Label - rockcastle/lvgl GitHub Wiki

Written for v5.1

Overview

The Labels are the basic objects to display text. There is no limitation in the text size because it's stored dynamically. You can modify the text in runtime at any time with lv_label_set_text().

You can use \n to make line break. For example: "line1\nline2\n\nline4"

The size of the label object can be automatically expanded to the text size or the text can be manipulated according to several long mode policies:

  • LV_LABEL_LONG_EXPAND: Expand the object size to the text size
  • LV_LABEL_LONG_BREAK: Keep the object width, break (wrap) the too long lines and expand the object height
  • LV_LABEL_LONG_DOTS: Keep the object size, break the text and write dots in the last line
  • LV_LABEL_LONG_SCROLL: Expand the object size and scroll the text on the parent (move the label object)
  • LV_LABEL_LONG_ROLL: Keep the size and roll just the text (not the object)

You can specify the long mode with: lv_label_set_long_mode(label, long_mode)

Labels are able to show text from a static array. Use: lv_label_set_static_text(label, char_array). In this case, the text is not stored in the dynamic memory but the given array is used instead. Keep in my the array can't be a local variable which destroys when the function exits.

You can also use a raw character array as label text. The array doesn't have to be \0 terminated. In this case, the text will be saved to the dynamic memory. To set a raw character array use the lv_label_set_array_text(label, char_array) function.

The label's text can be aligned to the left, right or middle with lv_label_set_align(label, LV_LABEL_ALIGN_LEFT/RIGHT/CENTER)

You can enable to draw a background for the label with lv_label_set_body_draw(label, draw)

In the text, you can use commands to re-color parts of the text. For example: "Write a #ff0000 red# word". This feature can be enabled individually for each label by lv_label_set_recolor() function.

The labels can display symbols besides letters. Learn more about symbols here.

The labels' default style is NULL so they inherit the parent's style.

Style usage

  • Use all properties from style.text
  • For background drawing style.body properties are used

Notes

The label's click enable attribute is disabled by default. You can enable clicking with lv_obj_set_click(label, true)

Example

Example of Label in LittlevGL Graphics Library 

/*Create label on the screen. By default it will inherit the style of the screen*/
lv_obj_t * title = lv_label_create(lv_scr_act(), NULL);
lv_label_set_text(title, "Title Label");
lv_obj_align(title, NULL, LV_ALIGN_IN_TOP_MID, 0, 20);  /*Align to the top*/

/*Create anew style*/
static lv_style_t style_txt;
lv_style_copy(&style_txt, &lv_style_plain);
style_txt.text.font = &lv_font_dejavu_40;
style_txt.text.letter_space = 2;
style_txt.text.line_space = 1;
style_txt.text.color = LV_COLOR_HEX(0x606060);

/*Create a new label*/
lv_obj_t * txt = lv_label_create(lv_scr_act(), NULL);
lv_obj_set_style(txt, &style_txt);                    /*Set the created style*/
lv_label_set_long_mode(txt, LV_LABEL_LONG_BREAK);     /*Break the long lines*/
lv_label_set_recolor(txt, true);                      /*Enable re-coloring by commands in the text*/
lv_label_set_align(txt, LV_LABEL_ALIGN_CENTER);       /*Center aligned lines*/
lv_label_set_text(txt, "Align lines to the middle\n\n"
                       "#000080 Re-color# #0000ff words of# #6666ff the text#\n\n"
                       "If a line become too long it can be automatically broken into multiple lines");
lv_obj_set_width(txt, 300);                           /*Set a width*/
lv_obj_align(txt, NULL, LV_ALIGN_CENTER, 0, 20);      /*Align to center*/