Add lv_label_set_text_fmt

src/lv_misc/lv_printf.c

@@ -139,16 +139,6 @@ static inline void _out_null(char character, void* buffer, size_t idx, size_t ma
 }
 
 
-// internal _putchar wrapper
-static inline void _out_char(char character, void* buffer, size_t idx, size_t maxlen)
-{
-  (void)buffer; (void)idx; (void)maxlen;
-  if (character) {
-    _putchar(character);
-  }
-}
-
-
 // internal output function wrapper
 static inline void _out_fct(char character, void* buffer, size_t idx, size_t maxlen)
 {

src/lv_objx/lv_label.c

@@ -13,6 +13,7 @@
 #include "../lv_core/lv_group.h"
 #include "../lv_misc/lv_color.h"
 #include "../lv_misc/lv_math.h"
+#include "../lv_misc/lv_printf.h"
 
 /*********************
  *      DEFINES
@@ -203,6 +204,51 @@ void lv_label_set_text(lv_obj_t * label, const char * text)
     lv_label_refr_text(label);
 }
 
+/**
+ * Set a new formatted text for a label. Memory will be allocated to store the text by the label.
+ * @param label pointer to a label object
+ * @param fmt `printf`-like format
+ */
+void lv_label_set_text_fmt(lv_obj_t * label, const char * fmt, ...)
+{
+    lv_obj_invalidate(label);
+
+    lv_label_ext_t * ext = lv_obj_get_ext_attr(label);
+
+    /*If text is NULL then refresh */
+    if(fmt == NULL) {
+        lv_label_refr_text(label);
+        return;
+    }
+
+    if(ext->text != NULL && ext->static_txt == 0) {
+            lv_mem_free(ext->text);
+            ext->text = NULL;
+    }
+
+    va_list ap, ap2;
+    va_start(ap, fmt);
+    va_copy(ap2, ap);
+
+    /*Allocate space for the new text by using trick from C99 standard section 7.19.6.12 */
+    uint32_t len = lv_vsnprintf(NULL, 0, fmt, ap);
+
+    va_end(ap);
+    
+
+    ext->text = lv_mem_alloc(len+1);
+    lv_mem_assert(ext->text);
+    if(ext->text == NULL) return;
+    ext->text[len-1] = 0; /* Ensure NULL termination */
+
+    lv_vsnprintf(ext->text, len, fmt, ap2);
+
+    va_end(ap2);
+    ext->static_txt = 0; /*Now the text is dynamically allocated*/
+
+    lv_label_refr_text(label);
+}
+
 /**
  * Set a new text for a label from a character array. The array don't has to be '\0' terminated.
  * Memory will be allocated to store the array by the label.

src/lv_objx/lv_label.h

@@ -21,6 +21,7 @@ extern "C" {
 
 #if LV_USE_LABEL != 0
 
+#include <stdarg.h>
 #include "../lv_core/lv_obj.h"
 #include "../lv_font/lv_font.h"
 #include "../lv_font/lv_symbol_def.h"
@@ -124,6 +125,13 @@ lv_obj_t * lv_label_create(lv_obj_t * par, const lv_obj_t * copy);
  */
 void lv_label_set_text(lv_obj_t * label, const char * text);
 
+/**
+ * Set a new formatted text for a label. Memory will be allocated to store the text by the label.
+ * @param label pointer to a label object
+ * @param fmt `printf`-like format
+ */
+void lv_label_set_text_fmt(lv_obj_t * label, const char * fmt, ...);
+
 /**
  * Set a new text for a label from a character array. The array don't has to be '\0' terminated.
  * Memory will be allocated to store the array by the label.