feat(dialog): Implemented android save dialog.

.changes/android-dialog-save.md

@@ -0,0 +1,5 @@
+---
+"dialog": patch:feat
+---
+
+Implement `save` API on Android.

plugins/dialog/android/src/main/java/DialogPlugin.kt

@@ -41,6 +41,11 @@ class MessageOptions {
   var cancelButtonLabel: String? = null
 }
 
+@InvokeArg
+class SaveFileDialogOptions {
+  var fileName: String? = null
+}
+
 @TauriPlugin
 class DialogPlugin(private val activity: Activity): Plugin(activity) {
   var filePickerOptions: FilePickerOptions? = null
@@ -204,4 +209,46 @@ class DialogPlugin(private val activity: Activity): Plugin(activity) {
         dialog.show()
       }
   }
+
+  @Command
+  fun saveFileDialog(invoke: Invoke) {
+    try {
+      val args = invoke.parseArgs(SaveFileDialogOptions::class.java)
+
+      val intent = Intent(Intent.ACTION_CREATE_DOCUMENT)
+      intent.addCategory(Intent.CATEGORY_OPENABLE)
+      intent.setType("text/plain")
+      intent.putExtra(Intent.EXTRA_TITLE, args.fileName ?: "")
+      startActivityForResult(invoke, intent, "saveFileDialogResult")
+    } catch (ex: Exception) {
+      val message = ex.message ?: "Failed to pick save file"
+      Logger.error(message)
+      invoke.reject(message)
+    }
+  }
+
+  @ActivityCallback
+  fun saveFileDialogResult(invoke: Invoke, result: ActivityResult) {
+    try {
+      when (result.resultCode) {
+        Activity.RESULT_OK -> {
+          val callResult = JSObject()
+          val intent: Intent? = result.data
+          if (intent != null) {
+            val uri = intent.data
+            if (uri != null) {
+              callResult.put("file", uri.toString())
+            }
+          }
+          invoke.resolve(callResult)
+        }
+        Activity.RESULT_CANCELED -> invoke.reject("File picker cancelled")
+        else -> invoke.reject("Failed to pick files")
+      }
+    } catch (ex: java.lang.Exception) {
+      val message = ex.message ?: "Failed to read file pick result"
+      Logger.error(message)
+      invoke.reject(message)
+    }
+  }
 }

plugins/dialog/guest-js/index.ts

@@ -40,11 +40,18 @@ interface DialogFilter {
  * @since 2.0.0
  */
 interface OpenDialogOptions {
-  /** The title of the dialog window. */
+  /** The title of the dialog window (desktop only). */
   title?: string;
   /** The filters of the dialog. */
   filters?: DialogFilter[];
-  /** Initial directory or file path. */
+  /**
+   * Initial directory or file path.
+   * If it's a directory path, the dialog interface will change to that folder.
+   * If it's not an existing directory, the file name will be set to the dialog's file name input and the dialog will be set to the parent folder.
+   *
+   * On mobile the file name is always used on the dialog's file name input.
+   * If not provided, Android uses `(invalid).txt` as default file name.
+   */
   defaultPath?: string;
   /** Whether the dialog allows multiple selection or not. */
   multiple?: boolean;
@@ -65,14 +72,17 @@ interface OpenDialogOptions {
  * @since 2.0.0
  */
 interface SaveDialogOptions {
-  /** The title of the dialog window. */
+  /** The title of the dialog window (desktop only). */
   title?: string;
   /** The filters of the dialog. */
   filters?: DialogFilter[];
   /**
    * Initial directory or file path.
    * If it's a directory path, the dialog interface will change to that folder.
    * If it's not an existing directory, the file name will be set to the dialog's file name input and the dialog will be set to the parent folder.
+   *
+   * On mobile the file name is always used on the dialog's file name input.
+   * If not provided, Android uses `(invalid).txt` as default file name.
    */
   defaultPath?: string;
   /** Whether to allow creating directories in the dialog. Enabled by default. **macOS Only** */

plugins/dialog/src/commands.rs

@@ -71,6 +71,18 @@ pub struct SaveDialogOptions {
     can_create_directories: Option<bool>,
 }
 
