feat(arc): add lv_arc_align_obj_to_angle and lv_arc_rotate_obj_to_angle

examples/widgets/arc/lv_example_arc_1.c

@@ -2,15 +2,34 @@
 
 #if LV_USE_ARC && LV_BUILD_EXAMPLES
 
+static void value_changed_event_cb(lv_event_t * e);
+
 void lv_example_arc_1(void)
 {
+    lv_obj_t * label = lv_label_create(lv_scr_act());
+
     /*Create an Arc*/
     lv_obj_t * arc = lv_arc_create(lv_scr_act());
     lv_obj_set_size(arc, 150, 150);
     lv_arc_set_rotation(arc, 135);
     lv_arc_set_bg_angles(arc, 0, 270);
-    lv_arc_set_value(arc, 40);
+    lv_arc_set_value(arc, 10);
     lv_obj_center(arc);
+    lv_obj_add_event_cb(arc, value_changed_event_cb, LV_EVENT_VALUE_CHANGED, label);
+
+    /*Manually update the label for the first time*/
+    lv_event_send(arc, LV_EVENT_VALUE_CHANGED, NULL);
+}
+
+static void value_changed_event_cb(lv_event_t * e)
+{
+    lv_obj_t * arc = lv_event_get_target(e);
+    lv_obj_t * label = lv_event_get_user_data(e);
+
+    lv_label_set_text_fmt(label, "%d%%", lv_arc_get_value(arc));
+
+    /*Rotate the label to the current position of the arc*/
+    lv_arc_rotate_obj_to_angle(arc, label, 25);
 }
 
 #endif

src/widgets/lv_arc.c

@@ -35,7 +35,8 @@ static void lv_arc_draw(lv_event_t * e);
 static void lv_arc_event(const lv_obj_class_t * class_p, lv_event_t * e);
 static void inv_arc_area(lv_obj_t * arc, uint16_t start_angle, uint16_t end_angle, lv_part_t part);
 static void inv_knob_area(lv_obj_t * obj);
-static void get_center(lv_obj_t * obj, lv_point_t * center, lv_coord_t * arc_r);
+static void get_center(const lv_obj_t * obj, lv_point_t * center, lv_coord_t * arc_r);
+static lv_coord_t get_angle(const lv_obj_t * obj);
 static void get_knob_area(lv_obj_t * arc, const lv_point_t * center, lv_coord_t r, lv_area_t * knob_area);
 static void value_update(lv_obj_t * arc);
 
@@ -317,6 +318,60 @@ lv_arc_mode_t lv_arc_get_mode(const lv_obj_t * obj)
     return ((lv_arc_t *) obj)->type;
 }
 
+/*=====================
+ * Other functions
+ *====================*/
+
+
+void lv_arc_align_obj_to_angle(const lv_obj_t * obj, lv_obj_t * obj_to_align, lv_coord_t r_offset)
+{
+    LV_ASSERT_OBJ(obj, MY_CLASS);
+    LV_ASSERT_NULL(obj_to_align);
+
+    lv_obj_update_layout(obj);
+
+    lv_point_t center;
+    lv_coord_t arc_r;
+    get_center(obj, &center, &arc_r);
+    lv_coord_t indic_width = lv_obj_get_style_arc_width(obj, LV_PART_INDICATOR);
+    lv_coord_t indic_width_half = indic_width / 2;
+    arc_r -= indic_width_half;
+    arc_r += r_offset;
+
+    uint16_t angle = get_angle(obj);
+    lv_coord_t knob_x = (arc_r * lv_trigo_sin(angle + 90)) >> LV_TRIGO_SHIFT;
+    lv_coord_t knob_y = (arc_r * lv_trigo_sin(angle)) >> LV_TRIGO_SHIFT;
+    lv_obj_align_to(obj_to_align, obj, LV_ALIGN_CENTER, knob_x, knob_y);
+}
+
+void lv_arc_rotate_obj_to_angle(const lv_obj_t * obj, lv_obj_t * obj_to_rotate, lv_coord_t r_offset)
+{
+    LV_ASSERT_OBJ(obj, MY_CLASS);
+    LV_ASSERT_NULL(obj_to_rotate);
+
+    lv_obj_update_layout(obj);
+
+    lv_point_t center;
+    lv_coord_t arc_r;
+    get_center(obj, &center, &arc_r);
+    lv_coord_t indic_width = lv_obj_get_style_arc_width(obj, LV_PART_INDICATOR);
+    lv_coord_t indic_width_half = indic_width / 2;
+    arc_r -= indic_width_half;
+
+    arc_r += r_offset;
+    lv_obj_align_to(obj_to_rotate, obj, LV_ALIGN_CENTER, 0, -arc_r);
+
+    lv_obj_update_layout(obj);
+
+    uint16_t angle = get_angle(obj);
+    lv_coord_t pivot_x = obj_to_rotate->coords.x1 - center.x;
+    lv_coord_t pivot_y = obj_to_rotate->coords.y1 - center.y;
+    lv_obj_set_style_transform_pivot_x(obj_to_rotate, -pivot_x, 0);
+    lv_obj_set_style_transform_pivot_y(obj_to_rotate, -pivot_y, 0);
+    lv_obj_set_style_transform_angle(obj_to_rotate, angle * 10 + 900, 0);
+}
+
+
 /**********************
  *   STATIC FUNCTIONS
  **********************/
@@ -345,7 +400,7 @@ static void lv_arc_constructor(const lv_obj_class_t * class_p, lv_obj_t * obj)
     arc->last_angle = arc->indic_angle_end;
 
