tor-browser

The Tor Browser
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VisualViewport.h (3356B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
      3 /* This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this
      5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 #ifndef mozilla_dom_VisualViewport_h
      8 #define mozilla_dom_VisualViewport_h
      9 
     10 #include "Units.h"
     11 #include "mozilla/DOMEventTargetHelper.h"
     12 #include "mozilla/WeakPtr.h"
     13 #include "mozilla/dom/VisualViewportBinding.h"
     14 
     15 class nsPresContext;
     16 
     17 namespace mozilla {
     18 
     19 class PresShell;
     20 
     21 namespace dom {
     22 
     23 /* Visual Viewport API spec:
     24 * https://wicg.github.io/visual-viewport/#the-visualviewport-interface */
     25 class VisualViewport final : public mozilla::DOMEventTargetHelper {
     26 public:
     27  explicit VisualViewport(nsPIDOMWindowInner* aWindow);
     28 
     29  double OffsetLeft() const;
     30  double OffsetTop() const;
     31  double PageLeft() const;
     32  double PageTop() const;
     33  MOZ_CAN_RUN_SCRIPT double Width() const;
     34  MOZ_CAN_RUN_SCRIPT double Height() const;
     35  double Scale() const;
     36  IMPL_EVENT_HANDLER(resize)
     37  IMPL_EVENT_HANDLER(scroll)
     38 
     39  virtual JSObject* WrapObject(JSContext* aCx,
     40                               JS::Handle<JSObject*> aGivenProto) override;
     41  void GetEventTargetParent(EventChainPreVisitor& aVisitor) override;
     42 
     43  void PostResizeEvent();
     44  MOZ_CAN_RUN_SCRIPT void FireResizeEvent();
     45 
     46  void PostScrollEvent(const nsPoint& aPrevVisualOffset,
     47                       const nsPoint& aPrevLayoutOffset);
     48 
     49  class VisualViewportScrollEvent : public Runnable {
     50   public:
     51    NS_DECL_NSIRUNNABLE
     52    VisualViewportScrollEvent(VisualViewport* aViewport,
     53                              nsPresContext* aPresContext,
     54                              const nsPoint& aPrevVisualOffset,
     55                              const nsPoint& aPrevLayoutOffset);
     56    bool HasPresContext(nsPresContext* aContext) const;
     57    void Revoke();
     58    nsPoint PrevVisualOffset() const { return mPrevVisualOffset; }
     59    nsPoint PrevLayoutOffset() const { return mPrevLayoutOffset; }
     60 
     61   private:
     62    VisualViewport* mViewport;
     63    WeakPtr<nsPresContext> mPresContext;
     64    // The VisualViewport "scroll" event is supposed to be fired only when the
     65    // *relative* offset between visual and layout viewport changes. The two
     66    // viewports are updated independently from each other, though, so the only
     67    // thing we can do is note the fact that one of the inputs into the relative
     68    // visual viewport offset changed and then check the offset again at the
     69    // next refresh driver tick, just before the event is going to fire.
     70    // Hopefully, at this point both visual and layout viewport positions have
     71    // been updated, so that we're able to tell whether the relative offset did
     72    // in fact change or not.
     73    const nsPoint mPrevVisualOffset;
     74    const nsPoint mPrevLayoutOffset;
     75  };
     76 
     77 private:
     78  virtual ~VisualViewport();
     79 
     80  MOZ_CAN_RUN_SCRIPT CSSSize VisualViewportSize() const;
     81  CSSPoint VisualViewportOffset() const;
     82  CSSPoint LayoutViewportOffset() const;
     83  Document* GetDocument() const;
     84  PresShell* GetPresShell() const;
     85  nsPresContext* GetPresContext() const;
     86 
     87  MOZ_CAN_RUN_SCRIPT void FireScrollEvent();
     88 
     89  RefPtr<VisualViewportScrollEvent> mScrollEvent;
     90 };
     91 
     92 }  // namespace dom
     93 }  // namespace mozilla
     94 
     95 #endif  // mozilla_dom_VisualViewport_h