Add chart gridline handling.

.indent.pro

@@ -51,6 +51,7 @@
 -T lxw_chart_axis
 -T lxw_chart_fill
 -T lxw_chart_font
+-T lxw_chart_gridline
 -T lxw_chart_legend
 -T lxw_chart_legend_position
 -T lxw_chart_line

include/xlsxwriter/chart.h

@@ -621,6 +621,14 @@ typedef struct lxw_chart_series {
 
 } lxw_chart_series;
 
+/* Struct for major/minor axis gridlines. */
+typedef struct lxw_chart_gridline {
+
+    uint8_t visible;
+    lxw_chart_line *line;
+
+} lxw_chart_gridline;
+
 /**
  * @brief Struct to represent an Excel chart axis.
  *
@@ -634,10 +642,12 @@ typedef struct lxw_chart_axis {
     char num_format[LXW_CHART_NUM_FORMAT_LEN];
     char default_num_format[LXW_CHART_NUM_FORMAT_LEN];
 
-    uint8_t default_major_gridlines;
     uint8_t major_tick_mark;
     uint8_t is_horizontal;
 
+    lxw_chart_gridline major_gridlines;
+    lxw_chart_gridline minor_gridlines;
+
     lxw_chart_font *num_font;
     lxw_chart_line *line;
     lxw_chart_fill *fill;
@@ -1382,6 +1392,100 @@ void chart_axis_set_max(lxw_chart_axis *axis, double max);
  */
 void chart_axis_set_log_base(lxw_chart_axis *axis, uint16_t log_base);
 
+
+/**
+ * @brief Turn on/off the major gridlines for an axis.
+ *
+ * @param axis    A pointer to a chart #lxw_chart_axis object.
+ * @param visible Turn off/on the major gridline. (0/1)
+ *
+ * Turn on or off the major gridlines for an X or Y axis. In most Excel charts
+ * the Y axis major gridlines are on by default and the X axis major
+ * gridlines are off by default.
+ *
+ * Example:
+ *
+ * @code
+ *     // Reverse the normal visible/hidden gridlines for a column chart.
+ *     chart_axis_major_gridlines_set_visible(chart->x_axis, LXW_TRUE);
+ *     chart_axis_major_gridlines_set_visible(chart->y_axis, LXW_FALSE);
+ * @endcode
+ *
+ * @image html chart_gridline1.png
+ */
+void chart_axis_major_gridlines_set_visible(lxw_chart_axis *axis,
+                                            uint8_t visible);
+
+/**
+ * @brief Turn on/off the minor gridlines for an axis.
+ *
+ * @param axis    A pointer to a chart #lxw_chart_axis object.
+ * @param visible Turn off/on the minor gridline. (0/1)
+ *
+ * Turn on or off the minor gridlines for an X or Y axis. In most Excel charts
+ * the X and Y axis minor gridlines are off by default.
+ *
+ * Example, turn on all major and minor gridlines:
+ *
+ * @code
+ *     chart_axis_major_gridlines_set_visible(chart->x_axis, LXW_TRUE);
+ *     chart_axis_minor_gridlines_set_visible(chart->x_axis, LXW_TRUE);
+ *     chart_axis_major_gridlines_set_visible(chart->y_axis, LXW_TRUE);
+ *     chart_axis_minor_gridlines_set_visible(chart->y_axis, LXW_TRUE);
+ * @endcode
+ *
+ * @image html chart_gridline2.png
+ */
+void chart_axis_minor_gridlines_set_visible(lxw_chart_axis *axis,
+                                            uint8_t visible);
+
+/**
+ * @brief Set the line properties for the chart axis major gridlines.
+ *
+ * @param axis A pointer to a chart #lxw_chart_axis object.
+ * @param line A #lxw_chart_line struct.
+ *
+ * Format the line properties of the major gridlines of a chart:
+ *
+ * @code
+ *     lxw_chart_line line1 = {.color = LXW_COLOR_RED,
+ *                             .width = 0.5,
+ *                             .dash_type = LXW_CHART_LINE_DASH_SQUARE_DOT};
+ *
+ *     lxw_chart_line line2 = {.color = LXW_COLOR_YELLOW};
+ *
+ *     lxw_chart_line line3 = {.width = 1.25,
+ *                             .dash_type = LXW_CHART_LINE_DASH_DASH};
+ *
+ *     lxw_chart_line line4 = {.color =  0x00B050};
+ *
+ *     chart_axis_major_gridlines_set_line(chart->x_axis, &line1);
+ *     chart_axis_minor_gridlines_set_line(chart->x_axis, &line2);
+ *     chart_axis_major_gridlines_set_line(chart->y_axis, &line3);
+ *     chart_axis_minor_gridlines_set_line(chart->y_axis, &line4);
+ * @endcode
+ *
+ * @image html chart_gridline3.png
+ *
+ * For more information see @ref chart_lines.
+ */
+void chart_axis_major_gridlines_set_line(lxw_chart_axis *axis,
+                                         lxw_chart_line *line);
+
+/**
+ * @brief Set the line properties for the chart axis minor gridlines.
+ *
+ * @param axis A pointer to a chart #lxw_chart_axis object.
+ * @param line A #lxw_chart_line struct.
+ *
+ * Format the line properties of the minor gridlines of a chart, see the
+ * example above.
+ *
+ * For more information see @ref chart_lines.
+ */
+void chart_axis_minor_gridlines_set_line(lxw_chart_axis *axis,
+                                         lxw_chart_line *line);
+
 /**
  * @brief Set the title of the chart.
  *

