ReadBufferFromQEMU

Warn:This Readme is made by ai Warn:You need to use a speical qemu located at:https://github.com/killjsj/qemu to have a ui called sharedbuffer

path for place custom qemu: in build version, create a folder called 'bin' in the game folder and throw all qemu build inside, in editor,create a folder called 'bin' in the project folder and throw all qemu build inside

A Godot 4.x C++ extension that captures QEMU virtual machine screen output via shared memory.

Features

• Reads screen buffer directly from QEMU's shared memory display
• Supports multiple virtual screens
• Cross-platform (Windows, Linux)
• Real-time frame updating via threading
• RGBA format conversion for various pixel formats

Requirements

• Godot 4.x with C++ support
• QEMU built with --display sharedbuffer support
• For Windows: Visual Studio 2017+ or MinGW-w64
• For Linux: GCC with pthread support

Project Structure

ReadBufferFromQemu/
├── src/
│   ├── read.h          # Main ReaderClass header
│   ├── read.cpp       # Implementation
│   ├── utils.h       # Shared memory utilities
│   ├── utils.cpp     # QEMU process management
│   ├── lock.h       # Cross-platform mutex
│   ├── structDefine.h # Shared memory structures
│   └── register_types.cpp # Godot extension registration
├── project/          # Godot test project
│   └── node_2d.gd   # Demo usage script
└── bin/             # Compiled libraries

Usage

GDScript Usage

extends ReaderClass

var screen_sprites: Array[Sprite2D] = []

func _ready() -> void:
    startMachine(['-m', '2048'])

func _process(_delta: float) -> void:
    sync_connection(_delta)
    var count = get_screen_count()

    if count > 0 and screen_sprites.size() != count:
        _setup_sprites(count)

    for i in range(screen_sprites.size()):
        if get_usable(i):
            screen_sprites[i].texture = get_texture(i)

API Reference

Method	Description
startMachine(args: PackedStringArray)	Start QEMU with given arguments
stopMachine()	Stop the QEMU process
sync_connection(delta: float)	Sync frame data to textures
get_screen_count() -> int	Get number of screens
get_usable(index: int) -> bool	Check if screen is available
get_width(index: int) -> int	Get screen width
get_height(index: int) -> int	Get screen height
get_texture(index: int) -> ImageTexture	Get screen texture

Building

Windows

scons platform=windows target=template_debug

Linux

scons platform=linux target=template_debug

How It Works

1. QEMU Connection: Spawns QEMU with --display sharedbuffer,id=sharedbuf_N
2. Shared Memory: Connects to control block (/QemuCtrl_sharedbuf_N) and data buffers
3. Threaded Reading: Background thread reads pixel data from shared memory
4. Format Conversion: Converts various PIXMAN formats to RGBA8
5. Texture Update: Main thread syncs data to Godot textures

Multi-Screen Support

Each virtual screen has its own:

• Shared memory mapping
• Lock (mutex) for synchronization
• Double buffering (A/B buffers)
• Independent dimensions

Supported Pixel Formats

• PIXMAN_a8r8g8b8 / PIXMAN_x8r8g8b8
• PIXMAN_a8b8g8r8 / PIXMAN_x8b8g8r8
• PIXMAN_b8g8r8a8 / PIXMAN_b8g8r8x8
• PIXMAN_r8g8b8a8 / PIXMAN_r8g8b8x8
• PIXMAN_rgba_float (96bpp/128bpp)

License

MIT