Windows: file open dialog multiselect fix

AUTHORS

@@ -23,3 +23,4 @@ Manmeet Singh
 Simon Fell
 Nick Larsen
 Thomas McAndrew
+Paweł Pykało

CHANGELOG.md

@@ -139,6 +139,7 @@ You can find its changes [documented below](#070---2021-01-01).
 - X11: window focus events ([#1938] by [@Maan2003]
 - Preserve the aspect ratio of a clipped region in an Image ([#2195] by [@barsae])
 - GTK: Hot state now properly resets when the mouse leaves the window via an occluded part. ([#2324] by [@xStrom])
+- Windows: generate `commands::OPEN_FILES` when using multiselect in file open dialog. ([#2332] by [@ppykalo])
 
 ### Visual
 
@@ -578,6 +579,7 @@ Last release without a changelog :(
 [@benoitryder]: https://github.com/benoitryder
 [@sprocklem]: https://github.com/sprocklem
 [@cbondurant]: https://github.com/cbondurant
+[@ppykalo]: https://github.com/ppykalo
 
 [#599]: https://github.com/linebender/druid/pull/599
 [#611]: https://github.com/linebender/druid/pull/611
@@ -884,6 +886,7 @@ Last release without a changelog :(
 [#2323]: https://github.com/linebender/druid/pull/2323
 [#2324]: https://github.com/linebender/druid/pull/2324
 [#2331]: https://github.com/linebender/druid/pull/2331
+[#2332]: https://github.com/linebender/druid/pull/2332
 
 [Unreleased]: https://github.com/linebender/druid/compare/v0.7.0...master
 [0.7.0]: https://github.com/linebender/druid/compare/v0.6.0...v0.7.0

druid-shell/src/backend/windows/dialog.rs

@@ -76,7 +76,7 @@ pub(crate) unsafe fn get_file_dialog_path(
     hwnd_owner: HWND,
     ty: FileDialogType,
     options: FileDialogOptions,
-) -> Result<OsString, Error> {
+) -> Result<Vec<OsString>, Error> {
     let mut pfd: *mut IFileDialog = null_mut();
     let (class, id) = match ty {
         FileDialogType::Open => (&CLSID_FileOpenDialog, IFileOpenDialog::uuidof()),
@@ -165,13 +165,34 @@ pub(crate) unsafe fn get_file_dialog_path(
 
     // show the dialog
     as_result(file_dialog.Show(hwnd_owner))?;
-    let mut result_ptr: *mut IShellItem = null_mut();
-    as_result(file_dialog.GetResult(&mut result_ptr))?;
-    let shell_item = ComPtr::from_raw(result_ptr);
-    let mut display_name: LPWSTR = null_mut();
-    as_result(shell_item.GetDisplayName(SIGDN_FILESYSPATH, &mut display_name))?;
-    let filename = display_name.to_os_string();
-    CoTaskMemFree(display_name as LPVOID);
-
-    Ok(filename)
+
+    let mut result_ptr_vec = Vec::new();
+    if let Ok(open_file_dialog) = file_dialog.cast::<IFileOpenDialog>() {
+        let mut results_ptr: *mut IShellItemArray = null_mut();
+        as_result(open_file_dialog.GetResults(&mut results_ptr))?;
+        let shell_items = ComPtr::from_raw(results_ptr);
+        let mut count = 0;
+        as_result(shell_items.GetCount(&mut count))?;
+        for i in 0..count {
+            let mut result_ptr: *mut IShellItem = null_mut();
+            as_result(shell_items.GetItemAt(i as DWORD, &mut result_ptr))?;
+            result_ptr_vec.push(result_ptr);
+        }
+    } else {
+        let mut result_ptr: *mut IShellItem = null_mut();
+        as_result(file_dialog.GetResult(&mut result_ptr))?;
+        result_ptr_vec.push(result_ptr);
+    }
+
+    let mut filename_vec = Vec::with_capacity(result_ptr_vec.len());
+    for result_ptr in result_ptr_vec {
+        let shell_item = ComPtr::from_raw(result_ptr);
+        let mut display_name: LPWSTR = null_mut();
+        as_result(shell_item.GetDisplayName(SIGDN_FILESYSPATH, &mut display_name))?;
+        let filename = display_name.to_os_string();
+        CoTaskMemFree(display_name as LPVOID);
+        filename_vec.push(filename);
+    }
+
+    Ok(filename_vec)
 }

druid-shell/src/backend/windows/window.rs

@@ -622,23 +622,38 @@ impl MyWndProc {
                     let info = unsafe {
                         get_file_dialog_path(hwnd, FileDialogType::Save, options)
                             .ok()
-                            .map(|os_str| FileInfo {
-                                path: os_str.into(),
+                            .map(|s| FileInfo {
+                                // `get_file_dialog_path` guarantees that save dialogs
+                                // only return one path
+                                path: s.first().unwrap().into(),
                                 format: None,
                             })
                     };
                     self.with_wnd_state(|s| s.handler.save_as(token, info));
                 }
                 DeferredOp::Open(options, token) => {
-                    let info = unsafe {
-                        get_file_dialog_path(hwnd, FileDialogType::Open, options)
-                            .ok()
-                            .map(|s| FileInfo {
-                                path: s.into(),
-                                format: None,
-                            })
+                    let multi_selection = options.multi_selection;
+                    let infos = unsafe {
+                        match get_file_dialog_path(hwnd, FileDialogType::Open, options) {
+                            Ok(infos) => infos
+                                .iter()
+                                .map(|path| FileInfo {
+                                    path: path.into(),
+                                    format: None,
+                                })
+                                .collect(),
+                            Err(err) => {
+                                tracing::error!("Error trying to open file: {}", err);
+                                vec![]
+                            }
+                        }
                     };
-                    self.with_wnd_state(|s| s.handler.open_file(token, info));
+
+                    if multi_selection {
+                        self.with_wnd_state(|s| s.handler.open_files(token, infos));
+                    } else {
+                        self.with_wnd_state(|s| s.handler.open_file(token, infos.first().cloned()));
+                    }
                 }
                 DeferredOp::ContextMenu(menu, pos) => {
                     let hmenu = menu.into_hmenu();