Text area (lv_textarea)¶
Overview¶
The Text Area is a Page with a Label and a cursor on it. Texts or characters can be added to it. Long lines are wrapped and when the text becomes long enough the Text area can be scrolled.
Parts and Styles¶
The Text area has the same parts as Page.
Expect LV_PAGE_PART_SCRL
because it can't be referenced and it's always transparent.
Refer the Page's documentation of details.
Besides the Page parts the virtual LV_TEXTAREA_PART_CURSOR
part exists to draw the cursor.
The cursor's area is always the bounding box of the current character.
A block cursor can be created by adding a background color and background opa to LV_TEXTAREA_PART_CURSOR
's style.
The create line cursor let the cursor transparent and set the border_side property.
Usage¶
Add text¶
You can insert text or characters to the current cursor's position with:
lv_textarea_add_char(textarea, 'c')
lv_textarea_add_text(textarea, "insert this text")
To add wide characters like 'á'
, 'ß'
or CJK characters use lv_textarea_add_text(ta, "á")
.
lv_textarea_set_text(ta, "New text")
changes the whole text.
Placeholder¶
A placeholder text can be specified - which is displayed when the Text area is empty - with lv_textarea_set_placeholder_text(ta, "Placeholder text")
Delete character¶
To delete a character from the left of the current cursor position use lv_textarea_del_char(textarea)
.
To delete from the right use lv_textarea_del_char_forward(textarea)
Move the cursor¶
The cursor position can be modified directly with lv_textarea_set_cursor_pos(textarea, 10)
.
The 0
position means "before the first characters",
LV_TA_CURSOR_LAST
means "after the last character"
You can step the cursor with
lv_textarea_cursor_right(textarea)
lv_textarea_cursor_left(textarea)
lv_textarea_cursor_up(textarea)
lv_textarea_cursor_down(textarea)
If lv_textarea_set_cursor_click_pos(textarea, true)
is called the cursor will jump to the position where the Text area was clicked.
Hide the cursor¶
The cursor can be hidden with lv_textarea_set_cursor_hidden(textarea, true)
.
Cursor blink time¶
The blink time of the cursor can be adjusted with lv_textarea_set_cursor_blink_time(textarea, time_ms)
.
One line mode¶
The Text area can be configures to be one lined with lv_textarea_set_one_line(ta, true)
.
In this mode the height is set automatically to show only one line, line break character are ignored, and word wrap is disabled.
Password mode¶
The text area supports password mode which can be enabled with lv_textarea_set_pwd_mode(textarea, true)
.
If the •
(Bullet, U+2022) character exists in the font, the entered characters are converted to it after some time or when a new character is entered.
If •
not exists, *
will be used.
In password mode lv_textarea_get_text(textarea)
gives the real text, not the bullet characters.
The visibility time can be adjusted with lv_textarea_set_pwd_show_time(textarea, time_ms)
.
Text align¶
The text can be aligned to the left, center or right with lv_textarea_set_text_align(textarea, LV_LABEL_ALIGN_LET/CENTER/RIGHT)
.
In one line mode, the text can be scrolled horizontally only if the text is left aligned.
Accepted characters¶
You can set a list of accepted characters with lv_textarae_set_accepted_chars(ta, "0123456789.+-")
.
Other characters will be ignored.
Max text length¶
The maximum number of characters can be limited with lv_textarea_set_max_length(textarea, max_char_num)
Very long texts¶
If there is a very long text in the Text area (e. g. > 20k characters) its scrolling and drawing might be slow.
However, by enabling LV_LABEL_LONG_TXT_HINT 1
in lv_conf.h it can be hugely improved.
It will save some info about the label to speed up its drawing.
Using LV_LABEL_LONG_TXT_HINT
the scrolling and drawing will as fast as with "normal" short texts.
Select text¶
A part of text can be selected if enabled with lv_textarea_set_text_sel(textarea, true)
.
It works like when you select a text on your PC with your mouse.
Scrollbars¶
The scrollbars can shown according to different policies set by lv_textarea_set_scrollbar_mode(textarea, LV_SCRLBAR_MODE_...)
