Medium-level API: Add support for registering hwnd_info callback

main/low/src/raw.rs

@@ -213,5 +213,8 @@ pub type HookPostCommand2 = extern "C" fn(
     proj: *mut ReaProject,
 );
 
+/// Function pointer type that REAPER uses for querying information about a window.
+pub type HwndInfo = extern "C" fn(hwnd: HWND, info_type: INT_PTR) -> c_int;
+
 /// Function pointer type for exposing custom API functions to ReaScript.
 pub type ApiVararg = unsafe extern "C" fn(*mut *mut c_void, c_int) -> *mut c_void;

main/medium/src/fn_traits.rs

@@ -1,7 +1,8 @@
 use crate::{
-    ActionValueChange, CommandId, Hmenu, KbdSectionInfo, MenuHookFlag, ReaProject, ReaperStr,
-    SectionContext, WindowContext,
+    ActionValueChange, CommandId, Hmenu, Hwnd, HwndInfoType, KbdSectionInfo, MenuHookFlag,
+    ReaProject, ReaperStr, SectionContext, WindowContext,
 };
+use reaper_low::raw::{HWND, INT_PTR};
 use reaper_low::{firewall, raw};
 use std::ffi::c_char;
 use std::os::raw::c_int;
@@ -64,6 +65,26 @@ pub(crate) extern "C" fn delegating_hook_command_2<T: HookCommand2>(
     })
     .unwrap_or(false)
 }
+/// Consumers need to implement this trait in order to define what should happen when REAPER wants to know something
+/// about a specific window.
+pub trait HwndInfo {
+    /// The actual callback function invoked by REAPER whenever it needs to know something about a window.
+    ///
+    /// Return 0 if not a known window, or if `info_type` is unknown.
+    fn call(window: Hwnd, info_type: HwndInfoType) -> i32;
+}
+
+pub(crate) extern "C" fn delegating_hwnd_info<T: HwndInfo>(
+    hwnd: HWND,
+    info_type: INT_PTR,
+) -> c_int {
+    firewall(|| {
+        let window = Hwnd::new(hwnd).expect("REAPER hwnd_info hwnd pointer was null");
+        let info_type = HwndInfoType::from_raw(info_type);
+        T::call(window, info_type)
+    })
+    .unwrap_or(0)
+}
 
 /// Consumers need to implement this trait in order to define what should happen when a custom menu is initialized or
 /// populated.

main/medium/src/misc_enums.rs

@@ -164,6 +164,34 @@ pub enum UndoBehavior {
     AddUndoPoint,
 }
 
+/// Possible things that REAPER wants to know when calling the `hwnd_info` function.
+#[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
+pub enum HwndInfoType {
+    /// REAPER queries if the window should be treated as a text-field for purposes of global hotkeys.
+    ///
+    /// - Return 1 if text field
+    /// - Return -1 if not a text field
+    IsTextField,
+    /// REAPER queries if global hotkeys should be processed for this context (6.60+).
+    ///
+    /// - Return 1 if global hotkey should be skipped (and default accelerator processing used instead)
+    /// - Return -1 if global hotkey should be forced
+    ShouldProcessGlobalHotkeys,
+    /// Represents a variant unknown to *reaper-rs*. Please contribute if you encounter a variant
+    /// that is supported by REAPER but not yet by *reaper-rs*. Thanks!
+    Unknown(Hidden<isize>),
+}
+
+impl HwndInfoType {
+    pub(crate) fn from_raw(value: isize) -> Self {
+        match value {
+            0 => Self::IsTextField,
+            1 => Self::ShouldProcessGlobalHotkeys,
+            x => Self::Unknown(Hidden(x)),
+        }
+    }
+}
+
 /// Determines whether to refresh the UI.
 #[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
 pub enum UiRefreshBehavior {
@@ -746,6 +774,8 @@ pub enum RegistrationObject<'a> {
     HookPostCommand(raw::HookPostCommand),
     /// A hook post command 2.
     HookPostCommand2(raw::HookPostCommand2),
+    /// Function that REAPER calls in order to query information about a window.
+    HwndInfo(raw::HwndInfo),
     /// A timer.
     Timer(raw::TimerFunction),
     /// A toggle action.
@@ -890,6 +920,10 @@ impl<'a> RegistrationObject<'a> {
                 key: reaper_str!("hookcustommenu").into(),
                 value: func as _,
             },
+            HwndInfo(func) => PluginRegistration {
+                key: reaper_str!("hwnd_info").into(),
+                value: func as _,
+            },
             Timer(func) => PluginRegistration {
                 key: reaper_str!("timer").into(),
                 value: func as _,

main/medium/src/reaper_session.rs

@@ -12,7 +12,7 @@ use crate::{
     delegating_hook_post_command, delegating_hook_post_command_2, delegating_toggle_action,
     AcceleratorPosition, BufferingBehavior, CommandId, ControlSurface, ControlSurfaceAdapter,
     FileInProjectCallback, GenericRegistrationHandle, Handle, HookCommand, HookCommand2,
-    HookCustomMenu, HookPostCommand, HookPostCommand2, MainThreadScope, MeasureAlignment,
+    HookCustomMenu, HookPostCommand, HookPostCommand2, HwndInfo, MainThreadScope, MeasureAlignment,
     OnAudioBuffer, OwnedAcceleratorRegister, OwnedAudioHookRegister, OwnedGaccelRegister,
     OwnedPreviewRegister, PluginRegistration, ProjectContext, ReaProject, RealTimeAudioThreadScope,
     Reaper, ReaperFunctionError, ReaperFunctionResult, ReaperMutex, ReaperString, ReaperStringArg,
@@ -21,7 +21,9 @@ use crate::{
 use reaper_low::raw::audio_hook_register_t;
 
 use crate::file_in_project_hook::OwnedFileInProjectHook;
-use crate::fn_traits::{delegating_hook_custom_menu, delegating_toolbar_icon_map};
+use crate::fn_traits::{
+    delegating_hook_custom_menu, delegating_hwnd_info, delegating_toolbar_icon_map,
+};
 use enumflags2::BitFlags;
 use std::collections::{HashMap, HashSet};
 use std::os::raw::{c_char, c_void};
@@ -318,6 +320,25 @@ impl ReaperSession {
         }
     }
 
+    /// Registers a function that REAPER calls in order to query information about a window (REAPER 6.29+).
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if the registration failed.
+    pub fn plugin_register_add_hwnd_info<T: HwndInfo>(&mut self) -> ReaperFunctionResult<()> {
+        unsafe {
+            self.plugin_register_add(RegistrationObject::HwndInfo(delegating_hwnd_info::<T>))?;
+        }
+        Ok(())
+    }
+
+    /// Unregisters a `hwnd_info` function.
+    pub fn plugin_register_remove_hwnd_info<T: HwndInfo>(&mut self) {
+        unsafe {
+            self.plugin_register_remove(RegistrationObject::HwndInfo(delegating_hwnd_info::<T>));
+        }
+    }
+
     /// Registers a custom menu hook.
     ///
     /// See [`plugin_register_add_hook_command`](#method.plugin_register_add_hook_command) for