.. _qnx:

=== QNX

What is QNX?

QNX is a commercial operating system first released in 1980. The operating system is based on a micro-kernel design, with the file system(s), network stack, and various other drivers each running in its own process with a separate address space.

See www.qnx.com for more details.

Highlight of QNX

• 64-bit only, runs on x86_64 and ARMv8
• Requires an MMU as the design mandates separation among processes
• Support for thousands of processes and millions of threads
• Up to 64 cores, up to 16TB of RAM
• Virtualization support (as host and guest)
• Full POSIX compatibility
• Safety certification to various automotive, industrial and medical standards

How to run LVGL on QNX?

There are two ways to use LVGL in your QNX project. The first is similar to how LVGL is used on other systems. The second is to build LVGL as either a shared or a static library.

Include LVGL in Your Project

Follow the generic instructions for getting started with LVGL. After copying lv_conf_template.h to lv_conf.h make the following changes to the latter:

1. Enable QNX support:

.. code-block:: c

#define LV_USE_QNX 1

2. Set colour depth to 32:

.. code-block:: c

#define LV_COLOR_DEPTH 32

3. (Optional) Enable double-buffering:

.. code-block:: c

#define LV_QNX_BUF_COUNT 2

Build LVGL as a Library

Note that this method is an alternative to including LVGL in your project. If you choose to build a library then you do not need to follow the instructions in the previous section.

The top-level qnx directory includes a recursive make file for building LVGL, both as a shared library and as a static library for the supported architectures. To build all libraries, simply invoke make in this directory:

.. code-block:: shell

# cd $(LVGL_ROOT)/env_support/qnx
# make

If you prefer to build for a specific architecture and variant, go to the appropriate directory and run make there. For example, to build a shared library for ARMv8:

.. code-block:: shell

# cd $(LVGL_ROOT)/env_support/qnx/aarch64/so.le
# make

As a general rule, if you only want to have one LVGL application in your system then it is better to use a static library. If you have more than one, and especially if they run concurrently, it is better to use the shared library.

Before building the library, you may wish to edit $(LVGL_ROOT)/env_support/qnx/lv_conf.h, e.g. to add fonts or disable double-buffering.

Writing a LVGL Application

To create a LVGL application for QNX, follow these steps in your code:

1. Initialize the library.
2. Create a window.
3. Add the input devices.
4. Create the UI.
5. Run the event loop.

Steps 2, 3 and 5 use QNX-specific calls, but the rest of the code should be identical to that of a LVGL application written for any other platform.

The following code shows how to create a "Hello World" application:

.. code-block:: 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(lv_screen_active(), 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);
}

Build the Application

Building the application consists of compiling the source with the LVGL headers, and then linking against the library. This can be done in many ways, using different build systems. The following is a simple make file for the example above, which builds for ARMv8 with the shared library:

.. code-block:: makefile

CC=qcc -Vgcc_ntoaarch64le

LVGL_ROOT=$(HOME)/src/lvgl
CCFLAGS=-I$(LVGL_ROOT)/env_support/qnx -I$(LVGL_ROOT)
LDFLAGS=-lscreen -llvgl -L$(LVGL_ROOT)/env_support/qnx/aarch64/so.le

lvgl_example: lvgl_example.c
	$(CC) $(CCFLAGS) -Wall -o $@ $< $(LDFLAGS)

clean:
	rm -f *.o *~ lvgl_example