.
Learn more at the Page object.
Scroll propagation¶
When the Text area is scrolled on an other scrollable object (like a Page) and the scrolling has reached the edge of the Text area, the scrolling can be propagated to the parent. In other words, when the Text area can't be scrolled further, the parent will be scrolled instead.
It can be enabled with lv_ta_set_scroll_propagation(ta, true)
.
Learn more at the Page object.
Edge flash¶
When the Text area is scrolled to edge a circle like flash animation can be shown if it is enabled with lv_ta_set_edge_flash(ta, true)
Events¶
Besides the Generic events the following Special events are sent by the Slider:
LV_EVENT_INSERT Sent when before a character or text is inserted. The event data is the text planned to insert.
lv_ta_set_insert_replace(ta, "New text")
replaces the text to insert. The new text can't be in a local variable which is destroyed when the event callback exists.""
means do not insert anything.LV_EVENT_VALUE_CHANGED When the content of the text area has been changed.
LV_EVENT_APPLY When LV_KEY_ENTER is sent to a text area which is in one line mode.
Keys¶
LV_KEY_UP/DOWN/LEFT/RIGHT Move the cursor
Any character Add the character to the current cursor position
Learn more about Keys.
Example¶
C¶
Simple Text area¶
code
#include "../../../lv_examples.h"
#include <stdio.h>
#if LV_USE_TEXTAREA
lv_obj_t * ta1;
static void event_handler(lv_obj_t * obj, lv_event_t event)
{
if(event == LV_EVENT_VALUE_CHANGED) {
printf("Value: %s\n", lv_textarea_get_text(obj));
}
else if(event == LV_EVENT_LONG_PRESSED_REPEAT) {
/*For simple test: Long press the Text are to add the text below*/
const char * txt = "\n\nYou can scroll it if the text is long enough.\n";
static uint16_t i = 0;
if(txt[i] != '\0') {
lv_textarea_add_char(ta1, txt[i]);
i++;
}
}
}
void lv_ex_textarea_1(void)
{
ta1 = lv_textarea_create(lv_scr_act(), NULL);
lv_obj_set_size(ta1, 200, 100);
lv_obj_align(ta1, NULL, LV_ALIGN_CENTER, 0, 0);
lv_textarea_set_text(ta1, "A text in a Text Area"); /*Set an initial text*/
lv_obj_set_event_cb(ta1, event_handler);
}
#endif
Text area with password field¶
code
#include "../../../lv_examples.h"
#include <stdio.h>
#if LV_USE_TEXTAREA && LV_USE_KEYBOARD
static void ta_event_cb(lv_obj_t * ta, lv_event_t event);
static lv_obj_t * kb;
void lv_ex_textarea_2(void)
{
/* Create the password box */
lv_obj_t * pwd_ta = lv_textarea_create(lv_scr_act(), NULL);
lv_textarea_set_text(pwd_ta, "");
lv_textarea_set_pwd_mode(pwd_ta, true);
lv_textarea_set_one_line(pwd_ta, true);
lv_textarea_set_cursor_hidden(pwd_ta, true);
lv_obj_set_width(pwd_ta, LV_HOR_RES / 2 - 20);
lv_obj_set_pos(pwd_ta, 5, 20);
lv_obj_set_event_cb(pwd_ta, ta_event_cb);
/* Create a label and position it above the text box */
lv_obj_t * pwd_label = lv_label_create(lv_scr_act(), NULL);
lv_label_set_text(pwd_label, "Password:");
lv_obj_align(pwd_label, pwd_ta, LV_ALIGN_OUT_TOP_LEFT, 0, 0);
/* Create the one-line mode text area */
lv_obj_t * oneline_ta = lv_textarea_create(lv_scr_act(), pwd_ta);
