Developer playground: Make panes resizable with wrapping text

CHANGELOG.md

@@ -51,7 +51,7 @@
 - Preserve trailing comments between the type and `=` in locally abstract value constraints (`let f: type a. t /* comment */ = value`). https://github.com/rescript-lang/rescript/pull/8575
 - Enforce function arity in interface/module inclusion and type coercion. Previously a curried implementation (e.g. `int => int => int`) could satisfy an uncurried interface (`(int, int) => int`) or be coerced to it, which could miscompile calls made through the interface type. Such mismatches are now compile errors with an explanatory hint. https://github.com/rescript-lang/rescript/pull/8559
 - Fix termination-analysis false positives for functions whose progress flows through un-annotated helpers: collecting the callees of a function binding was accidentally disabled in 2024 (the collection guard required a node shape that uncurried code never produces), so helpers calling `@progress` functions were no longer added to the function table. https://github.com/rescript-lang/rescript/pull/8568
-- Fix default values of optional parameters being computed at the wrong time for curried functions: in `(~x=default, y) => (~z=default, w) => ...`, `x`'s default was only computed when the *inner* function was applied. Each default is now computed when its own parameter group is applied. https://github.com/rescript-lang/rescript/pull/8568
+- Fix default values of optional parameters being computed at the wrong time for curried functions: in `(~x=default, y) => (~z=default, w) => ...`, `x`'s default was only computed when the _inner_ function was applied. Each default is now computed when its own parameter group is applied. https://github.com/rescript-lang/rescript/pull/8568
 - Fix bare labeled arrow types (`~x: int => string`) getting no arity: they printed identically to their parenthesized form (`(~x: int) => string`) but did not unify with it. https://github.com/rescript-lang/rescript/pull/8563
 - Fix losses of fidelity when code passes through an external PPX: the internal `@res.async` marker no longer leaks into the program, attributes on an arrow type or on an `await` expression are no longer dropped or relocated (previously this could crash the formatter), JSX elements keep their closing tag, and PPX-emitted OCaml-style `function` is desugared instead of crashing the compiler. https://github.com/rescript-lang/rescript/pull/8561
 - Preserve multibyte characters when wrapping long source lines in compiler code frames. https://github.com/rescript-lang/rescript/pull/8520
@@ -68,6 +68,7 @@
 
 #### :house: Internal
 
+- Developer playground: Make panes resizable with wrapping text. https://github.com/rescript-lang/rescript/pull/8628
 - Merge the duplicate Lam intermediate representation into Lambda, removing the conversion layer and obsolete supporting infrastructure. Lambda is now a single private, normalized representation, with generated JavaScript remaining semantically unchanged. https://github.com/rescript-lang/rescript/pull/8608
 - Add genType and source map controls and output to the developer playground. https://github.com/rescript-lang/rescript/pull/8448
 - Rework the object-type representation end to end: object rows are plain field chains carrying a per-field mutability state (no phantom setter members), object literals are typed directly and property access and assignment are first-class AST and Lambda nodes shared between the Lambda and JS pipelines, and dead class-system remnants (the field-presence lattice, the class-abbreviation memo on object types, method-send typing) are removed. https://github.com/rescript-lang/rescript/pull/8597

packages/dev-playground/package.json

@@ -9,7 +9,7 @@
     "prepare-pages-site": "node scripts/prepare-pages-site.mjs",
     "res:build": "rescript",
     "res:watch": "rescript -w",
-    "test": "rescript && node --test scripts/source-map-navigation.test.mjs",
+    "test": "rescript && node --test scripts/source-map-navigation.test.mjs scripts/pane-layout.test.mjs",
     "dev": "vite --host 127.0.0.1",
     "build": "rescript && vite build",
     "preview": "vite preview --host 127.0.0.1"

