examples(scale): Compass style rotating scale (#8445)

examples/widgets/lv_example_widgets.h

@@ -137,6 +137,7 @@ void lv_example_scale_8(void);
 void lv_example_scale_9(void);
 void lv_example_scale_10(void);
 void lv_example_scale_11(void);
+void lv_example_scale_12(void);
 
 void lv_example_slider_1(void);
 void lv_example_slider_2(void);

examples/widgets/scale/index.rst

@@ -64,6 +64,12 @@ A round scale style simulating a sunset/sunrise widget
 .. lv_example:: widgets/scale/lv_example_scale_11
   :language: c
 
+A round scale style simulating a compass
+----------------------------------------
+
+.. lv_example:: widgets/scale/lv_example_scale_12
+  :language: c
+
 Axis ticks and labels with scrolling on a chart
 -----------------------------------------------
 .. lv_example:: widgets/chart/lv_example_chart_2

examples/widgets/scale/lv_example_scale_12.c

@@ -0,0 +1,109 @@
+#include "../../lv_examples.h"
+#if LV_USE_SCALE && LV_BUILD_EXAMPLES
+
+static lv_obj_t * scale;
+static lv_obj_t * label;
+
+static const char * heading_to_cardinal(int32_t heading)
+{
+    /* Normalize heading to range [0, 360) */
+    while(heading < 0) heading += 360;
+    while(heading >= 360) heading -= 360;
+
+    if(heading < 23) return "N";
+    else if(heading < 68) return "NE";
+    else if(heading < 113) return "E";
+    else if(heading < 158) return "SE";
+    else if(heading < 203) return "S";
+    else if(heading < 248) return "SW";
+    else if(heading < 293) return "W";
+    else if(heading < 338) return "NW";
+
+    return "N";
+}
+
+static void set_heading_value(void * obj, int32_t v)
+{
+    LV_UNUSED(obj);
+    lv_scale_set_rotation(scale, 270 - v);
+    lv_label_set_text_fmt(label, "%d°\n%s", v, heading_to_cardinal(v));
+}
+
+static void draw_event_cb(lv_event_t * e)
+{
+    lv_draw_task_t * draw_task = lv_event_get_draw_task(e);
+    lv_draw_dsc_base_t * base_dsc = (lv_draw_dsc_base_t *)lv_draw_task_get_draw_dsc(draw_task);
+    lv_draw_label_dsc_t * label_draw_dsc = lv_draw_task_get_label_dsc(draw_task);
+    lv_draw_line_dsc_t * line_draw_dsc = lv_draw_task_get_line_dsc(draw_task);
+    if(base_dsc->part == LV_PART_INDICATOR) {
+        if(label_draw_dsc) {
+            if(base_dsc->id1 == 0) {
+                label_draw_dsc->color = lv_palette_main(LV_PALETTE_RED);
+            }
+        }
+        if(line_draw_dsc) {
+            if(base_dsc->id1 == 60) {
+                line_draw_dsc->color = lv_palette_main(LV_PALETTE_RED);
+            }
+        }
+    }
+}
+
+/**
+ * A round scale style simulating a compass
+ */
+void lv_example_scale_12(void)
+{
+    scale = lv_scale_create(lv_screen_active());
+
+    lv_obj_set_size(scale, 200, 200);
+    lv_scale_set_mode(scale, LV_SCALE_MODE_ROUND_INNER);
+    lv_obj_set_align(scale, LV_ALIGN_CENTER);
+
+    lv_scale_set_total_tick_count(scale, 61);
+    lv_scale_set_major_tick_every(scale, 5);
+
+    lv_obj_set_style_length(scale, 5, LV_PART_ITEMS);
+    lv_obj_set_style_length(scale, 10, LV_PART_INDICATOR);
+    lv_obj_set_style_line_width(scale, 3, LV_PART_INDICATOR);
+    lv_scale_set_range(scale, 0, 360);
+
+    static const char * custom_labels[] = {"N", "30", "60", "E", "120", "150", "S", "210", "240", "W", "300", "330", NULL};
+    lv_scale_set_text_src(scale, custom_labels);
+
+    lv_scale_set_angle_range(scale, 360);
+    lv_scale_set_rotation(scale, 270);
+
+    lv_obj_add_event_cb(scale, draw_event_cb, LV_EVENT_DRAW_TASK_ADDED, NULL);
+    lv_obj_add_flag(scale, LV_OBJ_FLAG_SEND_DRAW_TASK_EVENTS);
+
+    label = lv_label_create(lv_screen_active());
+    lv_obj_set_width(label, 100);
+    lv_obj_set_align(label, LV_ALIGN_CENTER);
+    lv_label_set_text(label, "0°\nN");
+    lv_obj_set_style_text_align(label, LV_TEXT_ALIGN_CENTER, 0);
+
+    set_heading_value(NULL, 0);
+
+    lv_obj_t * symbol = lv_label_create(scale);
+    lv_obj_set_align(symbol, LV_ALIGN_TOP_MID);
+    lv_obj_set_y(symbol, 5);
+    lv_label_set_text(symbol, LV_SYMBOL_UP);
+    lv_obj_set_style_text_align(symbol, LV_TEXT_ALIGN_CENTER, 0);
+    lv_obj_set_style_text_color(symbol, lv_palette_main(LV_PALETTE_RED), 0);
+
+    lv_anim_t anim_scale;
+    lv_anim_init(&anim_scale);
+    lv_anim_set_var(&anim_scale, scale);
+    lv_anim_set_exec_cb(&anim_scale, set_heading_value);
+    lv_anim_set_duration(&anim_scale, 5000);
+    lv_anim_set_repeat_delay(&anim_scale, 500);
+    lv_anim_set_repeat_count(&anim_scale, LV_ANIM_REPEAT_INFINITE);
+    lv_anim_set_reverse_duration(&anim_scale, 5000);
+    lv_anim_set_reverse_delay(&anim_scale, 500);
+    lv_anim_set_values(&anim_scale, 0, 360);
+    lv_anim_start(&anim_scale);
+
+}
+
+#endif