    loaded in the editor window. When scrolling past that part, the rest is
+    loaded. When moving to the right-most column and sorting it, the view
+    stay scrolled to the right end.
+
+    Regression test for spyder-ide/spyder#21627 .
+    """
+
+    # Make DataFrame with LARGE_COLS + 5 columns
+    df = DataFrame(numpy.zeros((10, LARGE_COLS + 5)))
+    editor = DataFrameEditor()
+    editor.setup_and_check(df)
+    model = editor.dataModel
+    with qtbot.waitExposed(editor):
+        editor.show()
+
+    # Check that initially, COLS_TO_LOAD columns are loaded in the editor
+    assert model.rowCount() == 10
+    assert model.columnCount() == COLS_TO_LOAD
+
+    # Press the End key to move to the right and wait
+    view = editor.dataTable
+    view.setCurrentIndex(view.model().index(0, 0))
+    qtbot.keyPress(view, Qt.Key_End)
+
+    # Check that now all the columns are loaded in the editor
+    def check_column_count():
+        assert model.columnCount() == LARGE_COLS + 5
+
+    qtbot.waitUntil(check_column_count)
+
+    # Press the End key to move to the right and wait
+    qtbot.keyPress(view, Qt.Key_End)
+    scrollbar = editor.dataTable.horizontalScrollBar()
+
+    # Check that we are at the far right
+    def check_at_far_right():
+        assert scrollbar.value() == scrollbar.maximum()
+
+    qtbot.waitUntil(check_at_far_right)
+
+    # Sort the rightmost column
+    old_index_model = editor.table_index.model()
+    view.sortByColumn(model.columnCount() - 1)
+
+    # Wait until the model for the index is updated
+    def check_index_model_updated():
+        assert editor.table_index.model() != old_index_model
+
+    qtbot.waitUntil(check_index_model_updated)
+
+    # Check that we are at the far right
+    assert scrollbar.value() == scrollbar.maximum()
+
+
 def test_dataframe_datetimeindex(qtbot):
     """Regression test for spyder-ide/spyder#11129 ."""
     ds = Series(