From e98b29aec68da27484fcfa2b2c9860bb25744adf Mon Sep 17 00:00:00 2001
From: Wez Furlong <wez@wezfurlong.org>
Date: Tue, 13 Aug 2019 22:53:35 -0700
Subject: [PATCH] add apply function to safely access inner data

---
 src/frontend/software/termwindow.rs | 17 +++++++++++++++--
 window/examples/basic.rs            | 13 +++++++++++++
 window/src/lib.rs                   | 18 +++++++++++++++++-
 window/src/os/macos/window.rs       | 14 ++++++++++++++
 4 files changed, 59 insertions(+), 3 deletions(-)

diff --git a/src/frontend/software/termwindow.rs b/src/frontend/software/termwindow.rs
index 2297e6487..51d3bdeeb 100644
--- a/src/frontend/software/termwindow.rs
+++ b/src/frontend/software/termwindow.rs
@@ -1,19 +1,20 @@
 use crate::config::Config;
 use crate::font::FontConfiguration;
 use crate::frontend::guicommon::host::{HostHelper, HostImpl, TabHost};
-use crate::frontend::guicommon::window::TerminalWindow;
 use crate::mux::tab::Tab;
 use crate::mux::window::WindowId as MuxWindowId;
 use crate::mux::Mux;
 use ::window::*;
 use failure::Fallible;
 use promise::Future;
+use std::any::Any;
 use std::rc::Rc;
 use std::sync::Arc;
 
 pub struct TermWindow {
-    config: Arc<Config>,
+    window: Option<Window>,
     fonts: Rc<FontConfiguration>,
+    config: Arc<Config>,
     width: usize,
     height: usize,
     cell_height: usize,
@@ -22,6 +23,10 @@ pub struct TermWindow {
 }
 
 impl WindowCallbacks for TermWindow {
+    fn created(&mut self, window: &Window) {
+        self.window.replace(window.clone());
+    }
+
     fn can_close(&mut self) -> bool {
         // self.host.close_current_tab();
         true
@@ -38,6 +43,13 @@ impl WindowCallbacks for TermWindow {
         */
         Connection::get().unwrap().terminate_message_loop();
     }
+
+    fn as_any(&mut self) -> &mut dyn Any {
+        self
+    }
+
+    fn paint(&mut self, ctx: &mut dyn PaintContext) {
+    }
 }
 
 impl Drop for TermWindow {
@@ -72,6 +84,7 @@ impl TermWindow {
             width,
             height,
             Box::new(Self {
+                window: None,
                 width,
                 height,
                 cell_height,
diff --git a/window/examples/basic.rs b/window/examples/basic.rs
index ef24a6169..c10232140 100644
--- a/window/examples/basic.rs
+++ b/window/examples/basic.rs
@@ -1,5 +1,6 @@
 use ::window::*;
 use failure::Fallible;
+use std::any::Any;
 
 struct MyWindow {
     allow_close: bool,
@@ -75,6 +76,10 @@ impl WindowCallbacks for MyWindow {
             spawn_window().unwrap();
         }
     }
+
+    fn as_any(&mut self) -> &mut dyn Any {
+        self
+    }
 }
 
 fn spawn_window() -> Fallible<()> {
@@ -90,6 +95,14 @@ fn spawn_window() -> Fallible<()> {
     )?;
 
     win.show();
+    win.apply(|myself, win| {
+        if let Some(myself) = myself.downcast_ref::<MyWindow>() {
+            eprintln!(
+                "got myself; allow_close={}, cursor_pos:{:?}",
+                myself.allow_close, myself.cursor_pos
+            );
+        }
+    });
     Ok(())
 }
 
diff --git a/window/src/lib.rs b/window/src/lib.rs
index d3c18e007..b54a9a6a1 100644
--- a/window/src/lib.rs
+++ b/window/src/lib.rs
@@ -1,3 +1,4 @@
+use std::any::Any;
 pub mod bitmaps;
 pub mod color;
 pub mod input;
@@ -100,7 +101,7 @@ pub enum MouseCursor {
 }
 
 #[allow(unused_variables)]
-pub trait WindowCallbacks {
+pub trait WindowCallbacks: Any {
     /// Called when the window close button is clicked.
     /// Return true to allow the close to continue, false to
     /// prevent it from closing.
@@ -134,6 +135,13 @@ pub trait WindowCallbacks {
     /// Called when the window is created and allows the embedding
     /// app to reference the window and operate upon it.
     fn created(&mut self, window: &Window) {}
+
+    /// An unfortunate bit of boilerplate; you need to provie an impl
+    /// of this method that returns `self` in order for the downcast_ref
+    /// method of the Any trait to be usable on WindowCallbacks.
+    /// https://stackoverflow.com/q/46045298/149111 and others have
+    /// some rationale on why Rust works this way.
+    fn as_any(&mut self) -> &mut dyn Any;
 }
 
 pub trait WindowOps {
@@ -152,6 +160,14 @@ pub trait WindowOps {
 
     /// Change the titlebar text for the window
     fn set_title(&self, title: &str);
+
+    /// Schedule a callback on the data associated with the window.
+    /// The `Any` that is passed in corresponds to the WindowCallbacks
+    /// impl you passed to `new_window`, pre-converted to Any so that
+    /// you can `downcast_ref` or `downcast_mut` it and operate on it.
+    fn apply<F: Send + 'static + Fn(&mut dyn Any, &dyn WindowOps)>(&self, func: F)
+    where
+        Self: Sized;
 }
 
 pub trait WindowOpsMut {
diff --git a/window/src/os/macos/window.rs b/window/src/os/macos/window.rs
index 6cd599bbd..9cb4c1cfe 100644
--- a/window/src/os/macos/window.rs
+++ b/window/src/os/macos/window.rs
@@ -19,6 +19,7 @@ use objc::declare::ClassDecl;
 use objc::rc::{StrongPtr, WeakPtr};
 use objc::runtime::{Class, Object, Sel};
 use objc::*;
+use std::any::Any;
 use std::cell::RefCell;
 use std::ffi::c_void;
 use std::rc::Rc;
@@ -119,6 +120,19 @@ impl WindowOps for Window {
         let title = title.to_owned();
         Connection::with_window_inner(self.0, move |inner| inner.set_title(&title));
     }
+
+    fn apply<F: Send + 'static + Fn(&mut dyn Any, &dyn WindowOps)>(&self, func: F)
+    where
+        Self: Sized,
+    {
+        Connection::with_window_inner(self.0, move |inner| {
+            let window = Window(inner.window_id);
+
+            if let Some(window_view) = WindowView::get_this(unsafe { &**inner.view }) {
+                func(window_view.inner.borrow_mut().callbacks.as_any(), &window);
+            }
+        });
+    }
 }
 
 impl WindowOpsMut for WindowInner {