feat(scale): update needles when scale is transformed (#9340)

src/widgets/scale/lv_scale.c

@@ -71,6 +71,9 @@ static void scale_free_line_needle_points_cb(lv_event_t * e);
 
 static bool scale_is_major_tick(lv_scale_t * scale, uint32_t tick_idx);
 
+static lv_result_t update_needle(lv_scale_t * scale, lv_obj_t * needle, int32_t length, int32_t value);
+static void needle_deleted_cb(lv_event_t * e);
+
 #if LV_USE_OBSERVER
     static void scale_section_min_value_observer_cb(lv_observer_t * observer, lv_subject_t * subject);
     static void scale_section_max_value_observer_cb(lv_observer_t * observer, lv_subject_t * subject);
@@ -297,6 +300,8 @@ void lv_scale_set_line_needle_value(lv_obj_t * obj, lv_obj_t * needle_line, int3
     needle_line_points[1].y = scale_height / 2 + needle_length_y;
 
     lv_line_set_points_mutable(needle_line, needle_line_points, 2);
+
+    update_needle(scale, needle_line, needle_length, value);
 }
 
 void lv_scale_set_image_needle_value(lv_obj_t * obj, lv_obj_t * needle_img, int32_t value)
@@ -320,6 +325,7 @@ void lv_scale_set_image_needle_value(lv_obj_t * obj, lv_obj_t * needle_img, int3
     }
 
     lv_image_set_rotation(needle_img, (scale->rotation + angle) * 10);
+    update_needle(scale, needle_img, 0, value);
 }
 
 void lv_scale_set_text_src(lv_obj_t * obj, const char * txt_src[])
@@ -586,6 +592,7 @@ static void lv_scale_constructor(const lv_obj_class_t * class_p, lv_obj_t * obj)
     scale->draw_ticks_on_top = false;
     scale->custom_label_cnt = 0;
     scale->txt_src = NULL;
+    lv_array_init(&scale->needles, 0, sizeof(lv_scale_needle_t));
 
     lv_obj_remove_flag(obj, LV_OBJ_FLAG_SCROLLABLE);
 
@@ -606,6 +613,13 @@ static void lv_scale_destructor(const lv_obj_class_t * class_p, lv_obj_t * obj)
     }
     lv_ll_clear(&scale->section_ll);
 
+    size_t needle_count = lv_array_size(&scale->needles);
+    for(size_t i = 0; i < needle_count; ++i) {
+        lv_scale_needle_t * scale_needle = lv_array_at(&scale->needles, i);
+        lv_obj_remove_event_cb(scale_needle->obj, needle_deleted_cb);
+    }
+    lv_array_deinit(&scale->needles);
+
     LV_TRACE_OBJ_CREATE("finished");
 }
 
@@ -656,6 +670,18 @@ static void lv_scale_event(const lv_obj_class_t * class_p, lv_event_t * event)
         /* NOTE: Extend scale draw size so the first tick label can be shown */
         lv_event_set_ext_draw_size(event, 100);
     }
+    else if(event_code == LV_EVENT_STYLE_CHANGED) {
+        size_t needle_count = lv_array_size(&scale->needles);
+        for(size_t i = 0; i < needle_count; ++i) {
+            lv_scale_needle_t * needle = lv_array_at(&scale->needles, i);
+            if(lv_obj_has_class(needle->obj, &lv_line_class)) {
+                lv_scale_set_line_needle_value(obj, needle->obj, needle->length, needle->value);
+            }
+            else {
+                lv_scale_set_image_needle_value(obj, needle->obj, needle->value);
+            }
+        }
+    }
     else {
         /* Nothing to do. Invalid event */
     }
@@ -1761,6 +1787,46 @@ static bool scale_is_major_tick(lv_scale_t * scale, uint32_t tick_idx)
     return scale->major_tick_every != 0 && tick_idx % scale->major_tick_every == 0;
 }
 
