LVGL

https://lvgl.io/docs/open
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### Basic GStreamer Setup Example

Source: https://lvgl.io/docs/open/libs/video_support/gstreamer

Initializes LVGL and runs a GStreamer application within the main loop.

```c
int main(void)
{
    /* Initialize LVGL */
    lv_init();

    /* Setup display driver */
    lv_display_t *display = lv_display_create(800, 480);
    /* ... configure display driver ... */

    /* Create and run your GStreamer application */
    lv_example_gstreamer_1();

    while (1) {
    	lv_timer_handler();
    }

    return 0;
}
```

--------------------------------

### Initialize LVGL with esp_bsp

Source: https://lvgl.io/docs/open/integration/chip_vendors/espressif/add_lvgl_to_esp32_idf_project

Example of starting the LVGL subsystem and running a demo when using the esp_bsp component.

```c
void app_main(void)
{
    bsp_display_start();
    bsp_display_backlight_on();

    bsp_display_lock(0);
    lv_demo_benchmark();
    bsp_display_unlock();
}
```

--------------------------------

### Initialize LVGL with PPA support

Source: https://lvgl.io/docs/open/integration/chip_vendors/espressif/hardware_accelerator_ppa

Example setup for the LVGL subsystem on ESP-IDF, utilizing double buffering to maximize PPA performance.

```c
#include "lvgl.h"
#include "bsp/esp-bsp.h"

void app_main(void)
{
      bsp_display_cfg_t cfg = {
      .lvgl_port_cfg = ESP_LVGL_PORT_INIT_CONFIG(),

      /* Use buffers with the same size of the screen in pixels */
      .buffer_size = BSP_LCD_H_RES * BSP_LCD_V_RES,
      /* Use double buffer (possible with SPIRAM) */
      .double_buffer = 1,
      .hw_cfg = {
   #if CONFIG_BSP_LCD_TYPE_HDMI
   #if CONFIG_BSP_LCD_HDMI_800x600_60HZ
            .hdmi_resolution = BSP_HDMI_RES_800x600,
   #elif CONFIG_BSP_LCD_HDMI_1280x720_60HZ
            .hdmi_resolution = BSP_HDMI_RES_1280x720,
   #elif CONFIG_BSP_LCD_HDMI_1280x800_60HZ
            .hdmi_resolution = BSP_HDMI_RES_1280x800,
   #elif CONFIG_BSP_LCD_HDMI_1920x1080_30HZ
            .hdmi_resolution = BSP_HDMI_RES_1920x1080,
   #endif
   #else
            .hdmi_resolution = BSP_HDMI_RES_NONE,
   #endif
            .dsi_bus = {
               .phy_clk_src = MIPI_DSI_PHY_CLK_SRC_DEFAULT,
               .lane_bit_rate_mbps = BSP_LCD_MIPI_DSI_LANE_BITRATE_MBPS,
            }
      },
      .flags = {
   #if CONFIG_BSP_LCD_COLOR_FORMAT_RGB888
            .buff_dma = false,
   #else
            .buff_dma = true,
   #endif
            /* Use SPIRAM when available */
            .buff_spiram = true,
            .sw_rotate = true,
      }
   };

   bsp_display_start_with_config(&cfg);
   bsp_display_backlight_on();
   bsp_display_lock(0);
   lv_demo_widgets();
   bsp_display_unlock();
}
```

--------------------------------

### Minimal UEFI application example

Source: https://lvgl.io/docs/open/integration/pc/uefi

A complete example showing initialization of the UEFI driver, display, input devices, and the main loop.

```c
#include "lvgl/lvgl.h"
#include "lvgl/examples/lv_examples.h"
#include "lvgl/demos/lv_demos.h"

EFI_STATUS EFIAPI EfiMain(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
{
    lv_uefi_init(ImageHandle, SystemTable);
    lv_init();

    if (!lv_is_initialized()) return EFI_NOT_READY;

    EFI_HANDLE handle = lv_uefi_display_get_active();
    if (!handle) handle = lv_uefi_display_get_any();
    if (!handle) {
        lv_deinit();
        return EFI_UNSUPPORTED;
    }

    lv_display_t *display = lv_uefi_display_create(handle);
    lv_display_set_default(display);

    lv_group_t *group = lv_group_create();
    lv_group_set_default(group);

    lv_obj_t *cursor = lv_image_create(lv_layer_top());
    lv_image_set_src(cursor, "E:cursor.png");

    lv_indev_t *indev;

    indev = lv_uefi_simple_text_input_indev_create();
    lv_indev_set_group(indev, group);
    lv_uefi_simple_text_input_indev_add_all(indev);

    indev = lv_uefi_simple_pointer_indev_create(NULL);
    lv_uefi_simple_pointer_indev_add_all(indev);
    lv_indev_set_cursor(indev, cursor);

    indev = lv_uefi_absolute_pointer_indev_create(NULL);
    lv_uefi_absolute_pointer_indev_add_all(indev);

    lv_demo_widgets();

    size_t counter = 0;
    while (counter < 10000) {
        counter++;
        gBS->Stall(1000);
        lv_tick_inc(1);
        lv_timer_handler();
    }

    return EFI_SUCCESS;
}
```

--------------------------------

### Example WORKDIR path

Source: https://lvgl.io/docs/open/integration/embedded_linux/distros/yocto/terms_and_variables

A concrete example of a resolved WORKDIR path for a specific recipe.

```bash
poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0
```

--------------------------------

### Arduino NV3007 Integration Example

Source: https://lvgl.io/docs/open/integration/external_display_controllers/nv3007

