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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 */
#ifndef mozilla_layers_DoubleTapToZoom_h
#define mozilla_layers_DoubleTapToZoom_h
#include "Units.h"
#include "mozilla/gfx/Matrix.h"
template <class T>
class RefPtr;
namespace mozilla {
namespace dom {
class Document;
namespace layers {
enum class CantZoomOutBehavior : int8_t { Nothing = 0, ZoomIn };
struct ZoomTarget {
// The preferred target rect that we'd like to zoom in on, if possible. An
// empty rect means the browser should zoom out.
CSSRect targetRect;
// If we are asked to zoom out but cannot (due to zoom constraints, etc), then
// zoom in some small amount to provide feedback to the user.
CantZoomOutBehavior cantZoomOutBehavior = CantZoomOutBehavior::Nothing;
// If zooming all the way in on |targetRect| is not possible (for example, due
// to a max zoom constraint), |elementBoundingRect| may be used to inform a
// more optimal target scroll position (for example, we may try to maximize
// the area of |elementBoundingRect| that's showing, while keeping
// |targetRect| in view and keeping the zoom as close to the desired zoom as
// possible).
Maybe<CSSRect> elementBoundingRect;
// The document relative (ie if the content inside the root scroll frame
// existed without that scroll frame) pointer position at the time of the
// double tap or location of the double tap if we can compute it. Only used if
// the rest of this ZoomTarget is asking to zoom out but we are already at the
// minimum zoom. In which case we zoom in a small amount on this point.
Maybe<CSSPoint> documentRelativePointerPosition;
struct DoubleTapToZoomMetrics {
// The visual viewport rect of the top-level content document.
CSSRect mVisualViewport;
// The scrollable rect of the root scroll container of the top-level content
// document.
CSSRect mRootScrollableRect;
// If double-tap-to-zoom happens inside an OOP iframe, this transform matrix
// is the matrix converting the coordinates relative to layout viewport origin
// of the OOP iframe to the document origin of the top level content document.
// If not, this is the identity matrix.
CSSToCSSMatrix4x4 mTransformMatrix;
bool operator==(const DoubleTapToZoomMetrics& aOther) const {
return mVisualViewport == aOther.mVisualViewport &&
mRootScrollableRect == aOther.mRootScrollableRect &&
mTransformMatrix == aOther.mTransformMatrix;
friend std::ostream& operator<<(std::ostream& aStream,
const DoubleTapToZoomMetrics& aUpdate);
* For a double tap at |aPoint|, return a ZoomTarget struct with contains a rect
* to which the browser should zoom in response (see ZoomTarget definition for
* more details). An empty rect means the browser should zoom out. |aDocument|
* should be the in-process root content document for the content that was
* tapped.
ZoomTarget CalculateRectToZoomTo(
const RefPtr<mozilla::dom::Document>& aInProcessRootContentDocument,
const CSSPoint& aPoint, const DoubleTapToZoomMetrics& aMetrics);
} // namespace layers
} // namespace mozilla
#endif /* mozilla_layers_DoubleTapToZoom_h */