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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CHROME_BROWSER_UI_VIEWS_TABS_DRAGGING_TAB_STRIP_SCROLL_SESSION_H_
#define CHROME_BROWSER_UI_VIEWS_TABS_DRAGGING_TAB_STRIP_SCROLL_SESSION_H_
#include "base/memory/raw_ptr.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "chrome/browser/ui/views/tabs/tab_style_views.h"
class TabDragWithScrollManager {
public:
virtual ~TabDragWithScrollManager() = default;
// Handles dragging tabs while the tabs are attached. `just_attached` should
// be true iff this is the first call to MoveAttached after attaching. This
// also starts a scroll session if needed.
// TODO(crbug.com/40875136): Make this an observer of the scroll_session
// class.
virtual void MoveAttached(gfx::Point point_in_screen) = 0;
// Returns a rect starting from the origin of the first dragged tab
// to the end of the last dragged tab.
virtual gfx::Rect GetEnclosingRectForDraggedTabs() = 0;
// Returns the point in screen when the last drag occurred.
virtual gfx::Point GetLastPointInScreen() = 0;
// Returns the `attached_context_`.
virtual views::View* GetAttachedContext() = 0;
// Get Scroll View from the `attached_context_`.
virtual views::ScrollView* GetScrollView() = 0;
};
// Interface that starts and stops a scrolling session. Current implementations
// are timer based implementations
class TabStripScrollSession {
public:
explicit TabStripScrollSession(TabDragWithScrollManager& drag_controller);
TabStripScrollSession(const TabStripScrollSession&) = delete;
TabStripScrollSession& operator=(const TabStripScrollSession&) = delete;
virtual ~TabStripScrollSession();
enum class ScrollWithDragStrategy {
kConstantSpeed = 1,
kVariableSpeed = 2,
kDisabled = 3
};
enum class TabScrollDirection {
kNoScroll,
kScrollTowardsLeadingTabs,
kScrollTowardsTrailingTabs
};
// Calculates which direction should the scrolling occur and
// starts the `Start()` method
virtual void MaybeStart() = 0;
// Check if the scroll session is still active
virtual bool IsRunning() = 0;
// Determines which direction should the scrolling happen.
virtual TabStripScrollSession::TabScrollDirection GetTabScrollDirection() = 0;
// The offset from the start or end of scroll view when the scrolling should
// begin.
int GetScrollableOffset() const;
protected:
// Start the scroll_session towards the direction passed
virtual void Start(TabScrollDirection direction) = 0;
// Direction in which the scroll is currently happening
TabScrollDirection scroll_direction_ = TabScrollDirection::kNoScroll;
// the controller for running operations like MoveAttached and getting
// the attached_context.
const raw_ref<TabDragWithScrollManager> tab_drag_with_scroll_manager_;
};
class TabStripScrollSessionWithTimer : public TabStripScrollSession {
public:
// enum for type of timer. constant timer scrolls at a constant velocity but
// variable timer scrolls faster towards the ends of the visible view of
// tab_strip
enum class ScrollSessionTimerType { kVariableTimer, kConstantTimer };
TabStripScrollSessionWithTimer(TabDragWithScrollManager& drag_controller,
ScrollSessionTimerType timer_type);
explicit TabStripScrollSessionWithTimer(const TabStripScrollSession&) =
delete;
TabStripScrollSessionWithTimer& operator=(const TabStripScrollSession&) =
delete;
~TabStripScrollSessionWithTimer() override;
void MaybeStart() override;
bool IsRunning() override;
TabStripScrollSession::TabScrollDirection GetTabScrollDirection() override;
// public method for unittest to use a mockTimer
void SetTimerForTesting(base::RepeatingTimer* testing_timer) {
scroll_timer_.reset(testing_timer);
}
// Getter to expose kScrollableOffsetFromScrollView to test class
int GetScrollableOffsetFromScrollViewForTesting() {
return GetScrollableOffset();
}
// Returns the base scroll offset which is the case with constant timer
double CalculateBaseScrollOffset();
private:
void Start(TabScrollDirection direction) override;
// Returns the offset to be scrolled per callback. For variable timer based
// implementation the maximum speed is 3*base_speed
int CalculateSpeed();
// Callback invoked by the timer
void TabScrollCallback();
// Returns the ratio of how far the bounds of the tab_strip are the
// dragged tabs at
double GetRatioInScrollableRegion();
// timer for scrolling and dragging
std::unique_ptr<base::RepeatingTimer> scroll_timer_;
// type of timer which can have a constant velocity or a variable velocity
// based on how close the tabs are to the end of the visible content view.
const ScrollSessionTimerType timer_type_ =
ScrollSessionTimerType::kConstantTimer;
};
#endif // CHROME_BROWSER_UI_VIEWS_TABS_DRAGGING_TAB_STRIP_SCROLL_SESSION_H_
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