Change mouse cursor on terminal mode change (#865)

Some terminals have functionality around changing the type of mouse
cursor dynamically (arrow and text) based on which mode(s) the VTE is
in. For example, gnome-terminal changes the cursor from text (default)
to an arrow when opening programs that track mouse events (e.g. vim,
emacs, tmux, htop, etc.). The programs all allow using the mouse
interactively under some circumstances (like executing `set mouse=a` in
vim).

The programs that use an interactive mouse set the terminal mode to
different values. Though they're not entirely the same terminal mode
across programs, an emulator like vte (the library gnome-terminal
implements), changes the mouse cursor if the mouse mode is one of the
following:

- 1000: Mouse Click Tracking
- 1001: Mouse Highlight Tracking
- 1002: Mouse Cell Motion Tracking
- 1003: Mouse All Motion Tracking
- 1004: Mouse Focus Tracking

See https://github.com/GNOME/vte/blob/6acfa59dfcceef65c1f7e3570db37ab245f049c4/src/vteseq.cc#L708
for more information.

This commit adds functionality that changes the winit/glutin
`MouseCursor` when a mouse-listening mode of 1000-1004 is set. It
behaves similarly to when the window title changes.

5 files changed, 71 insertions, 11 deletions

diff --git a/src/ansi.rs b/src/ansi.rs
index ec139294..3d66b497 100644
--- a/src/ansi.rs
+++ b/src/ansi.rs
@@ -21,7 +21,7 @@ use vte;
 
 use index::{Column, Line, Contains};
 
-use ::Rgb;
+use ::{MouseCursor, Rgb};
 
 // Parse color arguments
 //
@@ -178,6 +178,9 @@ pub trait Handler {
     /// OSC to set window title
     fn set_title(&mut self, &str) {}
 
+    /// Set the window's mouse cursor
+    fn set_mouse_cursor(&mut self, MouseCursor) {}
+
     /// Set the cursor style
     fn set_cursor_style(&mut self, _: Option<CursorStyle>) {}
 
@@ -402,7 +405,9 @@ pub enum Mode {
     /// ?1000
     ReportMouseClicks = 1000,
     /// ?1002
-    ReportMouseMotion = 1002,
+    ReportCellMouseMotion = 1002,
+    /// ?1003
+    ReportAllMouseMotion = 1003,
     /// ?1004
     ReportFocusInOut = 1004,
     /// ?1006
@@ -427,12 +432,16 @@ impl Mode {
                 12 => Mode::BlinkingCursor,
                 25 => Mode::ShowCursor,
                 1000 => Mode::ReportMouseClicks,
-                1002 => Mode::ReportMouseMotion,
+                1002 => Mode::ReportCellMouseMotion,
+                1003 => Mode::ReportAllMouseMotion,
                 1004 => Mode::ReportFocusInOut,
                 1006 => Mode::SgrMouse,
                 1049 => Mode::SwapScreenAndSetRestoreCursor,
                 2004 => Mode::BracketedPaste,
-                _ => return None
+                _ => {
+                    trace!("[unhandled] mode={:?}", num);
+                    return None
+                }
             })
         } else {
             Some(match num {
diff --git a/src/display.rs b/src/display.rs
index 8e3d8814..89403194 100644
--- a/src/display.rs
+++ b/src/display.rs
@@ -327,6 +327,10 @@ impl Display {
             self.window.set_title(&title);
         }
 
+        if let Some(mouse_cursor) = terminal.get_next_mouse_cursor() {
+            self.window.set_mouse_cursor(mouse_cursor);
+        }
+
         if let Some(is_urgent) = terminal.next_is_urgent.take() {
             // We don't need to set the urgent flag if we already have the
             // user's attention.
diff --git a/src/lib.rs b/src/lib.rs
index a8539328..1f3fcc96 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -81,6 +81,13 @@ use std::ops::Mul;
 pub use grid::Grid;
 pub use term::Term;
 
+/// Facade around [winit's MouseCursor](glutin::MouseCursor)
+#[derive(Debug, Eq, PartialEq, Copy, Clone)]
+pub enum MouseCursor {
+    Arrow,
+    Text,
+}
+
 #[derive(Debug, Eq, PartialEq, Copy, Clone, Default, Serialize, Deserialize)]
 pub struct Rgb {
     pub r: u8,
diff --git a/src/term/mod.rs b/src/term/mod.rs
index 98e08e6c..712247c4 100644
--- a/src/term/mod.rs
+++ b/src/term/mod.rs
@@ -28,7 +28,7 @@ use grid::{BidirectionalIterator, Grid, ClearRegion, ToRange, Indexed};
 use index::{self, Point, Column, Line, Linear, IndexRange, Contains, RangeInclusive};
 use selection::{self, Span, Selection};
 use config::{Config, VisualBellAnimation};
-use Rgb;
+use {MouseCursor, Rgb};
 
 pub mod cell;
 pub mod color;
@@ -648,6 +648,9 @@ pub struct Term {
     /// Would be nice to avoid the allocation...
     next_title: Option<String>,
 
+    /// Got a request to set the mouse cursor; it's buffered here until the next draw
+    next_mouse_cursor: Option<MouseCursor>,
+
     /// Alternate grid
     alt_grid: Grid<Cell>,
 