src/chart.c

@@ -133,6 +133,8 @@ lxw_chart_free(lxw_chart *chart)
         free(chart->x_axis->line);
         free(chart->x_axis->fill);
         free(chart->x_axis->pattern);
+        free(chart->x_axis->major_gridlines.line);
+        free(chart->x_axis->minor_gridlines.line);
         free(chart->x_axis);
     }
 
@@ -145,6 +147,8 @@ lxw_chart_free(lxw_chart *chart)
         free(chart->y_axis->line);
         free(chart->y_axis->fill);
         free(chart->y_axis->pattern);
+        free(chart->y_axis->major_gridlines.line);
+        free(chart->y_axis->minor_gridlines.line);
         free(chart->y_axis);
     }
 
@@ -218,8 +222,8 @@ lxw_chart_new(uint8_t type)
     lxw_strcpy(chart->x_axis->default_num_format, "General");
     lxw_strcpy(chart->y_axis->default_num_format, "General");
 
-    chart->x_axis->default_major_gridlines = LXW_FALSE;
-    chart->y_axis->default_major_gridlines = LXW_TRUE;
+    chart->x_axis->major_gridlines.visible = LXW_FALSE;
+    chart->y_axis->major_gridlines.visible = LXW_TRUE;
 
     chart->series_overlap_1 = 100;
 
@@ -2340,9 +2344,43 @@ _chart_write_lbl_offset(lxw_chart *self)
 STATIC void
 _chart_write_major_gridlines(lxw_chart *self, lxw_chart_axis *axis)
 {
+    if (!axis->major_gridlines.visible)
+        return;
 
-    if (axis->default_major_gridlines)
+    if (axis->major_gridlines.line) {
+        lxw_xml_start_tag(self->file, "c:majorGridlines", NULL);
+
+        /* Write the c:spPr element for the axis line. */
+        _chart_write_sp_pr(self, axis->major_gridlines.line, NULL, NULL);
+
+        lxw_xml_end_tag(self->file, "c:majorGridlines");
+    }
+    else {
         lxw_xml_empty_tag(self->file, "c:majorGridlines", NULL);
+    }
+}
+
+/*
+ * Write the <c:minorGridlines> element.
+ */
+STATIC void
+_chart_write_minor_gridlines(lxw_chart *self, lxw_chart_axis *axis)
+{
+    if (!axis->minor_gridlines.visible)
+        return;
+
+    if (axis->minor_gridlines.line) {
+        lxw_xml_start_tag(self->file, "c:minorGridlines", NULL);
+
+        /* Write the c:spPr element for the axis line. */
+        _chart_write_sp_pr(self, axis->minor_gridlines.line, NULL, NULL);
+
+        lxw_xml_end_tag(self->file, "c:minorGridlines");
+
+    }
+    else {
+        lxw_xml_empty_tag(self->file, "c:minorGridlines", NULL);
+    }
 }
 
