1 /*

     2  * Copyright (C) 2010 Google Inc. All rights reserved.

     3  *

     4  * Redistribution and use in source and binary forms, with or without

     5  * modification, are permitted provided that the following conditions are

     6  * met:

     7  *

     8  *     * Redistributions of source code must retain the above copyright

     9  * notice, this list of conditions and the following disclaimer.

    10  *     * Redistributions in binary form must reproduce the above

    11  * copyright notice, this list of conditions and the following disclaimer

    12  * in the documentation and/or other materials provided with the

    13  * distribution.

    14  *     * Neither the name of Google Inc. nor the names of its

    15  * contributors may be used to endorse or promote products derived from

    16  * this software without specific prior written permission.

    17  *

    18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

    19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

    20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

    21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

    22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

    23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

    24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

    25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

    26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

    27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

    28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    29  */

    30 

    31 #ifndef DragScrollTimer_h

    32 #define DragScrollTimer_h

    33 

    34 #include "IntSize.h"

    35 #include "Timer.h"

    36 #include "WebPoint.h"

    37 

    38 namespace WebCore { class FrameView; }

    39 

    40 namespace WebKit {

    41 

    42 //

    43 // Encapsulating a timer and associated state management for

    44 // scroll-on-drag behaviour.

    45 //

    46 class DragScrollTimer {

    47 public:

    48     DragScrollTimer();

    49     ~DragScrollTimer();

    50 

    51     void fired(WebCore::Timer<DragScrollTimer>*) { update(); }

    52     void triggerScroll(WebCore::FrameView*, const WebPoint&);

    53     void stop();

    54 

    55 private:

    56     void scroll();

    57     void update();

    58     WebCore::IntSize scrollDistanceFor(WebCore::FrameView*, const WebPoint&) const;

    59     bool shouldScroll() const { return !m_lastDistance.isZero(); }

    60 

    61     WebCore::Timer<DragScrollTimer> m_timer;

    62     WebCore::FrameView* m_view;

    63     WebCore::IntSize m_lastDistance;

    64     bool m_scrolling;

    65 };

    66 

    67 } // namespace WebKit

    68 

    69 #endif