+#[cfg(mobile)]
+fn set_default_path<R: Runtime>(
+    mut dialog_builder: FileDialogBuilder<R>,
+    default_path: PathBuf,
+) -> FileDialogBuilder<R> {
+    if let Some(file_name) = default_path.file_name() {
+        dialog_builder = dialog_builder.set_file_name(file_name.to_string_lossy());
+    }
+    dialog_builder
+}
+
+#[cfg(desktop)]
 fn set_default_path<R: Runtime>(
     mut dialog_builder: FileDialogBuilder<R>,
     default_path: PathBuf,
@@ -193,9 +205,9 @@ pub(crate) async fn save<R: Runtime>(
     dialog: State<'_, Dialog<R>>,
     options: SaveDialogOptions,
 ) -> Result<Option<PathBuf>> {
-    #[cfg(mobile)]
+    #[cfg(target_os = "ios")]
     return Err(crate::Error::FileSaveDialogNotImplemented);
-    #[cfg(desktop)]
+    #[cfg(any(desktop, target_os = "android"))]
     {
         let mut dialog_builder = dialog.file();
         #[cfg(any(windows, target_os = "macos"))]

plugins/dialog/src/error.rs

@@ -18,8 +18,8 @@ pub enum Error {
     #[cfg(mobile)]
     #[error("Folder picker is not implemented on mobile")]
     FolderPickerNotImplemented,
-    #[cfg(mobile)]
-    #[error("File save dialog is not implemented on mobile")]
+    #[cfg(target_os = "ios")]
+    #[error("File save dialog is not implemented on iOS")]
     FileSaveDialogNotImplemented,
     #[error(transparent)]
     Fs(#[from] tauri_plugin_fs::Error),

plugins/dialog/src/lib.rs

@@ -17,8 +17,10 @@ use tauri::{
     Manager, Runtime,
 };
 
+#[cfg(any(desktop, target_os = "ios"))]
+use std::fs;
+
 use std::{
-    fs,
     path::{Path, PathBuf},
     sync::mpsc::sync_channel,
 };
@@ -273,6 +275,7 @@ pub struct FileDialogBuilder<R: Runtime> {
 #[derive(Serialize)]
 #[serde(rename_all = "camelCase")]
 pub(crate) struct FileDialogPayload<'a> {
+    file_name: &'a Option<String>,
     filters: &'a Vec<Filter>,
     multiple: bool,
 }
@@ -298,6 +301,7 @@ impl<R: Runtime> FileDialogBuilder<R> {
     #[cfg(mobile)]
     pub(crate) fn payload(&self, multiple: bool) -> FileDialogPayload<'_> {
         FileDialogPayload {
+            file_name: &self.file_name,
             filters: &self.filters,
             multiple,
         }
@@ -471,7 +475,6 @@ impl<R: Runtime> FileDialogBuilder<R> {
     ///     })
     ///   })
     /// ```
-    #[cfg(desktop)]
     pub fn save_file<F: FnOnce(Option<PathBuf>) + Send + 'static>(self, f: F) {
         save_file(self, f)
     }
@@ -572,13 +575,13 @@ impl<R: Runtime> FileDialogBuilder<R> {
     ///   // the file path is `None` if the user closed the dialog
     /// }
     /// ```
-    #[cfg(desktop)]
     pub fn blocking_save_file(self) -> Option<PathBuf> {
         blocking_fn!(self, save_file)
     }
 }
 
 // taken from deno source code: https://github.com/denoland/deno/blob/ffffa2f7c44bd26aec5ae1957e0534487d099f48/runtime/ops/fs.rs#L913
+#[cfg(desktop)]
 #[inline]
 fn to_msec(maybe_time: std::result::Result<std::time::SystemTime, std::io::Error>) -> Option<u64> {
     match maybe_time {

plugins/dialog/src/mobile.rs

@@ -1,6 +1,7 @@
 // Copyright 2019-2023 Tauri Programme within The Commons Conservancy
 // SPDX-License-Identifier: Apache-2.0
 // SPDX-License-Identifier: MIT
+use std::path::PathBuf;
 
 use serde::{de::DeserializeOwned, Deserialize};
 use tauri::{
@@ -49,6 +50,11 @@ struct FilePickerResponse {
     files: Vec<FileResponse>,
 }
 
+#[derive(Debug, Deserialize)]
+struct SaveFileResponse {
+    file: PathBuf,
+}
+
 pub fn pick_file<R: Runtime, F: FnOnce(Option<FileResponse>) + Send + 'static>(
     dialog: FileDialogBuilder<R>,
     f: F,
@@ -83,6 +89,23 @@ pub fn pick_files<R: Runtime, F: FnOnce(Option<Vec<FileResponse>>) + Send + 'sta
     });
 }
 
+pub fn save_file<R: Runtime, F: FnOnce(Option<PathBuf>) + Send + 'static>(
+    dialog: FileDialogBuilder<R>,
+    f: F,
+) {
+    std::thread::spawn(move || {
+        let res = dialog
+            .dialog
+            .0
+            .run_mobile_plugin::<SaveFileResponse>("saveFileDialog", dialog.payload(false));
+        if let Ok(response) = res {
+            f(Some(response.file))
+        } else {
+            f(None)
+        }
+    });
+}
+
 #[derive(Debug, Deserialize)]
 struct ShowMessageDialogResponse {
     #[allow(dead_code)]