 /*
@@ -2660,6 +2698,9 @@ _chart_write_cat_axis(lxw_chart *self)
     /* Write the c:majorGridlines element. */
     _chart_write_major_gridlines(self, self->x_axis);
 
+    /* Write the c:minorGridlines element. */
+    _chart_write_minor_gridlines(self, self->x_axis);
+
     /* Write the axis title elements. */
     self->x_axis->title.is_horizontal = self->has_horiz_cat_axis;
     _chart_write_title(self, &self->x_axis->title);
@@ -2724,6 +2765,9 @@ _chart_write_val_axis(lxw_chart *self)
     /* Write the c:majorGridlines element. */
     _chart_write_major_gridlines(self, self->y_axis);
 
+    /* Write the c:minorGridlines element. */
+    _chart_write_minor_gridlines(self, self->y_axis);
+
     /* Write the axis title elements. */
     self->y_axis->title.is_horizontal = self->has_horiz_val_axis;
     _chart_write_title(self, &self->y_axis->title);
@@ -2778,6 +2822,12 @@ _chart_write_cat_val_axis(lxw_chart *self)
     /* Write the c:axPos element. */
     _chart_write_axis_pos(self, position, self->y_axis->reverse);
 
+    /* Write the c:majorGridlines element. */
+    _chart_write_major_gridlines(self, self->x_axis);
+
+    /* Write the c:minorGridlines element. */
+    _chart_write_minor_gridlines(self, self->x_axis);
+
     /* Write the axis title elements. */
     self->x_axis->title.is_horizontal = self->has_horiz_val_axis;
     _chart_write_title(self, &self->x_axis->title);
@@ -3203,8 +3253,9 @@ _chart_initialize_bar_chart(lxw_chart *self, uint8_t type)
     self->y_axis = tmp;
 
     /*Also reverse some of the defaults. */
-    self->x_axis->default_major_gridlines = LXW_FALSE;
-    self->y_axis->default_major_gridlines = LXW_TRUE;
+    self->x_axis->major_gridlines.visible = LXW_FALSE;
+    self->y_axis->major_gridlines.visible = LXW_TRUE;
+
     self->has_horiz_cat_axis = LXW_TRUE;
     self->has_horiz_val_axis = LXW_FALSE;
 
@@ -3322,7 +3373,8 @@ _chart_initialize_radar_chart(lxw_chart *self, uint8_t type)
     if (type == LXW_CHART_RADAR)
         _chart_set_default_marker_type(self, LXW_CHART_MARKER_NONE);
 
-    self->x_axis->default_major_gridlines = LXW_TRUE;
+    self->x_axis->major_gridlines.visible = LXW_TRUE;
+
     self->y_axis->major_tick_mark = LXW_TRUE;
 
     /* Initialize the function pointers for this chart type. */
@@ -3863,6 +3915,64 @@ chart_axis_set_log_base(lxw_chart_axis *axis, uint16_t log_base)
         axis->log_base = log_base;
 }
 
