Graphics support

For the Rockchip platform, there are mainly the following graphics
architectures to choose from:

Qt + Wayland

Qt + EGLFS

EGL program + X11

Wayland

None

Multi-window functional requirements, choose:

X11

Wayland

The functional requirements of the desktop, choose:

X11

4K video playback + full screen:

Qt + Wayland

Qt + EGLFS

X11

Wayland

4K video playback + multiple windows:

X11

Qt + Wayland

Wayland

If you don't understand the technology of graphics architecture, you
can continue reading.

X11

X11

 is the 11th version of the X display protocol.  The X protocol has
been used for 30 years. The Client/Server structure of the X protocol
was originally designed to send rendering requests to the X server by
the device (Client side) when the hardware performance was too weak
before (the X server was previously running on another Independent
hardware) rendering display.  However, with the continuous improvement
of modern hardware performance, Client and Server can be run on the
same hardware system at the same time, but the consequence of using
this remote communication structure on the local machine is the loss
of performance. At present, there are branches in the official Debian
branch. Wayland was developed to replace X11, but Wayland is currently
not compatible with existing software, so it has not been officially
replaced.


Reference materials:

   https://en.wikipedia.org/wiki/X.Org_Server
   https://www.comptechdoc.org/os/linux/howlinuxworks/linux_hlxwindows.html
   https://dri.freedesktop.org/wiki/DDX/
   https://www.freedesktop.org/wiki/Software/Glamor/
   https://en.wikipedia.org/wiki/X.Org_Server

Qt + EGLFS

Qt + EGLFS

 is a GUI system implemented by Qt itself. It does not support
multiple windows, but window composite is therefore missing.  The
method of Qt + EGLFS and dri2 is similar. The difference is that the
font buffer of Qt + EGLFS is directly sent to the DRM display after
using gpu composite by itself, while the X is sent to the Window
manager for composite, so EGLFS is efficient Advantageous.


Qt + Wayland

In

Wayland

,

Weston

 is the specific implementation of the Wayland display protocol, and
its corresponding relationship is just like the relationship between
Xorg (X server) and X.  The only disadvantage of the current
comparison between Wayland and X is the compatibility, so most of the
current mainstream system versions still use X.  Weston no longer uses
the X's Client/Server structure, but directly receives the kernel
events from the synthesizer and passes them to the client, which is
directly rendered by the client. Only the areas that need to be
updated are sent to the synthesizer, and the synthesizer notifies the
kernel. Arrange for page turning.  It should be noted that since
Ubuntu/Debian already has X11, the SDK adds Weston support in
Buildroot by default. In fact, if Ubuntu/Debian needs to install
Weston, it can also be built on the Minimal version. (Firefly Ubuntu
20.04 will come with Wayland and X by default, and you can switch
freely.)


It is recommended to use Buildroot/Yocto for Wayland development. In
terms of efficiency, Wayland is better than X11, mainly due to
compatibility issues. If you don't need a desktop, but also need
multiple windows, you can try Wayland.

None

In addition to X11 and Wayland, there is also

None

, which is also more exposed on embedded systems. For example, MiniGUI
and SDL are the same.  If you want to support DRM and opengl, you can
only choose Qt.

MiniGUI

 is a lightweight embedded graphics library. The requirements for
system resources fully take into account the hardware conditions of
embedded devices. For example, the minimum space occupied by the
MiniGUI library can be cut to about 500K.  In view of the
characteristics of the Buildroot system adapting to devices with tight
hardware resources, MiniGUI with Buildroot is a perfect fit.

Reference materials:

   https://wayland.freedesktop.org/architecture.html
   https://en.wikipedia.org/wiki/Wayland