feature(calendar): add interface to set a custom year list (#5227)

docs/widgets/calendar.rst

@@ -74,6 +74,14 @@ looks like ``const char * day_names[7] = {"Su", "Mo", ...};`` Only the
 pointer of the day names is saved so the elements should be static,
 global or constant variables.
 
+Custom year list
+----------------
+
+Sets a custom year list with :cpp:expr:`lv_calendar_header_dropdown_set_year_list(calendar, years_list)`
+where ``years_list`` is a pointer to the custom years list. It can be a constant string
+like ``static const char * years = "2023\n2022\n2021\n2020\n2019";``, 
+or can be generated dynamically into a buffer as well.
+
 .. _lv_calendar_events:
 
 Events

src/widgets/calendar/lv_calendar_header_dropdown.c

@@ -68,6 +68,31 @@ lv_obj_t * lv_calendar_header_dropdown_create(lv_obj_t * parent)
     return obj;
 }
 
+void lv_calendar_header_dropdown_set_year_list(lv_obj_t * parent, const char * years_list)
+{
+    /* Search for the header dropdown */
+    lv_obj_t * header = lv_obj_get_child_by_type(parent, 0, &lv_calendar_header_dropdown_class);
+    if(NULL == header) {
+        /* Header not found */
+        return;
+    }
+
+    /* Search for the year dropdown
+     * Index is 0 because in the header dropdown constructor the year dropdpwn (year_dd)
+     * is the first created child of the header */
+    const int32_t year_dropdown_index = 0;
+    lv_obj_t * year_dropdown = lv_obj_get_child_by_type(header, year_dropdown_index, &lv_dropdown_class);
+    if(NULL == year_dropdown) {
+        /* year dropdpwn not found */
+        return;
+    }
+
+    lv_dropdown_clear_options(year_dropdown);
+    lv_dropdown_set_options(year_dropdown, years_list);
+
+    lv_obj_invalidate(parent);
+}
+
 /**********************
  *  STATIC FUNCTIONS
  **********************/
@@ -121,8 +146,15 @@ static void year_event_cb(lv_event_t * e)
 
     const lv_calendar_date_t * d;
     d = lv_calendar_get_showed_date(calendar);
+
+    /* Get the first year on the options list
+     * NOTE: Assumes the first 4 digits in the option list are numbers */
+    const char * year_p = lv_dropdown_get_options(dropdown);
+    const uint32_t year = (year_p[0] - '0') * 1000 + (year_p[1] - '0') * 100 + (year_p[2] - '0') * 10 +
+                          (year_p[3] - '0');
+
     lv_calendar_date_t newd = *d;
-    newd.year = 2023 - sel;
+    newd.year = year - sel;
 
     lv_calendar_set_showed_date(calendar, newd.year, newd.month);
 }
@@ -134,7 +166,14 @@ static void value_changed_event_cb(lv_event_t * e)
     const lv_calendar_date_t * cur_date = lv_calendar_get_showed_date(calendar);
 
     lv_obj_t * year_dd = lv_obj_get_child(header, 0);
-    lv_dropdown_set_selected(year_dd, 2023 - cur_date->year);
+
+    /* Get the first year on the options list
+     * NOTE: Assumes the first 4 digits in the option list are numbers */
+    const char * year_p = lv_dropdown_get_options(year_dd);
+    const uint32_t year = (year_p[0] - '0') * 1000 + (year_p[1] - '0') * 100 + (year_p[2] - '0') * 10 +
+                          (year_p[3] - '0');
+
+    lv_dropdown_set_selected(year_dd, year - cur_date->year);
 
     lv_obj_t * month_dd = lv_obj_get_child(header, 1);
     lv_dropdown_set_selected(month_dd, cur_date->month - 1);

src/widgets/calendar/lv_calendar_header_dropdown.h

@@ -36,6 +36,15 @@ LV_ATTRIBUTE_EXTERN_DATA extern const lv_obj_class_t lv_calendar_header_dropdown
  */
 lv_obj_t * lv_calendar_header_dropdown_create(lv_obj_t * parent);
 
+/**
+ * Sets a custom calendar year list
+ * @param parent        pointer to a calendar object
+ * @param years_list    pointer to an const char array with the years list, see lv_dropdown set_options for more information.
+ *                      E.g. `const char * years = "2023\n2022\n2021\n2020\n2019"
+ *                      Only the pointer will be saved so this variable can't be local which will be destroyed later.
+ */
+void lv_calendar_header_dropdown_set_year_list(lv_obj_t * parent, const char * years_list);
+
 /**********************
  *      MACROS
  **********************/

tests/src/test_cases/widgets/test_calendar.c

@@ -208,4 +208,16 @@ void test_calendar_get_btnmatrix(void)
     TEST_ASSERT_NOT_NULL(btnm);
 }
 
+void test_calendar_custom_year_list(void)
+{
+    lv_obj_t  * calendar = lv_calendar_create(lv_screen_active());
+
+    lv_calendar_header_dropdown_create(calendar);
+
+    const char * years = "2024\n2023\n2022\n2021\n2020\n2019";
+    lv_calendar_header_dropdown_set_year_list(calendar, years);
+
+    TEST_ASSERT_EQUAL_SCREENSHOT("widgets/calendar_08.png");
+}
+
 #endif