+/*
+ * Set the axis major gridlines on/off.
+ */
+void
+chart_axis_major_gridlines_set_visible(lxw_chart_axis *axis, uint8_t visible)
+{
+    axis->major_gridlines.visible = visible;
+}
+
+/*
+ * Set a line type for the major gridlines.
+ */
+void
+chart_axis_major_gridlines_set_line(lxw_chart_axis *axis,
+                                    lxw_chart_line *line)
+{
+    if (!line)
+        return;
+
+    /* Free any previously allocated resource. */
+    free(axis->major_gridlines.line);
+
+    axis->major_gridlines.line = _chart_convert_line_args(line);
+
+    /* If the gridline has a format it should also be visible. */
+    if (axis->major_gridlines.line)
+        axis->major_gridlines.visible = LXW_TRUE;
+}
+
+/*
+ * Set the axis minor gridlines on/off.
+ */
+void
+chart_axis_minor_gridlines_set_visible(lxw_chart_axis *axis, uint8_t visible)
+{
+    axis->minor_gridlines.visible = visible;
+}
+
+/*
+ * Set a line type for the minor gridlines.
+ */
+void
+chart_axis_minor_gridlines_set_line(lxw_chart_axis *axis,
+                                    lxw_chart_line *line)
+{
+    if (!line)
+        return;
+
+    /* Free any previously allocated resource. */
+    free(axis->minor_gridlines.line);
+
+    axis->minor_gridlines.line = _chart_convert_line_args(line);
+
+    /* If the gridline has a format it should also be visible. */
+    if (axis->minor_gridlines.line)
+        axis->minor_gridlines.visible = LXW_TRUE;
+}
+
 /*
  * Set the chart title.
  */

test/functional/src/test_chart_gridlines01.c

@@ -0,0 +1,45 @@
+/*****************************************************************************
+ * Test cases for libxlsxwriter.
+ *
+ * Test to compare output against Excel files.
+ *
+ * Copyright 2014-2017, John McNamara, jmcnamara@cpan.org
+ *
+ */
+
+#include "xlsxwriter.h"
+
+int main() {
+
+    lxw_workbook  *workbook  = new_workbook("test_chart_gridlines01.xlsx");
+    lxw_worksheet *worksheet = workbook_add_worksheet(workbook, NULL);
+    lxw_chart     *chart     = workbook_add_chart(workbook, LXW_CHART_COLUMN);
+
+    /* For testing, copy the randomly generated axis ids in the target file. */
+    chart->axis_id_1 = 67390848;
+    chart->axis_id_2 = 68472192;
+
+    uint8_t data[5][3] = {
+        {1, 2,  3},
+        {2, 4,  6},
+        {3, 6,  9},
+        {4, 8,  12},
+        {5, 10, 15}
+    };
+
+    int row, col;
+    for (row = 0; row < 5; row++)
+        for (col = 0; col < 3; col++)
+            worksheet_write_number(worksheet, row, col, data[row][col], NULL);
+
+    chart_add_series(chart, NULL, "=Sheet1!$A$1:$A$5");
+    chart_add_series(chart, NULL, "=Sheet1!$B$1:$B$5");
+    chart_add_series(chart, NULL, "=Sheet1!$C$1:$C$5");
+
+    chart_axis_major_gridlines_set_visible(chart->x_axis, LXW_TRUE);
+    chart_axis_major_gridlines_set_visible(chart->y_axis, LXW_FALSE);
+
+    worksheet_insert_chart(worksheet, CELL("E9"), chart);
+
+    return workbook_close(workbook);
+}

test/functional/src/test_chart_gridlines02.c

@@ -0,0 +1,51 @@
+/*****************************************************************************
+ * Test cases for libxlsxwriter.
+ *
+ * Test to compare output against Excel files.
+ *
+ * Copyright 2014-2017, John McNamara, jmcnamara@cpan.org
+ *
+ */
+
+#include "xlsxwriter.h"
+
+int main() {
+
+    lxw_workbook  *workbook  = new_workbook("test_chart_gridlines02.xlsx");
+    lxw_worksheet *worksheet = workbook_add_worksheet(workbook, NULL);
+    lxw_chart     *chart     = workbook_add_chart(workbook, LXW_CHART_SCATTER);
+
+    /* For testing, copy the randomly generated axis ids in the target file. */
+    chart->axis_id_1 = 57940608;
+    chart->axis_id_2 = 57938688;
+
+    uint8_t data[5][3] = {
+        {1, 2,  3},
+        {2, 4,  6},
+        {3, 6,  9},
+        {4, 8,  12},
+        {5, 10, 15}
+    };
+
+    int row, col;
+    for (row = 0; row < 5; row++)
+        for (col = 0; col < 3; col++)
+            worksheet_write_number(worksheet, row, col, data[row][col], NULL);
+
+    chart_add_series(chart,
+         "=Sheet1!$A$1:$A$5",
+         "=Sheet1!$B$1:$B$5"
+    );
+
+    chart_add_series(chart,
+         "=Sheet1!$A$1:$A$5",
+         "=Sheet1!$C$1:$C$5"
+    );
+
+    chart_axis_major_gridlines_set_visible(chart->x_axis, LXW_TRUE);
+    chart_axis_major_gridlines_set_visible(chart->y_axis, LXW_FALSE);
+
+    worksheet_insert_chart(worksheet, CELL("E9"), chart);
+
+    return workbook_close(workbook);
+}

