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 #include <QTimer>

    20 

    21 #include "hgscrollbuffermanager.h"

    22 #include "trace.h"

    23 

    24 // -----------------------------------------------------------------------------

    25 // HgScrollBufferManager::HgScrollBufferManager()

    26 // -----------------------------------------------------------------------------

    27 //

    28 HgScrollBufferManager::HgScrollBufferManager(

    29         int bufferSize,

    30         int bufferTreshold,

    31         int initialPosition,

    32         int totalCount )

    33 :   mBufferSize( bufferSize ),

    34     mBufferTreshold( bufferTreshold ),

    35     mBufferPosition( initialPosition ),

    36     mDiff(0),

    37     mTotalCount( totalCount ),

    38     mResetOrdered(false),

    39     mRequestStart(0),

    40     mRequestCount(0),

    41     mReleaseStart(0),

    42     mReleaseCount(0),

    43     mFirstTime(true)

    44     {

    45     init();

    46     }

    47 

    48 // -----------------------------------------------------------------------------

    49 // HgScrollBufferManager::init()

    50 // -----------------------------------------------------------------------------

    51 //

    52 void HgScrollBufferManager::init()

    53     {

    54     mResetOrdered = ETrue;

    55     mTimer.setSingleShot(true);

    56     connect(&mTimer, SIGNAL(timeout()), this, SLOT(timeout()));

    57     }

    58 

    59 // -----------------------------------------------------------------------------

    60 // HgScrollBufferManager::~HgScrollBufferManager()

    61 // -----------------------------------------------------------------------------

    62 //

    63 HgScrollBufferManager::~HgScrollBufferManager()

    64     {

    65     mTimer.stop();

    66     }

    67 

    68 // -----------------------------------------------------------------------------

    69 // HgScrollBufferManager::resetBuffer()

    70 // -----------------------------------------------------------------------------

    71 //

    72 void HgScrollBufferManager::resetBuffer( int aPosition, int totalCount )

    73     {

    74     if( !mResetOrdered )

    75         {

    76         // release Old buffer

    77         mReleaseStart = mBufferPosition;

    78         mReleaseCount = mBufferSize;

    79         }

    80 

    81     // set position and count

    82     mBufferPosition = aPosition - (mBufferSize / 2);

    83     mTotalCount = totalCount;

    84     mDiff = 0;

    85 

    86     if( mBufferPosition + mBufferSize > mTotalCount - 1 )

    87         {

    88         mBufferPosition = mTotalCount - mBufferSize;

    89         }

    90 

    91     if(mBufferPosition < 0 )

    92         {

    93         mBufferPosition = 0;

    94         }

    95 

    96     //request new Buffer

    97     mRequestStart = mBufferPosition;

    98     mRequestCount = mBufferSize;

    99     mResetOrdered = ETrue;

   100     asyncUpdate();

   101     }

   102 

   103 void HgScrollBufferManager::scrollPositionChanged( int newPosition )

   104     {

   105     // If all the items fit in the buffer no need to move the buffer.

   106     if( mTotalCount <= mBufferSize ) return;

   107 

   108     bool forceUpdate = EFalse;

   109     newPosition -= mBufferSize / 2; // normalize index to Buffer start

   110 

   111     if(newPosition < 0)

   112         {

   113         newPosition = 0;

   114         forceUpdate = ETrue;

   115         }

   116     else if( newPosition > mTotalCount - mBufferSize )

   117         {

   118         newPosition = mTotalCount - mBufferSize;

   119         forceUpdate = ETrue;

   120         }

   121 

   122     mDiff = mBufferPosition - newPosition;

   123 

   124     // Too large change reset whole buffer

   125     if( mDiff >= mBufferSize || -mDiff >= mBufferSize || mResetOrdered )

   126         {

   127         resetBuffer(newPosition + (mBufferSize/2), mTotalCount );

   128         }

   129     // Move Up

   130     else if( mDiff >= mBufferTreshold )

   131         {

   132         mRequestCount = mDiff;

   133         mReleaseCount = mDiff;

   134         asyncUpdate();

   135         }

   136     // Move Down

   137     else if( -mDiff >= mBufferTreshold )

