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怎么使用原生 Android 版本的 Emacs

Revision as of 11:42, 2 October 2025 by Mwroot (talk | contribs) (→‎字体)

原生安卓版本的 Emacs，令安卓上的编程出现了很大的想象力。或许未来，在安卓上编程，会成为更方便的事情。以前，大家都绕道，用 Termux 安装 Emacs，终究是隔了一层。现在，gnu 本身发布了原生安卓版本的 Emacs，可以从 FDroid 分流下载。但是安装后，你会发现你遇到了重重难题。

不迷路

怎么让自己不迷路，知道自己在哪里？ 

# 查看 HOME 环境变量
M-: (getenv "HOME")
# 示例输出："/data/data/org.gnu.emacs/files"

# 查看 ~ 的展开路径
M-: (expand-file-name "~")
# 示例输出："/data/data/org.gnu.emacs/files"

# 查看工作起始目录
M-: default-directory
# 示例输出："~/"

# M-: 运行命令
# 注意 default 别写成 defualt
# 评估变量不用括号
# 调用函数要括号
# 输出就算一样，也是各有所用，并不重复
# 可以单独设置

文件夹

怎么让安卓版本的 Emacs 访问你的安卓里的文件夹呢？ 

# 授予管理所有文件的权限
M-x android-request-storage-access

# 授予管理某个文件夹的权限
M-x android-request-directory-access

设置工作目录

(setq default-directory "/sdcard/Emacs/")

M-x setenv RET HOME RET /sdcard/Emacs

;; ======== 固定 new-file 目录为 /storage/sdcard0/Emacs/ =========
(defvar my-android-emacs-dir "/storage/sdcard0/Emacs/"
  "默认用于新建文件和文件选择的目录（Android）。")

(setq-default default-directory (expand-file-name my-android-emacs-dir))

(add-hook 'emacs-startup-hook
          (lambda ()
            (let ((d (expand-file-name my-android-emacs-dir)))
              (dolist (buf (buffer-list))
                (with-current-buffer buf
                  (setq default-directory d))))))

(defun my-android-find-file-minibuffer-setup ()
  (when (memq this-command '(find-file find-file-other-window))
    (setq default-directory (expand-file-name my-android-emacs-dir))))
(add-hook 'minibuffer-setup-hook #'my-android-find-file-minibuffer-setup)

;; 强力：为 read-file-name 提供默认目录（覆盖大多数 UI 框架）
(defun my-android-read-file-name-wrapper (orig prompt &optional dir default-filename mustmatch initial)
  (let ((dir (or dir (expand-file-name my-android-emacs-dir))))
    (apply orig prompt dir default-filename mustmatch initial)))
(advice-add 'read-file-name :around #'my-android-read-file-name-wrapper)

;; 权限检查命令
(defun my-android-ensure-emacs-dir-access ()
  (interactive)
  (let ((d (expand-file-name my-android-emacs-dir)))
    (if (file-directory-p d)
        (message "目录可访问：%s" d)
      (if (fboundp 'android-request-directory-access)
          (message "请运行 M-x android-request-directory-access 并选择 %s 以授权。" d)
        (message "目录不可访问：%s。请在 系统 -> 应用 -> 特殊应用访问 -> All files access 打开 Emacs 并授予“文件与媒体”权限。" d)))))
(global-set-key (kbd "C-c e d") #'my-android-ensure-emacs-dir-access)
;; ================================================================

字体

怎么让原生安卓版本的 Emacs 识别并正常显示中文字体，而不是 16 进制的字符块呢？

首先，去下载某个字体。

其次，把它复制进原生安卓版本的 Emacs 的工作目录下的 fonts 文件夹。

最后，在 ~/.emacs.d/init.el 里调用该字体。 

(prefer-coding-system 'utf-8)
(set-default-coding-systems 'utf-8-unix)
(set-language-environment "UTF-8")

(set-face-attribute 'default nil :height 300)
(set-fontset-font t 'han "Noto Sans SC:pixelsize=50")


私有目录，一般是 /data/data/org.gnu.emacs/files/fonts。 

M-x copy-file RET /sdcard/Downloads/NotoSansSC-Regular.ttf RET ~/fonts/NotoSansSC-Regular.ttf RET


debug

;; 把整段粘进 *scratch* 并评估，或放到 init.el
(require 'cl-lib)

