--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/ganeswidgets/src/hgscrollbuffermanager.cpp Thu Jun 24 12:59:29 2010 +0300
@@ -0,0 +1,589 @@
+/*
+* Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies).
+* All rights reserved.
+* This component and the accompanying materials are made available
+* under the terms of "Eclipse Public License v1.0"
+* which accompanies this distribution, and is available
+* at the URL "http://www.eclipse.org/legal/epl-v10.html".
+*
+* Initial Contributors:
+* Nokia Corporation - initial contribution.
+*
+* Contributors:
+*
+* Description:
+*
+*/
+
+
+#include <QTimer>
+
+#include "hgscrollbuffermanager.h"
+#include "trace.h"
+
+// -----------------------------------------------------------------------------
+// HgScrollBufferManager::HgScrollBufferManager()
+// -----------------------------------------------------------------------------
+//
+HgScrollBufferManager::HgScrollBufferManager(
+ int bufferSize,
+ int bufferTreshold,
+ int initialPosition,
+ int totalCount )
+: mBufferSize( bufferSize ),
+ mBufferTreshold( bufferTreshold ),
+ mBufferPosition( initialPosition ),
+ mDiff(0),
+ mTotalCount( totalCount ),
+ mResetOrdered(false),
+ mRequestStart(0),
+ mRequestCount(0),
+ mReleaseStart(0),
+ mReleaseCount(0),
+ mFirstTime(true)
+ {
+ init();
+ }
+
+// -----------------------------------------------------------------------------
+// HgScrollBufferManager::init()
+// -----------------------------------------------------------------------------
+//
+void HgScrollBufferManager::init()
+ {
+ mResetOrdered = ETrue;
+ mTimer.setSingleShot(true);
+ connect(&mTimer, SIGNAL(timeout()), this, SLOT(timeout()));
+ }
+
+// -----------------------------------------------------------------------------
+// HgScrollBufferManager::~HgScrollBufferManager()
+// -----------------------------------------------------------------------------
+//
+HgScrollBufferManager::~HgScrollBufferManager()
+ {
+ mTimer.stop();
+ }
+
+// -----------------------------------------------------------------------------
+// HgScrollBufferManager::resetBuffer()
+// -----------------------------------------------------------------------------
+//
+void HgScrollBufferManager::resetBuffer( int aPosition, int totalCount )
+ {
+ if( !mResetOrdered )
+ {
+ // release Old buffer
+ mReleaseStart = mBufferPosition;
+ mReleaseCount = mBufferSize;
+ }
+
+ // set position and count
+ mBufferPosition = aPosition - (mBufferSize / 2);
+ mTotalCount = totalCount;
+ mDiff = 0;
+
+ if( mBufferPosition + mBufferSize > mTotalCount - 1 )
+ {
+ mBufferPosition = mTotalCount - mBufferSize;
+ }
+
+ if(mBufferPosition < 0 )
+ {
+ mBufferPosition = 0;
+ }
+
+ //request new Buffer
+ mRequestStart = mBufferPosition;
+ mRequestCount = mBufferSize;
+ mResetOrdered = ETrue;
+ asyncUpdate();
+ }
+
+void HgScrollBufferManager::scrollPositionChanged( int newPosition )
+ {
+ // If all the items fit in the buffer no need to move the buffer.