   138         {

   139         mRequestCount = -mDiff;

   140         mReleaseCount = -mDiff;

   141         asyncUpdate();

   142         }

   143     // Top or bottom has been reached

   144     else if( forceUpdate && mDiff )

   145         {

   146         int diff = mDiff < 0 ? -mDiff : mDiff;

   147         mRequestCount = diff;

   148         mReleaseCount = diff;

   149         asyncUpdate();

   150         }

   151     }

   152 

   153 void HgScrollBufferManager::timeout()

   154 {

   155     mFirstTime = false;

   156     

   157     if(mResetOrdered)

   158         {

   159         mResetOrdered = EFalse;

   160         }

   161     else

   162         {

   163         if(mDiff < 0)

   164             {

   165             mReleaseStart = mBufferPosition;

   166             mRequestStart = mBufferPosition + mBufferSize;

   167             }

   168         else if( mDiff > 0)

   169             {

   170             mReleaseStart = mBufferPosition + mBufferSize - mDiff;

   171             mRequestStart = mBufferPosition - mDiff;

   172             }

   173         }

   174 

   175     // Release

   176     int end = mReleaseStart + mReleaseCount < mTotalCount ?

   177         mReleaseStart + mReleaseCount: mTotalCount;

   178     end--;

   179     if(end >= mReleaseStart )

   180         {

   181         emit releaseItems( mReleaseStart, end );

   182         }

   183 

   184     mReleaseCount = 0;

   185 

   186     // Request

   187     end = mRequestStart + mRequestCount < mTotalCount ?

   188         mRequestStart + mRequestCount : mTotalCount;

   189 

   190     end--;

   191     if(end >= mRequestStart )

   192         {

   193         emit requestItems( mRequestStart, end );

   194         }

   195 

   196     mRequestCount = 0;

   197 

   198     // Move Buffer

   199     mBufferPosition -= mDiff;

   200     // Reset Diff

   201     mDiff = 0;

   202 }

   203 

   204 bool HgScrollBufferManager::positionInsideBuffer( int position )

   205 {

   206     return position >= mBufferPosition && position <= (mBufferPosition+mBufferSize);

   207 }

   208 

   209 void HgScrollBufferManager::asyncUpdate()

   210 {

   211     if (!mTimer.isActive() && mFirstTime) {

   212         mTimer.start(0);

   213     } else if (!mTimer.isActive()){

   214         timeout();

   215     }

   216 }

   217 

   218 void HgScrollBufferManager::currentBuffer(int& bufferStart, int& bufferEnd)

   219 {

   220     bufferStart = mBufferPosition;

   221     bufferEnd = mBufferPosition+mBufferSize > mTotalCount-1 ?

   222         mTotalCount-1 : mBufferPosition+mBufferSize;

   223 }

   224 

   225 void HgScrollBufferManager::addItems(int start, int end)

   226 {

   227     FUNC_LOG;

   228 

   229     mTotalCount += (end-start+1);

   230     int lastBufferItem = mBufferPosition+mBufferSize-1;

   231 

   232     if (start < mBufferPosition) {

   233         simpleAddItems(start, end);

   234         // New items push the buffer forward, items inside the buffer do not change

   235     }

   236     // Check buffer higher limit

   237     else if (start <= lastBufferItem && end > lastBufferItem) {

   238         simpleAddItems(start, lastBufferItem);

   239         // Items added after the buffer are ignored

   240     }

   241     else {

   242         simpleAddItems(start, end);

   243     }

   244 }

   245 

   246 void HgScrollBufferManager::removeItems(int start, int end)

   247 {

   248     FUNC_LOG;

   249 

   250     int lastBufferItem = mBufferPosition+mBufferSize-1;

   251     int removedItemCount = end-start+1;

   252 

   253     if (mTotalCount < mBufferSize) {

   254         // Do nothing

   255     }

   256     else if (start > lastBufferItem) {

   257         // Do nothing

   258     }

   259     else if (end < mBufferPosition) {

   260         mTotalCount = mTotalCount-removedItemCount;

   261         simpleRemoveItems(start, end);

   262     }

   263     else if (start < mBufferPosition && end > lastBufferItem) {

   264         mTotalCount = mTotalCount-removedItemCount;

