Fix orbitControl() breaking after touch swipe outside canvas.

src/events/pointer.js

@@ -9,6 +9,7 @@ function pointer(p5, fn, lifecycles){
     const events = [
       'pointerdown',
       'pointerup',
+      'pointercancel',
       'pointermove',
       'dragend',
       'dragover',
@@ -1394,6 +1395,16 @@ function pointer(p5, fn, lifecycles){
   fn._ondragend = fn._onpointerup;
   fn._ondragover = fn._onpointermove;
 
+  fn._onpointercancel = function(e) {
+    this._activePointers.delete(e.pointerId);
+    this._setMouseButton(e);
+    this._updatePointerCoords(e);
+
+    if (this._activePointers.size === 0) {
+      this.mouseIsPressed = false;
+    }
+  };
+
   /**
    * A function that's called once after a mouse button is pressed and released.
    *

test/unit/events/touch.js

@@ -32,6 +32,13 @@ suite('Touch Events', function() {
     myp5.remove();
   });
 
+  beforeEach(function() {
+    // Reset pointer state so tests don't leak active pointers into each other.
+    myp5._activePointers.clear();
+    myp5.touches = [];
+    myp5.mouseIsPressed = false;
+  });
+
   suite('p5.prototype.touches', function() {
     test('should be an empty array', function() {
       assert.deepEqual(myp5.touches, []);
@@ -44,7 +51,45 @@ suite('Touch Events', function() {
     });
 
     test('should contain the touch registered', function() {
+      window.dispatchEvent(touchEvent1);
       assert.strictEqual(myp5.touches[0].id, 1);
     });
   });
+
+  suite('p5.prototype._onpointercancel', function() {
+    test('should remove the cancelled touch from touches', function() {
+      window.dispatchEvent(touchEvent1);
+      window.dispatchEvent(touchEvent2);
+      assert.strictEqual(myp5.touches.length, 2);
+
+      // A cancelled pointer must be cleaned up even though no
+      // 'pointerup' event is dispatched.
+      const cancelEvent = new PointerEvent('pointercancel', {
+        pointerId: 1,
+        clientX: 100,
+        clientY: 100,
+        pointerType: 'touch'
+      });
+      window.dispatchEvent(cancelEvent);
+
+      assert.strictEqual(myp5.touches.length, 1);
+      assert.strictEqual(myp5.touches[0].id, 2);
+    });
+
+    test('should reset mouseIsPressed once all pointers are cancelled', function() {
+      window.dispatchEvent(touchEvent1);
+      assert.strictEqual(myp5.mouseIsPressed, true);
+
+      const cancelEvent = new PointerEvent('pointercancel', {
+        pointerId: 1,
+        clientX: 100,
+        clientY: 100,
+        pointerType: 'touch'
+      });
+      window.dispatchEvent(cancelEvent);
+
+      assert.strictEqual(myp5.touches.length, 0);
+      assert.strictEqual(myp5.mouseIsPressed, false);
+    });
+  });
 });