Span (lv_span)

Overview

A spangroup is the object that is used to display rich text. Different from the label object, spangroup can render text styled with different fonts, colors, and sizes into the spangroup object.

Parts and Styles

LV_PART_MAIN The spangroup has only one part.

Usage

Set text and style

The spangroup object uses span to describe text and text style. so, first we need to create span descriptor using lv_span_t * span = lv_spangroup_new_span(spangroup). Then use lv_span_set_text(span, "text") to set text. The style of the span is configured as with a normal style object by using its style member, eg:lv_style_set_text_color(&span->style, lv_palette_main(LV_PALETTE_RED)).

If spangroup object mode != LV_SPAN_MODE_FIXED you must call lv_spangroup_refr_mode() after you have modified span style(eg:set text, changed the font size, del span).

Retrieving a span child

Spangroups store their children differently from normal objects, so normal functions for getting children won't work.

lv_spangroup_get_child(spangroup, id) will return a pointer to the child span at index id. In addition, id can be negative to index from the end of the spangroup where -1 is the youngest child, -2 is second youngest, etc.

E.g. lv_span_t* span = lv_spangroup_get_child(spangroup, 0) will return the first child of the spangroup. lv_span_t* span = lv_spangroup_get_child(spangroup, -1) will return the last (or most recent) child.

Child Count

Use the function lv_spangroup_get_span_count(spangroup) to get back the number of spans the group is maintaining.

E.g. uint32_t size = lv_spangroup_get_span_count(spangroup)

Text align

Like label object, the spangroup can be set to one the following modes:

LV_TEXT_ALIGN_LEFT Align to left.
LV_TEXT_ALIGN_CENTER Align to center.
LV_TEXT_ALIGN_RIGHT Align to right.
LV_TEXT_ALIGN_AUTO Align auto.

Use function lv_spangroup_set_align(spangroup, LV_TEXT_ALIGN_CENTER) to set text align.

Modes

The spangroup can be set to one the following modes:

LV_SPAN_MODE_FIXED Fixes the object size.
LV_SPAN_MODE_EXPAND Expand the object size to the text size but stay on a single line.
LV_SPAN_MODE_BREAK Keep width, break the too long lines and auto expand height.

Use the function lv_spangroup_set_mode(spangroup, LV_SPAN_MODE_BREAK) to set object mode.

Overflow

The spangroup can be set to one the following modes:

LV_SPAN_OVERFLOW_CLIP truncates the text at the limit of the area.
LV_SPAN_OVERFLOW_ELLIPSIS will display an ellipsis (...) when text overflows the area.

Use function lv_spangroup_set_overflow(spangroup, LV_SPAN_OVERFLOW_CLIP) to set object overflow mode.

First line indent

Use function lv_spangroup_set_indent(spangroup, 20) to set the indent of the first line. all modes support pixel units, in addition to LV_SPAN_MODE_FIXED and LV_SPAN_MODE_BREAK mode supports percentage units too.

Lines

Use function lv_spangroup_set_max_lines(spangroup, 10) to set the maximum number of lines to be displayed in :cpp:enumerator::LV_SPAN_MODE_BREAK mode, negative values indicate no limit.

Events

No special events are sent by this widget.

Learn more about Events.

Keys

No Keys are processed by the object type.

Learn more about Keys.

Example

Span with custom styles

#include "../../lv_examples.h"
#if LV_USE_SPAN && LV_BUILD_EXAMPLES

/**
 * Create span.
 */
void lv_example_span_1(void)
{
    static lv_style_t style;
    lv_style_init(&style);
    lv_style_set_border_width(&style, 1);
    lv_style_set_border_color(&style, lv_palette_main(LV_PALETTE_ORANGE));
    lv_style_set_pad_all(&style, 2);

    lv_obj_t * spans = lv_spangroup_create(lv_screen_active());
    lv_obj_set_width(spans, 300);
    lv_obj_set_height(spans, 300);
    lv_obj_center(spans);
    lv_obj_add_style(spans, &style, 0);

    lv_spangroup_set_align(spans, LV_TEXT_ALIGN_LEFT);
    lv_spangroup_set_overflow(spans, LV_SPAN_OVERFLOW_CLIP);
    lv_spangroup_set_indent(spans, 20);
    lv_spangroup_set_mode(spans, LV_SPAN_MODE_BREAK);

    lv_span_t * span = lv_spangroup_new_span(spans);
    lv_span_set_text(span, "China is a beautiful country.");
    lv_style_set_text_color(&span->style, lv_palette_main(LV_PALETTE_RED));
    lv_style_set_text_decor(&span->style, LV_TEXT_DECOR_UNDERLINE);
    lv_style_set_text_opa(&span->style, LV_OPA_50);

    span = lv_spangroup_new_span(spans);
    lv_span_set_text_static(span, "good good study, day day up.");
#if LV_FONT_MONTSERRAT_24
    lv_style_set_text_font(&span->style,  &lv_font_montserrat_24);
#endif
    lv_style_set_text_color(&span->style, lv_palette_main(LV_PALETTE_GREEN));

    span = lv_spangroup_new_span(spans);
    lv_span_set_text_static(span, "LVGL is an open-source graphics library.");
    lv_style_set_text_color(&span->style, lv_palette_main(LV_PALETTE_BLUE));

    span = lv_spangroup_new_span(spans);
    lv_span_set_text_static(span, "the boy no name.");
    lv_style_set_text_color(&span->style, lv_palette_main(LV_PALETTE_GREEN));
#if LV_FONT_MONTSERRAT_20
    lv_style_set_text_font(&span->style, &lv_font_montserrat_20);
#endif
    lv_style_set_text_decor(&span->style, LV_TEXT_DECOR_UNDERLINE);

    span = lv_spangroup_new_span(spans);
    lv_span_set_text(span, "I have a dream that hope to come true.");
    lv_style_set_text_decor(&span->style, LV_TEXT_DECOR_STRIKETHROUGH);

    lv_spangroup_refr_mode(spans);
}

#endif

API

lv_span.h