lv_textarea_set_pwd_mode(oneline_ta, false);
lv_textarea_set_cursor_hidden(oneline_ta, true);
lv_obj_align(oneline_ta, NULL, LV_ALIGN_IN_TOP_RIGHT, -5, 20);
/* Create a label and position it above the text box */
lv_obj_t * oneline_label = lv_label_create(lv_scr_act(), NULL);
lv_label_set_text(oneline_label, "Text:");
lv_obj_align(oneline_label, oneline_ta, LV_ALIGN_OUT_TOP_LEFT, 0, 0);
/* Create a keyboard */
kb = lv_keyboard_create(lv_scr_act(), NULL);
lv_obj_set_size(kb, LV_HOR_RES, LV_VER_RES / 2);
lv_keyboard_set_textarea(kb, pwd_ta); /* Focus it on one of the text areas to start */
lv_keyboard_set_cursor_manage(kb, true); /* Automatically show/hide cursors on text areas */
}
static void ta_event_cb(lv_obj_t * ta, lv_event_t event)
{
if(event == LV_EVENT_CLICKED) {
/* Focus on the clicked text area */
if(kb != NULL)
lv_keyboard_set_textarea(kb, ta);
}
else if(event == LV_EVENT_INSERT) {
const char * str = lv_event_get_data();
if(str[0] == '\n') {
printf("Ready\n");
}
}
}
#endif
Text auto-formatting¶
code
#include "../../../lv_examples.h"
#include <stdio.h>
#if LV_USE_TEXTAREA && LV_USE_KEYBOARD
static void ta_event_cb(lv_obj_t * ta, lv_event_t event);
static lv_obj_t * kb;
/**
* Automatically format text like a clock. E.g. "12:34"
* Add the ':' automatically.
*/
void lv_ex_textarea_3(void)
{
/* Create the text area */
lv_obj_t * ta = lv_textarea_create(lv_scr_act(), NULL);
lv_obj_set_event_cb(ta, ta_event_cb);
lv_textarea_set_accepted_chars(ta, "0123456789:");
lv_textarea_set_max_length(ta, 5);
lv_textarea_set_one_line(ta, true);
lv_textarea_set_text(ta, "");
/*Create a custom map for the keyboard*/
static const char * kb_map[] = {
"1","2", "3", " ","\n",
"4", "5", "6", " ", "\n",
"7", "8", "9", LV_SYMBOL_BACKSPACE ,"\n",
"0",LV_SYMBOL_LEFT,LV_SYMBOL_RIGHT," ",""
};
static const lv_btnmatrix_ctrl_t kb_ctrl[] = {
LV_BTNMATRIX_CTRL_NO_REPEAT, LV_BTNMATRIX_CTRL_NO_REPEAT, LV_BTNMATRIX_CTRL_NO_REPEAT, LV_BTNMATRIX_CTRL_HIDDEN,
LV_BTNMATRIX_CTRL_NO_REPEAT, LV_BTNMATRIX_CTRL_NO_REPEAT, LV_BTNMATRIX_CTRL_NO_REPEAT, LV_BTNMATRIX_CTRL_HIDDEN,
LV_BTNMATRIX_CTRL_NO_REPEAT, LV_BTNMATRIX_CTRL_NO_REPEAT, LV_BTNMATRIX_CTRL_NO_REPEAT, LV_BTNMATRIX_CTRL_NO_REPEAT,
LV_BTNMATRIX_CTRL_NO_REPEAT, LV_BTNMATRIX_CTRL_NO_REPEAT, LV_BTNMATRIX_CTRL_NO_REPEAT, LV_BTNMATRIX_CTRL_HIDDEN,
};
/* Create a keyboard*/
kb = lv_keyboard_create(lv_scr_act(), NULL);
lv_obj_set_size(kb, LV_HOR_RES, LV_VER_RES / 2);
lv_keyboard_set_mode(kb, LV_KEYBOARD_MODE_NUM);
lv_keyboard_set_map(kb, LV_KEYBOARD_MODE_NUM, kb_map);
lv_keyboard_set_ctrl_map(kb, LV_KEYBOARD_MODE_NUM,kb_ctrl);
lv_keyboard_set_textarea(kb, ta);
}
static void ta_event_cb(lv_obj_t * ta, lv_event_t event)
{
if(event == LV_EVENT_VALUE_CHANGED) {
const char * txt = lv_textarea_get_text(ta);
if(txt[3] == ':') {
lv_textarea_del_char(ta);
}
else if(txt[0] >= '0' && txt[0] <= '9' &&
txt[1] >= '0' && txt[1] <= '9' &&
txt[2] != ':')
{
lv_textarea_set_cursor_pos(ta, 2);
lv_textarea_add_char(ta, ':');
}
}
}
#endif
MicroPython¶
No examples yet.
