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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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_WheelHandlingHelper_h_
#define mozilla_WheelHandlingHelper_h_
#include "mozilla/Attributes.h"
#include "mozilla/EventForwards.h"
#include "nsCoord.h"
#include "nsIFrame.h"
#include "nsPoint.h"
class nsIScrollableFrame;
class nsITimer;
namespace mozilla {
class EventStateManager;
/**
* DeltaValues stores two delta values which are along X and Y axis. This is
* useful for arguments and results of some methods.
*/
struct DeltaValues
{
DeltaValues()
: deltaX(0.0)
, deltaY(0.0)
{
}
DeltaValues(double aDeltaX, double aDeltaY)
: deltaX(aDeltaX)
, deltaY(aDeltaY)
{
}
explicit DeltaValues(WidgetWheelEvent* aEvent);
double deltaX;
double deltaY;
};
/**
* WheelHandlingUtils provides some static methods which are useful at handling
* wheel events.
*/
class WheelHandlingUtils
{
public:
/**
* Returns true if aFrame is a scrollable frame and it can be scrolled to
* either aDirectionX or aDirectionY along each axis. Or if aFrame is a
* plugin frame (in this case, aDirectionX and aDirectionY are ignored).
* Otherwise, false.
*/
static bool CanScrollOn(nsIFrame* aFrame,
double aDirectionX, double aDirectionY);
/**
* Returns true if the scrollable frame can be scrolled to either aDirectionX
* or aDirectionY along each axis. Otherwise, false.
*/
static bool CanScrollOn(nsIScrollableFrame* aScrollFrame,
double aDirectionX, double aDirectionY);
private:
static bool CanScrollInRange(nscoord aMin, nscoord aValue, nscoord aMax,
double aDirection);
};
/**
* ScrollbarsForWheel manages scrollbars state during wheel operation.
* E.g., on some platforms, scrollbars should show only while user attempts to
* scroll. At that time, scrollbars which may be possible to scroll by
* operation of wheel at the point should show temporarily.
*/
class ScrollbarsForWheel
{
public:
static void PrepareToScrollText(EventStateManager* aESM,
nsIFrame* aTargetFrame,
WidgetWheelEvent* aEvent);
static void SetActiveScrollTarget(nsIScrollableFrame* aScrollTarget);
// Hide all scrollbars (both mActiveOwner's and mActivatedScrollTargets')
static void MayInactivate();
static void Inactivate();
static bool IsActive();
static void OwnWheelTransaction(bool aOwn);
protected:
static const size_t kNumberOfTargets = 4;
static const DeltaValues directions[kNumberOfTargets];
static nsWeakFrame sActiveOwner;
static nsWeakFrame sActivatedScrollTargets[kNumberOfTargets];
static bool sHadWheelStart;
static bool sOwnWheelTransaction;
/**
* These two methods are called upon eWheelOperationStart/eWheelOperationEnd
* events to show/hide the right scrollbars.
*/
static void TemporarilyActivateAllPossibleScrollTargets(
EventStateManager* aESM,
nsIFrame* aTargetFrame,
WidgetWheelEvent* aEvent);
static void DeactivateAllTemporarilyActivatedScrollTargets();
};
/**
* WheelTransaction manages a series of wheel events as a transaction.
* While in a transaction, every wheel event should scroll the same scrollable
* element even if a different scrollable element is under the mouse cursor.
*
* Additionally, this class also manages wheel scroll speed acceleration.
*/
class WheelTransaction
{
public:
static nsIFrame* GetTargetFrame() { return sTargetFrame; }
static void EndTransaction();
/**
* WillHandleDefaultAction() is called before handling aWheelEvent on
* aTargetFrame.
*
* @return false if the caller cannot continue to handle the default
* action. Otherwise, true.
*/
static bool WillHandleDefaultAction(WidgetWheelEvent* aWheelEvent,
nsWeakFrame& aTargetWeakFrame);
static bool WillHandleDefaultAction(WidgetWheelEvent* aWheelEvent,
nsIFrame* aTargetFrame)
{
nsWeakFrame targetWeakFrame(aTargetFrame);
return WillHandleDefaultAction(aWheelEvent, targetWeakFrame);
}
static void OnEvent(WidgetEvent* aEvent);
static void Shutdown();
static uint32_t GetTimeoutTime();
static void OwnScrollbars(bool aOwn);
static DeltaValues AccelerateWheelDelta(WidgetWheelEvent* aEvent,
bool aAllowScrollSpeedOverride);
protected:
static void BeginTransaction(nsIFrame* aTargetFrame,
WidgetWheelEvent* aEvent);
// Be careful, UpdateTransaction may fire a DOM event, therefore, the target
// frame might be destroyed in the event handler.
static bool UpdateTransaction(WidgetWheelEvent* aEvent);
static void MayEndTransaction();
static nsIntPoint GetScreenPoint(WidgetGUIEvent* aEvent);
static void OnFailToScrollTarget();
static void OnTimeout(nsITimer* aTimer, void* aClosure);
static void SetTimeout();
static uint32_t GetIgnoreMoveDelayTime();
static int32_t GetAccelerationStart();
static int32_t GetAccelerationFactor();
static DeltaValues OverrideSystemScrollSpeed(WidgetWheelEvent* aEvent);
static double ComputeAcceleratedWheelDelta(double aDelta, int32_t aFactor);
static bool OutOfTime(uint32_t aBaseTime, uint32_t aThreshold);
static nsWeakFrame sTargetFrame;
static uint32_t sTime; // in milliseconds
static uint32_t sMouseMoved; // in milliseconds
static nsITimer* sTimer;
static int32_t sScrollSeriesCounter;
static bool sOwnScrollbars;
};
} // namespace mozilla
#endif // mozilla_WheelHandlingHelper_h_
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