test/functional/src/test_chart_gridlines04.c

@@ -0,0 +1,44 @@
+/*****************************************************************************
+ * Test cases for libxlsxwriter.
+ *
+ * Test to compare output against Excel files.
+ *
+ * Copyright 2014-2017, John McNamara, jmcnamara@cpan.org
+ *
+ */
+
+#include "xlsxwriter.h"
+
+int main() {
+
+    lxw_workbook  *workbook  = new_workbook("test_chart_gridlines04.xlsx");
+    lxw_worksheet *worksheet = workbook_add_worksheet(workbook, NULL);
+    lxw_chart     *chart     = workbook_add_chart(workbook, LXW_CHART_RADAR);
+
+    /* For testing, copy the randomly generated axis ids in the target file. */
+    chart->axis_id_1 = 54977280;
+    chart->axis_id_2 = 54978816;
+
+    uint8_t data[5][3] = {
+        {1, 2,  3},
+        {2, 4,  6},
+        {3, 6,  9},
+        {4, 8,  12},
+        {5, 10, 15}
+    };
+
+    int row, col;
+    for (row = 0; row < 5; row++)
+        for (col = 0; col < 3; col++)
+            worksheet_write_number(worksheet, row, col, data[row][col], NULL);
+
+    chart_add_series(chart, NULL, "=Sheet1!$A$1:$A$5");
+    chart_add_series(chart, NULL, "=Sheet1!$B$1:$B$5");
+    chart_add_series(chart, NULL, "=Sheet1!$C$1:$C$5");
+
+    chart_axis_major_gridlines_set_visible(chart->y_axis, LXW_FALSE);
+
+    worksheet_insert_chart(worksheet, CELL("E9"), chart);
+
+    return workbook_close(workbook);
+}

test/functional/src/test_chart_gridlines05.c

@@ -0,0 +1,49 @@
+/*****************************************************************************
+ * Test cases for libxlsxwriter.
+ *
+ * Test to compare output against Excel files.
+ *
+ * Copyright 2014-2017, John McNamara, jmcnamara@cpan.org
+ *
+ */
+
+#include "xlsxwriter.h"
+
+int main() {
+
+    lxw_workbook  *workbook  = new_workbook("test_chart_gridlines05.xlsx");
+    lxw_worksheet *worksheet = workbook_add_worksheet(workbook, NULL);
+    lxw_chart     *chart     = workbook_add_chart(workbook, LXW_CHART_COLUMN);
+
+    /* For testing, copy the randomly generated axis ids in the target file. */
+    chart->axis_id_1 = 80072064;
+    chart->axis_id_2 = 79959168;
+
+    uint8_t data[5][3] = {
+        {1, 2,  3},
+        {2, 4,  6},
+        {3, 6,  9},
+        {4, 8,  12},
+        {5, 10, 15}
+    };
+
+    int row, col;
+    for (row = 0; row < 5; row++)
+        for (col = 0; col < 3; col++)
+            worksheet_write_number(worksheet, row, col, data[row][col], NULL);
+
+    chart_add_series(chart, NULL, "=Sheet1!$A$1:$A$5");
+    chart_add_series(chart, NULL, "=Sheet1!$B$1:$B$5");
+    chart_add_series(chart, NULL, "=Sheet1!$C$1:$C$5");
+
+
+    chart_axis_major_gridlines_set_visible(chart->x_axis, LXW_TRUE);
+    chart_axis_minor_gridlines_set_visible(chart->x_axis, LXW_TRUE);
+    chart_axis_major_gridlines_set_visible(chart->y_axis, LXW_TRUE);
+    chart_axis_minor_gridlines_set_visible(chart->y_axis, LXW_TRUE);
+
+
+    worksheet_insert_chart(worksheet, CELL("E9"), chart);
+
+    return workbook_close(workbook);
+}