API¶
Typedefs
-
typedef uint8_t
lv_textarea_style_t
¶
Enums
-
enum [anonymous]¶
Possible text areas styles.
Values:
-
enumerator
LV_TEXTAREA_PART_BG
¶ Text area background style
-
enumerator
LV_TEXTAREA_PART_SCROLLBAR
¶ Scrollbar style
-
enumerator
LV_TEXTAREA_PART_EDGE_FLASH
¶ Edge flash style
-
enumerator
LV_TEXTAREA_PART_CURSOR
¶ Cursor style
-
enumerator
LV_TEXTAREA_PART_PLACEHOLDER
¶ Placeholder style
-
enumerator
_LV_TEXTAREA_PART_VIRTUAL_LAST
¶
-
enumerator
_LV_TEXTAREA_PART_REAL_LAST
¶
-
enumerator
Functions
-
LV_EXPORT_CONST_INT
(LV_TEXTAREA_CURSOR_LAST)¶
-
lv_obj_t *
lv_textarea_create
(lv_obj_t *par, const lv_obj_t *copy)¶ Create a text area objects
- Return
pointer to the created text area
- Parameters
par
: pointer to an object, it will be the parent of the new text areacopy
: pointer to a text area object, if not NULL then the new object will be copied from it
-
void
lv_textarea_add_char
(lv_obj_t *ta, uint32_t c)¶ Insert a character to the current cursor position. To add a wide char, e.g. 'Á' use `_lv_txt_encoded_conv_wc('Á')`
- Parameters
ta
: pointer to a text area objectc
: a character (e.g. 'a')
-
void
lv_textarea_add_text
(lv_obj_t *ta, const char *txt)¶ Insert a text to the current cursor position
- Parameters
ta
: pointer to a text area objecttxt
: a '\0' terminated string to insert
-
void
lv_textarea_del_char
(lv_obj_t *ta)¶ Delete a the left character from the current cursor position
- Parameters
ta
: pointer to a text area object
-
void
lv_textarea_del_char_forward
(lv_obj_t *ta)¶ Delete the right character from the current cursor position
- Parameters
ta
: pointer to a text area object
-
void
lv_textarea_set_text
(lv_obj_t *ta, const char *txt)¶ Set the text of a text area
- Parameters
ta
: pointer to a text areatxt
: pointer to the text
-
void
lv_textarea_set_placeholder_text
(lv_obj_t *ta, const char *txt)¶ Set the placeholder text of a text area
- Parameters
ta
: pointer to a text areatxt
: pointer to the text
-
void
lv_textarea_set_cursor_pos
(lv_obj_t *ta, int32_t pos)¶ Set the cursor position
- Parameters
obj
: pointer to a text area objectpos
: the new cursor position in character index < 0 : index from the end of the text LV_TEXTAREA_CURSOR_LAST: go after the last character
Hide/Unhide the cursor.
- Parameters
ta
: pointer to a text area objecthide
: true: hide the cursor
-
void
lv_textarea_set_cursor_click_pos
(lv_obj_t *ta, bool en)¶ Enable/Disable the positioning of the cursor by clicking the text on the text area.
