<!-- Copyright © SixtyFPS GmbH <> ; SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-1.2 OR LicenseRef-Slint-commercial -->

# Slint

[![Component Registry](](

Slint is a declarative GUI toolkit to build native user interfaces for desktop and embedded applications written in Rust, C++, or JavaScript.

This component provides the C++ version of [Slint]( for the [Espressif IoT Development Framework](

It has been tested on ESP32-S3 devices.


## Getting Started

### Prerequisites

* Install the [Espressif IoT Development Framework]( and open a terminal or command prompt with the environment set up.
On Windows, follow the [Using the Command Prompt]( instructions, on macOS and Linux, follow the
[Set up the Environment Variables]( instructions.
* Make sure that you have [Rust]( installed.
* Install the Rust toolchains for [Espressif SoCs with Xtensa and RISC-V targets](

### Hello World

The following steps will guide from the a bare-bones esp-idf "hello_world" to a GUI with Slint.

1. Start by creating a new project:
```bash create-project slint-hello-world
cd slint-hello-world
2. Select your chipset with ` set-target`, for example if you're using an `ESP32S3` chipset, run
```bash set-target esp32s3
3. Add a [Board Support Package]( that matches your device as a dependency. For example, if you're using an ESP-BOX, run
```bash add-dependency esp-box
4. Add Slint as a dependency:
```bash add-dependency slint/slint
5. Ensure that Espressif's Rust toolchain is selected for building. Either set the `RUSTUP_TOOLCHAIN` environment variable to the value `esp` or create a file called `rust-toolchain.toml` in your project directory with the following contents:
channel = "esp"
6. Remove `main/slint-hello-world.c`.
7. Create a new file `main/slint-hello-world.cpp` with the following contents:
#include <stdio.h>
#include <esp_err.h>
#include <bsp/display.h>
#include <bsp/esp-bsp.h>
#include <slint-esp.h>


#include "appwindow.h"

extern "C" void app_main(void)
    /* Initialize display  */
    esp_lcd_panel_io_handle_t io_handle = NULL;
    esp_lcd_panel_handle_t panel_handle = NULL;
    const bsp_display_config_t bsp_disp_cfg = {
        .max_transfer_sz = DRAW_BUF_SIZE * sizeof(uint16_t),
    bsp_display_new(&bsp_disp_cfg, &panel_handle, &io_handle);

     /* Set display brightness to 100% */

    std::optional<esp_lcd_touch_handle_t> touch_handle;

    /* Allocate a drawing buffer */
    static std::vector<slint::platform::Rgb565Pixel> buffer(BSP_LCD_H_RES * BSP_LCD_V_RES);

    /* Initialize Slint's ESP platform support*/
    slint_esp_init(slint::PhysicalSize({ BSP_LCD_H_RES, BSP_LCD_V_RES }), panel_handle,
                                       touch_handle, buffer);
    /* Instantiate the UI */
    auto ui = AppWindow::create();
    /* Show it on the screen and run the event loop */
8. Create `main/appwindow.slint` with the following contents:
import { VerticalBox, AboutSlint } from "std-widgets.slint";
export component AppWindow {
    VerticalBox {
        AboutSlint {}
        Text {
            text: "Hello World";
            font-size: 18px;
            horizontal-alignment: center;
9. Edit `main/CMakeLists.txt` to adjust for the new `slint-hello-world.cpp`, add `slint` as required component,
   and instruction the build system to compile `appwindow.slint` to `appwindow.h`. The file should look like this:
idf_component_register(SRCS "slint-hello-world.cpp" INCLUDE_DIRS "." REQUIRES slint)
slint_target_sources(${COMPONENT_LIB} appwindow.slint)
10. Open the configuration editor with ` menuconfig`:
    * Change the stack size under `Component config --> ESP System Settings --> Main task stack size` to at least `8192`. You may need to tweak this value in the future if you run into stack overflows.
    * You may need additional device-specific settings. For example if your device has external SPI RAM,
       you may need to enable that. For details for ESP32-S3 based devices see how to [Configure the PSRAM](
    * Quit the editor with `Q` and save the configuration.

    Alternatively, check in a default sdkconfig tweaked from your board that adds the right amount of ram, flash, and use `CONFIG_MAIN_TASK_STACK_SIZE=8192`

11.  Build the project with ` build`.
12.  Connect your device, then flash and run it with ` flash monitor`.
13.  Observe Slint rendering "Hello World" on the screen 🎉.

Congratulations, you're all set up to develop with Slint. For more information, check out our [online documentation](

If you have feedback or questions, feel free to reach out to the Slint community:

-   [Chat with us]( on Mattermost.
-   [Ask questions]( on GitHub
-   Contact us on [Twitter]( or [Mastodon](
-   [Report a bug]( on Github

## Troubleshooting

You may run into compile or run-time issues due to Slint's requirements. The following sections
track issues we're aware of and how to solve them.

### Rust Compilation Error During Slint Build

You see the following error:

error: the `-Z` flag is only accepted on the nightly channel of Cargo, but this is the `stable` channel

Solution: You need to configure your Rust toolchain to use the esp channel. Either set the `RUSTUP_TOOLCHAIN` environment variable to the value `esp` or create a file called `rust-toolchain.toml` in your project directory with the following contents:
channel = "esp"

### Error compiling Slint for ESP-IDF on Windows

You see errors about `slint-compiler`:

Error copying file (if different) from "C:/path/build/./cargo/build/x86_64-pc-windows-msvc/release/slint-compiler" to "C:/path/build/_deps/slint-build".

Solution: At the moment development development on Windows while targeting ESP-IDF is not supported. We're working on a fix and in the meantime we recommend
using [Windows Subsystem for Linux](

### The device crashes at boot or enter a boot loop

One reason could be that you don't have enough ram for the heap or the stack.
Make sure that the stack is big enough (~8KiB), and that all the RAM was made available for the heap allocator.

## License

You can use Slint under ***any*** of the following licenses, at your choice:

1. [GNU GPLv3](,
2. [Paid license](

See also the [Licensing FAQ](

Slint is also available with a third license (Royalty Free) for desktop applications.

## Links

[Website]( · [GitHub]( · [Docs](


Supports all targets

To add this component to your project, run: add-dependency "slint/slint^1.6.0"

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slint/slint version: 1.6.0