Merge pull request #793 from MiSimon/feature_ta_placeholder_text

Placeholder text for lv_ta

lv_objx/lv_label.c

@@ -555,7 +555,7 @@ uint16_t lv_label_get_letter_on(const lv_obj_t * label, lv_point_t * pos)
     uint32_t i = line_start;
     uint32_t i_current = i;
     uint32_t letter;
-    while(i < new_line_start - 1) {
+    while(i <= new_line_start - 1) {
         letter = lv_txt_encoded_next(txt, &i);    /*Be careful 'i' already points to the next character*/
         /*Handle the recolor command*/
         if((flag & LV_TXT_FLAG_RECOLOR) != 0) {

lv_objx/lv_ta.c

@@ -53,6 +53,7 @@ static void pwd_char_hider(lv_obj_t * ta);
 static bool char_is_accepted(lv_obj_t * ta, uint32_t c);
 static void get_cursor_style(lv_obj_t * ta, lv_style_t * style_res);
 static void refr_cursor_area(lv_obj_t * ta);
+static void placeholder_update(lv_obj_t * ta);
 static void update_cursor_position_on_click(lv_obj_t * ta, lv_indev_t * click_source);
 
 /**********************
@@ -248,6 +249,8 @@ void lv_ta_add_char(lv_obj_t * ta, uint32_t c)
 
     /*Revert the original edge flash state*/
     lv_ta_set_edge_flash(ta, edge_flash_en);
+
+    placeholder_update(ta);
 }
 
 /**
@@ -311,6 +314,8 @@ void lv_ta_add_text(lv_obj_t * ta, const char * txt)
 
     /*Revert the original edge flash state*/
     lv_ta_set_edge_flash(ta, edge_flash_en);
+
+    placeholder_update(ta);
 }
 
 /**
@@ -350,6 +355,8 @@ void lv_ta_del_char(lv_obj_t * ta)
 
     /*Move the cursor to the place of the deleted character*/
     lv_ta_set_cursor_pos(ta, ext->cursor.pos - 1);
+
+    placeholder_update(ta);
 }
 
 /**
@@ -423,6 +430,33 @@ void lv_ta_set_text(lv_obj_t * ta, const char * txt)
         pwd_char_hider(ta);
 #endif
     }
+
+    placeholder_update(ta);
+}
+
+/**
+* Set the placeholder text of a text area
+* @param ta pointer to a text area
+* @param txt pointer to the text
+*/
+void lv_ta_set_placeholder_text(lv_obj_t * ta, const char * txt)
+{
+    lv_ta_ext_t * ext = lv_obj_get_ext_attr(ta);
+
+    /*Create the placeholder label only when it is needed*/
+    if(ext->placeholder == NULL) {
+        ext->placeholder = lv_label_create(ta, NULL);
+
+        if(ext->one_line) {
+            lv_label_set_long_mode(ext->placeholder, LV_LABEL_LONG_EXPAND);
+        } else {
+            lv_label_set_long_mode(ext->placeholder, LV_LABEL_LONG_BREAK);
+        }
+    }
+
+    lv_label_set_text(ext->placeholder, txt);
+
+    placeholder_update(ta);
 }
 
 /**
@@ -576,6 +610,7 @@ void lv_ta_set_one_line(lv_obj_t * ta, bool en)
         lv_page_set_scrl_fit(ta, true, true);
         lv_obj_set_height(ta, font_h + (style_ta->body.padding.ver + style_scrl->body.padding.ver) * 2);
         lv_label_set_long_mode(ext->label, LV_LABEL_LONG_EXPAND);
+        if(ext->placeholder) lv_label_set_long_mode(ext->placeholder, LV_LABEL_LONG_EXPAND);
         lv_obj_set_pos(lv_page_get_scrl(ta), style_ta->body.padding.hor, style_ta->body.padding.ver);
     } else {
         lv_style_t * style_ta = lv_obj_get_style(ta);
@@ -583,10 +618,13 @@ void lv_ta_set_one_line(lv_obj_t * ta, bool en)
         ext->one_line = 0;
         lv_page_set_scrl_fit(ta, false, true);
         lv_label_set_long_mode(ext->label, LV_LABEL_LONG_BREAK);
+        if(ext->placeholder) lv_label_set_long_mode(ext->placeholder, LV_LABEL_LONG_BREAK);
+
         lv_obj_set_height(ta, LV_TA_DEF_HEIGHT);
         lv_obj_set_pos(lv_page_get_scrl(ta), style_ta->body.padding.hor, style_ta->body.padding.ver);
     }
 
