1 /*

     2 * Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies).

     3 * All rights reserved.

     4 * This component and the accompanying materials are made available

     5 * under the terms of "Eclipse Public License v1.0"

     6 * which accompanies this distribution, and is available

     7 * at the URL "http://www.eclipse.org/legal/epl-v10.html".

     8 *

     9 * Initial Contributors:

    10 * Nokia Corporation - initial contribution.

    11 *

    12 * Contributors:

    13 *

    14 * Description:

    15 *

    16 */

    17 

    18 

    19 #ifndef HGSCROLLBUFFERMANAGER_H_

    20 #define HGSCROLLBUFFERMANAGER_H_

    21 

    22 #include <QObject>

    23 #include <QTimer>

    24 

    25 class UpdatePair

    26 {

    27 public:

    28     UpdatePair(int start, int count);

    29 

    30     int start() const;

    31     int end() const;

    32 

    33     bool adjacent(int start, int count) const;

    34     bool contains(const UpdatePair &other) const;

    35     void extend(int start, int count);

    36     void subtract(int start, int count);

    37 

    38     void shiftRight(int count);

    39     void shiftLeft(int count);

    40 

    41     bool operator== (const UpdatePair &other) const;

    42     bool operator< (const UpdatePair &other) const;

    43 

    44 private:

    45     int mStart;

    46     int mCount;

    47 };

    48 

    49 class UpdateBuffer : public QList<UpdatePair>

    50 {

    51 public:

    52     UpdateBuffer();

    53 

    54     void add(int start, int count);

    55     void remove(int start, int count);

    56     void shiftRight(int startingFrom, int amount);

    57     void shiftLeft(int startingFrom, int amount);

    58 };

    59 

    60 class HgScrollBufferManager: public QObject

    61     {

    62     Q_OBJECT

    63 public:

    64 

    65     HgScrollBufferManager(

    66             int bufferSize,

    67             int bufferTreshold,

    68             int initialPosition,

    69             int totalCount);

    70 

    71     virtual ~HgScrollBufferManager();

    72 

    73     void resetBuffer(int aPosition, int aTotalCount);

    74 

    75     void scrollPositionChanged(int newPosition);

    76 

    77     bool positionInsideBuffer(int position);

    78 

    79     void addItems(int start, int count);

    80     void removeItems(int start, int end);

    81     void moveItems(int start, int end, int target);

    82 

    83     void flushRequestBuffers();

    84 

    85     void currentBuffer(int& bufferStart, int& bufferEnd);

    86 

    87 signals:

    88 

    89     void releaseItems(int releaseStart, int releaseEnd);

    90     void requestItems(int requestStart, int requestEnd);

    91 

    92 protected slots:

    93 

    94     void timeout();

    95 

    96 protected:

    97 

    98     void init();

    99     void asyncUpdate();

   100 

   101     int changeBufferPosition(int newPos);

   102 

   103     void simpleAddItems(int start, int end);

   104     void simpleRemoveItems(int start, int end);

   105 

   106     void appendRequestBuffer(int start, int end);

   107     void appendReleaseBuffer(int start, int end);

   108 

   109 private:

   110 

   111     int mBufferSize;

   112     int mBufferTreshold;

   113     int mBufferPosition;

   114     int mDiff;

   115     int mTotalCount;

   116 

   117     bool mResetOrdered;

   118 

   119     int mRequestStart;

   120     int mRequestCount;

   121     int mReleaseStart;

   122     int mReleaseCount;

   123     QTimer mTimer;

   124     bool mFirstTime;

   125     

   126     UpdateBuffer mRequestBuffer;

   127     UpdateBuffer mReleaseBuffer;

   128     

   129 private:

   130     Q_DISABLE_COPY(HgScrollBufferManager)

   131     };

   132 

   133 #endif /*HGSCROLLBUFFERMANAGER_H_*/