platform: pick folder

src/gui/platform/android/mod.rs

@@ -161,6 +161,16 @@ impl PlatformCallbacks for Android {
         Some("".to_string())
     }
 
+    fn pick_folder(&self) -> Option<String> {
+        // Clear previous result.
+        let mut w_path = PICKED_FILE_PATH.write();
+        *w_path = None;
+        // Launch file picker.
+        let _ = self.call_java_method("pickFolder", "()V", &[]);
+        // Return empty string to identify async pick.
+        Some("".to_string())
+    }
+
     fn picked_file(&self) -> Option<String> {
         let has_file = {
             let r_path = PICKED_FILE_PATH.read();

src/gui/platform/desktop/mod.rs

@@ -260,6 +260,17 @@ impl PlatformCallbacks for Desktop {
         None
     }
 
+    fn pick_folder(&self) -> Option<String> {
+        let file = FileDialog::new()
+            .set_title(t!("choose_folder"))
+            .set_directory(dirs::home_dir().unwrap())
+            .pick_folder();
+        if let Some(file) = file {
+            return Some(file.to_str().unwrap_or_default().to_string());
+        }
+        None
+    }
+
     fn picked_file(&self) -> Option<String> {
         None
     }

src/gui/platform/mod.rs

@@ -33,6 +33,7 @@ pub trait PlatformCallbacks {
     fn switch_camera(&self);
     fn share_data(&self, name: String, data: Vec<u8>) -> Result<(), std::io::Error>;
     fn pick_file(&self) -> Option<String>;
+    fn pick_folder(&self) -> Option<String>;
     fn picked_file(&self) -> Option<String>;
     fn request_user_attention(&self);
     fn user_attention_required(&self) -> bool;