Complete example demonstrating SPI configuration, callback implementation, and LVGL initialization for the NV3007.

```cpp
#include <lvgl.h>

/* Platform-specific includes */
#include <SPI.h>

#define LCD_DC 21
#define LCD_CS 5
#define LCD_RST 4
#define LCD_SCK 18
#define LCD_MOSI 23
#define LCD_MISO -1
#define LCD_BL 15
#define SPI_CLK 40000000

#define BUFFER_SIZE 142 * 50
uint8_t buf[BUFFER_SIZE];

/*  Tell LVGL how much time has elapsed */
static uint32_t my_tick(void)
{
    return millis();
}

/*  Define your platform-specific functions to send commands and data */
void my_lcd_send_cmd(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, const uint8_t *param, size_t param_size)
{
    SPI.beginTransaction(SPISettings(SPI_CLK, MSBFIRST, SPI_MODE0));
    /* Send command */
    digitalWrite(LCD_DC, LOW); /* command mode */
    digitalWrite(LCD_CS, LOW); /* CS low */
    SPI.transferBytes(cmd, NULL, cmd_size);

    /* Send parameters (if any) */
    if (param != NULL && param_size > 0)
    {
        digitalWrite(LCD_DC, HIGH); /* data mode */
        SPI.transferBytes(param, NULL, param_size);
    }
    digitalWrite(LCD_CS, HIGH); /* CS high */
    SPI.endTransaction();
}

void my_lcd_send_color(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, uint8_t *param, size_t param_size)
{
    SPI.beginTransaction(SPISettings(SPI_CLK, MSBFIRST, SPI_MODE0));
    digitalWrite(LCD_CS, LOW);

    /* Send the command first */
    digitalWrite(LCD_DC, LOW);
    SPI.transferBytes(cmd, NULL, cmd_size);

    /* Then send the pixel data */
    if (param && param_size > 0)
    {
        digitalWrite(LCD_DC, HIGH);
        SPI.transferBytes(param, NULL, param_size);
    }

    digitalWrite(LCD_CS, HIGH);
    SPI.endTransaction();

    /* Important: signal LVGL that we're done */
    lv_display_flush_ready(disp);
}

void setup()
{

    pinMode(LCD_BL, OUTPUT);
    digitalWrite(LCD_BL, HIGH); /*  turn on backlight */

    pinMode(LCD_DC, OUTPUT);
    pinMode(LCD_CS, OUTPUT);
    pinMode(LCD_RST, OUTPUT);
    /*  reset sequence */
    digitalWrite(LCD_RST, HIGH);
    delay(100);
    digitalWrite(LCD_RST, LOW);
    delay(120);
    digitalWrite(LCD_RST, HIGH);
    delay(120);

    SPI.begin(LCD_SCK, LCD_MISO, LCD_MOSI, LCD_CS); /*  SCK, MISO, MOSI, SS */

    digitalWrite(LCD_CS, HIGH); /*  disable device */
    delay(100);             /*  wait for device to stabilize */

    lv_init();

    lv_tick_set_cb(my_tick);

    /*  Create NV3007 display */
    lv_display_t *disp = lv_nv3007_create(142, 428, LV_LCD_FLAG_NONE, my_lcd_send_cmd, my_lcd_send_color);
    lv_nv3007_set_gap(disp, 0, 14);
    lv_display_set_rotation(disp, LV_DISPLAY_ROTATION_270);
    lv_display_set_color_format(disp, LV_COLOR_FORMAT_RGB565_SWAPPED);
    lv_display_set_buffers(disp, buf, NULL, BUFFER_SIZE, LV_DISPLAY_RENDER_MODE_PARTIAL);

    /*  Create a simple label on the display */
    lv_obj_t *label = lv_label_create(lv_screen_active());
    lv_label_set_text(label, "Hello NV3007!");
    lv_obj_align(label, LV_ALIGN_CENTER, 0, 0);
}

void loop()
{
    lv_task_handler();
    delay(5);
}
```

--------------------------------

### Install NuttX Prerequisites

Source: https://lvgl.io/docs/open/integration/rtos/nuttx

Install necessary build tools and dependencies on a Linux-based system.

```bash
$ sudo apt-get install automake bison build-essential flex gcc-arm-none-eabi gperf git libncurses5-dev libtool libusb-dev libusb-1.0.0-dev pkg-config kconfig-frontends openocd
```

--------------------------------

### Execute SDK Installer

Source: https://lvgl.io/docs/open/integration/embedded_linux/distros/yocto/lvgl_recipe

Run the generated shell script to install the SDK into a target directory.

```bash
$ ./sdk/poky-glibc-x86_64-core-image-base-cortexa53-raspberrypi3-64-toolchain-5.0.4.sh
Poky (Yocto Project Reference Distro) SDK installer version 5.0.4
=================================================================
Enter target directory for SDK (default: /opt/poky/5.0.4): /opt/poky/sdk-with-lvgl
You are about to install the SDK to "/opt/poky/sdk-with-lvgl". Proceed [Y/n]? y
```

--------------------------------

### Install Build Host Packages

Source: https://lvgl.io/docs/open/integration/embedded_linux/distros/yocto/lvgl_recipe

Installs essential dependencies on an Ubuntu-based build host.

```bash
sudo apt install gawk wget git diffstat unzip texinfo gcc build-essential \
chrpath socat cpio python3 python3-pip python3-pexpect xz-utils \
debianutils iputils-ping python3-git python3-jinja2 python3-subunit zstd \
liblz4-tool file locales libacl1
```

--------------------------------

### Get Text Selection Start

Source: https://lvgl.io/docs/open/api/public/widgets/lv_label_h

Retrieves the starting index of the current text selection.

```c
uint32_t lv_label_get_text_selection_start(const lv_obj_t *obj)
```

--------------------------------

### Install libpng via APT

Source: https://lvgl.io/docs/open/libs/image_support/libpng

Use this command to install the libpng development headers on Debian-based systems.

```bash
sudo apt install libpng-dev
```

--------------------------------

### Get Arc Label Start Angle

Source: https://lvgl.io/docs/open/api/public/widgets/lv_arclabel_h

Retrieves the start angle of the arc label, which may be fractional if LV_USE_FLOAT is enabled.

```c
lv_value_precise_t lv_arclabel_get_angle_start(lv_obj_t *obj)
```

--------------------------------

### Initialize and Run LVGL

Source: https://lvgl.io/docs/open/getting_started/porting

This example demonstrates the core integration flow, including driver initialization, display buffer configuration, and the main timer handler loop.

```c
void main(void)
{
    your_driver_init();

    lv_init();

    lv_tick_set_cb(my_get_millis);

    lv_display_t * display = lv_display_create(320, 240);

    /* LVGL will render to this 1/10 screen sized buffer for 2 bytes/pixel */
    static uint8_t buf[320 * 240 / 10 * 2];
    lv_display_set_buffers(display, buf, NULL, sizeof(buf), LV_DISPLAY_RENDER_MODE_PARTIAL);

    /* This callback will display the rendered image */
    lv_display_set_flush_cb(display, my_flush_cb);

    /* Create widgets */
    lv_obj_t * label = lv_label_create(lv_screen_active());
    lv_label_set_text(label, "Hello LVGL!");

    /* Make LVGL periodically execute its tasks */
    while(1) {
        /* Provide updates to currently-displayed Widgets here. */
        lv_timer_handler();
        my_sleep(5);  /*Wait 5 milliseconds before processing LVGL timer again*/
    }
}

/* Return the elapsed milliseconds since startup.
 * It needs to be implemented by the user */
uint32_t my_get_millis(void)
{
    return my_tick_ms;
}

/* Copy rendered image to screen.
 * This needs to be implemented by the user. */
void my_flush_cb(lv_display_t * disp, const lv_area_t * area, uint8_t * px_buf)
{
    /* Show the rendered image on the display */
    my_display_update(area, px_buf);

    /* Indicate that the buffer is available.
     * If DMA were used, call in the DMA complete interrupt. */
    lv_display_flush_ready(disp);
}
```