     lv_obj_add_flag(obj, LV_OBJ_FLAG_CLICKABLE);
-    lv_obj_clear_flag(obj, LV_OBJ_FLAG_SCROLL_CHAIN);
+    lv_obj_clear_flag(obj, LV_OBJ_FLAG_SCROLL_CHAIN | LV_OBJ_FLAG_SCROLLABLE);
     lv_obj_set_ext_click_area(obj, LV_DPI_DEF / 10);
 
 
@@ -675,7 +730,7 @@ static void inv_knob_area(lv_obj_t * obj)
     lv_obj_invalidate_area(obj, &a);
 }
 
-static void get_center(lv_obj_t * obj, lv_point_t * center, lv_coord_t * arc_r)
+static void get_center(const lv_obj_t * obj, lv_point_t * center, lv_coord_t * arc_r)
 {
     lv_coord_t left_bg = lv_obj_get_style_pad_left(obj, LV_PART_MAIN);
     lv_coord_t right_bg = lv_obj_get_style_pad_right(obj, LV_PART_MAIN);
@@ -691,15 +746,9 @@ static void get_center(lv_obj_t * obj, lv_point_t * center, lv_coord_t * arc_r)
     if(arc_r) *arc_r = r;
 }
 
-static void get_knob_area(lv_obj_t * obj, const lv_point_t * center, lv_coord_t r, lv_area_t * knob_area)
+static lv_coord_t get_angle(const lv_obj_t * obj)
 {
-    LV_ASSERT_OBJ(obj, MY_CLASS);
     lv_arc_t * arc = (lv_arc_t *)obj;
-
-    lv_coord_t indic_width = lv_obj_get_style_arc_width(obj, LV_PART_INDICATOR);
-    lv_coord_t indic_width_half = indic_width / 2;
-    r -= indic_width_half;
-
     uint16_t angle = arc->rotation;
     if(arc->type == LV_ARC_MODE_NORMAL) {
         angle += arc->indic_angle_end;
@@ -712,6 +761,18 @@ static void get_knob_area(lv_obj_t * obj, const lv_point_t * center, lv_coord_t
         if(arc->value < range_midpoint) angle += arc->indic_angle_start;
         else angle += arc->indic_angle_end;
     }
+
+    return angle;
+}
+
+
+static void get_knob_area(lv_obj_t * obj, const lv_point_t * center, lv_coord_t r, lv_area_t * knob_area)
+{
+    lv_coord_t indic_width = lv_obj_get_style_arc_width(obj, LV_PART_INDICATOR);
+    lv_coord_t indic_width_half = indic_width / 2;
+    r -= indic_width_half;
+
+    lv_coord_t angle = get_angle(obj);
     lv_coord_t knob_x = (r * lv_trigo_sin(angle + 90)) >> LV_TRIGO_SHIFT;
     lv_coord_t knob_y = (r * lv_trigo_sin(angle)) >> LV_TRIGO_SHIFT;
 