   265         mBufferPosition = qBound(0, mBufferPosition, mTotalCount-mBufferSize);

   266         resetBuffer(mBufferPosition, mTotalCount);

   267     }

   268     // Check buffer higher limit

   269     else if (start <= lastBufferItem && end > lastBufferItem) {

   270         mTotalCount = mTotalCount-(end-lastBufferItem);

   271         simpleRemoveItems(lastBufferItem+1, end);

   272         mTotalCount = mTotalCount-(lastBufferItem-start+1);

   273         simpleRemoveItems(start, lastBufferItem);

   274         // Order does matter

   275         mTotalCount = mTotalCount-(end-lastBufferItem);

   276         simpleRemoveItems(lastBufferItem+1, end);

   277         mTotalCount = mTotalCount-(lastBufferItem-start+1);

   278         simpleRemoveItems(start, lastBufferItem);

   279     }

   280     // Check buffer lower limit

   281     else if (start < mBufferPosition && end >= mBufferPosition) {

   282         // Order does matter

   283         mTotalCount = mTotalCount-(end-mBufferPosition+1);

   284         simpleRemoveItems(mBufferPosition, end);

   285         mTotalCount = mTotalCount-(mBufferPosition-start);

   286         simpleRemoveItems(start, mBufferPosition-1);

   287     }

   288     else {

   289         mTotalCount = mTotalCount-removedItemCount;

   290         simpleRemoveItems(start, end);

   291     }

   292 }

   293 

   294 void HgScrollBufferManager::moveItems(int start, int end, int target)

   295 {

   296     int lastBufferItem = mBufferPosition+mBufferSize-1;

   297 

   298     INFO("Move" << start << "-" << end << "to" << target << ",buffer:" << mBufferPosition << "-" << lastBufferItem << "total count:" << mTotalCount);

   299 

   300     if (mTotalCount < mBufferSize) {

   301         // Do nothing

   302     }

   303     else if (start < mBufferPosition && end > lastBufferItem) {

   304         resetBuffer(mBufferPosition, mTotalCount);

   305     }

   306     else if (start > lastBufferItem && target > lastBufferItem) {

   307         // Do nothing

   308     }

   309     else if (start > lastBufferItem && target < mBufferPosition) {

   310         simpleAddItems(start, end);

   311     }

   312     else if (end < mBufferPosition && target < mBufferPosition) {

   313         // Do nothing

   314     }

   315     else if (end < mBufferPosition && target > lastBufferItem) {

   316         simpleRemoveItems(start, end);

   317     }

   318     else if (start >= mBufferPosition && end <= lastBufferItem &&

   319              target >= mBufferPosition && target <= lastBufferItem) {

   320         // Do nothing

   321     }

   322     else {

   323         // Rare and complicated use cases: reset the whole buffer

   324         resetBuffer(mBufferPosition, mTotalCount);

   325     }

   326 }

   327 

   328 void HgScrollBufferManager::flushRequestBuffers()

   329 {

   330     FUNC_LOG;

   331 

   332     qSort(mReleaseBuffer);

   333     int releaseCount = mReleaseBuffer.count();

   334     int lastReleased = -1;

   335     for (int i = 0; i < releaseCount; i++) {

   336         UpdatePair update = mReleaseBuffer.at(i);

   337         emit releaseItems(qMax(lastReleased+1, update.start()), update.end());

   338         lastReleased = update.end();

   339     }

   340     mReleaseBuffer.clear();

   341 

   342     qSort(mRequestBuffer);

   343     int requestCount = mRequestBuffer.count();

   344     int lastRequested = -1;

   345     for (int i = 0; i < requestCount; i++) {

   346         UpdatePair update = mRequestBuffer.at(i);

   347         emit requestItems(qMax(lastRequested+1, update.start()), update.end());

   348         lastRequested = update.end();

   349     }

   350     mRequestBuffer.clear();

   351 }

   352 

   353 int HgScrollBufferManager::changeBufferPosition(int newPos)