--------------------------------

### lv_label_get_text_selection_start

Source: https://lvgl.io/docs/open/api/public/widgets/lv_label_h

Get the start index of the selected text.

```APIDOC
## lv_label_get_text_selection_start

### Description
Gets the selection start index.

### Signature
`uint32_t lv_label_get_text_selection_start(const lv_obj_t *obj)`

### Parameters
- **obj** (const lv_obj_t *) - Required - Pointer to a label object.

### Returns
- **uint32_t** - Selection start index.
```

--------------------------------

### Create a QNX LVGL Application

Source: https://lvgl.io/docs/open/integration/rtos/qnx

Example of initializing LVGL, creating a window, adding input devices, and running the event loop on QNX.

```c
#include <lvgl.h>

int
main(int argc, char **argv)
{
    /* Initialize the library. */
    lv_init();

    /* Create a 800x480 window. */
    lv_display_t *disp = lv_qnx_window_create(800, 480);
    lv_qnx_window_set_title(disp, "LVGL Example");

    /* Add keyboard and mouse devices. */
    lv_qnx_add_keyboard_device(disp);
    lv_qnx_add_pointer_device(disp);

    /* Generate the UI. */
    lv_obj_set_style_bg_color(lv_screen_active(), lv_color_hex(0x003a57), LV_PART_MAIN);

    lv_obj_t * label = lv_label_create(lv_screen_active());
    lv_label_set_text(label, "Hello world");
    lv_obj_set_style_text_color(label, lv_color_hex(0xffffff), LV_PART_MAIN);
    lv_obj_align(label, LV_ALIGN_CENTER, 0, 0);

    /* Run the event loop until it exits. */
    return lv_qnx_event_loop(disp);
}
```

--------------------------------

### Install Buildroot system dependencies

Source: https://lvgl.io/docs/open/integration/embedded_linux/distros/buildroot/custom_image

Installs the required host packages on Ubuntu to support the Buildroot compilation process.

```bash
sudo apt install sed make binutils gcc g++ bash patch gzip bzip2 perl tar \
        cpio python3 unzip rsync wget libncurses-dev
```

--------------------------------

### lv_arclabel_get_angle_start

Source: https://lvgl.io/docs/open/api/public/widgets/lv_arclabel_h

Get the start angle of an arc label.

```APIDOC
## lv_value_precise_t lv_arclabel_get_angle_start(lv_obj_t *obj)

### Description
Get the start angle of an arc label.

### Parameters
- **obj** (lv_obj_t *) - Pointer to an arc label object

### Returns
- **lv_value_precise_t** - The start angle [0..360]
```

--------------------------------

### Install Dependencies for mkttf

Source: https://lvgl.io/docs/open/main-modules/fonts/bdf_fonts

Installs necessary tools like imagemagick, python3-fontforge, and potrace on Ubuntu systems.

```bash
sudo apt install imagemagick python3-fontforge potrace
```

--------------------------------

### Get Arc Angles

Source: https://lvgl.io/docs/open/api/public/widgets/lv_arc_h

Retrieves the start or end angles for the arc or its background.

```c
lv_value_precise_t lv_arc_get_angle_start(lv_obj_t *obj)
```

```c
lv_value_precise_t lv_arc_get_angle_end(lv_obj_t *obj)
```

```c
lv_value_precise_t lv_arc_get_bg_angle_start(lv_obj_t *obj)
```

```c
lv_value_precise_t lv_arc_get_bg_angle_end(lv_obj_t *obj)
```

--------------------------------

### Initialize GLFW and LVGL

Source: https://lvgl.io/docs/open/integration/embedded_linux/drivers/glfw

A complete example demonstrating how to initialize LVGL, create a GLFW window, set up a texture display, and run the main event loop.

```c
#include "lvgl/lvgl.h"
#include "lvgl/examples/lv_examples.h"
#include "lvgl/demos/lv_demos.h"

#define WIDTH 640
#define HEIGHT 480

int main()
{
    /* initialize lvgl */
    lv_init();

    /* create a window and initialize OpenGL */
    lv_opengles_window_t * window = lv_opengles_glfw_window_create(WIDTH, HEIGHT, true);

    /* create a display that flushes to a texture */
    lv_display_t * texture = lv_opengles_texture_create(WIDTH, HEIGHT);
    lv_display_set_default(texture);

    /* add the texture to the window */
    unsigned int texture_id = lv_opengles_texture_get_texture_id(texture);
    lv_opengles_window_texture_t * window_texture = lv_opengles_window_add_texture(window, texture_id, WIDTH, HEIGHT);

    /* get the mouse indev of the window texture */
    lv_indev_t * mouse = lv_opengles_window_texture_get_mouse_indev(window_texture);

    /* add a cursor to the mouse indev */
    LV_IMAGE_DECLARE(mouse_cursor_icon);
    lv_obj_t * cursor_obj = lv_image_create(lv_screen_active());
    lv_image_set_src(cursor_obj, &mouse_cursor_icon);
    lv_indev_set_cursor(mouse, cursor_obj);

    /* create Widgets on the screen */
    lv_demo_widgets();

    while (1)
    {
        uint32_t time_until_next = lv_timer_handler();
        if(time_until_next == LV_NO_TIMER_READY) time_until_next = LV_DEF_REFR_PERIOD; /*handle LV_NO_TIMER_READY. Another option is to `sleep` for longer*/
        lv_delay_ms(time_until_next);
    }

    return 0;
}
```

--------------------------------

### Get Animation Delay

Source: https://lvgl.io/docs/open/api/public/core/lv_anim_h

Retrieves the configured start delay of an animation in milliseconds.

```c
uint32_t lv_anim_get_delay(const lv_anim_t *a)
```

--------------------------------

### Configure Media Sources

Source: https://lvgl.io/docs/open/libs/video_support/gstreamer

Demonstrates setting up various media sources using URI, File, and WebRTC factories.

```c
/* Load from web URL */
lv_gstreamer_set_src(streamer, LV_GSTREAMER_FACTORY_URI_DECODE,
                     LV_GSTREAMER_PROPERTY_URI_DECODE,
                     "https://example.com/stream.webm");

/* Load from local file */
lv_gstreamer_set_src(streamer, LV_GSTREAMER_FACTORY_URI_DECODE,
                     LV_GSTREAMER_PROPERTY_URI_DECODE,
                     "file:///path/to/video.mp4");

/* RTSP stream */
lv_gstreamer_set_src(streamer, LV_GSTREAMER_FACTORY_URI_DECODE,
                     LV_GSTREAMER_PROPERTY_URI_DECODE,
                     "rtsp://camera.local/stream");
```

```c
/* Direct file access */
lv_gstreamer_set_src(streamer, LV_GSTREAMER_FACTORY_FILE,
                     LV_GSTREAMER_PROPERTY_FILE,
                     "/path/to/video.mp4");
```

```c
/* WebRTC stream */
lv_gstreamer_set_src(streamer, LV_GSTREAMER_FACTORY_WEBRTCSRC,
                     LV_GSTREAMER_PROPERTY_WEBRTCSRC,
                     "ws://signalserver:port/");
```

