Initial Windows App SDK support

The beginnings of the `windows-app` crate. Includes the wiring necessary to bootstrap dynamic dependencies for unpackaged Windows apps and a window handle helper.

.gitattributes

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+*       text=auto
+*       text eol=lf
+*.png   -text
+*.winmd -text
+*.dll   -text
+*.lib   -text

.github/SUPPORT.md

@@ -1,25 +1,23 @@
-# TODO: The maintainer of this repo has not yet edited this file
-
-**REPO OWNER**: Do you want Customer Service & Support (CSS) support for this product/project?
-
-- **No CSS support:** Fill out this template with information about how to file issues and get help.
-- **Yes CSS support:** Fill out an intake form at [aka.ms/spot](https://aka.ms/spot). CSS will work with/help you to determine next steps. More details also available at [aka.ms/onboardsupport](https://aka.ms/onboardsupport).
-- **Not sure?** Fill out a SPOT intake as though the answer were "Yes". CSS will help you decide.
-
-*Then remove this first heading from this SUPPORT.MD file before publishing your repo.*
-
-# Support
-
-## How to file issues and get help  
-
-This project uses GitHub Issues to track bugs and feature requests. Please search the existing 
-issues before filing new issues to avoid duplicates.  For new issues, file your bug or 
-feature request as a new Issue.
-
-For help and questions about using this project, please **REPO MAINTAINER: INSERT INSTRUCTIONS HERE 
-FOR HOW TO ENGAGE REPO OWNERS OR COMMUNITY FOR HELP. COULD BE A STACK OVERFLOW TAG OR OTHER
-CHANNEL. WHERE WILL YOU HELP PEOPLE?**.
-
-## Microsoft Support Policy  
-
-Support for this **PROJECT or PRODUCT** is limited to the resources listed above.
+**REPO OWNER**: Do you want Customer Service & Support (CSS) support for this product/project?
+
+- **No CSS support:** Fill out this template with information about how to file issues and get help.
+- **Yes CSS support:** Fill out an intake form at [aka.ms/spot](https://aka.ms/spot). CSS will work with/help you to determine next steps. More details also available at [aka.ms/onboardsupport](https://aka.ms/onboardsupport).
+- **Not sure?** Fill out a SPOT intake as though the answer were "Yes". CSS will help you decide.
+
+*Then remove this first heading from this SUPPORT.MD file before publishing your repo.*
+
+# Support
+
+## How to file issues and get help  
+
+This project uses GitHub Issues to track bugs and feature requests. Please search the existing 
+issues before filing new issues to avoid duplicates.  For new issues, file your bug or 
+feature request as a new Issue.
+
+For help and questions about using this project, please **REPO MAINTAINER: INSERT INSTRUCTIONS HERE 
+FOR HOW TO ENGAGE REPO OWNERS OR COMMUNITY FOR HELP. COULD BE A STACK OVERFLOW TAG OR OTHER
+CHANNEL. WHERE WILL YOU HELP PEOPLE?**.
+
+## Microsoft Support Policy  
+
+Support for this **PROJECT or PRODUCT** is limited to the resources listed above.

.gitignore

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+/target
+/.vscode
+/.vs
+Cargo.lock

Cargo.toml

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+[package]
+name = "windows-app"
+version = "0.2.0"
+authors = ["Microsoft"]
+edition = "2018"
+license = "MIT OR Apache-2.0"
+description = "Windows App SDK"
+repository = "https://github.com/microsoft/windows-app-rs"
+documentation = "https://docs.rs/windows-app"
+readme = "README.md"
+exclude = [".github", ".windows", "docs"]
+
+[dependencies]
+bindings = { package = "windows_app_bindings", path = "bindings" }
+windows = "0.12"

bindings/Cargo.toml

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+[package]
+name = "windows_app_bindings"
+version = "0.2.0"
+authors = ["Microsoft"]
+edition = "2018"
+license = "MIT OR Apache-2.0"
+description = "Implementation for windows-app crate"
+
+[dependencies]
+windows = "0.12.0"
+
+[build-dependencies]
+windows = "0.12.0"

bindings/build.rs

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+fn main() {
+    windows::build! {
+        Windows::Win32::UI::WindowsAndMessaging::MessageBoxW
+    };
+}

bindings/src/lib.rs

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+windows::include_bindings!();

build.rs

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+fn main() {
+    let arch = match std::env::var("CARGO_CFG_TARGET_ARCH").unwrap().as_str() {
+        "x86_64" => "x64",
+        "x86" => "x86",
+        "arm" => "arm",
+        "aarch64" => "arm64",
+        unexpected => panic!(
+            "Unexpected `{}` architecture set by `CARGO_CFG_TARGET_ARCH`",
+            unexpected
+        ),
+    };
+    println!("cargo:rustc-link-search=native=.windows/{}", arch);
+    println!("cargo:rerun-if-changed=build.rs");
+    println!("cargo:rerun-if-changed=.windows");
+}

