dom/base/VisualViewport.h

   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 "mozilla/DOMEventTargetHelper.h"
  11 #include "mozilla/WeakPtr.h"
  12 #include "mozilla/dom/VisualViewportBinding.h"
  13 #include "Units.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   void PostScrollEvent(const nsPoint& aPrevVisualOffset,
  45                        const nsPoint& aPrevLayoutOffset);
  46
  47   // These two events are modelled after the ScrollEvent class in
  48   // nsGfxScrollFrame.h.
  49   class VisualViewportResizeEvent : public Runnable {
  50    public:
  51     NS_DECL_NSIRUNNABLE
  52     VisualViewportResizeEvent(VisualViewport* aViewport,
  53                               nsPresContext* aPresContext);
  54     bool HasPresContext(nsPresContext* aContext) const;
  55     void Revoke();
  56
  57    private:
  58     VisualViewport* mViewport;
  59     WeakPtr<nsPresContext> mPresContext;
  60   };
  61
  62   class VisualViewportScrollEvent : public Runnable {
  63    public:
  64     NS_DECL_NSIRUNNABLE
  65     VisualViewportScrollEvent(VisualViewport* aViewport,
  66                               nsPresContext* aPresContext,
  67                               const nsPoint& aPrevVisualOffset,
  68                               const nsPoint& aPrevLayoutOffset);
  69     bool HasPresContext(nsPresContext* aContext) const;
  70     void Revoke();
  71     nsPoint PrevVisualOffset() const { return mPrevVisualOffset; }
  72     nsPoint PrevLayoutOffset() const { return mPrevLayoutOffset; }
  73
  74    private:
  75     VisualViewport* mViewport;
  76     WeakPtr<nsPresContext> mPresContext;
  77     // The VisualViewport "scroll" event is supposed to be fired only when the
  78     // *relative* offset between visual and layout viewport changes. The two
  79     // viewports are updated independently from each other, though, so the only
  80     // thing we can do is note the fact that one of the inputs into the relative
  81     // visual viewport offset changed and then check the offset again at the
  82     // next refresh driver tick, just before the event is going to fire.
  83     // Hopefully, at this point both visual and layout viewport positions have
  84     // been updated, so that we're able to tell whether the relative offset did
  85     // in fact change or not.
  86     const nsPoint mPrevVisualOffset;
  87     const nsPoint mPrevLayoutOffset;
  88   };
  89
  90  private:
  91   virtual ~VisualViewport();
  92
  93   MOZ_CAN_RUN_SCRIPT CSSSize VisualViewportSize() const;
  94   CSSPoint VisualViewportOffset() const;
  95   CSSPoint LayoutViewportOffset() const;
  96   Document* GetDocument() const;
  97   PresShell* GetPresShell() const;
  98   nsPresContext* GetPresContext() const;
  99
 100   void FireResizeEvent();
 101   void FireScrollEvent();
 102
 103   RefPtr<VisualViewportResizeEvent> mResizeEvent;
 104   RefPtr<VisualViewportScrollEvent> mScrollEvent;
 105 };
 106
 107 }  // namespace dom
 108 }  // namespace mozilla
 109
 110 #endif  // mozilla_dom_VisualViewport_h