--------------------------------

### Include LVGL Demos and Examples

Source: https://lvgl.io/docs/open/integration/frameworks/platformio

Modify build_src_filter in platformio.ini to force the compilation of library demos and examples.

```ini
build_src_filter =
    +<*>
    ; Force compile LVGL demos and examples, remove when working on your own project
    +<../.pio/libdeps/${PIOENV}/lvgl/demos>
    +<../.pio/libdeps/${PIOENV}/lvgl/examples>
```

--------------------------------

### Get elapsed milliseconds

Source: https://lvgl.io/docs/open/api/public/tick/lv_tick_h

Retrieves the total elapsed milliseconds since the system started.

```c
uint32_t lv_tick_get(void)
```

--------------------------------

### Build and install the SDK

Source: https://lvgl.io/docs/open/integration/embedded_linux/distros/buildroot/quick_start

Compiles the SDK and extracts it to the user's home directory.

```bash
cd output
make sdk
mkdir -p ~/sdk
tar -xzf images/aarch64-buildroot-linux-gnu_sdk-buildroot.tar.gz -C ~/sdk
```

--------------------------------

### Initialize Display with Flags

Source: https://lvgl.io/docs/open/integration/external_display_controllers/gen_mipi

Example of creating a display instance using multiple configuration flags combined with bitwise OR.

```c
lv_display_t * disp;

disp = lv_lcd_generic_mipi_create(MY_DISPLAY_PIXEL_WIDTH,
                                  MY_DISPLAY_PIXEL_HEIGHT,
                                  LV_LCD_FLAG_MIRROR_X | LV_LCD_FLAG_BGR,
                                  my_lcd_send_cmd,
                                  my_lcd_send_color);
```

--------------------------------

### Get Background Gradient Stops

Source: https://lvgl.io/docs/open/api/public/core/lv_obj_style_gen_h

Retrieves the start and end stop points for the background gradient.

```c
static int32_t lv_obj_get_style_bg_main_stop(const lv_obj_t *obj, lv_part_t part)
```

```c
static int32_t lv_obj_get_style_bg_grad_stop(const lv_obj_t *obj, lv_part_t part)
```

--------------------------------

### Initialize SDL Driver and LVGL

Source: https://lvgl.io/docs/open/integration/pc/sdl

Basic setup for initializing LVGL, creating an SDL window, and setting up input devices.

```c
#define SDL_MAIN_HANDLED        /* To fix SDL's "undefined reference to WinMain" issue */
#include "lvgl/lvgl.h"

static lv_display_t *display;
static lv_indev_t *mouse;
static lv_indev_t *mouse_wheel;
static lv_indev_t *keyboard;

int main()
{
    /* Initialize LVGL */
    lv_init();

    display = lv_sdl_window_create(SDL_HOR_RES, SDL_VER_RES);
    mouse = lv_sdl_mouse_create();
    mouse_wheel = lv_sdl_mousewheel_create();
    keyboard = lv_sdl_keyboard_create();

    /* Create widgets on the screen */
    lv_demo_widgets();

    while (1) {
        lv_timer_handler();
        lv_delay_ms(5);
    }

    return 0;
}
```

--------------------------------

### Initialize X11 Display and Inputs

Source: https://lvgl.io/docs/open/integration/embedded_linux/drivers/X11

Minimal setup for opening an X11 window and enabling input support.

```c
int main(int argc, char ** argv)
{
    ...

    /* initialize X11 display driver */
    lv_display_t * disp = lv_x11_window_create("LVGL X11 Simulation", monitor_hor_res, monitor_ver_res);

    /* initialize X11 input drivers (for keyboard, mouse & mousewheel) */
    lv_x11_inputs_create(disp, NULL);

    ...

    while(true)
    {
        ...

        /* Periodically call the lv_timer handler */
        lv_timer_handler();
    }
}
```

--------------------------------

### Get next input device

Source: https://lvgl.io/docs/open/api/public/indev/lv_indev_h

Iterates through registered input devices. Pass NULL to start from the first device.

```c
lv_indev_t * lv_indev_get_next(lv_indev_t *indev)
```

--------------------------------

### Configure and build FFmpeg from source

Source: https://lvgl.io/docs/open/libs/video_support/ffmpeg

Manual configuration and build steps for FFmpeg when installing from source.

```bash
./configure --disable-all --disable-autodetect --disable-podpages --disable-asm --enable-avcodec --enable-avformat --enable-decoders --enable-encoders --enable-demuxers --enable-parsers --enable-protocol='file' --enable-swscale --enable-zlib
make
sudo make install
```

--------------------------------

### Get two fingers swipe distance

Source: https://lvgl.io/docs/open/api/public/indev/lv_indev_gesture_h

Retrieves the distance in pixels from the starting center for a two-finger swipe gesture.

```c
float lv_event_get_two_fingers_swipe_distance(lv_event_t *gesture_event)
```

--------------------------------

### Get next line index

Source: https://lvgl.io/docs/open/api/private/misc/lv_text_private_h

Determines the byte index of the start of the next line, considering line breaks.

```c
uint32_t lv_text_get_next_line(const char *txt, uint32_t len, const lv_font_t *font, int32_t *used_width, lv_text_attributes_t *attributes)
```

--------------------------------

### Initialize SDK Environment

Source: https://lvgl.io/docs/open/integration/embedded_linux/distros/yocto/lvgl_recipe

Source the environment setup script to configure the shell for cross-compilation.

```bash
source /opt/poky/sdk-with-lvgl/environment-setup-cortexa53-poky-linux
```

--------------------------------

### Set animation get value callback

Source: https://lvgl.io/docs/open/api/public/core/lv_anim_h

Sets a callback to retrieve the current value, allowing start and end values to be relative to the current state.

```c
void lv_anim_set_get_value_cb(lv_anim_t *a, lv_anim_get_value_cb_t get_value_cb)
```