test/functional/src/test_chart_gridlines06.c

@@ -0,0 +1,53 @@
+/*****************************************************************************
+ * Test cases for libxlsxwriter.
+ *
+ * Test to compare output against Excel files.
+ *
+ * Copyright 2014-2017, John McNamara, jmcnamara@cpan.org
+ *
+ */
+
+#include "xlsxwriter.h"
+
+int main() {
+
+    lxw_workbook  *workbook  = new_workbook("test_chart_gridlines06.xlsx");
+    lxw_worksheet *worksheet = workbook_add_worksheet(workbook, NULL);
+    lxw_chart     *chart     = workbook_add_chart(workbook, LXW_CHART_SCATTER);
+
+    /* For testing, copy the randomly generated axis ids in the target file. */
+    chart->axis_id_1 = 82812288;
+    chart->axis_id_2 = 46261376;
+
+    uint8_t data[5][3] = {
+        {1, 2,  3},
+        {2, 4,  6},
+        {3, 6,  9},
+        {4, 8,  12},
+        {5, 10, 15}
+    };
+
+    int row, col;
+    for (row = 0; row < 5; row++)
+        for (col = 0; col < 3; col++)
+            worksheet_write_number(worksheet, row, col, data[row][col], NULL);
+
+    chart_add_series(chart,
+         "=Sheet1!$A$1:$A$5",
+         "=Sheet1!$B$1:$B$5"
+    );
+
+    chart_add_series(chart,
+         "=Sheet1!$A$1:$A$5",
+         "=Sheet1!$C$1:$C$5"
+    );
+
+    chart_axis_major_gridlines_set_visible(chart->x_axis, LXW_TRUE);
+    chart_axis_minor_gridlines_set_visible(chart->x_axis, LXW_TRUE);
+    chart_axis_major_gridlines_set_visible(chart->y_axis, LXW_TRUE);
+    chart_axis_minor_gridlines_set_visible(chart->y_axis, LXW_TRUE);
+
+    worksheet_insert_chart(worksheet, CELL("E9"), chart);
+
+    return workbook_close(workbook);
+}

test/functional/src/test_chart_gridlines08.c

@@ -0,0 +1,45 @@
+/*****************************************************************************
+ * Test cases for libxlsxwriter.
+ *
+ * Test to compare output against Excel files.
+ *
+ * Copyright 2014-2017, John McNamara, jmcnamara@cpan.org
+ *
+ */
+
+#include "xlsxwriter.h"
+
+int main() {
+
+    lxw_workbook  *workbook  = new_workbook("test_chart_gridlines08.xlsx");
+    lxw_worksheet *worksheet = workbook_add_worksheet(workbook, NULL);
+    lxw_chart     *chart     = workbook_add_chart(workbook, LXW_CHART_RADAR);
+
+    /* For testing, copy the randomly generated axis ids in the target file. */
+    chart->axis_id_1 = 60019072;
+    chart->axis_id_2 = 60020608;
+
+    uint8_t data[5][3] = {
+        {1, 2,  3},
+        {2, 4,  6},
+        {3, 6,  9},
+        {4, 8,  12},
+        {5, 10, 15}
+    };
+
+    int row, col;
+    for (row = 0; row < 5; row++)
+        for (col = 0; col < 3; col++)
+            worksheet_write_number(worksheet, row, col, data[row][col], NULL);
+
+    chart_add_series(chart, NULL, "=Sheet1!$A$1:$A$5");
+    chart_add_series(chart, NULL, "=Sheet1!$B$1:$B$5");
+    chart_add_series(chart, NULL, "=Sheet1!$C$1:$C$5");
+
+    chart_axis_major_gridlines_set_visible(chart->y_axis, LXW_TRUE);
+    chart_axis_minor_gridlines_set_visible(chart->y_axis, LXW_TRUE);
+
+    worksheet_insert_chart(worksheet, CELL("E9"), chart);
+
+    return workbook_close(workbook);
+}

