1 files changed, 110 insertions, 0 deletions
diff --git a/dom/base/VisualViewport.h b/dom/base/VisualViewport.h
new file mode 100644
index 0000000000..8878702457
--- /dev/null
+++ b/dom/base/VisualViewport.h
@@ -0,0 +1,110 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_VisualViewport_h
+#define mozilla_dom_VisualViewport_h
+
+#include "mozilla/DOMEventTargetHelper.h"
+#include "mozilla/WeakPtr.h"
+#include "mozilla/dom/VisualViewportBinding.h"
+#include "Units.h"
+
+class nsPresContext;
+
+namespace mozilla {
+
+class PresShell;
+
+namespace dom {
+
+/* Visual Viewport API spec:
+ * https://wicg.github.io/visual-viewport/#the-visualviewport-interface */
+class VisualViewport final : public mozilla::DOMEventTargetHelper {
+ public:
+  explicit VisualViewport(nsPIDOMWindowInner* aWindow);
+
+  double OffsetLeft() const;
+  double OffsetTop() const;
+  double PageLeft() const;
+  double PageTop() const;
+  MOZ_CAN_RUN_SCRIPT double Width() const;
+  MOZ_CAN_RUN_SCRIPT double Height() const;
+  double Scale() const;
+  IMPL_EVENT_HANDLER(resize)
+  IMPL_EVENT_HANDLER(scroll)
+
+  virtual JSObject* WrapObject(JSContext* aCx,
+                               JS::Handle<JSObject*> aGivenProto) override;
+  void GetEventTargetParent(EventChainPreVisitor& aVisitor) override;
+
+  void PostResizeEvent();
+  void PostScrollEvent(const nsPoint& aPrevVisualOffset,
+                       const nsPoint& aPrevLayoutOffset);
+
+  // These two events are modelled after the ScrollEvent class in
+  // nsGfxScrollFrame.h.
+  class VisualViewportResizeEvent : public Runnable {
+   public:
+    NS_DECL_NSIRUNNABLE
+    VisualViewportResizeEvent(VisualViewport* aViewport,
+                              nsPresContext* aPresContext);
+    bool HasPresContext(nsPresContext* aContext) const;
+    void Revoke();
+
+   private:
+    VisualViewport* mViewport;
+    WeakPtr<nsPresContext> mPresContext;
+  };
+
+  class VisualViewportScrollEvent : public Runnable {
+   public:
+    NS_DECL_NSIRUNNABLE
+    VisualViewportScrollEvent(VisualViewport* aViewport,
+                              nsPresContext* aPresContext,
+                              const nsPoint& aPrevVisualOffset,
+                              const nsPoint& aPrevLayoutOffset);
+    bool HasPresContext(nsPresContext* aContext) const;
+    void Revoke();
+    nsPoint PrevVisualOffset() const { return mPrevVisualOffset; }
+    nsPoint PrevLayoutOffset() const { return mPrevLayoutOffset; }
+
+   private:
+    VisualViewport* mViewport;
+    WeakPtr<nsPresContext> mPresContext;
+    // The VisualViewport "scroll" event is supposed to be fired only when the
+    // *relative* offset between visual and layout viewport changes. The two
+    // viewports are updated independently from each other, though, so the only
+    // thing we can do is note the fact that one of the inputs into the relative
+    // visual viewport offset changed and then check the offset again at the
+    // next refresh driver tick, just before the event is going to fire.
+    // Hopefully, at this point both visual and layout viewport positions have
+    // been updated, so that we're able to tell whether the relative offset did
+    // in fact change or not.
+    const nsPoint mPrevVisualOffset;
+    const nsPoint mPrevLayoutOffset;
+  };
+
+ private:
+  virtual ~VisualViewport();
+
+  MOZ_CAN_RUN_SCRIPT CSSSize VisualViewportSize() const;
+  CSSPoint VisualViewportOffset() const;
+  CSSPoint LayoutViewportOffset() const;
+  Document* GetDocument() const;
+  PresShell* GetPresShell() const;
+  nsPresContext* GetPresContext() const;
+
+  void FireResizeEvent();
+  void FireScrollEvent();
+
+  RefPtr<VisualViewportResizeEvent> mResizeEvent;
+  RefPtr<VisualViewportScrollEvent> mScrollEvent;
+};
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif  // mozilla_dom_VisualViewport_h