--------------------------------

### lv_obj_is_click_focusable

Source: https://lvgl.io/docs/open/api/public/core/lv_obj_h

Get whether the object gets focused when clicked.

```APIDOC
## bool lv_obj_is_click_focusable(const lv_obj_t *obj)

### Description
Get whether the object gets focused when clicked.

### Parameters
- **obj** (const lv_obj_t *) - Required - Pointer to a widget

### Returns
- **bool** - true if click focusable is enabled
```

--------------------------------

### Create X11 window and inputs

Source: https://lvgl.io/docs/open/api/public/drivers/x11/lv_x11_h

Demonstrates initializing an X11 display driver with input support, either with or without a custom mouse cursor.

```c
lv_display_t* disp = lv_x11_window_create("My Window Title", window_width, window_width);
lv_x11_inputs_create(disp, NULL);
```

```c
lv_image_dsc_t mouse_symbol = {.....};
lv_display_t* disp = lv_x11_window_create("My Window Title", window_width, window_width);
lv_x11_inputs_create(disp, &mouse_symbol);
```

--------------------------------

### Configure LV_USE_DEMO_BENCHMARK

Source: https://lvgl.io/docs/open/api/public/config/lv_conf_internal_h

Enable the system benchmarking demo.

```c
#define LV_USE_DEMO_BENCHMARK 0
```

--------------------------------

### Video Start Command

Source: https://lvgl.io/docs/open/api/private/drivers/display/ft81x/lv_ft81x_defines_h

Definition for the video start command.

```c
#define CMD_VIDEOSTART 0xFFFFFF40
```

--------------------------------

### Start animation

Source: https://lvgl.io/docs/open/api/public/core/lv_anim_h

Starts an animation based on an initialized lv_anim_t structure.

```c
lv_anim_t * lv_anim_start(const lv_anim_t *a)
```

--------------------------------

### Execute the build process

Source: https://lvgl.io/docs/open/integration/embedded_linux/distros/yocto/lvgl_recipe

Run the bitbake command to start building the core-image-base image.

```bash
bitbake core-image-base
```

--------------------------------

### Install libjpeg-turbo

Source: https://lvgl.io/docs/open/libs/image_support/libjpeg_turbo

Install the development headers for libjpeg-turbo on Debian-based systems.

```bash
sudo apt install libjpeg-turbo8-dev
```

--------------------------------

### Start animation timeline

Source: https://lvgl.io/docs/open/api/public/core/lv_anim_timeline_h

Starts the animation timeline and returns the total duration.

```c
uint32_t lv_anim_timeline_start(lv_anim_timeline_t *at)
```

--------------------------------

### Full X11 Initialization with Custom Exit Handling

Source: https://lvgl.io/docs/open/integration/embedded_linux/drivers/X11

Advanced setup including a custom mouse cursor and manual application exit handling.

```c
bool terminated = false;

#if !LV_X11_DIRECT_EXIT
static void on_close_cb(lv_event_t * e)
{
    ...

    terminated = true;
}
#endif

int main(int argc, char ** argv)
{
    ...

    /* initialize X11 display driver */
    lv_display_t * disp = lv_x11_window_create("LVGL X11 Simulation", monitor_hor_res, monitor_ver_res);
    lv_display_add_event_cb(disp, on_close_cb, LV_EVENT_DELETE, disp);

    /* initialize X11 input drivers (for keyboard, mouse & mousewheel) */
    LV_IMAGE_DECLARE(my_mouse_cursor_icon);
    lv_x11_inputs_create(disp, &my_mouse_cursor_icon);

    #if !LV_X11_DIRECT_EXIT
    /* set optional window close callback to enable application cleanup and exit */
    lv_x11_window_set_close_cb(disp, on_close_cb, disp);
    #endif

    ...

    while(!terminated)
    {
        ...

        /* Periodically call the lv_timer handler */
        lv_timer_handler();
    }
}
```

--------------------------------

### Configure LV_USE_DEMO_FLEX_LAYOUT

Source: https://lvgl.io/docs/open/api/public/config/lv_conf_internal_h

Enable the flex layout demo.

```c
#define LV_USE_DEMO_FLEX_LAYOUT 0
```

--------------------------------

### Set Arc Background Start Angle

Source: https://lvgl.io/docs/open/api/public/widgets/lv_arc_h

Sets the starting angle for the arc background.

```c
void lv_arc_set_bg_start_angle(lv_obj_t *obj, lv_value_precise_t start)
```

--------------------------------

### Implement OpenGL Display Flush and Initialization

Source: https://lvgl.io/docs/open/integration/embedded_linux/drivers/opengl_driver

Example showing the flush callback implementation and display initialization for an OpenGL-backed LVGL display.

```c
#include "lvgl/lvgl.h"

#define WIDTH 640
#define HEIGHT 480

/* This flush callback works with both FULL and DIRECT render modes*/
static void flush_cb(lv_display_t *disp, const lv_area_t *area, uint8_t *px_map)
{
    if (lv_display_flush_is_last(disp)) {
        const int32_t disp_width = lv_display_get_horizontal_resolution(disp);
        const int32_t disp_height = lv_display_get_horizontal_resolution(disp);
        /* The texture occupies the full screen even if `area` is not the full screen which happens with RENDER_MODE_DIRECT */
        lv_area_t full_area;
        lv_area_set(&full_area, 0, 0, disp_width, disp_height);

        /* Get the texture id containing LVGL generated UI */
        unsigned int texture_id = lv_opengles_texture_get_texture_id(disp);
        /* This function will render to the current context */
        lv_opengles_render_texture(texture_id, &full_area, LV_OPA_COVER, disp_width, disp_height, &full_area, false, true);
    }
    lv_display_flush_ready(disp);
}

int main()
{
    /* initialize lvgl */
    lv_init();
    /* Don't forget the tick callback */

    /* NOTE: OpenGL context must be created before this point */

    /* Create a display that flushes to a texture. The OpenGL texture will be created for you */
    lv_display_t * texture = lv_opengles_texture_create(WIDTH, HEIGHT);
    /* If you already have an OpenGL texture ready, you can use it instead:
     * lv_display_t * texture = lv_opengles_texture_create_from_texture_id(WIDTH, HEIGHT, my_texture_id); */

    /* Set the display render mode and flush callback
     * lv_display_set_render_mode(texture, LV_DISPLAY_RENDER_MODE_FULL);
     * lv_display_set_flush_cb(texture, flush_cb); */

    /* get the texture ID for use in your application */
    unsigned int texture_id = lv_opengles_texture_get_texture_id(texture);

    /* create Widgets on the screen */
    lv_demo_widgets();

    while (1)
    {
        uint32_t time_until_next = lv_timer_handler();
        if(time_until_next == LV_NO_TIMER_READY) time_until_next = LV_DEF_REFR_PERIOD;
        lv_delay_ms(time_until_next);
    }

    return 0;
}
```

