Added worksheet_set_top_left_cell() function.

Added worksheet_set_top_left_cell() function to set the first
visible cell in the worksheet.

include/xlsxwriter/worksheet.h

@@ -2236,6 +2236,7 @@ typedef struct lxw_worksheet {
     struct lxw_rel_tuples *external_table_links;
 
     struct lxw_panes panes;
+    char top_left_cell[LXW_MAX_CELL_NAME_LENGTH];
 
     struct lxw_protection_obj protection;
 
@@ -4578,6 +4579,27 @@ void worksheet_set_selection(lxw_worksheet *worksheet,
                              lxw_row_t first_row, lxw_col_t first_col,
                              lxw_row_t last_row, lxw_col_t last_col);
 
+/**
+ * @brief Set the first visible cell at the top left of a worksheet.
+ *
+ * @param worksheet Pointer to a lxw_worksheet instance to be updated.
+ * @param row       The cell row (zero indexed).
+ * @param col       The cell column (zero indexed).
+ *
+ * The `%worksheet_set_top_left_cell()` function can be used to set the
+ * top leftmost visible cell in the worksheet:
+ *
+ * @code
+ *     worksheet_set_top_left_cell(worksheet, 31, 26);
+ *     worksheet_set_top_left_cell(worksheet, CELL("AA32")); // Same as above.
+ * @endcode
+ *
+ * @image html top_left_cell.png
+ *
+ */
+void worksheet_set_top_left_cell(lxw_worksheet *worksheet, lxw_row_t row,
+                                 lxw_col_t col);
+
 /**
  * @brief Set the page orientation as landscape.
  *

src/worksheet.c

@@ -2396,28 +2396,29 @@ _worksheet_write_sheet_view(lxw_worksheet *self)
         LXW_PUSH_ATTRIBUTES_STR("showGridLines", "0");
 
     /* Hide zeroes in cells. */
-    if (!self->show_zeros) {
+    if (!self->show_zeros)
         LXW_PUSH_ATTRIBUTES_STR("showZeros", "0");
-    }
 
     /* Display worksheet right to left for Hebrew, Arabic and others. */
-    if (self->right_to_left) {
+    if (self->right_to_left)
         LXW_PUSH_ATTRIBUTES_STR("rightToLeft", "1");
-    }
 
     /* Show that the sheet tab is selected. */
     if (self->selected)
         LXW_PUSH_ATTRIBUTES_STR("tabSelected", "1");
 
     /* Turn outlines off. Also required in the outlinePr element. */
-    if (!self->outline_on) {
+    if (!self->outline_on)
         LXW_PUSH_ATTRIBUTES_STR("showOutlineSymbols", "0");
-    }
 
     /* Set the page view/layout mode if required. */
     if (self->page_view)
         LXW_PUSH_ATTRIBUTES_STR("view", "pageLayout");
 
+    /* Set the top left cell if required. */
+    if (self->top_left_cell[0])
+        LXW_PUSH_ATTRIBUTES_STR("topLeftCell", self->top_left_cell);
+
     /* Set the zoom level. */
     if (self->zoom != 100 && !self->page_view) {
         LXW_PUSH_ATTRIBUTES_INT("zoomScale", self->zoom);
@@ -9465,6 +9466,18 @@ worksheet_set_selection(lxw_worksheet *self,
     STAILQ_INSERT_TAIL(self->selections, selection, list_pointers);
 }
 
+/*
+ * Set the first visible cell at the top left of the worksheet.
+ */
+void
+worksheet_set_top_left_cell(lxw_worksheet *self, lxw_row_t row, lxw_col_t col)
+{
+    if (row == 0 && col == 0)
+        return;
+
+    lxw_rowcol_to_cell(self->top_left_cell, row, col);
+}
+
 /*
  * Set panes and mark them as frozen. With extra options.
  */

test/functional/src/test_top_left_cell01.c

@@ -0,0 +1,20 @@
+/*****************************************************************************
+ * Test cases for libxlsxwriter.
+ *
+ * Test to compare output against Excel files.
+ *
+ * Copyright 2014-2021, John McNamara, jmcnamara@cpan.org
+ *
+ */
+
+#include "xlsxwriter.h"
+
+int main() {
+
+    lxw_workbook  *workbook  = workbook_new("test_top_left_cell01.xlsx");
+    lxw_worksheet *worksheet = workbook_add_worksheet(workbook, NULL);
+
+    worksheet_set_top_left_cell(worksheet, 15, 0);
+
+    return workbook_close(workbook);
+}

test/functional/src/test_top_left_cell02.c

@@ -0,0 +1,20 @@
+/*****************************************************************************
+ * Test cases for libxlsxwriter.
+ *
+ * Test to compare output against Excel files.
+ *
+ * Copyright 2014-2021, John McNamara, jmcnamara@cpan.org
+ *
+ */
+
+#include "xlsxwriter.h"
+
+int main() {
+
+    lxw_workbook  *workbook  = workbook_new("test_top_left_cell02.xlsx");
+    lxw_worksheet *worksheet = workbook_add_worksheet(workbook, NULL);
+
+    worksheet_set_top_left_cell(worksheet, 15, 6);
+
+    return workbook_close(workbook);
+}

test/functional/src/test_top_left_cell03.c

@@ -0,0 +1,20 @@
+/*****************************************************************************
+ * Test cases for libxlsxwriter.
+ *
+ * Test to compare output against Excel files.
+ *
+ * Copyright 2014-2021, John McNamara, jmcnamara@cpan.org
+ *
+ */
+
+#include "xlsxwriter.h"
+
+int main() {
+
+    lxw_workbook  *workbook  = workbook_new("test_top_left_cell03.xlsx");
+    lxw_worksheet *worksheet = workbook_add_worksheet(workbook, NULL);
+
+    worksheet_set_top_left_cell(worksheet, CELL("AA32"));
+
+    return workbook_close(workbook);
+}

test/functional/test_top_left_cell.py

@@ -0,0 +1,24 @@
+###############################################################################
+#
+# Tests for libxlsxwriter.
+#
+# Copyright 2014-2021, John McNamara, jmcnamara@cpan.org
+#
+
+import base_test_class
+
+class TestCompareXLSXFiles(base_test_class.XLSXBaseTest):
+    """
+    Test file created with libxlsxwriter against a file created by Excel.
+
+    """
+
+    def test_top_left_cell01(self):
+        self.run_exe_test('test_top_left_cell01')
+
+    def test_top_left_cell02(self):
+        self.run_exe_test('test_top_left_cell02')
+
+    def test_top_left_cell03(self):
+        self.run_exe_test('test_top_left_cell03')
+