@@ -769,6 +772,11 @@ impl Term {
         self.next_title.take()
     }
 
+    #[inline]
+    pub fn get_next_mouse_cursor(&mut self) -> Option<MouseCursor> {
+        self.next_mouse_cursor.take()
+    }
+
     pub fn new(config: &Config, size: SizeInfo) -> Term {
         let template = Cell::default();
 
@@ -786,6 +794,7 @@ impl Term {
 
         Term {
             next_title: None,
+            next_mouse_cursor: None,
             dirty: false,
             visual_bell: VisualBell::new(config),
             next_is_urgent: None,
@@ -1168,6 +1177,12 @@ impl ansi::Handler for Term {
         }
     }
 
+    /// Set the mouse cursor
+    #[inline]
+    fn set_mouse_cursor(&mut self, cursor: MouseCursor) {
+        self.next_mouse_cursor = Some(cursor);
+    }
+
     /// A character to be displayed
     #[inline]
     fn input(&mut self, c: char) {
@@ -1767,8 +1782,15 @@ impl ansi::Handler for Term {
             },
             ansi::Mode::ShowCursor => self.mode.insert(mode::TermMode::SHOW_CURSOR),
             ansi::Mode::CursorKeys => self.mode.insert(mode::TermMode::APP_CURSOR),
-            ansi::Mode::ReportMouseClicks => self.mode.insert(mode::TermMode::MOUSE_REPORT_CLICK),
-            ansi::Mode::ReportMouseMotion => self.mode.insert(mode::TermMode::MOUSE_MOTION),
+            ansi::Mode::ReportMouseClicks => {
+                self.mode.insert(mode::TermMode::MOUSE_REPORT_CLICK);
+                self.set_mouse_cursor(MouseCursor::Arrow);
+            },
+            ansi::Mode::ReportCellMouseMotion |
+            ansi::Mode::ReportAllMouseMotion => {
+                self.mode.insert(mode::TermMode::MOUSE_MOTION);
+                self.set_mouse_cursor(MouseCursor::Arrow);
+            },
             ansi::Mode::ReportFocusInOut => self.mode.insert(mode::TermMode::FOCUS_IN_OUT),
             ansi::Mode::BracketedPaste => self.mode.insert(mode::TermMode::BRACKETED_PASTE),
             ansi::Mode::SgrMouse => self.mode.insert(mode::TermMode::SGR_MOUSE),
@@ -1797,8 +1819,15 @@ impl ansi::Handler for Term {
             },
             ansi::Mode::ShowCursor => self.mode.remove(mode::TermMode::SHOW_CURSOR),
             ansi::Mode::CursorKeys => self.mode.remove(mode::TermMode::APP_CURSOR),
-            ansi::Mode::ReportMouseClicks => self.mode.remove(mode::TermMode::MOUSE_REPORT_CLICK),
-            ansi::Mode::ReportMouseMotion => self.mode.remove(mode::TermMode::MOUSE_MOTION),
+            ansi::Mode::ReportMouseClicks => {
+                self.mode.remove(mode::TermMode::MOUSE_REPORT_CLICK);
+                self.set_mouse_cursor(MouseCursor::Text);
+            },
+            ansi::Mode::ReportCellMouseMotion |
+            ansi::Mode::ReportAllMouseMotion => {
+                self.mode.remove(mode::TermMode::MOUSE_MOTION);
+                self.set_mouse_cursor(MouseCursor::Text);
+            },
             ansi::Mode::ReportFocusInOut => self.mode.remove(mode::TermMode::FOCUS_IN_OUT),
             ansi::Mode::BracketedPaste => self.mode.remove(mode::TermMode::BRACKETED_PASTE),
             ansi::Mode::SgrMouse => self.mode.remove(mode::TermMode::SGR_MOUSE),
diff --git a/src/window.rs b/src/window.rs
index e42151fd..aec4b76d 100644
--- a/src/window.rs
+++ b/src/window.rs
@@ -16,9 +16,12 @@ use std::fmt::{self, Display};
 use std::ops::Deref;
 
 use gl;
-use glutin::{self, EventsLoop, WindowBuilder, Event, MouseCursor, CursorState, ControlFlow, ContextBuilder};
+use glutin::{self, ContextBuilder, ControlFlow, CursorState, Event, EventsLoop,
+             MouseCursor as GlutinMouseCursor, WindowBuilder};
 use glutin::GlContext;
 
+use MouseCursor;
+
 use config::WindowConfig;
 
 /// Window errors
@@ -200,7 +203,7 @@ impl Window {
         let window = ::glutin::GlWindow::new(window, context, &event_loop)?;
 
         // Text cursor
-        window.set_cursor(MouseCursor::Text);
+        window.set_cursor(GlutinMouseCursor::Text);
 
         // Set OpenGL symbol loader
         gl::load_with(|symbol| window.get_proc_address(symbol) as *const _);
@@ -284,6 +287,14 @@ impl Window {
         self.window.set_title(title);
     }
 
+    #[inline]
+    pub fn set_mouse_cursor(&self, cursor: MouseCursor) {
+        self.window.set_cursor(match cursor {
+            MouseCursor::Arrow => GlutinMouseCursor::Arrow,
+            MouseCursor::Text => GlutinMouseCursor::Text,
+        });
+    }
+
     /// Set cursor visible
     pub fn set_cursor_visible(&mut self, visible: bool) {
         if visible != self.cursor_visible {