--------------------------------

### Configure Calendar Week Start

Source: https://lvgl.io/docs/open/api/public/config/lv_conf_internal_h

Set whether the calendar week starts on Monday.

```c
#define LV_CALENDAR_WEEK_STARTS_MONDAY 0
```

--------------------------------

### Create QNX window

Source: https://lvgl.io/docs/open/api/public/drivers/qnx/lv_qnx_h

Initializes a new window to serve as an LVGL display with the specified resolution.

```c
lv_display_t * lv_qnx_window_create(int32_t hor_res, int32_t ver_res)
```

--------------------------------

### Configure and Build NuttX Simulator

Source: https://lvgl.io/docs/open/integration/rtos/nuttx

Set up the simulator board configuration and compile the project.

```bash
$ ./tools/configure.sh sim:lvgl_fb
$ make
```

--------------------------------

### Test UEFI protocol installation

Source: https://lvgl.io/docs/open/api/private/drivers/uefi/lv_uefi_private_h

Checks if a specific protocol is installed on a given handle.

```c
bool lv_uefi_protocol_test(EFI_HANDLE handle, EFI_GUID *protocol)
```

--------------------------------

### Initialize Project Directory

Source: https://lvgl.io/docs/open/integration/embedded_linux/distros/torizon

Commands to create the project workspace and clone the necessary LVGL repositories.

```sh
mkdir -p ~/lvgl_torizon_os/
cd ~/lvgl_torizon_os/
touch Dockerfile

git clone --depth 1 https://github.com/lvgl/lv_port_linux
git -C lv_port_linux submodule update --init
```

--------------------------------

### Initialize and configure hardware button input

Source: https://lvgl.io/docs/open/main-modules/indev/button

Complete setup including input device creation, type assignment, coordinate mapping, and read callback registration, followed by the implementation of the read callback.

```c
static const lv_point_t points_array[] = {
    {12,30}, /* First button is assigned to x=12; y=30 */
    {60,90}  /* Second button is assigned to x=60; y=90 */
};

lv_indev_t * indev = lv_indev_create();
lv_indev_set_type(indev, LV_INDEV_TYPE_BUTTON);
lv_indev_set_button_points(indev, points_array);
lv_indev_set_read_cb(indev, button_read);

...

void button_read(lv_indev_t * indev, lv_indev_data_t * data)
{
    /* Get the ID (0,1,2...) of the pressed button.
     * Let's say it returns -1 if no button was pressed */
    int btn_pr = my_btn_read();

    /* Is there a button press? */
    if(btn_pr >= 0) {
       data->btn_id = btn_pr;           /* Save the ID of the pressed button */
       data->state = LV_INDEV_STATE_PRESSED;  /* Set the pressed state */
    } else {
       data->state = LV_INDEV_STATE_RELEASED; /* Set the released state */
    }
}
```

--------------------------------

### Set x-axis start point

Source: https://lvgl.io/docs/open/api/public/widgets/lv_chart_h

Sets the index of the starting point in the data array for the x-axis.

```c
void lv_chart_set_x_start_point(lv_obj_t *obj, lv_chart_series_t *ser, uint32_t id)
```

--------------------------------

### Launch LVGL Demo on Hardware

Source: https://lvgl.io/docs/open/integration/rtos/nuttx

Start the LVGL demo using the NSH terminal after resetting the board.

```bash
nsh> lvgldemo
```

--------------------------------

### Initialize SD Card for LVGL

Source: https://lvgl.io/docs/open/libs/fs_support/arduino_sd

Example of the initialization command required before LVGL can access the SD card file system.

```cpp
SD.begin(0, SPI, 40000000)
```

--------------------------------

### Commit Message Examples

Source: https://lvgl.io/docs/open/contributing/pull_requests

Various examples of valid commit messages for different types of changes.

```text
fix(image): update size when a new source is set
```

```text
fix(bar): fix memory leak

The animations weren't deleted in the destructor.

Fixes: #1234
```

```text
feat(span): add span widget

The span widget allows mixing different font sizes, colors and styles.
It's similar to HTML <span>
```

```text
docs(porting): fix typo
```

```text
chore: bump version to release candidate tag
```

```text
feat(drm)!: replace lv_drm_init() arguments

BREAKING CHANGE: lv_drm_init(card, connector) is now
lv_drm_init(device). Replace calls like lv_drm_init(0, 1) with
lv_drm_init("/dev/dri/card0").
```

--------------------------------

### Compile the application

Source: https://lvgl.io/docs/open/integration/embedded_linux/distros/buildroot/quick_start

Sets up the environment and compiles the benchmark application using CMake.

```bash
cd ../application/lv_benchmark
source ../setup-build-env.sh
cmake -B build -S .
make -j $(nproc) -C build
cd ../..
```

--------------------------------

### Set animation start callback

Source: https://lvgl.io/docs/open/api/public/core/lv_anim_h

Registers a callback to be triggered when the animation actually starts, accounting for any delay.

```c
void lv_anim_set_start_cb(lv_anim_t *a, lv_anim_start_cb_t start_cb)
```

--------------------------------

### Launch Kconfig Menu

Source: https://lvgl.io/docs/open/integration/overview

Commands to navigate to the repository and open the menuconfig interface.

```bash
cd <lvgl_repo>
menuconfig
```

--------------------------------

### Initialize and Run LVGL in main.cpp

Source: https://lvgl.io/docs/open/integration/frameworks/platformio

Standard setup for initializing LVGL, setting the tick callback, and running the timer handler in the main loop.

```cpp
#include <Arduino.h>
#include <lvgl.h>

#define BUF_SIZE 320 * 50
uint8_t lv_buffer[BUF_SIZE];

/* Tick source, tell LVGL how much time (milliseconds) has passed */
static uint32_t my_tick(void)
{
    return millis();
}

void setup() {

    /* Initialize LVGL */
    lv_init();
    /* Set the tick callback */
    lv_tick_set_cb(my_tick);
    /* Initialize the display driver */
    lv_lovyan_gfx_create(320, 480, lv_buffer, BUF_SIZE, true);

    lv_obj_t *label = lv_label_create(lv_screen_active());
    lv_label_set_text(label, "Hello PlatformIO, I'm LVGL!");
    lv_obj_align(label, LV_ALIGN_CENTER, 0, 0 );

}

void loop() {
    lv_timer_handler(); // Update the UI-
    delay(5);
}
```

--------------------------------

### Install FFmpeg dependencies

Source: https://lvgl.io/docs/open/libs/video_support/ffmpeg

Use this command on Linux systems to install the necessary FFmpeg development libraries.

```bash
sudo apt install libavformat-dev libavcodec-dev libswscale-dev libavutil-dev
```

