Gauge (lv_gauge)

Overview

The gauge is a meter with scale labels and needles.

Scale

You can use the lv_gauge_set_scale(gauge, angle, line_num, label_cnt) function to adjust the scale angle and the number of the scale lines and labels. The default settings are 220 degrees, 6 scale labels, and 21 lines.

Needles

The gauge can show more than one needle. Use the lv_gauge_set_needle_count(gauge, needle_num, color_array) function to set the number of needles and an array with colors for each needle. The array must be static or global variable because only its pointer is stored.

You can use lv_gauge_set_value(gauge, needle_id, value) to set the value of a needle.

Range

The range of the gauge can be specified by lv_gauge_set_range(gauge, min, max). The default range is 0..100.

Critical value

To set a critical value, use lv_gauge_set_critical_value(gauge, value). The scale color will be changed to line.color after this value. (default: 80)

Styles

The gauge uses one style at a time which can be set by lv_gauge_set_style(gauge, LV_GAUGE_STYLE_MAIN, &style). The gauge’s properties are derived from the following style attributes:

  • body.main_color - Line’s color at the beginning of the scale.

  • body.grad_color - Line’s color at the end of the scale (gradient with main color).

  • body.padding.left - Line length.

  • body.padding.inner - Label distance from the scale lines.

  • body.radius - Radius of needle origin circle.

  • line.width - Line width.

  • line.color - Line’s color after the critical value.

  • text.font/color/letter_space - Label attributes.

Events

Only the Generic events are sent by the object type.

Learn more about Events.

Keys

No Keys are processed by the object type.

Learn more about Keys.

Example

C

Simple Gauge

Simple Gauge example in LittlevGL

code

#include "lvgl/lvgl.h"

void lv_ex_gauge_1(void)
{
    /*Create a style*/
    static lv_style_t style;
    lv_style_copy(&style, &lv_style_pretty_color);
    style.body.main_color = lv_color_hex3(0x666);     /*Line color at the beginning*/
    style.body.grad_color =  lv_color_hex3(0x666);    /*Line color at the end*/
    style.body.padding.left = 10;                      /*Scale line length*/
    style.body.padding.inner = 8 ;                    /*Scale label padding*/
    style.body.border.color = lv_color_hex3(0x333);   /*Needle middle circle color*/
    style.line.width = 3;
    style.text.color = lv_color_hex3(0x333);
    style.line.color = LV_COLOR_RED;                  /*Line color after the critical value*/

    /*Describe the color for the needles*/
    static lv_color_t needle_colors[3];
    needle_colors[0] = LV_COLOR_BLUE;
    needle_colors[1] = LV_COLOR_ORANGE;
    needle_colors[2] = LV_COLOR_PURPLE;

    /*Create a gauge*/
    lv_obj_t * gauge1 = lv_gauge_create(lv_scr_act(), NULL);
    lv_gauge_set_style(gauge1, LV_GAUGE_STYLE_MAIN, &style);
    lv_gauge_set_needle_count(gauge1, 3, needle_colors);
    lv_obj_set_size(gauge1, 150, 150);
    lv_obj_align(gauge1, NULL, LV_ALIGN_CENTER, 0, 20);

    /*Set the values*/
    lv_gauge_set_value(gauge1, 0, 10);
    lv_gauge_set_value(gauge1, 1, 20);
    lv_gauge_set_value(gauge1, 2, 30);
}

MicroPython

Simple Gauge

Simple Gauge example in LittlevGL with MicroPython

code

# Create a style
style = lv.style_t()
lv.style_copy(style, lv.style_pretty_color)
style.body.main_color = lv.color_hex3(0x666)     # Line color at the beginning
style.body.grad_color =  lv.color_hex3(0x666)    # Line color at the end
style.body.padding.left = 10                     # Scale line length
style.body.padding.inner = 8                     # Scale label padding
style.body.border.color = lv.color_hex3(0x333)   # Needle middle circle color
style.line.width = 3
style.text.color = lv.color_hex3(0x333)
style.line.color = lv.color_hex3(0xF00)          # Line color after the critical value

# Describe the color for the needles
needle_colors = [
    lv.color_make(0x00, 0x00, 0xFF),
    lv.color_make(0xFF, 0xA5, 0x00),
    lv.color_make(0x80, 0x00, 0x80)
]

# Create a gauge
gauge1 = lv.gauge(lv.scr_act())
gauge1.set_style(lv.gauge.STYLE.MAIN, style)
gauge1.set_needle_count(len(needle_colors), needle_colors)
gauge1.set_size(150, 150)
gauge1.align(None, lv.ALIGN.CENTER, 0, 20)

