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.

1 files changed, 34 insertions, 5 deletions

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),