   354 {

   355     FUNC_LOG;

   356     INFO("Change buffer position to" << newPos << "total count:" << mTotalCount);

   357     HANDLE_ERROR_BOOL((newPos >= 0));

   358     HANDLE_ERROR_BOOL((newPos+mBufferSize <= mTotalCount));

   359 

   360     int bufferShift = newPos-mBufferPosition;

   361     if (bufferShift > 0) {

   362         mRequestBuffer.shiftRight(mBufferPosition, bufferShift);

   363         mReleaseBuffer.shiftRight(mBufferPosition, bufferShift);

   364     }

   365     else if (bufferShift < 0) {

   366         mRequestBuffer.shiftLeft(mBufferPosition, -bufferShift);

   367         mReleaseBuffer.shiftLeft(mBufferPosition, -bufferShift);

   368     }

   369     mBufferPosition = newPos;

   370     return bufferShift;

   371 }

   372 

   373 /**

   374     This function manages only simple item additions: all items are either

   375     outside the buffer or inside it.

   376     Firs call prepare, then update model, then call fecth.

   377 */

   378 void HgScrollBufferManager::simpleAddItems(int start, int end)

   379 {

   380     FUNC_LOG;

   381 

   382     int lastBufferItem = mBufferPosition+mBufferSize-1;

   383     int numAddedItems = end-start+1; // [start, end] inclusive

   384 

   385     if (mTotalCount < mBufferSize) {

   386         appendRequestBuffer(start, numAddedItems);

   387     }

   388     else if (start > lastBufferItem) {

   389         // Do nothing

   390     }

   391     else if (start <= mBufferPosition) {

   392         changeBufferPosition(mBufferPosition+numAddedItems);

   393         // No need to fetch items, the indexes just change

   394     }

   395     else {

   396         // free from end

   397         appendReleaseBuffer(lastBufferItem+1-numAddedItems, numAddedItems);

   398         mReleaseBuffer.shiftRight(start, numAddedItems);

   399         mRequestBuffer.shiftRight(start, numAddedItems);

   400         appendRequestBuffer(start, numAddedItems);

   401     }

   402 }

   403 

   404 /**

   405     This function manages only simple item removals: all items are either

   406     outside the buffer or inside it.

   407     Firs call prepare, then update model, then call fecth.

   408 */

   409 void HgScrollBufferManager::simpleRemoveItems(int start, int end)

   410 {

   411     FUNC_LOG;

   412 

   413     int lastBufferItem = mBufferPosition+mBufferSize-1;

   414     int numRemovedItems = end-start+1; // [start, end] inclusive

   415 

   416     if (start > lastBufferItem) {

   417         // Do nothing

   418     }

   419     else if (end < mBufferPosition) {

   420         changeBufferPosition(qMax(0, mBufferPosition-numRemovedItems));

   421         // No need to fetch items, the indexes just change

   422     }

   423     else {

   424         if (mTotalCount < mBufferPosition+mBufferSize) {

   425             // Buffer is at the end of items

   426             int bufferShift = changeBufferPosition(qMax(0, mTotalCount-mBufferSize));

   427             // Fetch from beginning

   428             // Releasing removed items has been done outside this class

   429             appendRequestBuffer(mBufferPosition, qAbs(bufferShift));

   430         }

   431         else {

   432             // Fetch from end

   433             appendRequestBuffer(lastBufferItem+1-numRemovedItems, numRemovedItems);

   434         }

   435     }

   436 }

   437 

   438 void HgScrollBufferManager::appendRequestBuffer(int start, int count)

   439 {

   440     FUNC_LOG;

   441     INFO("Request items" << start << ":" << count)

   442 

   443     mRequestBuffer.add(start, count);

   444     mReleaseBuffer.remove(start, count);

   445 }

   446 

   447 void HgScrollBufferManager::appendReleaseBuffer(int start, int count)

   448 {

   449     FUNC_LOG;

   450     INFO("Release items" << start << ":" << count)

   451 

   452     mReleaseBuffer.add(start, count);

   453     mRequestBuffer.remove(start, count);

   454 }

   455 

   456 UpdatePair::UpdatePair(int start, int count) : mStart(start), mCount(count)

   457 {

   458     HANDLE_ERROR_BOOL(mCount > 0);

   459 }

   460 

   461 int UpdatePair::start() const

   462 {

   463     return mStart;