- Parameters
ta
: pointer to a text area objecten
: true: enable click positions; false: disable
-
void
lv_textarea_set_pwd_mode
(lv_obj_t *ta, bool en)¶ Enable/Disable password mode
- Parameters
ta
: pointer to a text area objecten
: true: enable, false: disable
-
void
lv_textarea_set_one_line
(lv_obj_t *ta, bool en)¶ Configure the text area to one line or back to normal
- Parameters
ta
: pointer to a Text area objecten
: true: one line, false: normal
-
void
lv_textarea_set_text_align
(lv_obj_t *ta, lv_label_align_t align)¶ Set the alignment of the text area. In one line mode the text can be scrolled only with
LV_LABEL_ALIGN_LEFT
. This function should be called if the size of text area changes.- Parameters
ta
: pointer to a text are objectalign
: the desired alignment fromlv_label_align_t
. (LV_LABEL_ALIGN_LEFT/CENTER/RIGHT)
-
void
lv_textarea_set_accepted_chars
(lv_obj_t *ta, const char *list)¶ Set a list of characters. Only these characters will be accepted by the text area
- Parameters
ta
: pointer to Text Arealist
: list of characters. Only the pointer is saved. E.g. "+-.,0123456789"
-
void
lv_textarea_set_max_length
(lv_obj_t *ta, uint32_t num)¶ Set max length of a Text Area.
- Parameters
ta
: pointer to Text Areanum
: the maximal number of characters can be added (lv_textarea_set_text
ignores it)
-
void
lv_textarea_set_insert_replace
(lv_obj_t *ta, const char *txt)¶ In
LV_EVENT_INSERT
the text which planned to be inserted can be replaced by an other text. It can be used to add automatic formatting to the text area.- Parameters
ta
: pointer to a text area.txt
: pointer to a new string to insert. If""
no text will be added. The variable must be live after theevent_cb
exists. (Should beglobal
orstatic
)
-
static inline void
lv_textarea_set_scrollbar_mode
(lv_obj_t *ta, lv_scrollbar_mode_t mode)¶ Set the scroll bar mode of a text area
- Parameters
ta
: pointer to a text area objectsb_mode
: the new mode from 'lv_scrollbar_mode_t' enum
-
static inline void
lv_textarea_set_scroll_propagation
(lv_obj_t *ta, bool en)¶ Enable the scroll propagation feature. If enabled then the Text area will move its parent if there is no more space to scroll.
- Parameters
ta
: pointer to a Text areaen
: true or false to enable/disable scroll propagation
-
static inline void
lv_textarea_set_edge_flash
(lv_obj_t *ta, bool en)¶ Enable the edge flash effect. (Show an arc when the an edge is reached)
- Parameters
page
: pointer to a Text Areaen
: true or false to enable/disable end flash
-
void
lv_textarea_set_text_sel
(lv_obj_t *ta, bool en)¶ Enable/disable selection mode.
- Parameters
ta
: pointer to a text area objecten
: true or false to enable/disable selection mode
-
void
lv_textarea_set_pwd_show_time
(lv_obj_t *ta, uint16_t time)¶ Set how long show the password before changing it to '*'
- Parameters
ta
: pointer to Text areatime
: show time in milliseconds. 0: hide immediately.
-
void
lv_textarea_set_cursor_blink_time
(lv_obj_t *ta, uint16_t time)¶ Set cursor blink animation time
- Parameters
ta
: pointer to Text areatime
: blink period. 0: disable blinking
-
const char *
lv_textarea_get_text
(const lv_obj_t *ta)¶ Get the text of a text area. In password mode it gives the real text (not '*'s).
- Return
pointer to the text
- Parameters
ta
: pointer to a text area object
-
const char *
lv_textarea_get_placeholder_text
(lv_obj_t *ta)¶ Get the placeholder text of a text area
- Return
pointer to the text
- Parameters
ta
: pointer to a text area object
-
lv_obj_t *
lv_textarea_get_label
(const lv_obj_t *ta)¶ Get the label of a text area
- Return
pointer to the label object
- Parameters
ta
: pointer to a text area object
-
uint32_t
lv_textarea_get_cursor_pos
(const lv_obj_t *ta)¶ Get the current cursor position in character index
- Return
the cursor position
- Parameters
ta
: pointer to a text area object
Get whether the cursor is hidden or not
- Return
true: the cursor is hidden
- Parameters
ta
: pointer to a text area object
-
bool
lv_textarea_get_cursor_click_pos
(lv_obj_t *ta)¶ Get whether the cursor click positioning is enabled or not.
