use ESM module syntax & minor cleanups

The biggest change here is moving various element classes under
more scope-specific directories, which helps to avoid circular
dependencies and is just cleaner to navigate and expand in the
future.

Otherwise this is a largely uncritical port to ESM module syntax!
There are probably a number of changes and other cleanups that
remain much needed.

Whenever I make changes to tui-lib it's hard to believe it's
already been <INSERT COUNTING NUMBER HERE> years since the
previous time. First commits are from January 2017, and the
code originates a month earlier in KAaRMNoD!

1 files changed, 32 insertions, 0 deletions

diff --git a/ui/controls/FocusBox.js b/ui/controls/FocusBox.js
new file mode 100644
index 0000000..64f84c9
--- /dev/null
+++ b/ui/controls/FocusBox.js
@@ -0,0 +1,32 @@
+import {FocusElement} from 'tui-lib/ui/primitives'
+
+import * as ansi from 'tui-lib/util/ansi'
+
+export default class FocusBox extends FocusElement {
+  // A box (not to be confused with Pane!) that can be selected. When it's
+  // selected, it applies an invert effect to its children. (This won't work
+  // well if you have elements inside of it that have their own attributes,
+  // since they're likely to reset all effects after drawing - including the
+  // invert from the FocusBox! Bad ANSI limitations; it's relatively likely
+  // I'll implement maaaaaagic to help deal with this - maybe something
+  // similar to 'pushMatrix' from Processing - at some point... [TODO])
+
+  constructor() {
+    super()
+
+    this.cursorX = null
+    this.cursorY = null
+  }
+
+  drawTo(writable) {
+    if (this.isSelected) {
+      writable.write(ansi.invert())
+    }
+  }
+
+  didRenderTo(writable) {
+    if (this.isSelected) {
+      writable.write(ansi.resetAttributes())
+    }
+  }
+}