   464 }

   465 

   466 int UpdatePair::end() const

   467 {

   468     return mStart+mCount-1;

   469 }

   470 

   471 bool UpdatePair::adjacent(int start, int count) const

   472 {

   473     if (start+count < mStart) return false;

   474     if (start > mStart+mCount) return false;

   475     return true;

   476 }

   477 

   478 bool UpdatePair::contains(const UpdatePair &other) const

   479 {

   480     if (other.mStart+other.mCount-1 < mStart) return false;

   481     if (other.mStart > mStart+mCount-1) return false;

   482     return true;

   483 }

   484 

   485 void UpdatePair::extend(int start, int count)

   486 {

   487     int end = qMax(mStart+mCount, start+count);

   488     mStart = qMin(mStart, start);

   489     mCount = end-mStart;

   490     INFO("Pair extended to:" << mStart << ":" << mCount);

   491 }

   492 

   493 void UpdatePair::subtract(int start, int count)

   494 {

   495     int end = qMin(mStart+mCount, start+count);

   496     mStart = qMax(mStart, start);

   497     mCount = end-mStart;

   498     INFO("Pair reduced to:" << mStart << ":" << mCount);

   499 }

   500 

   501 void UpdatePair::shiftRight(int count)

   502 {

   503     mStart += count;

   504     INFO("Pair shifted to:" << mStart << ":" << mCount);

   505 }

   506 

   507 void UpdatePair::shiftLeft(int count)

   508 {

   509     mStart -= count;

   510     HANDLE_ERROR_BOOL((mStart >= 0));

   511     INFO("Pair shifted to:" << mStart << ":" << mCount);

   512 }

   513 

   514 bool UpdatePair::operator== (const UpdatePair &other) const

   515 {

   516     return mStart == other.mStart && mCount == other.mCount;

   517 }

   518 

   519 bool UpdatePair::operator< (const UpdatePair &other) const

   520 {

   521     return (mStart < other.mStart || mStart == other.mStart && mCount < other.mCount);

   522 }

   523 

   524 UpdateBuffer::UpdateBuffer()

   525 {

   526     FUNC_LOG;

   527 }

   528 

   529 void UpdateBuffer::add(int start, int count)

   530 {

   531     FUNC_LOG;

   532 

   533     int itemCount = this->count();

   534     for (int i = 0; i < itemCount; i++) {

   535         if (at(i).contains(UpdatePair(start, count))) {

   536             // It is already there

   537             return;

   538         }

   539         if (at(i).adjacent(start, count)) {

   540             (*this)[i].extend(start, count);

   541             return;

   542         }

   543     }

   544     append(UpdatePair(start, count));

   545 }

   546 

   547 void UpdateBuffer::remove(int start, int count)

   548 {

   549     FUNC_LOG;

   550 

   551     int itemCount = this->count();

   552     for (int i = itemCount-1; i >= 0; i--) {

   553         UpdatePair pair = at(i);

   554         UpdatePair comp = UpdatePair(start, count);

   555         if (comp.contains(pair)) {

   556             INFO("Removing pair" << pair.start() << "-" << pair.end());

   557             removeAt(i);

   558         }

   559         else if (pair.contains(comp)) {

   560             // Subtraction from middle is not applicable in mediawall use cases

   561             (*this)[i].subtract(start, count);

   562         }

   563         // Item may be present in multiple pairs.

   564     }

   565 }

   566 

   567 void UpdateBuffer::shiftRight(int startingFrom, int amount)

   568 {

   569     FUNC_LOG;

   570 

   571     int itemCount = this->count();

   572     for (int i = 0; i < itemCount; i++) {

   573         if (at(i).start() >= startingFrom) {

   574             (*this)[i].shiftRight(amount);

   575         }

   576     }

   577 }

   578 

   579 void UpdateBuffer::shiftLeft(int startingFrom, int amount)

   580 {

   581     FUNC_LOG;

   582 

   583     int itemCount = this->count();

   584     for (int i = 0; i < itemCount; i++) {

   585         if (at(i).start() >= startingFrom) {

   586             (*this)[i].shiftLeft(amount);

   587         }

   588     }

   589 }