src/bootstrap.rs

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+use bindings::Windows::Win32::{
+    Foundation::HWND,
+    UI::WindowsAndMessaging::{MessageBoxW, MB_ICONERROR, MB_OK},
+};
+
+#[repr(C)]
+#[derive(Clone, Copy)]
+pub struct PackageVersion {
+    pub revision: u8,
+    pub build: u8,
+    pub minor: u8,
+    pub major: u8,
+}
+
+impl PackageVersion {
+    pub fn new(major: u8, minor: u8, build: u8, revision: u8) -> Self {
+        Self {
+            revision,
+            build,
+            minor,
+            major,
+        }
+    }
+
+    fn to_major_minor(self) -> u32 {
+        ((self.major as u32) << 8) | self.minor as u32
+    }
+}
+
+#[test]
+#[allow(non_snake_case)]
+fn package_version_zero_produces_zero_major_minor() {
+    let v = PackageVersion {
+        major: 0,
+        minor: 0,
+        revision: 0,
+        build: 0,
+    };
+    assert_eq!(v.to_major_minor(), 0);
+}
+
+#[test]
+fn package_version_max_produces_correct_major_minor() {
+    let v = PackageVersion {
+        major: 255,
+        minor: 255,
+        revision: 42,
+        build: 42,
+    };
+    assert_eq!(v.to_major_minor(), 255 << 8 | 255);
+}
+
+#[test]
+fn package_version_mixed_produces_correct_major_minor() {
+    let v = PackageVersion {
+        major: 0,
+        minor: 8,
+        revision: 42,
+        build: 192,
+    };
+    assert_eq!(v.to_major_minor(), 0 << 8 | 8);
+}
+
+#[test]
+fn package_version_has_expected_c_representation() {
+    let v = PackageVersion {
+        major: 1,
+        minor: 2,
+        build: 3,
+        revision: 4,
+    };
+    unsafe {
+        let bytes = &v as *const _ as *const u8;
+        assert_eq!(std::slice::from_raw_parts(bytes, 4), [4, 3, 2, 1]);
+    }
+}
+
+#[link(name = "Microsoft.ProjectReunion.Bootstrap")]
+extern "system" {
+    fn MddBootstrapInitialize(
+        majorMinorVersion: u32,
+        versionTag: *const u16,
+        minVersion: PackageVersion,
+    ) -> windows::HRESULT;
+
+    fn MddBootstrapShutdown() -> windows::HRESULT;
+}
+
+/// Locates the Windows App framework package compatible with the (currently internal)
+/// versioning criteria and loads it into the current process. If multiple packages meet
+/// the criteria, the best candidate is selected.
+pub fn initialize() -> windows::Result<()> {
+    initialize_without_dialog()
+    .map_err(|outer_error| {
+        unsafe {
+            MessageBoxW(
+                HWND::default(),
+                "To run this application, the Windows App preview runtime must be installed.\n\nhttps://aka.ms/projectreunion/0.8preview",
+                "This application could not be started",
+                MB_OK | MB_ICONERROR,
+            );
+            outer_error
+        }
+    })
+}
+
+pub fn initialize_without_dialog() -> windows::Result<()> {
+    let version_tag: Vec<u16> = "preview".encode_utf16().collect();
+    let mdd_version = PackageVersion {
+        major: 0,
+        minor: 8,
+        revision: 0,
+        build: 0,
+    };
+    let min_framework_version = PackageVersion {
+        major: 0,
+        minor: 1,
+        revision: 0,
+        build: 0,
+    };
+    unsafe {
+        MddBootstrapInitialize(
+            mdd_version.to_major_minor(),
+            version_tag.as_ptr(),
+            min_framework_version,
+        )
+        .ok()
+    }
+}
+
+/// Undo the changes made by `initialize()`
+pub fn uninitialize() -> windows::Result<()> {
+    unsafe { MddBootstrapShutdown().ok() }
+}

src/lib.rs

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+pub mod bootstrap;
+
+use windows::{IInspectable, Interface, HRESULT};
+
+#[repr(transparent)]
+struct IWindowNative(windows::IUnknown);
+
+#[allow(dead_code)]
+impl IWindowNative {
+    pub fn handle(&self) -> Option<isize> {
+        unsafe {
+            let mut hwnd = 0;
+            match self.WindowHandle(&mut hwnd as *mut isize) {
+                HRESULT(0) => Some(hwnd),
+                _ => None,
+            }
+        }
+    }
+
+    #[allow(non_snake_case)]
+    unsafe fn WindowHandle(&self, hwnd: *mut isize) -> windows::HRESULT {
+        (::windows::Interface::vtable(self).3)(::windows::Abi::abi(self), hwnd)
+    }
+}
+
+#[repr(C)]
+struct IWindowNative_vtbl(
+    // IUnknown::QueryInterface
+    pub  unsafe extern "system" fn(
+        this: ::windows::RawPtr,
+        iid: &::windows::Guid,
+        interface: *mut ::windows::RawPtr,
+    ) -> ::windows::HRESULT,
+    // IUnknown::AddRef
+    pub unsafe extern "system" fn(this: ::windows::RawPtr) -> u32,
+    // IUnknown::Release
+    pub unsafe extern "system" fn(this: ::windows::RawPtr) -> u32,
+    // HRESULT WindowHandle(HWND* hWnd);
+    pub unsafe extern "system" fn(this: ::windows::RawPtr, hwnd: *const isize) -> ::windows::HRESULT,
+);
+
+unsafe impl ::windows::Interface for IWindowNative {
+    type Vtable = IWindowNative_vtbl;
+    // {eecdbf0e-bae9-4cb6-a68e-9598e1cb57bb}
+    const IID: ::windows::Guid = ::windows::Guid::from_values(
+        0xeecdbf0e,
+        0xbae9,
+        0x4cb6,
+        [0xa6, 0x8e, 0x95, 0x98, 0xe1, 0xcb, 0x57, 0xbb],
+    );
+}
+
+pub fn window_handle(window: &IInspectable) -> Option<isize> {
+    window.cast::<IWindowNative>().unwrap().handle()
+}