+static lv_result_t update_needle(lv_scale_t * scale, lv_obj_t * needle, int32_t length, int32_t value)
+{
+    /* First try to find the needle in the haystack (scale's needle list) */
+    size_t needle_count = lv_array_size(&scale->needles);
+    for(size_t i = 0; i < needle_count; ++i) {
+        lv_scale_needle_t * scale_needle = lv_array_at(&scale->needles, i);
+        if(scale_needle->obj == needle) {
+            scale_needle->value = value;
+            scale_needle->length = length;
+            return LV_RESULT_OK;
+        }
+    }
+
+    /* Needle is not yet part of the haystack */
+    lv_scale_needle_t scale_needle = {.obj = needle, .length = length, .value = value};
+    lv_result_t res = lv_array_push_back(&scale->needles, &scale_needle);
+    if(res != LV_RESULT_OK) {
+        LV_LOG_WARN("Failed to attach needle to scale - not enough memory");
+        return LV_RESULT_INVALID;
+    }
+
+    lv_obj_add_event_cb(needle, needle_deleted_cb, LV_EVENT_DELETE, scale);
+    return LV_RESULT_OK;
+}
+
+static void needle_deleted_cb(lv_event_t * e)
+{
+    lv_scale_t * scale = lv_event_get_user_data(e);
+    lv_obj_t * needle = lv_event_get_target_obj(e);
+
+    size_t needle_count = lv_array_size(&scale->needles);
+    for(size_t i = 0; i < needle_count; ++i) {
+        lv_scale_needle_t * scale_needle = lv_array_at(&scale->needles, i);
+        if(scale_needle->obj == needle) {
+            lv_array_remove(&scale->needles, i);
+            return;
+        }
+    }
+}
+
 #if LV_USE_OBSERVER
 
 static void scale_section_min_value_observer_cb(lv_observer_t * observer, lv_subject_t * subject)

src/widgets/scale/lv_scale_private.h

@@ -55,6 +55,11 @@ struct _lv_scale_section_t {
     uint32_t last_tick_idx_is_major  : 1;  /**< Internal (set during drawing): true if
                                             * `last_tick_idx_in_section` represents a major tick. */
 };
+typedef struct {
+    lv_obj_t * obj;
+    int32_t value;
+    int32_t length;
+} lv_scale_needle_t;
 
 struct _lv_scale_t {
     lv_obj_t obj;                      /**< Base Widget part of Scale */
@@ -77,6 +82,7 @@ struct _lv_scale_t {
     int32_t custom_label_cnt;          /**< Number of custom labels provided in `txt_src` */
     int32_t last_tick_width;           /**< Width of last tick in pixels */
     int32_t first_tick_width;          /**< Width of first tick in pixels */
+    lv_array_t needles;                /**< Needle list of this scale */
 };
 
 

tests/CMakeLists.txt

@@ -292,7 +292,9 @@ set(TEST_INCLUDE_DIRS
     $<BUILD_INTERFACE:${LVGL_CONF_DIR}>
 )
 
-file(GLOB_RECURSE TEST_IMAGES_SRC ${LVGL_TEST_DIR}/test_images/*.c)
+file(GLOB_RECURSE TEST_IMAGES_SRC 
+	${LVGL_TEST_DIR}/test_images/*.c 
+	${LVGL_TEST_DIR}/../examples/assets/*.c)
 
 add_library(test_common
     STATIC

tests/src/test_cases/widgets/test_scale.c

@@ -542,4 +542,41 @@ void test_scale_set_line_needle_value(void)
     );
 }
 
+void test_scale_needle_updates_when_style_changes(void)
+{
+
+    lv_obj_t * scale = lv_scale_create(lv_screen_active());
+
+    lv_obj_align(scale, LV_ALIGN_LEFT_MID, 0, 0);
+    lv_obj_set_style_width(scale, 200, LV_PART_MAIN);
+    lv_obj_set_style_height(scale, 200, LV_PART_MAIN);
+
+    lv_scale_set_mode(scale, LV_SCALE_MODE_ROUND_INNER);
+
+    lv_scale_set_range(scale, 0, 100);
+    lv_scale_set_angle_range(scale, 270);
+    lv_scale_set_rotation(scale, 135);
+
+    lv_scale_set_total_tick_count(scale, 20);
+    lv_scale_set_major_tick_every(scale, 5);
+
+    lv_obj_t * needle_line = lv_line_create(scale);
+    lv_obj_set_style_line_width(needle_line, 6, LV_PART_MAIN);
+    lv_obj_set_style_line_rounded(needle_line, true, LV_PART_MAIN);
+    lv_scale_set_line_needle_value(scale, needle_line, 60, 26);
+
+    LV_IMAGE_DECLARE(img_hand);
+    lv_obj_t * needle_img = lv_image_create(scale);
+    lv_image_set_src(needle_img, &img_hand);
+    lv_scale_set_image_needle_value(scale, needle_img, 78);
+    lv_obj_align(needle_img, LV_ALIGN_CENTER, 47, -2);
+    lv_image_set_pivot(needle_img, 3, 4);
+
+    TEST_ASSERT_EQUAL_SCREENSHOT("widgets/scale_7.png");
+
+    lv_obj_align(scale, LV_ALIGN_RIGHT_MID, 0, 0);
+
+    TEST_ASSERT_EQUAL_SCREENSHOT("widgets/scale_8.png");
+}
+
 #endif