(defun my-android-debug-info ()
  "Gather Android/`default-directory' debug info and show it in *emacs-android-debug* buffer.
Run `M-x my-android-debug-info' and copy the buffer content to paste here."
  (interactive)
  (let* ((buf (get-buffer-create "*emacs-android-debug*"))
         (dir (if (and (boundp 'my-android-emacs-dir) my-android-emacs-dir)
                  (expand-file-name my-android-emacs-dir)
                "/storage/sdcard0/Emacs/")))
    (with-current-buffer buf
      (setq buffer-read-only nil)
      (erase-buffer)
      (insert (format "===== emacs-android-debug (timestamp: %s) =====\n\n"
                      (current-time-string)))

      ;; basic vars
      (insert (format "my-android-emacs-dir bound: %s\n"
                      (if (boundp 'my-android-emacs-dir) "yes" "no")))
      (when (boundp 'my-android-emacs-dir)
        (insert (format "my-android-emacs-dir value: %s\n" my-android-emacs-dir)))
      (insert (format "resolved my-android-emacs-dir: %s\n\n" dir))

      ;; env
      (insert "=== Environment ===\n")
      (dolist (v '("HOME" "ANDROID_DATA" "EXTERNAL_STORAGE" "EMACS"))
        (insert (format "%-18s = %s\n" v (or (getenv v) ""))))
      (insert "\n")

      ;; home/dirs and current
      (insert "=== Home / Directories ===\n")
      (insert (format "getenv \"HOME\": %s\n" (or (getenv "HOME") "")))
      (insert (format "expand-file-name \"~\": %s\n" (expand-file-name "~")))
      (insert (format "default-directory (current buffer): %s\n\n" default-directory))

      ;; hooks and minibuffer
      (insert "=== Minibuffer & Hooks ===\n")
      (insert (format "minibuffer-setup-hook length: %d\n" (length minibuffer-setup-hook)))
      (insert (format "emacs-startup-hook length: %d\n" (length emacs-startup-hook)))
      (insert (format "my-android-find-file-minibuffer-setup present in minibuffer-setup-hook?: %s\n"
                      (if (memq #'my-android-find-file-minibuffer-setup minibuffer-setup-hook) "yes" "no")))
      (insert "\n")

      ;; buffers
      (insert "=== Buffers and their default-directory ===\n")
      (dolist (b (buffer-list))
        (with-current-buffer b
          (insert (format "%-30s -> %s\n" (buffer-name b) default-directory))))
      (insert "\n")

      ;; features commonly related to file UIs
      (insert "=== Common UI features loaded ===\n")
      (dolist (f '(ivy helm vertico counsel selectrum))
        (insert (format "%-10s : %s\n" f (if (featurep f) "loaded" "not loaded"))))
      (insert "\n")

      ;; read-file-name info
      (insert "=== read-file-name / advice info ===\n")
      (insert (format "read-file-name-function: %s\n" read-file-name-function))
      (insert (format "symbol property 'advice on read-file-name: %s\n"
                      (if (get 'read-file-name 'advice) "present" "none")))
      (insert (format "symbol-function of read-file-name: %s\n\n" (symbol-function 'read-file-name)))

      ;; filesystem checks
      (insert "=== Filesystem checks for resolved my-android-emacs-dir ===\n")
      (insert (format "file-exists-p: %s\n" (file-exists-p dir)))
      (insert (format "file-directory-p: %s\n" (file-directory-p dir)))
      (insert "directory-files (attempt, up to first 20 entries):\n")
      (condition-case err
          (let ((lst (directory-files dir nil nil t)))
            (insert (format "  total entries: %d\n" (length lst)))
            (dolist (e (cl-subseq lst 0 (min 20 (length lst))))
              (insert (format "    %s\n" e))))
        (error (insert (format "  ERROR listing directory: %s\n" err))))
      (insert "\n")

      ;; android helpers
      (insert "=== Android helper functions availability ===\n")
      (insert (format "android-request-directory-access fboundp: %s\n"
                      (if (fboundp 'android-request-directory-access) "yes" "no")))
      (insert (format "android-request-storage-access fboundp: %s\n"
                      (if (fboundp 'android-request-storage-access) "yes" "no")))
      (insert "\n")

      (insert "===== End of report =====\n")
      (goto-char (point-min))
      ;; make read-only for safety and show it
      (view-mode 1)
      (display-buffer buf))))
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