+    placeholder_update(ta);
     refr_cursor_area(ta);
 }
 
@@ -675,6 +713,9 @@ void lv_ta_set_style(lv_obj_t * ta, lv_ta_style_t type, lv_style_t * style)
             lv_obj_refresh_ext_size(lv_page_get_scrl(ta)); /*Refresh ext. size because of cursor drawing*/
             refr_cursor_area(ta);
             break;
+        case LV_TA_STYLE_PLACEHOLDER:
+            if(ext->placeholder) lv_label_set_style(ext->placeholder, style);
+            break;
     }
 }
 
@@ -701,6 +742,21 @@ const char * lv_ta_get_text(const lv_obj_t * ta)
     return txt;
 }
 
+/**
+* Get the placeholder text of a text area
+* @param ta pointer to a text area object
+* @return pointer to the text
+*/
+const char * lv_ta_get_placeholder_text(lv_obj_t * ta)
+{
+    lv_ta_ext_t * ext = lv_obj_get_ext_attr(ta);
+
+    const char * txt = NULL;
+
+    if(ext->placeholder) txt = lv_label_get_text(ext->label);
+
+    return txt;
+}
 
 /**
  * Get the label of a text area
@@ -805,6 +861,9 @@ lv_style_t * lv_ta_get_style(const lv_obj_t * ta, lv_ta_style_t type)
         case LV_TA_STYLE_CURSOR:
             style = ext->cursor.style;
             break;
+        case LV_TA_STYLE_PLACEHOLDER:
+            if(ext->placeholder) style = lv_label_get_style(ext->placeholder);
+            break;
         default:
             style = NULL;
             break;
@@ -1038,6 +1097,11 @@ static lv_res_t lv_ta_signal(lv_obj_t * ta, lv_signal_t sign, void * param)
                 /*In not one line mode refresh the Label width because 'hpad' can modify it*/
                 lv_obj_set_width(ext->label, lv_obj_get_width(scrl) - 2 * style_scrl->body.padding.hor);
                 lv_obj_set_pos(ext->label, style_scrl->body.padding.hor, style_scrl->body.padding.ver);         /*Be sure the Label is in the correct position*/
+
+                if(ext->placeholder) {
+                    lv_obj_set_width(ext->placeholder, lv_obj_get_width(scrl) - 2 * style_scrl->body.padding.hor);
+                    lv_obj_set_pos(ext->placeholder, style_scrl->body.padding.hor, style_scrl->body.padding.ver);         /*Be sure the placeholder is in the correct position*/
+                }
             }
             lv_label_set_text(ext->label, NULL);
 
@@ -1053,6 +1117,19 @@ static lv_res_t lv_ta_signal(lv_obj_t * ta, lv_signal_t sign, void * param)
                 lv_obj_set_pos(ext->label, style_scrl->body.padding.hor, style_scrl->body.padding.ver);
                 lv_label_set_text(ext->label, NULL);    /*Refresh the label*/
 