packages/dev-playground/scripts/pane-layout.test.mjs

@@ -0,0 +1,64 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import {
+  current,
+  finishDrag,
+  make,
+  moveDrag,
+  nudge,
+  orientationForWidth,
+  ratioForPosition,
+  setOrientation,
+  startDrag,
+} from "../src/PaneLayout.res.mjs";
+
+const closeTo = (actual, expected) =>
+  assert.ok(
+    Math.abs(actual - expected) < 0.000001,
+    `${actual} is not close to ${expected}`,
+  );
+
+test("switches to stacked panes from the container width", () => {
+  assert.equal(orientationForWidth(901), "Columns");
+  assert.equal(orientationForWidth(900), "Rows");
+});
+
+test("calculates a divider ratio and respects both pane minimums", () => {
+  closeTo(ratioForPosition(500, 1000, 360, 420), 0.5);
+  closeTo(ratioForPosition(0, 1000, 360, 420), 360 / 992);
+  closeTo(ratioForPosition(1000, 1000, 360, 420), 1 - 420 / 992);
+  closeTo(ratioForPosition(100, 300, 180, 180), 0.5);
+});
+
+test("keeps drag and ratio state isolated between layout instances", () => {
+  const first = make();
+  const second = make();
+
+  assert.notEqual(first.containerId, second.containerId);
+  startDrag(first, 7, 600, 1000, 360, 420);
+
+  assert.equal(current(first).dragging, true);
+  assert.equal(current(second).dragging, false);
+  assert.equal(current(second).columnRatio, 0.5);
+
+  const draggedRatio = current(first).columnRatio;
+  moveDrag(first, 8, 450);
+  assert.equal(current(first).columnRatio, draggedRatio);
+  finishDrag(first, 8);
+  assert.equal(current(first).dragging, true);
+  finishDrag(first, 7);
+  assert.equal(current(first).dragging, false);
+});
+
+test("stores independent ratios for columns and stacked rows", () => {
+  const layout = make();
+
+  nudge(layout, 0.025, 1000, 360, 420);
+  closeTo(current(layout).columnRatio, 0.525);
+
+  setOrientation(layout, orientationForWidth(600));
+  nudge(layout, -0.025, 800, 180, 180);
+  closeTo(current(layout).columnRatio, 0.525);
+  closeTo(current(layout).rowRatio, 0.475);
+});

packages/dev-playground/src/Bindings.res

@@ -114,7 +114,13 @@ module Url = {
 
 module Event = {
   @get external target: Dom.event => {..} = "target"
+  @get external currentTarget: Dom.event => Dom.element = "currentTarget"
   @get external key: Dom.event => string = "key"
+  @get external button: Dom.event => int = "button"
+  @get external clientX: Dom.event => float = "clientX"
+  @get external clientY: Dom.event => float = "clientY"
+  @get external pointerId: Dom.event => int = "pointerId"
+  @get external detail: Dom.event => int = "detail"
   @send external preventDefault: Dom.event => unit = "preventDefault"
 
   let value = (event: Dom.event): string => (event->target)["value"]
@@ -129,11 +135,6 @@ module Event = {
     let scrollTop: float = (event->target)["scrollTop"]
     scrollTop->Math.round->Float.toInt
   }
-
-  let scrollLeft = (event: Dom.event): int => {
-    let scrollLeft: float = (event->target)["scrollLeft"]
-    scrollLeft->Math.round->Float.toInt
-  }
 }
 
 module EventTarget = {
@@ -160,6 +161,20 @@ type scrollIntoViewOptions = {
   inline: string,
 }
 
+type boundingRect = {
+  left: float,
+  top: float,
+  width: float,
+  height: float,
+}
+
+type classList
+
+module ClassList = {
+  @send external add: (classList, string) => unit = "add"
+  @send external remove: (classList, string) => unit = "remove"
+}
+
 module Element = {
   @send external setAttribute: (Dom.element, string, string) => unit = "setAttribute"
   @send
@@ -170,6 +185,15 @@ module Element = {
   @send external appendChild: (Dom.element, Dom.element) => unit = "appendChild"
   @send external removeChild: (Dom.element, Dom.element) => unit = "removeChild"
   @send external focus: Dom.element => unit = "focus"
+  @send external setPointerCapture: (Dom.element, int) => unit = "setPointerCapture"
+  @send external releasePointerCapture: (Dom.element, int) => unit = "releasePointerCapture"
+  @send external hasPointerCapture: (Dom.element, int) => bool = "hasPointerCapture"
+  @send external getBoundingClientRect: Dom.element => boundingRect = "getBoundingClientRect"
+  @get external classList: Dom.element => classList = "classList"
+  @send @return(nullable)
+  external querySelector: (Dom.element, string) => option<Dom.element> = "querySelector"
+  @get @return(nullable)
+  external parentElement: Dom.element => option<Dom.element> = "parentElement"
   @send
   external scrollIntoView: (Dom.element, scrollIntoViewOptions) => unit = "scrollIntoView"
   @get external style: Dom.element => CssStyle.t = "style"
@@ -181,6 +205,20 @@ module Element = {
     "__devPlaygroundScrollHandler"
 }
 
+type resizeObserver
+type resizeObserverEntry
+
+module ResizeObserverEntry = {
+  @get external contentRect: resizeObserverEntry => boundingRect = "contentRect"
+}
+
+module ResizeObserver = {
+  @val external supported: option<unknown> = "globalThis.ResizeObserver"
+  @new external make: (array<resizeObserverEntry> => unit) => resizeObserver = "ResizeObserver"
+  @send external observe: (resizeObserver, Dom.element) => unit = "observe"
+  @send external disconnect: resizeObserver => unit = "disconnect"
+}
+
 module ScriptElement = {
   @set external setSrc: (Dom.element, string) => unit = "src"
   @set external setAsync: (Dom.element, bool) => unit = "async"