Merge branch 'grid-fix-drawing-invalid-cells' of https://github.com/discnl/wxWidgets

Fix drawing of grid cells appearing inside a multicell.

See https://github.com/wxWidgets/wxWidgets/pull/2176

src/generic/grid.cpp

@@ -158,6 +158,24 @@ wxDEFINE_EVENT( wxEVT_GRID_TABBING, wxGridEvent );
 // implementation
 // ============================================================================
 
+namespace
+{
+
+// Helper function for consistent cell span determination based on cell size.
+wxGrid::CellSpan GetCellSpan(int numRows, int numCols)
+{
+    if ( numRows == 1 && numCols == 1 )
+        return wxGrid::CellSpan_None; // just a normal cell
+
+    if ( numRows < 0 || numCols < 0 )
+        return wxGrid::CellSpan_Inside; // covered by a multi-span cell
+
+    // this cell spans multiple cells to its right/bottom
+    return wxGrid::CellSpan_Main;
+}
+
+} // anonymous namespace
+
 wxIMPLEMENT_ABSTRACT_CLASS(wxGridCellEditorEvtHandler, wxEvtHandler);
 
 wxBEGIN_EVENT_TABLE( wxGridCellEditorEvtHandler, wxEvtHandler )
@@ -6217,7 +6235,15 @@ void wxGrid::DrawGridCellArea( wxDC& dc, const wxGridCellCoordsArray& cells )
                 {
                     if (!m_table->IsEmptyCell(row + l, j))
                     {
-                        if ( GetCellAttrPtr(row + l, j)->CanOverflow() )
+                        wxGridCellAttrPtr attr = GetCellAttrPtr(row + l, j);
+                        int numRows, numCols;
+                        attr->GetSize(&numRows, &numCols);
+                        if ( GetCellSpan(numRows, numCols)
+                                 == wxGrid::CellSpan_Inside )
+                            // As above: don't bother drawing inside cells.
+                            continue;
+
+                        if ( attr->CanOverflow() )
                         {
                             wxGridCellCoords cell(row + l, j);
                             bool marked = false;
@@ -9120,14 +9146,7 @@ wxGrid::GetCellSize( int row, int col, int *num_rows, int *num_cols ) const
 {
     GetCellAttrPtr(row, col)->GetSize( num_rows, num_cols );
 
-    if ( *num_rows == 1 && *num_cols == 1 )
+    return GetCellSpan(*num_rows, *num_cols);
-        return CellSpan_None; // just a normal cell
-
-    if ( *num_rows < 0 || *num_cols < 0 )
-        return CellSpan_Inside; // covered by a multi-span cell
-
-    // this cell spans multiple cells to its right/bottom
-    return CellSpan_Main;
 }
 
 wxGridCellRenderer* wxGrid::GetCellRenderer(int row, int col) const

tests/controls/gridtest.cpp

@@ -1423,6 +1423,32 @@ TEST_CASE_METHOD(GridTestCase, "Grid::AutoSizeColumn", "[grid]")
     }
 }
 
+TEST_CASE_METHOD(GridTestCase, "Grid::DrawInvalidCell", "[grid][multicell]")
+{
+    // Set up a multicell with inside an overflowing cell.
+    // This is artificial and normally inside cells are probably not expected
+    // to have a value but this is merely done to check if inside cells are
+    // drawn, which they shouldn't be.
+    m_grid->SetCellSize(0, 0, 2, 1);
+    m_grid->SetCellValue( 1, 0, wxString('W', 42) );
+
+    // Update()s, yields and sleep are needed to try to make the test fail with
+    // macOS, GTK and MSW.
+    // MSW needs just the yields (or updates), macOS in addition needs to sleep
+    // (doesn't work with updates) and for GTK it's usually enough to just do
+    // two updates (not yields). This test does all unconditionally.
+    m_grid->Update();
+    wxYield();
+    wxMilliSleep(20);
+
+    // Try to force redrawing of the inside cell: if it still draws there will
+    // be an infinite recursion.
+    m_grid->SetColSize(1, m_grid->GetColSize(1) + 1);
+
+    m_grid->Update();
+    wxYield();
+}
+
 // Test wxGridBlockCoords here because it'a a part of grid sources.
 
 std::ostream& operator<<(std::ostream& os, const wxGridBlockCoords& block) {