@@ -765,6 +826,7 @@ static void value_update(lv_obj_t * obj)
         case LV_ARC_MODE_NORMAL:
             angle = lv_map(arc->value, arc->min_value, arc->max_value, arc->bg_angle_start, bg_end);
             lv_arc_set_angles(obj, arc->bg_angle_start, angle);
+
             break;
         default:
             LV_LOG_WARN("Invalid mode: %d", arc->type);

src/widgets/lv_arc.h

@@ -85,83 +85,83 @@ lv_obj_t * lv_arc_create(lv_obj_t * parent);
 
 /**
  * Set the start angle of an arc. 0 deg: right, 90 bottom, etc.
- * @param arc   pointer to an arc object
+ * @param obj   pointer to an arc object
  * @param start the start angle
  */
-void lv_arc_set_start_angle(lv_obj_t * arc, uint16_t start);
+void lv_arc_set_start_angle(lv_obj_t * obj, uint16_t start);
 
 /**
  * Set the end angle of an arc. 0 deg: right, 90 bottom, etc.
- * @param arc   pointer to an arc object
+ * @param obj   pointer to an arc object
  * @param end   the end angle
  */
-void lv_arc_set_end_angle(lv_obj_t * arc, uint16_t end);
+void lv_arc_set_end_angle(lv_obj_t * obj, uint16_t end);
 
 /**
  * Set the start and end angles
- * @param arc   pointer to an arc object
+ * @param obj   pointer to an arc object
  * @param start the start angle
  * @param end   the end angle
  */
-void lv_arc_set_angles(lv_obj_t * arc, uint16_t start, uint16_t end);
+void lv_arc_set_angles(lv_obj_t * obj, uint16_t start, uint16_t end);
 
 /**
  * Set the start angle of an arc background. 0 deg: right, 90 bottom, etc.
- * @param arc   pointer to an arc object
+ * @param obj   pointer to an arc object
  * @param start the start angle
  */
-void lv_arc_set_bg_start_angle(lv_obj_t * arc, uint16_t start);
+void lv_arc_set_bg_start_angle(lv_obj_t * obj, uint16_t start);
 
 /**
  * Set the start angle of an arc background. 0 deg: right, 90 bottom etc.
- * @param arc   pointer to an arc object
+ * @param obj   pointer to an arc object
  * @param end   the end angle
  */
-void lv_arc_set_bg_end_angle(lv_obj_t * arc, uint16_t end);
+void lv_arc_set_bg_end_angle(lv_obj_t * obj, uint16_t end);
 
 /**
  * Set the start and end angles of the arc background
- * @param arc   pointer to an arc object
+ * @param obj   pointer to an arc object
  * @param start the start angle
  * @param end   the end angle
  */
-void lv_arc_set_bg_angles(lv_obj_t * arc, uint16_t start, uint16_t end);
+void lv_arc_set_bg_angles(lv_obj_t * obj, uint16_t start, uint16_t end);
 
 /**
  * Set the rotation for the whole arc
- * @param arc       pointer to an arc object
+ * @param obj       pointer to an arc object
  * @param rotation  rotation angle
  */
-void lv_arc_set_rotation(lv_obj_t * arc, uint16_t rotation);
+void lv_arc_set_rotation(lv_obj_t * obj, uint16_t rotation);
 
 /**
  * Set the type of arc.
- * @param arc   pointer to arc object
+ * @param obj   pointer to arc object
  * @param mode  arc's mode
  */
-void lv_arc_set_mode(lv_obj_t * arc, lv_arc_mode_t type);
+void lv_arc_set_mode(lv_obj_t * obj, lv_arc_mode_t type);
 
 /**
  * Set a new value on the arc
- * @param arc   pointer to an arc object
+ * @param obj   pointer to an arc object
  * @param value new value
  */
-void lv_arc_set_value(lv_obj_t * arc, int16_t value);
+void lv_arc_set_value(lv_obj_t * obj, int16_t value);
 
