Add support for drag and drop files in Windows (#1953)

* Add support for drag and drop files in Windows

* Add two drag and drop filename quoting patterns (mainly) for Windows, change doc examples.

* Code style cleanup

* Improve Windows quoting pattern and rename DoubleQuoteAlways to WindowsAlwaysQuoted

* Improve special char finding for DroppedFileQuoting::Windows and fix doc.

config/src/config.rs

@@ -1476,11 +1476,19 @@ pub enum DroppedFileQuoting {
     SpacesOnly,
     /// Use POSIX style shell word escaping
     Posix,
+    /// Use Windows style shell word escaping
+    Windows,
+    /// Always double quote the file name
+    WindowsAlwaysQuoted,
 }
 
 impl Default for DroppedFileQuoting {
     fn default() -> Self {
-        Self::SpacesOnly
+        if cfg!(windows) {
+            Self::Windows
+        } else {
+            Self::SpacesOnly
+        }
     }
 }
 
@@ -1491,6 +1499,15 @@ impl DroppedFileQuoting {
             Self::SpacesOnly => s.replace(" ", "\\ "),
             // https://docs.rs/shlex/latest/shlex/fn.quote.html
             Self::Posix => shlex::quote(s).into_owned().to_string(),
+            Self::Windows => {
+                let chars_need_quoting = [' ', '\t', '\n', '\x0b', '\"'];
+                if s.chars().any(|c| chars_need_quoting.contains(&c)) {
+                    format!("\"{}\"", s)
+                } else {
+                    s.to_string()
+                }
+            }
+            Self::WindowsAlwaysQuoted => format!("\"{}\"", s),
         }
     }
 }

docs/config/lua/config/quote_dropped_files.md

@@ -3,25 +3,29 @@
 *Since: nightly builds only*
 
 Controls how file names are quoted (or not) when dragging and dropping.
-There are three possible values:
+There are five possible values:
 
 * `"None"` - no quoting is performed, the file name is passed through as-is.
-* `"SpacesOnly"` - backslash-escape only spaces, leaving all other characters as-is.  This is the default.
+* `"SpacesOnly"` - backslash-escape only spaces, leaving all other characters as-is.  This is the default for non-Windows platforms.
 * `"Posix"` - use POSIX style shell word escaping.
+* `"Windows"` - use Windows style shell word escaping: double-quote filename with space characters in it, and leaving others as-is. This is the default on Windows.
+* `"WindowsAlwaysQuoted"` - like `"Windows"`, while always double-quote the filename.
 
 For example:
 
-|`quote_dropped_files` |file name    |quoted result  |
-|----------------------|-------------|---------------|
-|`"None"`              |`hello world`|`hello world`  |
-|`"SpacesOnly"`        |`hello world`|`hello\ world` |
-|`"Posix"`             |`hello world`|`"hello world"`|
+| `quote_dropped_files`   | file name        | quoted result       |
+|-------------------------|------------------|---------------------|
+| `"None"`                | `hello ($world)` | `hello ($world)`    |
+| `"SpacesOnly"`          | `hello ($world)` | `hello\ ($world)`   |
+| `"Posix"`               | `hello ($world)` | `"hello (\$world)"` |
+| `"Windows"`             | `hello ($world)` | `"hello ($world)"`  |
+| `"WindowsAlwaysQuoted"` | `hello ($world)` | `"hello ($world)"`  |
 
 Drag and drop support for files is a platform dependent feature
 
 |Platform  |Supported since    |
 |----------|-------------------|
 |macOS     |nightly builds only|
-|Windows   |Not yet            |
+|Windows   |nightly builds only|
 |X11       |Not yet            |
 |Wayland   |Not yet            |

window/src/os/windows/window.rs

@@ -22,6 +22,7 @@ use std::convert::TryInto;
 use std::ffi::OsString;
 use std::io::{self, Error as IoError};
 use std::os::windows::ffi::OsStringExt;
+use std::path::PathBuf;
 use std::ptr::{null, null_mut};
 use std::rc::Rc;
 use std::sync::Mutex;
@@ -33,6 +34,7 @@ use winapi::shared::windef::*;
 use winapi::shared::winerror::S_OK;
 use winapi::um::imm::*;
 use winapi::um::libloaderapi::GetModuleHandleW;
+use winapi::um::shellapi::{DragAcceptFiles, DragFinish, DragQueryFileW, HDROP};
 use winapi::um::sysinfoapi::{GetTickCount, GetVersionExW};
 use winapi::um::uxtheme::{
     CloseThemeData, GetThemeFont, GetThemeSysFont, OpenThemeData, SetWindowTheme,
@@ -637,6 +639,11 @@ impl Window {
         apply_theme(hwnd.0);
         enable_blur_behind(hwnd.0);
 
+        // Make window capable of accepting drag and drop
+        unsafe {
+            DragAcceptFiles(hwnd.0, winapi::shared::minwindef::TRUE);
+        }
+
         Connection::get()
             .expect("Connection::init was not called")
             .windows
@@ -2406,6 +2413,35 @@ unsafe fn key(hwnd: HWND, msg: UINT, wparam: WPARAM, lparam: LPARAM) -> Option<L
     None
 }
 
+unsafe fn drop_files(hwnd: HWND, _msg: UINT, wparam: WPARAM, _lparam: LPARAM) -> Option<LRESULT> {
+    let inner = rc_from_hwnd(hwnd)?;
+    let h_drop = wparam as HDROP;
+
+    // Get the number of files dropped
+    let file_count = DragQueryFileW(h_drop, 0xFFFFFFFF, null_mut(), 0);
+
+    let mut filenames: Vec<PathBuf> = Vec::with_capacity(file_count as usize);
+
+    for idx in 0..file_count {
+        // The returned size of buffer is in characters, not including the terminating null character
+        let buf_size = DragQueryFileW(h_drop, idx, null_mut(), 0);
+        if buf_size > 0 {
+            // Windows will truncate the filename and add null terminator if space isn't enough
+            let buf_size = buf_size as usize + 1;
+            let mut wide_buf = vec![0u16; buf_size];
+            DragQueryFileW(h_drop, idx, wide_buf.as_mut_ptr(), wide_buf.len() as u32);
+            wide_buf.pop(); // Drops the null terminator
+            filenames.push(OsString::from_wide(&wide_buf).into());
+        }
+    }
+
+    let mut inner = inner.borrow_mut();
+    inner.events.dispatch(WindowEvent::DroppedFile(filenames));
+
+    DragFinish(h_drop);
+    Some(0)
+}
+
 unsafe fn do_wnd_proc(hwnd: HWND, msg: UINT, wparam: WPARAM, lparam: LPARAM) -> Option<LRESULT> {
     match msg {
         WM_NCCREATE => wm_nccreate(hwnd, msg, wparam, lparam),
@@ -2434,6 +2470,7 @@ unsafe fn do_wnd_proc(hwnd: HWND, msg: UINT, wparam: WPARAM, lparam: LPARAM) ->
         | WM_RBUTTONDOWN | WM_RBUTTONUP | WM_MBUTTONDOWN | WM_MBUTTONUP => {
             mouse_button(hwnd, msg, wparam, lparam)
         }
+        WM_DROPFILES => drop_files(hwnd, msg, wparam, lparam),
         WM_ERASEBKGND => Some(1),
         WM_CLOSE => {
             if let Some(inner) = rc_from_hwnd(hwnd) {