Add chart major and minor units.

include/xlsxwriter/chart.h

@@ -689,10 +689,17 @@ typedef struct lxw_chart_axis {
     uint8_t label_position;
     uint8_t hidden;
     uint8_t reverse;
+
     uint8_t has_min;
-    uint8_t has_max;
     double min;
+    uint8_t has_max;
     double max;
+
+    uint8_t has_major_unit;
+    double major_unit;
+    uint8_t has_minor_unit;
+    double minor_unit;
+
     uint16_t log_base;
 
 } lxw_chart_axis;
@@ -1522,6 +1529,48 @@ 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 Set the increment of the major units in the axis.
+ *
+ * @param axis A pointer to a chart #lxw_chart_axis object.
+ * @param unit The increment of the major units.
+ *
+ * Set the increment of the major units in the axis range.
+ *
+ * @code
+ *     // Turn on the minor gridline (it is off by default).
+ *     chart_axis_minor_gridlines_set_visible(chart->y_axis, LXW_TRUE);
+ *
+ *     chart_axis_set_major_unit(chart->y_axis, 4);
+ *     chart_axis_set_minor_unit(chart->y_axis, 2);
+ * @endcode
+ *
+ * @image html chart_set_major_units.png
+ *
+ * **Axis types**: This function is applicable to value and date axes only.
+ *                 See @ref ww_charts_axes.
+ */
+void chart_axis_set_major_unit(lxw_chart_axis *axis, double unit);
+
+/**
+ * @brief Set the increment of the minor units in the axis.
+ *
+ * @param axis A pointer to a chart #lxw_chart_axis object.
+ * @param unit The increment of the minor units.
+ *
+ * Set the increment of the minor units in the axis range.
+ *
+ * @code
+ *     chart_axis_set_minor_unit(chart->y_axis, 2);
+ * @endcode
+ *
+ * See the image above
+ *
+ * **Axis types**: This function is applicable to value and date axes only.
+ *                 See @ref ww_charts_axes.
+ */
+void chart_axis_set_minor_unit(lxw_chart_axis *axis, double unit);
+
 /**
  * @brief Turn on/off the major gridlines for an axis.
  *

src/chart.c

@@ -2320,32 +2320,70 @@ _chart_write_auto(lxw_chart *self)
  * Write the <c:lblAlgn> element.
  */
 STATIC void
-_chart_write_lbl_algn(lxw_chart *self)
+_chart_write_label_align(lxw_chart *self)
 {
     struct xml_attribute_list attributes;
     struct xml_attribute *attribute;
-    char val[] = "ctr";
 
     LXW_INIT_ATTRIBUTES();
-    LXW_PUSH_ATTRIBUTES_STR("val", val);
+    LXW_PUSH_ATTRIBUTES_STR("val", "ctr");
 
     lxw_xml_empty_tag(self->file, "c:lblAlgn", &attributes);
 
     LXW_FREE_ATTRIBUTES();
 }
 
+/*
+ * Write the <c:majorUnit> element.
+ */
+STATIC void
+_chart_write_major_unit(lxw_chart *self, lxw_chart_axis *axis)
+{
+    struct xml_attribute_list attributes;
+    struct xml_attribute *attribute;
+
+    if (!axis->has_major_unit)
+        return;
+
+    LXW_INIT_ATTRIBUTES();
+    LXW_PUSH_ATTRIBUTES_DBL("val", axis->major_unit);
+
+    lxw_xml_empty_tag(self->file, "c:majorUnit", &attributes);
+
+    LXW_FREE_ATTRIBUTES();
+}
+
+/*
+ * Write the <c:minorUnit> element.
+ */
+STATIC void
+_chart_write_minor_unit(lxw_chart *self, lxw_chart_axis *axis)
+{
+    struct xml_attribute_list attributes;
+    struct xml_attribute *attribute;
+
+    if (!axis->has_minor_unit)
+        return;
+
+    LXW_INIT_ATTRIBUTES();
+    LXW_PUSH_ATTRIBUTES_DBL("val", axis->minor_unit);
+
+    lxw_xml_empty_tag(self->file, "c:minorUnit", &attributes);
+
+    LXW_FREE_ATTRIBUTES();
+}
+
 /*
  * Write the <c:lblOffset> element.
  */
 STATIC void
-_chart_write_lbl_offset(lxw_chart *self)
+_chart_write_label_offset(lxw_chart *self)
 {
     struct xml_attribute_list attributes;
     struct xml_attribute *attribute;
-    char val[] = "100";
 
     LXW_INIT_ATTRIBUTES();
-    LXW_PUSH_ATTRIBUTES_STR("val", val);
+    LXW_PUSH_ATTRIBUTES_STR("val", "100");
 
     lxw_xml_empty_tag(self->file, "c:lblOffset", &attributes);
 
@@ -2753,10 +2791,10 @@ _chart_write_cat_axis(lxw_chart *self)
     _chart_write_auto(self);
 