# Set the values
gauge1.set_value(0, 10)
gauge1.set_value(1, 20)
gauge1.set_value(2, 30)

API

Typedefs

typedef uint8_t lv_gauge_style_t

Enums

enum [anonymous]

Values:

LV_GAUGE_STYLE_MAIN

Functions

lv_obj_t *lv_gauge_create(lv_obj_t *par, const lv_obj_t *copy)

Create a gauge objects

Return

pointer to the created gauge

Parameters
  • par: pointer to an object, it will be the parent of the new gauge

  • copy: pointer to a gauge object, if not NULL then the new object will be copied from it

void lv_gauge_set_needle_count(lv_obj_t *gauge, uint8_t needle_cnt, const lv_color_t colors[])

Set the number of needles

Parameters
  • gauge: pointer to gauge object

  • needle_cnt: new count of needles

  • colors: an array of colors for needles (with ‘num’ elements)

void lv_gauge_set_value(lv_obj_t *gauge, uint8_t needle_id, int16_t value)

Set the value of a needle

Parameters
  • gauge: pointer to a gauge

  • needle_id: the id of the needle

  • value: the new value

static void lv_gauge_set_range(lv_obj_t *gauge, int16_t min, int16_t max)

Set minimum and the maximum values of a gauge

Parameters
  • gauge: pointer to he gauge object

  • min: minimum value

  • max: maximum value

static void lv_gauge_set_critical_value(lv_obj_t *gauge, int16_t value)

Set a critical value on the scale. After this value ‘line.color’ scale lines will be drawn

Parameters
  • gauge: pointer to a gauge object

  • value: the critical value

void lv_gauge_set_scale(lv_obj_t *gauge, uint16_t angle, uint8_t line_cnt, uint8_t label_cnt)

Set the scale settings of a gauge

Parameters
  • gauge: pointer to a gauge object

  • angle: angle of the scale (0..360)

  • line_cnt: count of scale lines. The get a given “subdivision” lines between label, line_cnt = (sub_div + 1) * (label_cnt - 1) + 1

  • label_cnt: count of scale labels.

static void lv_gauge_set_style(lv_obj_t *gauge, lv_gauge_style_t type, lv_style_t *style)

Set the styles of a gauge

Parameters
  • gauge: pointer to a gauge object

  • type: which style should be set (can be only LV_GAUGE_STYLE_MAIN)

  • style: set the style of the gauge

int16_t lv_gauge_get_value(const lv_obj_t *gauge, uint8_t needle)

Get the value of a needle

Return

the value of the needle [min,max]

Parameters
  • gauge: pointer to gauge object

  • needle: the id of the needle

uint8_t lv_gauge_get_needle_count(const lv_obj_t *gauge)

Get the count of needles on a gauge

Return

count of needles

Parameters
  • gauge: pointer to gauge

static int16_t lv_gauge_get_min_value(const lv_obj_t *lmeter)

Get the minimum value of a gauge

Return

the minimum value of the gauge

Parameters
  • gauge: pointer to a gauge object

static int16_t lv_gauge_get_max_value(const lv_obj_t *lmeter)

Get the maximum value of a gauge

Return

the maximum value of the gauge

Parameters
  • gauge: pointer to a gauge object

static int16_t lv_gauge_get_critical_value(const lv_obj_t *gauge)

Get a critical value on the scale.

Return

the critical value

Parameters
  • gauge: pointer to a gauge object

uint8_t lv_gauge_get_label_count(const lv_obj_t *gauge)

Set the number of labels (and the thicker lines too)

Return

count of labels

Parameters
  • gauge: pointer to a gauge object

static uint8_t lv_gauge_get_line_count(const lv_obj_t *gauge)

Get the scale number of a gauge

Return

number of the scale units

Parameters
  • gauge: pointer to a gauge object

static uint16_t lv_gauge_get_scale_angle(const lv_obj_t *gauge)

Get the scale angle of a gauge

Return

angle of the scale

Parameters
  • gauge: pointer to a gauge object

static const lv_style_t *lv_gauge_get_style(const lv_obj_t *gauge, lv_gauge_style_t type)

Get the style of a gauge

Return

pointer to the gauge’s style

Parameters
  • gauge: pointer to a gauge object

  • type: which style should be get (can be only LV_GAUGE_STYLE_MAIN)

struct lv_gauge_ext_t

Public Members

lv_lmeter_ext_t lmeter
int16_t *values
const lv_color_t *needle_colors
uint8_t needle_count
uint8_t label_count