feat(span): add lv_spangroup_bind_span_text and lv_spangroup_set_span_text_fmt

examples/widgets/span/lv_example_span_1.c

@@ -24,6 +24,10 @@ void lv_example_span_1(void)
     lv_style_set_border_color(&style, lv_palette_main(LV_PALETTE_ORANGE));
     lv_style_set_pad_all(&style, 2);
 
+    static lv_subject_t subject;
+    lv_subject_init_int(&subject, 23);
+
+
     lv_obj_t * spans = lv_spangroup_create(lv_screen_active());
     /* Setting a fixed width and height to LV_SIZE_CONTENT will make the text wrap */
     lv_obj_set_width(spans, 300);
@@ -36,14 +40,15 @@ void lv_example_span_1(void)
     lv_spangroup_set_overflow(spans, LV_SPAN_OVERFLOW_CLIP);
     lv_spangroup_set_indent(spans, 20);
 
+
     lv_span_t * span = lv_spangroup_add_span(spans);
-    lv_span_set_text(span, "China is a beautiful country.");
+    lv_span_set_text(span, "good good study, day day up.");
     lv_style_set_text_color(lv_span_get_style(span), lv_palette_main(LV_PALETTE_RED));
     lv_style_set_text_decor(lv_span_get_style(span), LV_TEXT_DECOR_UNDERLINE);
     lv_style_set_text_opa(lv_span_get_style(span), LV_OPA_50);
 
     span = lv_spangroup_add_span(spans);
-    lv_span_set_text_static(span, "good good study, day day up.");
+    lv_spangroup_bind_span_text(spans, span, &subject, "%d users");
 #if LV_FONT_MONTSERRAT_24
     lv_style_set_text_font(lv_span_get_style(span),  &lv_font_montserrat_24);
 #endif

src/misc/lv_text_private.h

@@ -80,7 +80,7 @@ void lv_text_ins(char * txt_buf, uint32_t pos, const char * ins_txt);
 void lv_text_cut(char * txt, uint32_t pos, uint32_t len);
 
 /**
- * return a new formatted text. Memory will be allocated to store the text.
+ * Return a new formatted text. Memory will be allocated to store the text.
  * @param fmt `printf`-like format
  * @param ap items to print
 

src/others/observer/lv_observer.c

@@ -55,6 +55,17 @@ typedef struct {
     const char * value;
 } subject_set_string_user_data_t;
 
+typedef struct {
+    lv_subject_t * subject;
+    void * element; /**< E.g. span of a span group*/
+    const char * fmt;
+} bind_element_string_t;
+
+typedef struct {
+    lv_subject_t * subject;
+    void * element; /**< E.g. min_value of a scale section*/
+    int32_t * num;
+} bind_element_num_t;
 
 typedef struct {
     lv_subject_t * subject;
@@ -92,6 +103,10 @@ static void lv_subject_notify_if_changed(lv_subject_t * subject);
     static void label_text_observer_cb(lv_observer_t * observer, lv_subject_t * subject);
 #endif
 
+#if LV_USE_SPAN
+    static void span_text_observer_cb(lv_observer_t * observer, lv_subject_t * subject);
+#endif
+
 #if LV_USE_ARC
     static void arc_value_changed_event_cb(lv_event_t * e);
     static void arc_value_observer_cb(lv_observer_t * observer, lv_subject_t * subject);
@@ -779,6 +794,54 @@ lv_observer_t * lv_label_bind_text(lv_obj_t * obj, lv_subject_t * subject, const
 }
 #endif /*LV_USE_LABEL*/
 
+#if LV_USE_SPAN
+lv_observer_t * lv_spangroup_bind_span_text(lv_obj_t * obj, lv_span_t * span, lv_subject_t * subject, const char * fmt)
+{
+    LV_ASSERT_NULL(subject);
+    LV_ASSERT_NULL(obj);
+    LV_ASSERT_NULL(span);
+
+    if(fmt == NULL) {
+        if(subject->type == LV_SUBJECT_TYPE_INT) {
+            fmt = "%d";
+        }
+#if LV_USE_FLOAT
+        else if(subject->type == LV_SUBJECT_TYPE_FLOAT) {
+            fmt = "%0.1f";
+        }
+#endif
+        else if(subject->type != LV_SUBJECT_TYPE_STRING && subject->type != LV_SUBJECT_TYPE_POINTER) {
+            LV_LOG_WARN("Incompatible subject type: %d", subject->type);
+            return NULL;
+        }
+    }
+    else {
+        if(subject->type != LV_SUBJECT_TYPE_STRING && subject->type != LV_SUBJECT_TYPE_POINTER &&
+           subject->type != LV_SUBJECT_TYPE_INT && subject->type != LV_SUBJECT_TYPE_FLOAT) {
+            LV_LOG_WARN("Incompatible subject type: %d", subject->type);
+            return NULL;
+        }
+    }
+
+    bind_element_string_t * user_data = lv_zalloc(sizeof(bind_element_string_t));
+    if(user_data == NULL) {
+        LV_LOG_WARN("Couldn't allocate user_data");
+        LV_ASSERT_MALLOC(user_data);
+        return NULL;
+    }
+
+    user_data->subject = subject;
+    user_data->element = span;
+    user_data->fmt = fmt;
+
+    lv_observer_t * observer = lv_subject_add_observer_obj(subject, span_text_observer_cb, obj, user_data);
+    observer->auto_free_user_data = 1;
+
+    return observer;
+}
+#endif /*LV_USE_SPAN*/
+
+
 #if LV_USE_ARC
 lv_observer_t * lv_arc_bind_value(lv_obj_t * obj, lv_subject_t * subject)
 {
@@ -1090,6 +1153,39 @@ static void label_text_observer_cb(lv_observer_t * observer, lv_subject_t * subj
 