     /* Write the c:lblAlgn element. */
-    _chart_write_lbl_algn(self);
+    _chart_write_label_align(self);
 
     /* Write the c:lblOffset element. */
-    _chart_write_lbl_offset(self);
+    _chart_write_label_offset(self);
 
     lxw_xml_end_tag(self->file, "c:catAx");
 }
@@ -2822,6 +2860,12 @@ _chart_write_val_axis(lxw_chart *self)
     /* Write the c:crossBetween element. */
     _chart_write_cross_between(self, self->x_axis->position_axis);
 
+    /* Write the c:majorUnit element. */
+    _chart_write_major_unit(self, self->y_axis);
+
+    /* Write the c:minorUnit element. */
+    _chart_write_minor_unit(self, self->y_axis);
+
     lxw_xml_end_tag(self->file, "c:valAx");
 }
 
@@ -2886,6 +2930,12 @@ _chart_write_cat_val_axis(lxw_chart *self)
     /* Write the c:crossBetween element. */
     _chart_write_cross_between(self, self->y_axis->position_axis);
 
+    /* Write the c:majorUnit element. */
+    _chart_write_major_unit(self, self->x_axis);
+
+    /* Write the c:minorUnit element. */
+    _chart_write_minor_unit(self, self->x_axis);
+
     lxw_xml_end_tag(self->file, "c:valAx");
 }
 
@@ -3543,7 +3593,7 @@ lxw_chart_add_data_cache(lxw_series_range *range, uint8_t *data,
     /* Initialize the series range data cache. */
     for (i = 0; i < rows; i++) {
         data_point = calloc(1, sizeof(struct lxw_series_data_point));
-	RETURN_ON_MEM_ERROR(data_point, LXW_ERROR_MEMORY_MALLOC_FAILED);
+        RETURN_ON_MEM_ERROR(data_point, LXW_ERROR_MEMORY_MALLOC_FAILED);
         STAILQ_INSERT_TAIL(range->data_cache, data_point, list_pointers);
         data_point->number = data[i * cols + col];
     }
@@ -3998,6 +4048,30 @@ chart_axis_set_log_base(lxw_chart_axis *axis, uint16_t log_base)
         axis->log_base = log_base;
 }
 
+/*
+ * Set major unit for a value axis.
+ */
+void
+chart_axis_set_major_unit(lxw_chart_axis *axis, double unit)
+{
+    LXW_WARN_VALUE_AND_DATE_AXIS_ONLY("chart_axis_set_major_unit");
+
+    axis->has_major_unit = LXW_TRUE;
+    axis->major_unit = unit;
+}
+
+/*
+ * Set minor unit for a value axis.
+ */
+void
+chart_axis_set_minor_unit(lxw_chart_axis *axis, double unit)
+{
+    LXW_WARN_VALUE_AND_DATE_AXIS_ONLY("chart_axis_set_minor_unit");
+
+    axis->has_minor_unit = LXW_TRUE;
+    axis->minor_unit = unit;
+}
+
 /*
  * Set the axis major gridlines on/off.
  */

test/functional/src/test_chart_axis15.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_axis15.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 = 45705856;
+    chart->axis_id_2 = 54518528;
+
+    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_set_major_unit(chart->y_axis, 2);
+    chart_axis_set_minor_unit(chart->y_axis, 0.4);
+
+    worksheet_insert_chart(worksheet, CELL("E9"), chart);
+
+    return workbook_close(workbook);
+}

test/functional/src/test_chart_scatter06.c

@@ -0,0 +1,55 @@
+/*****************************************************************************
+ * 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_scatter06.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 = 57708544;
+    chart->axis_id_2 = 44297600;
+
+    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_set_major_unit(chart->x_axis, 3);
+    chart_axis_set_minor_unit(chart->x_axis, 1);
+
+    chart_axis_set_major_unit(chart->y_axis, 4);
+    chart_axis_set_minor_unit(chart->y_axis, 2);
+
+
+    worksheet_insert_chart(worksheet, CELL("E9"), chart);
+
+    return workbook_close(workbook);
+}

test/functional/test_chart_axis.py

@@ -53,6 +53,9 @@ class TestCompareXLSXFiles(base_test_class.XLSXBaseTest):
     # def test_chart_axis14(self):
     #     self.run_exe_test('test_chart_axis14')
 
+    def test_chart_axis15(self):
+        self.run_exe_test('test_chart_axis15')
+
     def test_chart_axis17(self):
         self.run_exe_test('test_chart_axis17')
 

test/functional/test_chart_scatter.py

@@ -28,6 +28,8 @@ class TestCompareXLSXFiles(base_test_class.XLSXBaseTest):
     def test_chart_scatter05(self):
         self.run_exe_test('test_chart_scatter05')
 
+    def test_chart_scatter06(self):
+        self.run_exe_test('test_chart_scatter06')
 
     def test_chart_scatter12(self):
         self.run_exe_test('test_chart_scatter12')