fix: use xmake-managed CMake for builds

README.md

@@ -80,7 +80,7 @@ Windows 安装包会自动打包 `crossdesk_service.exe` 和 `crossdesk_session_
 
 依赖：
 - [xmake](https://xmake.io/#/guide/installation)
-- [cmake](https://cmake.org/download/) 3.21 及以上
+- [cmake](https://cmake.org/download/) 3.21 及以上（系统版本过低时由 xmake 自动安装）
 
 ### Linux
 
@@ -97,12 +97,11 @@ sudo apt-get install -y \
   libxtst-dev libxcb-randr0-dev libxcb-xtest0-dev libxcb-xinerama0-dev \
   libxcb-shape0-dev libxcb-xkb-dev libxcb-xfixes0-dev libxcb-shm0-dev \
   libasound2-dev libsndio-dev libpulse-dev
-
-# Ubuntu 20.04 自带的 CMake 3.16 不满足 Slint 1.17 的要求
-python3 -m pip install --user cmake==3.31.6
-export PATH="$HOME/.local/bin:$PATH"
 ```
 
+Ubuntu 20.04 自带的 CMake 3.16 不满足要求时，xmake 会自动下载并使用
+CMake 3.21 或更高版本，无需手动替换系统 CMake。
+
 Ubuntu 20.04 默认的 GCC 9 缺少 Slint C++ API 所需的部分 C++20 标准库，
 因此上述命令同时安装并在后续配置中指定 GCC 10。
 

README_EN.md

@@ -85,7 +85,7 @@ If the remote Windows service is not installed, not running, or temporarily unav
 
 Requirements:
 - [xmake](https://xmake.io/#/guide/installation)
-- [cmake](https://cmake.org/download/) 3.21 or later
+- [cmake](https://cmake.org/download/) 3.21 or later (installed automatically by xmake when the system version is too old)
 
 ### Linux
 
@@ -103,12 +103,12 @@ sudo apt-get install -y \
   libxtst-dev libxcb-randr0-dev libxcb-xtest0-dev libxcb-xinerama0-dev \
   libxcb-shape0-dev libxcb-xkb-dev libxcb-xfixes0-dev libxcb-shm0-dev \
   libasound2-dev libsndio-dev libpulse-dev
-
-# Ubuntu 20.04's CMake 3.16 is too old for Slint 1.17.
-python3 -m pip install --user cmake==3.31.6
-export PATH="$HOME/.local/bin:$PATH"
 ```
 
+When Ubuntu 20.04's bundled CMake 3.16 is too old, xmake automatically
+downloads and uses CMake 3.21 or later; replacing the system CMake manually is
+not required.
+
 Ubuntu 20.04's default GCC 9 lacks parts of the C++20 standard library needed
 by Slint's C++ API, so the commands above install GCC 10 and the configuration
 below selects it explicitly.

thirdparty/slint/xmake.lua

@@ -9,7 +9,7 @@ package("slint")
 
     add_configs("shared", {description = "Build the Slint runtime as a shared library", default = true, type = "boolean", readonly = true})
 
-    add_deps("cmake")
+    add_deps("cmake >=3.21 <4.0")
     add_deps("rust 1.92.0", {host = true, private = true, system = false})
 
     on_load(function(package)