 #endif /*LV_USE_LABEL*/
 
+#if LV_USE_SPAN
+
+static void span_text_observer_cb(lv_observer_t * observer, lv_subject_t * subject)
+{
+    bind_element_string_t * user_data = observer->user_data;
+
+    if(user_data->fmt == NULL) {
+        lv_spangroup_set_span_text(observer->target, user_data->element, subject->value.pointer);
+    }
+    else {
+        switch(subject->type) {
+
+            case LV_SUBJECT_TYPE_INT:
+                lv_spangroup_set_span_text_fmt(observer->target, user_data->element, user_data->fmt, subject->value.num);
+                break;
+#if LV_USE_FLOAT
+            case LV_SUBJECT_TYPE_FLOAT:
+                lv_spangroup_set_span_text_fmt(observer->target, user_data->element, user_data->fmt, subject->value.float_v);
+                break;
+#endif
+            case LV_SUBJECT_TYPE_STRING:
+            case LV_SUBJECT_TYPE_POINTER:
+                lv_spangroup_set_span_text_fmt(observer->target, user_data->element, user_data->fmt, subject->value.pointer);
+                break;
+            default:
+                return;
+        }
+    }
+}
+
+#endif /*LV_USE_SPAN*/
+
+
 #if LV_USE_ARC
 
 static void arc_value_changed_event_cb(lv_event_t * e)

src/others/observer/lv_observer.h

@@ -545,6 +545,24 @@ lv_observer_t * lv_obj_bind_checked(lv_obj_t * obj, lv_subject_t * subject);
 lv_observer_t * lv_label_bind_text(lv_obj_t * obj, lv_subject_t * subject, const char * fmt);
 #endif
 
+#if LV_USE_LABEL
+
+/**
+ * Bind an integer, string, or pointer Subject to a Label.
+ * @param obj       pointer to Spangroup
+ * @param span      pointer to Span
+ * @param subject   pointer to Subject
+ * @param fmt       optional printf-like format string with 1 format specifier (e.g. "%d °C")
+ *                  or NULL to bind to the value directly.
+ * @return          pointer to newly-created Observer
+ * @note            `fmt == NULL` can be used only with string and pointer Subjects.
+ * @note            If Subject is a pointer and `fmt == NULL`, pointer must point
+ *                  to a `\0` terminated string.
+ */
+lv_observer_t * lv_spangroup_bind_span_text(lv_obj_t * obj, lv_span_t * span, lv_subject_t * subject, const char * fmt);
+
+#endif
+
 #if LV_USE_ARC
 /**
  * Bind an integer subject to an Arc's value.

src/widgets/label/lv_label.h

@@ -84,26 +84,28 @@ lv_obj_t * lv_label_create(lv_obj_t * parent);
  * Set a new text for a label. Memory will be allocated to store the text by the label.
  * @param obj           pointer to a label object
  * @param text          '\0' terminated character string. NULL to refresh with the current text.
+ * @note If `LV_USE_ARABIC_PERSIAN_CHARS` is enabled the text will be modified to have the correct Arabic
+ * characters in it.
  */
 void lv_label_set_text(lv_obj_t * obj, const char * text);
 
 /**
  * Set a new formatted text for a label. Memory will be allocated to store the text by the label.
  * @param obj           pointer to a label object
- * @param fmt           `printf`-like format
- *
+ * @param fmt           `printf`-like format string
  * Example:
  * @code
  * lv_label_set_text_fmt(label1, "%d user", user_num);
  * @endcode
+ * @note It ignores `LV_USE_ARABIC_PERSIAN_CHARS`
  */
 void lv_label_set_text_fmt(lv_obj_t * obj, const char * fmt, ...) LV_FORMAT_ATTRIBUTE(2, 3);
 