--------------------------------

### Configure LV_USE_DEMO_MUSIC

Source: https://lvgl.io/docs/open/api/public/config/lv_conf_internal_h

Enable the music player demo.

```c
#define LV_USE_DEMO_MUSIC 0
```

--------------------------------

### LGFX::init

Source: https://lvgl.io/docs/open/api/private/drivers/display/lovyan_gfx/lv_lgfx_user_hpp

Initializes the display driver.

```APIDOC
## bool LGFX::init(void)

### Description
Initializes the display hardware.

### Returns
- **bool** - Returns true if initialization was successful, false otherwise.
```

--------------------------------

### Run RZ/G2L and RZ/G2UL Project

Source: https://lvgl.io/docs/open/integration/chip_vendors/renesas/rzg_family

Execute the benchmark demo on the RZ/G2L or RZ/G2UL board.

```bash
./lvgl_demo_benchmark
```

--------------------------------

### Install Wayland Dependencies

Source: https://lvgl.io/docs/open/integration/embedded_linux/drivers/wayland

Commands to install required Wayland development packages on Ubuntu and Fedora systems.

```bash
sudo apt-get install libwayland-dev libxkbcommon-dev libwayland-bin wayland-protocols
```

```bash
sudo dnf install wayland-devel libxkbcommon-devel wayland-utils wayland-protocols-devel
```

--------------------------------

### Install DRM Development Headers

Source: https://lvgl.io/docs/open/integration/embedded_linux/drivers/drm

Install the required libdrm development files on Debian or Ubuntu systems.

```bash
sudo apt-get install libdrm-dev
```

--------------------------------

### void lv_grid_init(void)

Source: https://lvgl.io/docs/open/api/public/layouts/lv_grid_h

Initializes the grid layout module.

```APIDOC
## void lv_grid_init(void)

### Description
Initializes the grid layout module.
```

--------------------------------

### lv_nanovg_utils_init

Source: https://lvgl.io/docs/open/api/private/draw/nanovg/lv_nanovg_utils_h

Initializes the NanoVG utility system.

```APIDOC
## lv_nanovg_utils_init

### Description
Initializes the NanoVG utility system using the provided draw unit.

### Signature
`void lv_nanovg_utils_init(struct _lv_draw_nanovg_unit_t *u)`

### Parameters
- **u** (struct _lv_draw_nanovg_unit_t *) - Pointer to the nanovg unit.
```

--------------------------------

### Verify Library Installation

Source: https://lvgl.io/docs/open/integration/embedded_linux/distros/buildroot/app_deployment

Locate installed libraries within the target sysroot to ensure dependencies are met.

```bash
find build/ -name "*libdrm*"
```

--------------------------------

### Display BitBake help options

Source: https://lvgl.io/docs/open/integration/embedded_linux/distros/yocto/core_components

Use these commands to list available command-line options for the BitBake tool.

```bash
$ bitbake -h
$ bitbake --help
```

--------------------------------

### Set animation timeline delay

Source: https://lvgl.io/docs/open/api/public/core/lv_anim_timeline_h

Sets the delay before the animation starts, applicable when playing from the start or reversing from the end.

```c
void lv_anim_timeline_set_delay(lv_anim_timeline_t *at, uint32_t delay)
```

--------------------------------

### Configure LV_USE_DEMO_WIDGETS

Source: https://lvgl.io/docs/open/api/public/config/lv_conf_internal_h

Enable the widget demo. May require increasing LV_MEM_SIZE.

```c
#define LV_USE_DEMO_WIDGETS 0
```

--------------------------------

### Verify LVGL Installation

Source: https://lvgl.io/docs/open/integration/embedded_linux/distros/yocto/lvgl_recipe

Locate LVGL files within the installed SDK sysroot to confirm successful inclusion.

```bash
cd /opt/poky/sdk-with-lvgl/sysroots/cortexa53-poky-linux
find . -name "*lvgl*"
```

--------------------------------

### Generic MIPI Display Controller Implementation

Source: https://lvgl.io/docs/open/integration/external_display_controllers/gen_mipi

Example implementation showing the required I/O initialization, command transmission, and color flushing functions for a generic MIPI display.

```c
#include "src/drivers/display/st7789/lv_st7789.h"

#define LCD_H_RES        240
#define LCD_V_RES        320
#define LCD_BUF_LINES    60

lv_display_t * my_disp;

...

/* Initialize LCD I/O bus, reset LCD */
static int32_t my_lcd_io_init(void)
{
    ...
    return HAL_OK;
}

/* Send command to the LCD controller */
static void my_lcd_send_cmd(lv_display_t * disp, const uint8_t * cmd, size_t cmd_size,
                            const uint8_t *param, size_t param_size)
{
    MY_PIN_PREP_TO_SEND_CMD();
    MY_PIN_LCD_CONTROLLER_CHIP_SELECT();
    /* Any delay here needed to meet LCD controller requirements. */

    /* Send command to LCD controller here. */

    MY_PIN_PREP_TO_SEND_DATA();
    /* Any delay here needed to meet LCD controller requirements. */

    /* Send data to LCD controller here. */

    MY_PIN_LCD_CONTROLLER_CHIP_DESELECT();
    /* Any delay here needed to meet LCD controller requirements. */
}

/* Send pixel data to the LCD controller */
static void my_lcd_send_color(lv_display_t * disp, const uint8_t * cmd, size_t cmd_size,
                              uint8_t * param, size_t param_size)
{
    MY_PIN_PREP_TO_SEND_CMD();
    MY_PIN_LCD_CONTROLLER_CHIP_SELECT();
    /* Any delay here needed to meet LCD controller requirements. */

    /* Send command to LCD controller here. */

    MY_PIN_PREP_TO_SEND_DATA();
    /* Any delay here needed to meet LCD controller requirements. */

    /* Send data to LCD controller here in a manner efficient for large blocks of data. */

    /* If data transfer is done with DMA, these 2 steps are not made here, but
     * are instead made immediately after the DMA transfer completes. */
    MY_PIN_LCD_CONTROLLER_CHIP_DESELECT();
    lv_display_flush_ready(disp);
}

int main(int argc, char ** argv)
{
    ...

    /* Initialize LVGL */
    lv_init();

    /* Initialize LCD bus I/O */
    if (my_lcd_io_init() != 0)
        return;

    /* Create the LVGL display object and the LCD display driver */
    my_disp = lv_lcd_generic_mipi_create(LCD_H_RES, LCD_V_RES, LV_LCD_FLAG_NONE,
                                         my_lcd_send_cmd, my_lcd_send_color);

    /* Set display orientation to landscape */
    lv_display_set_rotation(my_disp, LV_DISPLAY_ROTATION_90);

    /* Configure draw buffers, etc. */
    uint8_t * buf1 = NULL;
    uint8_t * buf2 = NULL;

    uint32_t buf_size = LCD_H_RES * LCD_BUF_LINES
            * lv_color_format_get_size(lv_display_get_color_format(my_disp));

    buf1 = lv_malloc(buf_size);
    if(buf1 == NULL) {
        LV_LOG_ERROR("display draw buffer malloc failed");
        return;
    }

    /* Allocate secondary buffer if needed */
    ...

    lv_display_set_buffers(my_disp, buf1, buf2, buf_size, LV_DISPLAY_RENDER_MODE_PARTIAL);

    ui_init(my_disp);

    while(true) {
        ...

        /* Periodically call the lv_timer handler */
        lv_timer_handler();
    }
}
```

