Respect starting directory for dialogs on Windows (#1452)

* 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.

* Fix: Use winapi feature instead of build.rs

As it turns out, the winapi crate already exposes shell32.lib via a
cargo feature, so there is no need to link it manually.

AUTHORS

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

CHANGELOG.md

@@ -57,6 +57,7 @@ You can find its changes [documented below](#060---2020-06-01).
 - `TextBox::with_text_alignment` and `TextBox::set_text_alignment` ([#1371] by [@cmyr])
 - Add default minimum size to `WindowConfig`. ([#1438] by [@colinfruit])
 - Open and save dialogs send configurable commands. ([#1463] by [@jneem])
+- Windows: Dialogs now respect the parameter passed to `force_starting_directory()` ([#1452] by [@MaximilianKoestler])
 
 ### Changed
 
@@ -364,6 +365,7 @@ 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
@@ -553,6 +555,7 @@ Last release without a changelog :(
 [#1441]: https://github.com/linebender/druid/pull/1441
 [#1448]: https://github.com/linebender/druid/pull/1448
 [#1463]: https://github.com/linebender/druid/pull/1463
+[#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/Cargo.toml

@@ -60,7 +60,8 @@ wio = "0.2.2"
 version = "0.3.9"
 features = ["d2d1_1", "dwrite", "winbase", "libloaderapi", "errhandlingapi", "winuser",
             "shellscalingapi", "shobjidl", "combaseapi", "synchapi", "dxgi1_3", "dcomp",
-            "d3d11", "dwmapi", "wincon", "fileapi", "processenv", "winbase", "handleapi"]
+            "d3d11", "dwmapi", "wincon", "fileapi", "processenv", "winbase", "handleapi",
+            "shellapi"]
 
 [target.'cfg(target_os="macos")'.dependencies]
 block = "0.1.6"

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();