 /**
  * Set a new formatted text for a label. Memory will be allocated to store the text by the label.
  * @param obj           pointer to a label object
- * @param fmt           `printf`-like format
- * @param args          variadic argments list
+ * @param fmt           `printf`-like format string
+ * @param args          variadic arguments list
  *
  * Example:
  * @code
@@ -112,6 +114,7 @@ void lv_label_set_text_fmt(lv_obj_t * obj, const char * fmt, ...) LV_FORMAT_ATTR
  * lv_label_set_text_vfmt(label1, fmt, args);
  * va_end(args);
  * @endcode
+ * @note It ignores `LV_USE_ARABIC_PERSIAN_CHARS`
  */
 void lv_label_set_text_vfmt(lv_obj_t * obj, const char * fmt, va_list args);
 
@@ -120,6 +123,7 @@ void lv_label_set_text_vfmt(lv_obj_t * obj, const char * fmt, va_list args);
  * has to be 'alive' while the label exists.
  * @param obj           pointer to a label object
  * @param text          pointer to a text. NULL to refresh with the current text.
+ * @note It ignores `LV_USE_ARABIC_PERSIAN_CHARS`
  */
 void lv_label_set_text_static(lv_obj_t * obj, const char * text);
 

src/widgets/span/lv_span.c

@@ -199,6 +199,29 @@ void lv_span_set_text(lv_span_t * span, const char * text)
 #endif
 }
 
+void lv_span_set_text_fmt(lv_span_t * span, const char * fmt, ...)
+{
+    if(span == NULL || fmt == NULL) {
+        return;
+    }
+
+    va_list args;
+    va_start(args, fmt);
+    char * text = lv_text_set_text_vfmt(fmt, args);
+    LV_ASSERT_MALLOC(text);
+    if(text == NULL) return;
+
+    va_end(args);
+
+    if(span->txt == NULL && span->static_flag) {
+        lv_free(span->txt);
+    }
+
+    span->static_flag = 0;
+    span->txt = text;
+}
+
+
 void lv_spangroup_set_span_text(lv_obj_t * obj, lv_span_t * span, const char * text)
 {
     lv_span_set_text(span, text);
@@ -234,6 +257,30 @@ void lv_spangroup_set_span_text_static(lv_obj_t * obj, lv_span_t * span, const c
     lv_spangroup_refresh(obj);
 }
 
+void lv_spangroup_set_span_text_fmt(lv_obj_t * obj, lv_span_t * span, const char * fmt, ...)
+{
+    if(span == NULL || fmt == NULL) {
+        return;
+    }
+
+    va_list args;
+    va_start(args, fmt);
+    char * text = lv_text_set_text_vfmt(fmt, args);
+    LV_ASSERT_MALLOC(text);
+    if(text == NULL) return;
+
+    va_end(args);
+
+    if(span->txt == NULL && span->static_flag) {
+        lv_free(span->txt);
+    }
+
+    span->static_flag = 0;
+    span->txt = text;
+
+    lv_spangroup_refresh(obj);
+}
+
 void lv_spangroup_set_span_style(lv_obj_t * obj, lv_span_t * span, const lv_style_t * style)
 {
     LV_ASSERT_OBJ(obj, MY_CLASS);

src/widgets/span/lv_span.h

@@ -91,6 +91,17 @@ void lv_spangroup_delete_span(lv_obj_t * obj, lv_span_t * span);
  */
 void lv_span_set_text(lv_span_t * span, const char * text);
 
+
+/**
+ * Set a new text for a span using a printf-like formatting string.
+ * Memory will be allocated to store the text by the span.
+ * As the spangroup is not passed a redraw (invalidation) can't be triggered automatically.
+ * Therefore `lv_spangroup_refresh(spangroup)` needs to be called manually,
+ * @param span  pointer to a span.
+ * @param fmt   `printf`-like format string
+ */
+void lv_span_set_text_fmt(lv_span_t * span, const char * fmt, ...);
+
 /**
  * Set a static text. It will not be saved by the span so the 'text' variable
  * has to be 'alive' while the span exist.
@@ -118,6 +129,15 @@ void lv_spangroup_set_span_text(lv_obj_t * obj, lv_span_t * span, const char * t
  */
 void lv_spangroup_set_span_text_static(lv_obj_t * obj, lv_span_t * span, const char * text);
 
+/**
+ * Set a new text for a span using a printf-like formatting string.
+ * Memory will be allocated to store the text by the span.
+ * @param obj   pointer to a spangroup widget.
+ * @param span  pointer to a span.
+ * @param fmt   `printf`-like format string
+ */
+void lv_spangroup_set_span_text_fmt(lv_obj_t * obj, lv_span_t * span, const char * fmt, ...);
+
 /**
  * Set a static text. It will not be saved by the span so the 'text' variable
  * has to be 'alive' while the span exist.