Merge pull request #113 from mitchellh/alt-scroll

Mouse Alt Scroll (mode 1007) and Horizontal Scroll

src/Surface.zig

@@ -1075,19 +1075,59 @@ pub fn scrollCallback(self: *Surface, xoff: f64, yoff: f64) !void {
     }
 
     // log.info("SCROLL: {} {}", .{ xoff, yoff });
-    _ = xoff;
 
     // Positive is up
-    const sign: isize = if (yoff > 0) -1 else 1;
-    const delta: isize = sign * @max(@divFloor(self.grid_size.rows, 15), 1);
-    log.info("scroll: delta={}", .{delta});
+    const y_sign: isize = if (yoff > 0) -1 else 1;
+    const y_delta_unsigned: usize = if (yoff == 0) 0 else @max(@divFloor(self.grid_size.rows, 15), 1);
+    const y_delta: isize = y_sign * @intCast(isize, y_delta_unsigned);
+
+    // Positive is right
+    const x_sign: isize = if (xoff < 0) -1 else 1;
+    const x_delta_unsigned: usize = if (xoff == 0) 0 else 1;
+    const x_delta: isize = x_sign * @intCast(isize, x_delta_unsigned);
+    log.info("scroll: delta_y={} delta_x={}", .{ y_delta, x_delta });
 
     {
         self.renderer_state.mutex.lock();
         defer self.renderer_state.mutex.unlock();
 
+        // If we're in alternate screen with alternate scroll enabled, then
+        // we convert to cursor keys. This only happens if we're:
+        // (1) alt screen (2) no explicit mouse reporting and (3) alt
+        // scroll mode enabled.
+        if (self.io.terminal.active_screen == .alternate and
+            self.io.terminal.modes.mouse_event == .none and
+            self.io.terminal.modes.mouse_alternate_scroll)
+        {
+            if (y_delta_unsigned > 0) {
+                const seq = if (y_delta < 0) "\x1bOA" else "\x1bOB";
+                for (0..y_delta_unsigned) |_| {
+                    _ = self.io_thread.mailbox.push(.{
+                        .write_stable = seq,
+                    }, .{ .forever = {} });
+                }
+            }
+
+            if (x_delta_unsigned > 0) {
+                const seq = if (x_delta < 0) "\x1bOC" else "\x1bOD";
+                for (0..x_delta_unsigned) |_| {
+                    _ = self.io_thread.mailbox.push(.{
+                        .write_stable = seq,
+                    }, .{ .forever = {} });
+                }
+            }
+
+            // After sending all our messages we have to notify our IO thread
+            try self.io_thread.wakeup.notify();
+            return;
+        }
+
+        // We have mouse events, are not in an alternate scroll buffer,
+        // or have alternate scroll disabled. In this case, we just run
+        // the normal logic.
+
         // Modify our viewport, this requires a lock since it affects rendering
-        try self.io.terminal.scrollViewport(.{ .delta = delta });
+        try self.io.terminal.scrollViewport(.{ .delta = y_delta });
 
         // If we're scrolling up or down, then send a mouse event. This requires
         // a lock since we read terminal state.
@@ -1095,6 +1135,10 @@ pub fn scrollCallback(self: *Surface, xoff: f64, yoff: f64) !void {
             const pos = try self.rt_surface.getCursorPos();
             try self.mouseReport(if (yoff < 0) .five else .four, .press, self.mouse.mods, pos);
         }
+        if (xoff != 0) {
+            const pos = try self.rt_surface.getCursorPos();
+            try self.mouseReport(if (xoff > 0) .six else .seven, .press, self.mouse.mods, pos);
+        }
     }
 
     try self.queueRender();

src/terminal/Terminal.zig

@@ -80,6 +80,7 @@ modes: packed struct {
     deccolm: bool = false, // 3,
     deccolm_supported: bool = false, // 40
 
+    mouse_alternate_scroll: bool = true, // 1007
     mouse_event: MouseEvents = .none,
     mouse_format: MouseFormat = .x10,
 

src/terminal/ansi.zig

@@ -101,6 +101,10 @@ pub const Mode = enum(u16) {
     /// Report mouse position in the SGR format.
     mouse_format_sgr = 1006,
 
+    /// Report mouse scroll events as cursor up/down keys. Any other mouse
+    /// mode overrides this.
+    mouse_alternate_scroll = 1007,
+
     /// Report mouse position in the urxvt format.
     mouse_format_urxvt = 1015,
 

src/termio/Exec.zig

@@ -951,6 +951,8 @@ const StreamHandler = struct {
             .mouse_format_urxvt => self.terminal.modes.mouse_format = if (enabled) .urxvt else .x10,
             .mouse_format_sgr_pixels => self.terminal.modes.mouse_format = if (enabled) .sgr_pixels else .x10,
 
+            .mouse_alternate_scroll => self.terminal.modes.mouse_alternate_scroll = enabled,
+
             else => if (enabled) log.warn("unimplemented mode: {}", .{mode}),
         }
     }