test/functional/src/test_chart_gridlines09.c

@@ -0,0 +1,60 @@
+/*****************************************************************************
+ * Test cases for libxlsxwriter.
+ *
+ * Test to compare output against Excel files.
+ *
+ * Copyright 2014-2017, John McNamara, jmcnamara@cpan.org
+ *
+ */
+
+#include "xlsxwriter.h"
+
+int main() {
+
+    lxw_workbook  *workbook  = new_workbook("test_chart_gridlines09.xlsx");
+    lxw_worksheet *worksheet = workbook_add_worksheet(workbook, NULL);
+    lxw_chart     *chart     = workbook_add_chart(workbook, LXW_CHART_COLUMN);
+
+    /* For testing, copy the randomly generated axis ids in the target file. */
+    chart->axis_id_1 = 48744320;
+    chart->axis_id_2 = 49566848;
+
+    uint8_t data[5][3] = {
+        {1, 2,  3},
+        {2, 4,  6},
+        {3, 6,  9},
+        {4, 8,  12},
+        {5, 10, 15}
+    };
+
+    int row, col;
+    for (row = 0; row < 5; row++)
+        for (col = 0; col < 3; col++)
+            worksheet_write_number(worksheet, row, col, data[row][col], NULL);
+
+    chart_add_series(chart, NULL, "=Sheet1!$A$1:$A$5");
+    chart_add_series(chart, NULL, "=Sheet1!$B$1:$B$5");
+    chart_add_series(chart, NULL, "=Sheet1!$C$1:$C$5");
+
+
+    lxw_chart_line line1 = {.color = LXW_COLOR_RED,
+                            .width = 0.5,
+                            .dash_type = LXW_CHART_LINE_DASH_SQUARE_DOT};
+
+    lxw_chart_line line2 = {.color = LXW_COLOR_YELLOW};
+
+    lxw_chart_line line3 = {.width = 1.25,
+                            .dash_type = LXW_CHART_LINE_DASH_DASH};
+
+    lxw_chart_line line4 = {.color =  0x00B050};
+
+    chart_axis_major_gridlines_set_line(chart->x_axis, &line1);
+    chart_axis_minor_gridlines_set_line(chart->x_axis, &line2);
+    chart_axis_major_gridlines_set_line(chart->y_axis, &line3);
+    chart_axis_minor_gridlines_set_line(chart->y_axis, &line4);
+
+
+    worksheet_insert_chart(worksheet, CELL("E9"), chart);
+
+    return workbook_close(workbook);
+}

test/functional/test_chart_gridlines.py

@@ -0,0 +1,39 @@
+###############################################################################
+#
+# Tests for libxlsxwriter.
+#
+# Copyright 2014-2017, 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_chart_gridlines01(self):
+        self.run_exe_test('test_chart_gridlines01')
+
+    def test_chart_gridlines02(self):
+        self.run_exe_test('test_chart_gridlines02')
+
+    # test_chart_gridlines03 is a stock chart.
+
+    def test_chart_gridlines04(self):
+        self.run_exe_test('test_chart_gridlines04')
+
+    def test_chart_gridlines05(self):
+        self.run_exe_test('test_chart_gridlines05')
+
+    def test_chart_gridlines06(self):
+        self.run_exe_test('test_chart_gridlines06')
+
+    # test_chart_gridlines07 is a stock chart.
+
+    def test_chart_gridlines08(self):
+        self.run_exe_test('test_chart_gridlines08')
+
+    def test_chart_gridlines09(self):
+        self.run_exe_test('test_chart_gridlines09')