feature: Linux AppImages support portable data dir (#2062)

Signed-off-by: leo <longshuang@msn.cn>

Author: love-linger

README.md

@@ -64,27 +64,6 @@
 > [!WARNING]
 > **Linux** only tested on **Debian 12** on both **X11** & **Wayland**.
 
-## Translation Status
-
-You can find the current translation status in [TRANSLATION.md](https://github.com/sourcegit-scm/sourcegit/blob/develop/TRANSLATION.md)
-
-### Translate Utility Script
-
-A script that assists with translations by reading the target language, comparing it with the base language, and going through missing keys one by one, so the translator can provide the translations interactively without needing to check each key manually.
-
-#### Usage
-
-Check for a given language (e.g., `pt_BR`) and optionally check for missing translations:
-
-```bash
-python translate_helper.py pt_BR [--check]
-```
-
-- `pt_BR` is the target language code (change as needed), it should correspond to a file named `pt_BR.axaml` in the `src/Resources/Locales/` directory, so you can replace it with any other language code you want to translate, e.g., `de_DE`, `es_ES`, etc.
-- `--check` is an optional flag used to only check for missing keys without prompting for translations, useful for getting a list of missing translations.
-
-The script will read the base language file (`en_US.axaml`) and the target language file (e.g., `pt_BR.axaml`), identify missing keys, and prompt you to provide translations for those keys. If the `--check` flag is used, it will only list the missing keys without prompting for translations.
-
 ## How to Use
 
 **To use this tool, you need to install Git(>=2.25.1) first.**
@@ -101,7 +80,7 @@ This software creates a folder `$"{System.Environment.SpecialFolder.ApplicationD
 
 > [!TIP]
 > * You can open this data storage directory from the main menu `Open Data Storage Directory`.
-> * You can create a `data` folder next to the `SourceGit` executable to force this app to store data (user settings, downloaded avatars and crash logs) into it (Portable-Mode). Only works on Windows.
+> * You can create a `data` folder next to the `SourceGit` executable to force this app to store data (user settings, downloaded avatars and crash logs) into it (Portable-Mode). Only works with Windows packages and Linux AppImages.
 
 For **Windows** users:
 
@@ -261,6 +240,27 @@ Thanks to all the people who contribute.
 
 [![Contributors](https://contrib.rocks/image?repo=sourcegit-scm/sourcegit&columns=20)](https://github.com/sourcegit-scm/sourcegit/graphs/contributors)
 
+## Translation Status
+
+You can find the current translation status in [TRANSLATION.md](https://github.com/sourcegit-scm/sourcegit/blob/develop/TRANSLATION.md)
+
+### Translate Utility Script
+
+A script that assists with translations by reading the target language, comparing it with the base language, and going through missing keys one by one, so the translator can provide the translations interactively without needing to check each key manually.
+
+#### Usage
+
+Check for a given language (e.g., `pt_BR`) and optionally check for missing translations:
+
+```bash
+python translate_helper.py pt_BR [--check]
+```
+
+- `pt_BR` is the target language code (change as needed), it should correspond to a file named `pt_BR.axaml` in the `src/Resources/Locales/` directory, so you can replace it with any other language code you want to translate, e.g., `de_DE`, `es_ES`, etc.
+- `--check` is an optional flag used to only check for missing keys without prompting for translations, useful for getting a list of missing translations.
+
+The script will read the base language file (`en_US.axaml`) and the target language file (e.g., `pt_BR.axaml`), identify missing keys, and prompt you to provide translations for those keys. If the `--check` flag is used, it will only list the missing keys without prompting for translations.
+
 ## Third-Party Components
 
 For detailed license information, see [THIRD-PARTY-LICENSES.md](THIRD-PARTY-LICENSES.md).

src/Native/OS.cs

@@ -149,6 +149,19 @@ public static void SetupDataDir()
                     return;
                 }
             }
+            else if (OperatingSystem.IsLinux())
+            {
+                var appImage = Environment.GetEnvironmentVariable("APPIMAGE");
+                if (!string.IsNullOrEmpty(appImage) && File.Exists(appImage))
+                {
+                    var portableDir = Path.Combine(Path.GetDirectoryName(appImage)!, "data");
+                    if (Directory.Exists(portableDir))
+                    {
+                        DataDir = portableDir;
+                        return;
+                    }
+                }
+            }
 
             var osAppDataDir = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);
             if (string.IsNullOrEmpty(osAppDataDir))