LVGL v8 gesture

SiFli SDK provides a unified wrapper for the swipe-right-to-exit (page-back) gesture on LVGL v8, with the corresponding header lvsf_gesture.h. It offers a consistent trigger and follow-finger animation for switching between pages. An application only needs to enable / disable the gesture within the page lifecycle to achieve a consistent swipe-right-back interaction.

The swipe-right-to-exit animation has three forms, determined by the size of the trigger area of the follow-finger animation, which is set by the position of line (the trigger line):

Swipe-right-to-exit from anywhere on the full screen: line is at the right edge of the screen;
Swipe-right-to-exit within a limited area: line is close to the left edge of the screen but leaves a gap;
Full-screen swipe-right-to-exit without the follow-finger animation: line is at the left edge of the screen.

Features

Uniformly wraps the swipe-right-to-exit gesture, ensuring a consistent trigger for page switching.
Supports configuring the position of the right-swipe trigger area line and whether to return directly.
Supports enabling / disabling the gesture animation; the state switch takes effect after entering idle.
Supports realignment of the gesture bars and custom gesture images.

Use Cases

Swipe right on a secondary page to return to the previous page.
When it conflicts with in-page gestures such as tiled page turning, temporarily disable the swipe-right-to-exit gesture in on_resume and restore it in on_pause.
Scenarios that require restricting swipe-right-back to only the left screen-edge area.

Supported Boards

Any platform supported by the general LVGL v8 examples, and any board from 55x onward (such as 58x, 56x, 52x).

Configuration and Initialization

The gesture module is initialized uniformly by the GUI framework, so applications normally do not need to call lvsf_gesture_init() manually. Enable / disable it as needed within the page lifecycle:

#include "lvsf/lvsf_gesture.h"

API Reference

The interface signatures below are taken verbatim from middleware/lvgl/lvsf/lvsf_gesture.h:

Function	Description	Parameters / Returns
`void lvsf_gesture_init(lv_obj_t *parent)`	Initialize the gesture module	`parent`: the parent object to which the gesture widget is attached
`void lvsf_gesture_deinit(void)`	Deinitialize the gesture module	No return value
`void lvsf_gesture_set_image(uint32_t idx, const void *src_img)`	Set the gesture indicator image	`idx`: image index; `src_img`: image source
`void lvsf_gesture_disable(void)`	Disable the gesture; the state switch is executed after entering idle	No return value
`void lvsf_gesture_enable(void)`	Enable the gesture; the state switch is executed after entering idle	No return value
`void lvsf_gesture_bars_realign(void)`	Realign the gesture bars	No return value

Note

The page-level gesture parameter configuration interfaces described in the solution document—such as lv_gesture_init() and gui_app_gesture_set_parem(left_area, goback_en)—belong to the GUI framework layer (not lvsf_gesture.h), and are used to set the right-swipe trigger area line position and whether to return directly.

Typical Usage

In a tiled page that already has a swipe-right page-turn gesture, temporarily disable the swipe-right-to-exit gesture and restore it on leaving:

static void on_resume(void)
{
    /* The page already has a swipe-right page-turn gesture, so disable swipe-right-to-exit */
    lvsf_gesture_disable();
}

static void on_pause(void)
{
    /* Restore the swipe-right-to-exit gesture when leaving the page */
    lvsf_gesture_enable();
}

Demo

gesture swipe-right-to-exit area illustration