Start file dialogs on the desktop

crates/edit/Cargo.toml

@@ -19,6 +19,7 @@ harness = false
 debug-latency = []
 
 [dependencies]
+dirs = "6.0.0"
 lsh.workspace = true
 stdext.workspace = true
 

crates/edit/src/bin/edit/draw_editor.rs

@@ -199,7 +199,7 @@ pub fn draw_handle_save(ctx: &mut Context, state: &mut State) {
             }
         } else {
             // No path? Show the file picker.
-            state.wants_file_picker = StateFilePicker::SaveAs;
+            show_file_picker(state, StateFilePicker::SaveAs);
             state.wants_save = false;
             ctx.needs_rerender();
         }

crates/edit/src/bin/edit/draw_menubar.rs

@@ -43,14 +43,14 @@ fn draw_menu_file(ctx: &mut Context, state: &mut State) {
         draw_add_untitled_document(ctx, state);
     }
     if ctx.menubar_menu_button(loc(LocId::FileOpen), 'O', kbmod::CTRL | vk::O) {
-        state.wants_file_picker = StateFilePicker::Open;
+        show_file_picker(state, StateFilePicker::Open);
     }
     if state.documents.active().is_some() {
         if ctx.menubar_menu_button(loc(LocId::FileSave), 'S', kbmod::CTRL | vk::S) {
             state.wants_save = true;
         }
         if ctx.menubar_menu_button(loc(LocId::FileSaveAs), 'A', vk::NULL) {
-            state.wants_file_picker = StateFilePicker::SaveAs;
+            show_file_picker(state, StateFilePicker::SaveAs);
         }
     }
     #[allow(irrefutable_let_patterns)]

crates/edit/src/bin/edit/main.rs

@@ -301,7 +301,10 @@ fn handle_args(state: &mut State) -> apperr::Result<bool> {
         dir = Some(parent.to_path_buf());
     }
 
-    state.file_picker_pending_dir = DisplayablePathBuf::from_path(dir.unwrap_or(cwd));
+    // EN: With no explicit file or directory, file dialogs begin on the desktop.
+    // 中文：未指定檔案或目錄時，檔案對話框預設由桌面開始。
+    let default_dir = sys::desktop_dir().unwrap_or(cwd);
+    state.file_picker_pending_dir = DisplayablePathBuf::from_path(dir.unwrap_or(default_dir));
     Ok(false)
 }
 
@@ -381,11 +384,11 @@ fn draw(ctx: &mut Context, state: &mut State) {
         if key == kbmod::CTRL | vk::N {
             draw_add_untitled_document(ctx, state);
         } else if key == kbmod::CTRL | vk::O {
-            state.wants_file_picker = StateFilePicker::Open;
+            show_file_picker(state, StateFilePicker::Open);
         } else if key == kbmod::CTRL | vk::S {
             state.wants_save = true;
         } else if key == kbmod::CTRL_SHIFT | vk::S {
-            state.wants_file_picker = StateFilePicker::SaveAs;
+            show_file_picker(state, StateFilePicker::SaveAs);
         } else if key == kbmod::CTRL | vk::W {
             state.wants_close = true;
         } else if key == kbmod::CTRL | vk::P {

crates/edit/src/bin/edit/state.rs

@@ -15,6 +15,7 @@ use edit::{buffer, icu};
 use crate::apperr;
 use crate::documents::DocumentManager;
 use crate::localization::*;
+use crate::sys;
 
 #[repr(transparent)]
 pub struct FormatApperr(apperr::Error);
@@ -243,6 +244,41 @@ impl State {
     }
 }
 
+/// EN: Opens a file picker and selects a useful cross-platform starting directory.
+/// 中文：開啟檔案選擇器，並選擇適用於各平台的起始資料夾。
+pub fn show_file_picker(state: &mut State, picker: StateFilePicker) {
+    debug_assert!(matches!(picker, StateFilePicker::Open | StateFilePicker::SaveAs));
+
+    // EN: Open starts on the desktop. Save As keeps a named document beside its source,
+    // EN: while a new untitled document starts on the desktop as well.
+    // 中文：開啟舊檔由桌面開始；另存已命名檔案時沿用來源目錄，未命名檔案則由桌面開始。
+    let target_dir = if picker == StateFilePicker::Open {
+        sys::desktop_dir().ok()
+    } else {
+        state
+            .documents
+            .active()
+            .and_then(|doc| doc.path.as_deref())
+            .and_then(Path::parent)
+            .map(Path::to_path_buf)
+            .or_else(|| sys::desktop_dir().ok())
+    };
+
+    if let Some(target_dir) = target_dir
+        && state.file_picker_pending_dir.as_path() != target_dir
+    {
+        state.file_picker_pending_dir = DisplayablePathBuf::from_path(target_dir);
+        state.file_picker_pending_dir_revision =
+            state.file_picker_pending_dir_revision.wrapping_add(1);
+    }
+
+    state.wants_file_picker = picker;
+    state.file_picker_pending_name.clear();
+    state.file_picker_entries = None;
+    state.file_picker_overwrite_warning = None;
+    state.file_picker_autocomplete.clear();
+}
+
 pub fn draw_add_untitled_document(ctx: &mut Context, state: &mut State) {
     if let Err(err) = state.documents.add_untitled() {
         error_log_add(ctx, state, err);

crates/edit/src/sys/mod.rs

@@ -15,3 +15,11 @@ pub use std::fs::canonicalize;
 pub use unix::*;
 #[cfg(windows)]
 pub use windows::*;
+
+/// EN: Returns the user's desktop directory through the platform-neutral directory provider.
+/// 中文：透過跨平台目錄提供者取得使用者的桌面資料夾。
+pub fn desktop_dir() -> std::io::Result<std::path::PathBuf> {
+    dirs::desktop_dir().ok_or_else(|| {
+        std::io::Error::new(std::io::ErrorKind::NotFound, "desktop directory is unavailable")
+    })
+}