 /**
  * Set minimum and the maximum values of an arc
- * @param arc   pointer to the arc object
+ * @param obj   pointer to the arc object
  * @param min   minimum value
  * @param max   maximum value
  */
-void lv_arc_set_range(lv_obj_t * arc, int16_t min, int16_t max);
+void lv_arc_set_range(lv_obj_t * obj, int16_t min, int16_t max);
 
 /**
  * Set a change rate to limit the speed how fast the arc should reach the pressed point.
- * @param arc       pointer to an arc object
+ * @param obj       pointer to an arc object
  * @param rate      the change rate
  */
-void lv_arc_set_change_rate(lv_obj_t * arc, uint16_t rate);
+void lv_arc_set_change_rate(lv_obj_t * obj, uint16_t rate);
 
 /*=====================
  * Getter functions
@@ -169,56 +169,56 @@ void lv_arc_set_change_rate(lv_obj_t * arc, uint16_t rate);
 
 /**
  * Get the start angle of an arc.
- * @param arc   pointer to an arc object
+ * @param obj   pointer to an arc object
  * @return      the start angle [0..360]
  */
 uint16_t lv_arc_get_angle_start(lv_obj_t * obj);
 
 /**
  * Get the end angle of an arc.
- * @param arc   pointer to an arc object
+ * @param obj   pointer to an arc object
  * @return      the end angle [0..360]
  */
 uint16_t lv_arc_get_angle_end(lv_obj_t * obj);
 
 /**
  * Get the start angle of an arc background.
- * @param arc   pointer to an arc object
+ * @param obj   pointer to an arc object
- * @return the  start angle [0..360]
+ * @return      the  start angle [0..360]
  */
 uint16_t lv_arc_get_bg_angle_start(lv_obj_t * obj);
 
 /**
  * Get the end angle of an arc background.
- * @param arc   pointer to an arc object
+ * @param obj   pointer to an arc object
  * @return      the end angle [0..360]
  */
 uint16_t lv_arc_get_bg_angle_end(lv_obj_t * obj);
 
 /**
  * Get the value of an arc
- * @param arc       pointer to an arc object
+ * @param obj       pointer to an arc object
- * @return the      value of the arc
+ * @return          the value of the arc
  */
 int16_t lv_arc_get_value(const lv_obj_t * obj);
 
 /**
  * Get the minimum value of an arc
- * @param arc   pointer to an arc object
+ * @param obj   pointer to an arc object
  * @return      the minimum value of the arc
  */
 int16_t lv_arc_get_min_value(const lv_obj_t * obj);
 
 /**
  * Get the maximum value of an arc
- * @param arc   pointer to an arc object
+ * @param obj   pointer to an arc object
  * @return      the maximum value of the arc
  */
 int16_t lv_arc_get_max_value(const lv_obj_t * obj);
 
 /**
  * Get whether the arc is type or not.
- * @param arc       pointer to an arc object
+ * @param obj       pointer to an arc object
  * @return          arc's mode
  */
 lv_arc_mode_t lv_arc_get_mode(const lv_obj_t * obj);
@@ -227,6 +227,22 @@ lv_arc_mode_t lv_arc_get_mode(const lv_obj_t * obj);
  * Other functions
  *====================*/
 
+/**
+ * Align an object to the current position of the arc (knob)
+ * @param obj           pointer to an arc object
+ * @param obj_to_align  pointer to an object to align
+ * @param r_offset      consider the radius larger with this value (< 0: for smaller radius)
+ */
+void lv_arc_align_obj_to_angle(const lv_obj_t * obj, lv_obj_t * obj_to_align, lv_coord_t r_offset);
+
+/**
+ * Rotate an object to the current position of the arc (knob)
+ * @param obj           pointer to an arc object
+ * @param obj_to_align  pointer to an object to rotate
+ * @param r_offset      consider the radius larger with this value (< 0: for smaller radius)
+ */
+void lv_arc_rotate_obj_to_angle(const lv_obj_t * obj, lv_obj_t * obj_to_rotate, lv_coord_t r_offset);
+
 /**********************
  *      MACROS
  **********************/