- Return
true: enable click positions; false: disable
- Parameters
ta
: pointer to a text area object
-
bool
lv_textarea_get_pwd_mode
(const lv_obj_t *ta)¶ Get the password mode attribute
- Return
true: password mode is enabled, false: disabled
- Parameters
ta
: pointer to a text area object
-
bool
lv_textarea_get_one_line
(const lv_obj_t *ta)¶ Get the one line configuration attribute
- Return
true: one line configuration is enabled, false: disabled
- Parameters
ta
: pointer to a text area object
-
const char *
lv_textarea_get_accepted_chars
(lv_obj_t *ta)¶ Get a list of accepted characters.
- Return
list of accented characters.
- Parameters
ta
: pointer to Text Area
-
uint32_t
lv_textarea_get_max_length
(lv_obj_t *ta)¶ Get max length of a Text Area.
- Return
the maximal number of characters to be add
- Parameters
ta
: pointer to Text Area
-
static inline lv_scrollbar_mode_t
lv_textarea_get_scrollbar_mode
(const lv_obj_t *ta)¶ Get the scroll bar mode of a text area
- Return
scrollbar mode from 'lv_scrollbar_mode_t' enum
- Parameters
ta
: pointer to a text area object
-
static inline bool
lv_textarea_get_scroll_propagation
(lv_obj_t *ta)¶ Get the scroll propagation property
- Return
true or false
- Parameters
ta
: pointer to a Text area
-
static inline bool
lv_textarea_get_edge_flash
(lv_obj_t *ta)¶ Get the scroll propagation property
- Return
true or false
- Parameters
ta
: pointer to a Text area
-
bool
lv_textarea_text_is_selected
(const lv_obj_t *ta)¶ Find whether text is selected or not.
- Return
whether text is selected or not
- Parameters
ta
: Text area object
-
bool
lv_textarea_get_text_sel_en
(lv_obj_t *ta)¶ Find whether selection mode is enabled.
- Return
true: selection mode is enabled, false: disabled
- Parameters
ta
: pointer to a text area object
-
uint16_t
lv_textarea_get_pwd_show_time
(lv_obj_t *ta)¶ Set how long show the password before changing it to '*'
- Return
show time in milliseconds. 0: hide immediately.
- Parameters
ta
: pointer to Text area
-
uint16_t
lv_textarea_get_cursor_blink_time
(lv_obj_t *ta)¶ Set cursor blink animation time
- Return
time blink period. 0: disable blinking
- Parameters
ta
: pointer to Text area
-
void
lv_textarea_clear_selection
(lv_obj_t *ta)¶ Clear the selection on the text area.
- Parameters
ta
: Text area object
-
void
lv_textarea_cursor_right
(lv_obj_t *ta)¶ Move the cursor one character right
- Parameters
ta
: pointer to a text area object
-
void
lv_textarea_cursor_left
(lv_obj_t *ta)¶ Move the cursor one character left
- Parameters
ta
: pointer to a text area object
-
struct
lv_textarea_ext_t
¶ Public Members
-
lv_page_ext_t
page
¶
-
char *
placeholder_txt
¶
-
lv_style_list_t
style_placeholder
¶
-
char *
pwd_tmp
¶
-
const char *
accepted_chars
¶
-
uint32_t
max_length
¶
-
uint16_t
pwd_show_time
¶
-
lv_style_list_t
style
¶
-
lv_coord_t
valid_x
¶
-
uint32_t
pos
¶
-
uint16_t
blink_time
¶
-
lv_area_t
area
¶
-
uint32_t
txt_byte_pos
¶
-
uint8_t
state
¶
-
uint8_t
click_pos
¶
-
struct lv_textarea_ext_t::[anonymous]
cursor
¶
-
uint32_t
sel_start
¶
-
uint32_t
sel_end
¶
-
uint8_t
text_sel_in_prog
¶
-
uint8_t
text_sel_en
¶
-
uint8_t
pwd_mode
¶
-
uint8_t
one_line
¶
-
lv_page_ext_t