VisualViewport.h - mozsearch

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/* -*- 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;

  MOZ_CAN_RUN_SCRIPT void FireResizeEvent();

  MOZ_CAN_RUN_SCRIPT void FireScrollEvent();

  RefPtr<VisualViewportResizeEvent> mResizeEvent;

  RefPtr<VisualViewportScrollEvent> mScrollEvent;

};

}  // namespace dom

}  // namespace mozilla

#endif  // mozilla_dom_VisualViewport_h