lv_qrcode.h

API reference for lv_qrcode.h

Summary

Set when a property change is turned into a new QR code bitmap. With LV_QRCODE_UPDATE_MODE_IMMEDIATE (the default) changing the size or the quiet zone re-encodes the stored data right away. With LV_QRCODE_UPDATE_MODE_DEFERRED such a change only marks the bitmap as out of date and several changes are collapsed into a single re-encode on the next redraw.

void lv_qrcode_set_update_mode(lv_obj_t *obj, lv_qrcode_update_mode_t mode)

Name	Type	Description
`obj`	`lv_obj_t *`	pointer to a QR code object
`mode`	`lv_qrcode_update_mode_t`	the mode to use

In deferred mode you are expected to call lv_qrcode_render() yourself once the properties are set. It encodes right away and returns the result, leaving the next redraw nothing to do. If it is forgotten, the encode is done by the redraw instead: the bitmap is still correct, but the work is charged to that refresh and its result cannot be reported to anyone, so a warning is logged. Prefer the explicit call.

Switching back to LV_QRCODE_UPDATE_MODE_IMMEDIATE while the bitmap is out of date also re-encodes it, but this function returns void, so an encode failure can only be logged, not reported. A warning is emitted in that case. Call lv_qrcode_render() first and switch the mode afterwards to get the result.

public/widgets/lv_qrcode.h:146function

lv_qrcode_get_update_mode

Get when a property change is turned into a new QR code bitmap.

lv_qrcode_update_mode_t lv_qrcode_get_update_mode(lv_obj_t *obj)

Name	Type	Description
`obj`	`lv_obj_t *`	pointer to a QR code object

Returns: lv_qrcode_update_mode_t — the update mode currently in use

public/widgets/lv_qrcode.h:56function

lv_qrcode_create

Create an empty QR code (an lv_canvas) object.

lv_obj_t * lv_qrcode_create(lv_obj_t *parent)

Name	Type	Description
`parent`	`lv_obj_t *`	pointer to a parent widget May be `NULL`.. When NULL, the widget is created as a screen on the active display.

Returns: lv_obj_t * — pointer to the created QR code object

public/widgets/lv_qrcode.h:90function

lv_qrcode_update

Set the data of a QR code object and generate the bitmap. A copy of the data is stored, so a later lv_qrcode_set_size() or lv_qrcode_set_quiet_zone() can re-encode it. The properties may therefore be set before or after the data, in any order. Use lv_qrcode_render() to re-encode the stored payload without passing it again.

lv_result_t lv_qrcode_update(lv_obj_t *obj, const void *data, uint32_t data_len)

Name	Type	Description
`obj`	`lv_obj_t *`	pointer to a QR code object
`data`	`const void *`	data to display
`data_len`	`uint32_t`	length of `data` in bytes

Returns: lv_result_t — LV_RESULT_OK: if no error; LV_RESULT_INVALID: on error

public/widgets/lv_qrcode.h:110function

lv_qrcode_render

(Re)generate the QR code bitmap from the payload that is already stored. Unlike lv_qrcode_update() this needs no payload, so it is the way to apply property changes made in LV_QRCODE_UPDATE_MODE_DEFERRED: set the size and quiet zone, then call this once to encode them and get the result. The bitmap is regenerated whether or not anything changed.

lv_result_t lv_qrcode_render(lv_obj_t *obj)

Name	Type	Description
`obj`	`lv_obj_t *`	pointer to a QR code object

Returns: lv_result_t — LV_RESULT_OK: if no error; LV_RESULT_INVALID: on error (e.g. no data set, or the payload does not fit the current size)

public/widgets/lv_qrcode.h:164function

lv_qrcode_is_render_valid

Check whether the QR code bitmap is free of a known encode failure. Most encodes report their result directly: lv_qrcode_update() returns it. The ones that cannot are the re-encodes triggered by a property change - they happen in a void setter or, in LV_QRCODE_UPDATE_MODE_DEFERRED, in the draw pass. Use this to detect those, e.g. after shrinking the object below the size its payload needs.

bool lv_qrcode_is_render_valid(lv_obj_t *obj)

Name	Type	Description
`obj`	`lv_obj_t *`	pointer to a QR code object

Returns: bool — true: no encode attempt is known to have failed. A property change re-arms the Widget, so this is also true while a deferred re-encode is still pending; false: the last encode attempt failed, or no data has been set yet

A failed encode leaves the bitmap marked as out of date, so it is never reported as current, and it is not retried on every redraw - only a property change makes the Widget try again. Encode failures are not logged when the caller can see the result; the one exception is the re-encode done by the redraw, which has no caller, so that one is logged.

Enums

public/widgets/lv_qrcode.h:39enum

lv_qrcode_update_mode_t

Controls when a property change is turned into a new QR code bitmap. Only the properties that require re-encoding (size, quiet zone) are affected; lv_qrcode_update() always encodes right away and the colors are always a palette-only write.

Name	Value	Description
`LV_QRCODE_UPDATE_MODE_IMMEDIATE`	`0`	Re-encode as soon as a property changes (default)
`LV_QRCODE_UPDATE_MODE_DEFERRED`		Only mark the bitmap out of date and re-encode once, on the next redraw

Used by 1 function

lv_qrcode_set_update_mode — param mode

Variables

public/widgets/lv_qrcode.h:44variable

lv_qrcode_class

const lv_obj_class_t lv_qrcode_class

lv_qrcode.h

Functions

lv_qrcode_set_size

lv_qrcode_set_dark_color

lv_qrcode_set_light_color

lv_qrcode_set_data

lv_qrcode_set_quiet_zone

lv_qrcode_set_update_mode