--------------------------------

### Configure Image Installation

Source: https://lvgl.io/docs/open/integration/embedded_linux/distros/yocto/lvgl_recipe

Add these lines to local.conf to include the LVGL library in the generated image and host SDK.

```bash
IMAGE_INSTALL:append = " lvgl"
TOOLCHAIN_HOST_TASK:append = " lvgl"
```

--------------------------------

### Breaking Change Commit Examples

Source: https://lvgl.io/docs/open/contributing/pull_requests

Examples of how to flag breaking changes using the '!' syntax and the 'BREAKING CHANGE' footer.

```text
feat(drm)!: replace lv_drm_init() arguments
```

```text
feat(drm)!: replace lv_drm_init() arguments

The card and connector arguments have been merged into a single
device path string for consistency with other driver APIs.

BREAKING CHANGE: lv_drm_init(card, connector) is now
lv_drm_init(device). Replace calls like lv_drm_init(0, 1) with
lv_drm_init("/dev/dri/card0").
```

--------------------------------

### Execute build script

Source: https://lvgl.io/docs/open/integration/embedded_linux/distros/buildroot/custom_image

Set permissions and run the build script to initialize the output directory.

```bash
chmod +x build.sh
./build.sh
```

--------------------------------

### Set Arc Start Angle

Source: https://lvgl.io/docs/open/api/public/widgets/lv_arc_h

Sets the starting angle of the arc. 0 degrees is at the right, 90 degrees is at the bottom.

```c
void lv_arc_set_start_angle(lv_obj_t *obj, lv_value_precise_t start)
```

--------------------------------

### Partial Render Mode Example

Source: https://lvgl.io/docs/open/main-modules/display/setup

Example of setting up draw buffers for partial rendering. This configuration is suitable when draw buffers are smaller than the display resolution, recommended to be at least 1/10th of the display size. Ensure BYTES_PER_PIXEL is correctly defined for your color format.

```c
/* Declare buffer for 1/10 screen size; BYTES_PER_PIXEL will be 2 for RGB565. */
#define BYTES_PER_PIXEL (LV_COLOR_FORMAT_GET_SIZE(LV_COLOR_FORMAT_RGB565))
static uint8_t buf1[MY_DISP_HOR_RES * MY_DISP_VER_RES / 10 * BYTES_PER_PIXEL];
/* Set display buffer for display `display1`. */
lv_display_set_buffers(display1, buf1, NULL, sizeof(buf1), LV_DISPLAY_RENDER_MODE_PARTIAL);
```

--------------------------------

### Install libwebp dependencies

Source: https://lvgl.io/docs/open/libs/image_support/libwebp

Use system package managers to install the necessary development files for libwebp on Linux or macOS.

```bash
# Linux
sudo apt install libwebp-dev
# macOS
brew install webp
```

--------------------------------

### Example path for unpacked source code

Source: https://lvgl.io/docs/open/integration/embedded_linux/distros/yocto/terms_and_variables

Shows the default directory structure for unpacked source code within the build directory.

```bash
poky/build/tmp/work/qemux86-poky-linux/db/5.1.19-r3/db-5.1.19
```

--------------------------------

### Initialize Recipe Directory

Source: https://lvgl.io/docs/open/integration/embedded_linux/distros/yocto/lvgl_recipe

Commands to create the necessary directory structure for a new LVGL application recipe.

```bash
cd ../sources/meta-mylvgl
mkdir -p recipes-lvglapp/lvgl-fbdev-benchmark/files
touch recipes-lvglapp/lvgl-fbdev-benchmark/lvglbenchmarkfbdev_2.4.bb
```

--------------------------------

### Initialize XKB descriptor

Source: https://lvgl.io/docs/open/api/public/drivers/indev/lv_xkb_h

Initializes an XKB descriptor with the provided rule names.

```c
bool lv_xkb_init(lv_xkb_t *dsc, struct xkb_rule_names names)
```

--------------------------------

### Systrace Log Format Example

Source: https://lvgl.io/docs/open/debugging/profiler

This is an example of the processed trace log output in the Android systrace format, which can be imported into Perfetto for visualization.

```text
# tracer: nop
#
LVGL-1 [0] 2892.002993: tracing_mark_write: B|1|lv_timer_handler
LVGL-1 [0] 2892.002993: tracing_mark_write: B|1|_lv_display_refr_timer
LVGL-1 [0] 2892.003459: tracing_mark_write: B|1|refr_invalid_areas
LVGL-1 [0] 2892.003461: tracing_mark_write: B|1|lv_draw_rect
LVGL-1 [0] 2892.003550: tracing_mark_write: E|1|lv_draw_rect
LVGL-1 [0] 2892.003552: tracing_mark_write: B|1|lv_draw_rect
LVGL-1 [0] 2892.003556: tracing_mark_write: E|1|lv_draw_rect
LVGL-1 [0] 2892.003560: tracing_mark_write: B|1|lv_draw_rect
LVGL-1 [0] 2892.003573: tracing_mark_write: E|1|lv_draw_rect
...
```

--------------------------------

### Create NuttX Workspace

Source: https://lvgl.io/docs/open/integration/rtos/nuttx

Initialize a directory for NuttX development.

```bash
$ mkdir ~/nuttxspace
$ cd ~/nuttxspace
```

--------------------------------

### Example of Built-in Stringified IDs

Source: https://lvgl.io/docs/open/debugging/obj_id

When `LV_USE_OBJ_ID_BUILTIN` is enabled, `lv_obj_stringify_id` generates unique string identifiers for widgets. The example shows the sequence of generated IDs for common widgets.

```text
Screen
  obj1
Label
  label1
Button
  btn1
Label
  label2
Label
  label3
Image
  image1
```

--------------------------------

### Configure LV_USE_DEMO_GLTF

Source: https://lvgl.io/docs/open/api/public/config/lv_conf_internal_h

Enable the GLTF demo.

```c
#define LV_USE_DEMO_GLTF 0
```
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