add(style): cursor style to indicate a cursor position

src/render.zig

@@ -88,7 +88,9 @@ pub const Buffered = struct {
 
     /// Write *virtual screen* to alternate screen (should be called once and last during each render loop iteration in the main loop).
     pub fn flush(this: *@This()) !void {
+        try terminal.hideCursor();
         // TODO measure timings of rendered frames?
+        var cursor_position: ?Point = null;
         const writer = terminal.writer();
         const s = this.screen;
         const vs = this.virtual_screen;
@@ -99,12 +101,20 @@ pub const Buffered = struct {
                 const cvs = vs[idx];
                 if (cs.eql(cvs)) continue;
 
+                if (cvs.style.cursor) cursor_position = .{
+                    .x = @truncate(col),
+                    .y = @truncate(row),
+                };
                 // render differences found in virtual screen
-                try terminal.setCursorPosition(.{ .y = @truncate(row + 1), .x = @truncate(col + 1) });
+                try terminal.setCursorPosition(.{ .y = @truncate(row), .x = @truncate(col) });
                 try cvs.value(writer);
                 // update screen to be the virtual screen for the next frame
                 s[idx] = vs[idx];
             }
         }
+        if (cursor_position) |point| {
+            try terminal.showCursor();
+            try terminal.setCursorPosition(point);
+        }
     }
 };

src/style.zig

@@ -37,6 +37,7 @@ pub const Emphasis = enum(u8) {
 fg: Color = .default,
 bg: Color = .default,
 ul: Color = .default,
+cursor: bool = false,
 ul_style: Underline = .off,
 emphasis: []const Emphasis,
 

src/terminal.zig

@@ -91,7 +91,7 @@ pub fn writer() Writer {
 
 pub fn setCursorPosition(pos: Point) !void {
     var buf: [64]u8 = undefined;
-    const value = try std.fmt.bufPrint(&buf, "\x1b[{d};{d}H", .{ pos.y, pos.x });
+    const value = try std.fmt.bufPrint(&buf, "\x1b[{d};{d}H", .{ pos.y + 1, pos.x + 1 });
     _ = try std.posix.write(std.posix.STDIN_FILENO, value);
 }