feat(dialog): Implemented android save dialog. (#1657)

* Implemented android save dialog.

* small cleanup

* lint

---------

Co-authored-by: Lucas Nogueira <lucas@tauri.app>

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)]