Respect starting directory for dialogs on Windows

Before this change, FileDialogOptions::starting_directory had not been
used on Windows and therefore had no influence on the starting directory
of a FileDialog window.

This has now been fixed.

The use of `SHCreateItemFromParsingName` makes it mandatory to
explicitly link against shell32.lib because this is not done
automatically since Rust 1.33.0.

See rust-lang/rust#56568 for details.

AUTHORS

@@ -14,3 +14,4 @@ Andrey Kabylin
 Garrett Risley
 Robert Wittams
 Jaap Aarts
+Maximilian Köstler

CHANGELOG.md

@@ -56,6 +56,7 @@ You can find its changes [documented below](#060---2020-06-01).
 - `WidgetPod::is_initialized` to check if a widget has received `WidgetAdded`. ([#1259] by [@finnerale])
 - `TextBox::with_text_alignment` and `TextBox::set_text_alignment` ([#1371] by [@cmyr])
 - Add default minimum size to `WindowConfig`. ([#1438] by [@colinfruit])
+- Windows: Dialogs now respect the parameter passed to `force_starting_directory()` ([#1452] by [@MaximilianKoestler])
 
 ### Changed
 
@@ -362,6 +363,7 @@ Last release without a changelog :(
 [@colinfruit]: https://github.com/colinfruit
 [@Maan2003]: https://github.com/Maan2003
 [@derekdreery]: https://github.com/derekdreery
+[@MaximilianKoestler]: https://github.com/MaximilianKoestler
 
 [#599]: https://github.com/linebender/druid/pull/599
 [#611]: https://github.com/linebender/druid/pull/611
@@ -550,6 +552,7 @@ Last release without a changelog :(
 [#1438]: https://github.com/linebender/druid/pull/1438
 [#1441]: https://github.com/linebender/druid/pull/1441
 [#1448]: https://github.com/linebender/druid/pull/1448
+[#1452]: https://github.com/linebender/druid/pull/1452
 
 [Unreleased]: https://github.com/linebender/druid/compare/v0.6.0...master
 [0.6.0]: https://github.com/linebender/druid/compare/v0.5.0...v0.6.0

druid-shell/build.rs

@@ -0,0 +1,26 @@
+// Copyright 2020 The Druid Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Build script to modify the build environment
+
+use std::env;
+
+fn main() {
+    let env = env::var("TARGET").unwrap();
+    if env.contains("windows") {
+        // Since https://github.com/rust-lang/rust/pull/56568, shell32 is not included in all
+        // Windows binaries by default.
+        println!("cargo:rustc-link-lib=shell32");
+    }
+}

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

@@ -26,6 +26,7 @@ use std::convert::TryInto;
 use std::ffi::OsString;
 use std::ptr::null_mut;
 
+use winapi::ctypes::c_void;
 use winapi::shared::minwindef::*;
 use winapi::shared::ntdef::LPWSTR;
 use winapi::shared::windef::*;
@@ -147,6 +148,21 @@ pub(crate) unsafe fn get_file_dialog_path(
 
     as_result(file_dialog.SetOptions(flags))?;
 
+    // set a starting directory
+    if let Some(path) = options.starting_directory {
+        let mut item: *mut IShellItem = null_mut();
+        if let Err(err) = as_result(SHCreateItemFromParsingName(
+            path.as_os_str().to_wide().as_ptr(),
+            null_mut(),
+            &IShellItem::uuidof(),
+            &mut item as *mut *mut IShellItem as *mut *mut c_void,
+        )) {
+            log::warn!("Failed to convert path: {}", err.to_string());
+        } else {
+            as_result(file_dialog.SetDefaultFolder(item))?;
+        }
+    }
+
     // show the dialog
     as_result(file_dialog.Show(hwnd_owner))?;
     let mut result_ptr: *mut IShellItem = null_mut();