+                refr_cursor_area(ta);
+            }
+        }
+        /*Set the placeholder width according to the text area width*/
+        if(ext->placeholder) {
+            if(lv_obj_get_width(ta) != lv_area_get_width(param) ||
+                   lv_obj_get_height(ta) != lv_area_get_height(param)) {
+                lv_obj_t * scrl = lv_page_get_scrl(ta);
+                lv_style_t * style_scrl = lv_obj_get_style(scrl);
+                lv_obj_set_width(ext->placeholder, lv_obj_get_width(scrl) - 2 * style_scrl->body.padding.hor);
+                lv_obj_set_pos(ext->placeholder, style_scrl->body.padding.hor, style_scrl->body.padding.ver);
+                lv_label_set_text(ext->placeholder, NULL);    /*Refresh the label*/
+
                 refr_cursor_area(ta);
             }
         }
@@ -1362,6 +1439,28 @@ static void refr_cursor_area(lv_obj_t * ta)
     lv_inv_area(&area_tmp);
 }
 
+static void placeholder_update(lv_obj_t * ta)
+{
+    lv_ta_ext_t * ext = lv_obj_get_ext_attr(ta);
+    const char * ta_text;
+
+    if(ext->placeholder == NULL) return;
+
+    ta_text = lv_ta_get_text(ta);
+
+    if(ta_text[0] == '\0') {
+        /*Be sure the main label and the placeholder has the same coordinates*/
+        lv_obj_t * scrl = lv_page_get_scrl(ta);
+        lv_style_t * style_scrl = lv_obj_get_style(scrl);
+        lv_obj_set_pos(ext->placeholder, style_scrl->body.padding.hor, style_scrl->body.padding.ver);
+        lv_obj_set_pos(ext->label, style_scrl->body.padding.hor, style_scrl->body.padding.ver);
+
+        lv_obj_set_width(ext->placeholder, lv_obj_get_width(scrl) - 2 * style_scrl->body.padding.hor);
+        lv_obj_set_hidden(ext->placeholder, false);
+    }
+    else lv_obj_set_hidden(ext->placeholder, true);
+}
+
 static void update_cursor_position_on_click(lv_obj_t * ta, lv_indev_t * click_source)
 {
     lv_ta_ext_t * ext = lv_obj_get_ext_attr(ta);

lv_objx/lv_ta.h

@@ -59,6 +59,7 @@ typedef struct
     lv_page_ext_t page; /*Ext. of ancestor*/
     /*New data for this type */
     lv_obj_t * label;           /*Label of the text area*/
+    lv_obj_t * placeholder;     /*Place holder label of the text area, only visible if text is an empty string*/
     char * pwd_tmp;             /*Used to store the original text in password mode*/
     const char * accapted_chars;/*Only these characters will be accepted. NULL: accept all*/
     uint16_t max_length;        /*The max. number of characters. 0: no limit*/
@@ -80,6 +81,7 @@ enum {
     LV_TA_STYLE_SB,
     LV_TA_STYLE_EDGE_FLASH,
     LV_TA_STYLE_CURSOR,
+    LV_TA_STYLE_PLACEHOLDER,
 };
 typedef uint8_t lv_ta_style_t;
 
@@ -139,6 +141,13 @@ void lv_ta_del_char_forward(lv_obj_t * ta);
  */
 void lv_ta_set_text(lv_obj_t * ta, const char * txt);
 
+/**
+* Set the placeholder text of a text area
+* @param ta pointer to a text area
+* @param txt pointer to the text
+*/
+void lv_ta_set_placeholder_text(lv_obj_t * ta, const char * txt);
+
 /**
  * Set the cursor position
  * @param obj pointer to a text area object
@@ -251,6 +260,13 @@ void lv_ta_set_style(lv_obj_t *ta, lv_ta_style_t type, lv_style_t *style);
  */
 const char * lv_ta_get_text(const lv_obj_t * ta);
 
+/**
+* Get the placeholder text of a text area
+* @param ta pointer to a text area object
+* @return pointer to the text
+*/
+const char * lv_ta_get_placeholder_text(lv_obj_t * ta);
+
 /**
  * Get the label of a text area
  * @param ta pointer to a text area object