+ if( mTotalCount <= mBufferSize ) return;
+
+ bool forceUpdate = EFalse;
+ newPosition -= mBufferSize / 2; // normalize index to Buffer start
+
+ if(newPosition < 0)
+ {
+ newPosition = 0;
+ forceUpdate = ETrue;
+ }
+ else if( newPosition > mTotalCount - mBufferSize )
+ {
+ newPosition = mTotalCount - mBufferSize;
+ forceUpdate = ETrue;
+ }
+
+ mDiff = mBufferPosition - newPosition;
+
+ // Too large change reset whole buffer
+ if( mDiff >= mBufferSize || -mDiff >= mBufferSize || mResetOrdered )
+ {
+ resetBuffer(newPosition + (mBufferSize/2), mTotalCount );
+ }
+ // Move Up
+ else if( mDiff >= mBufferTreshold )
+ {
+ mRequestCount = mDiff;
+ mReleaseCount = mDiff;
+ asyncUpdate();
+ }
+ // Move Down
+ else if( -mDiff >= mBufferTreshold )
+ {
+ mRequestCount = -mDiff;
+ mReleaseCount = -mDiff;
+ asyncUpdate();
+ }
+ // Top or bottom has been reached
+ else if( forceUpdate && mDiff )
+ {
+ int diff = mDiff < 0 ? -mDiff : mDiff;
+ mRequestCount = diff;
+ mReleaseCount = diff;
+ asyncUpdate();
+ }
+ }
+
+void HgScrollBufferManager::timeout()
+{
+ mFirstTime = false;
+
+ if(mResetOrdered)
+ {
+ mResetOrdered = EFalse;
+ }
+ else
+ {
+ if(mDiff < 0)
+ {
+ mReleaseStart = mBufferPosition;
+ mRequestStart = mBufferPosition + mBufferSize;
+ }
+ else if( mDiff > 0)
+ {
+ mReleaseStart = mBufferPosition + mBufferSize - mDiff;
+ mRequestStart = mBufferPosition - mDiff;
+ }
+ }
+
+ // Release
+ int end = mReleaseStart + mReleaseCount < mTotalCount ?
+ mReleaseStart + mReleaseCount: mTotalCount;
+ end--;
+ if(end >= mReleaseStart )
+ {
+ emit releaseItems( mReleaseStart, end );
+ }
+
+ mReleaseCount = 0;
+
+ // Request
+ end = mRequestStart + mRequestCount < mTotalCount ?
+ mRequestStart + mRequestCount : mTotalCount;
+
+ end--;
+ if(end >= mRequestStart )
+ {
+ emit requestItems( mRequestStart, end );
+ }
+
+ mRequestCount = 0;
+
+ // Move Buffer
+ mBufferPosition -= mDiff;
+ // Reset Diff
+ mDiff = 0;
+}
+
+bool HgScrollBufferManager::positionInsideBuffer( int position )
+{
+ return position >= mBufferPosition && position <= (mBufferPosition+mBufferSize);
+}
+
+void HgScrollBufferManager::asyncUpdate()
+{
+ if (!mTimer.isActive() && mFirstTime) {
+ mTimer.start(0);
+ } else if (!mTimer.isActive()){
+ timeout();
+ }
+}
+
+void HgScrollBufferManager::currentBuffer(int& bufferStart, int& bufferEnd)
+{
+ bufferStart = mBufferPosition;
+ bufferEnd = mBufferPosition+mBufferSize > mTotalCount-1 ?
+ mTotalCount-1 : mBufferPosition+mBufferSize;
+}
+
+void HgScrollBufferManager::addItems(int start, int end)
+{
+ FUNC_LOG;
+
+ mTotalCount += (end-start+1);
+ int lastBufferItem = mBufferPosition+mBufferSize-1;
+
+ if (start < mBufferPosition) {
+ simpleAddItems(start, end);
+ // New items push the buffer forward, items inside the buffer do not change
+ }
+ // Check buffer higher limit
+ else if (start <= lastBufferItem && end > lastBufferItem) {
+ simpleAddItems(start, lastBufferItem);
+ // Items added after the buffer are ignored
+ }
+ else {
+ simpleAddItems(start, end);
+ }
+}
+
+void HgScrollBufferManager::removeItems(int start, int end)
+{
+ FUNC_LOG;
+
+ int lastBufferItem = mBufferPosition+mBufferSize-1;
+ int removedItemCount = end-start+1;
+
+ if (mTotalCount < mBufferSize) {
+ // Do nothing
+ }
+ else if (start > lastBufferItem) {
+ // Do nothing
+ }
+ else if (end < mBufferPosition) {
+ mTotalCount = mTotalCount-removedItemCount;
+ simpleRemoveItems(start, end);
+ }
+ else if (start < mBufferPosition && end > lastBufferItem) {
+ mTotalCount = mTotalCount-removedItemCount;
+ mBufferPosition = qBound(0, mBufferPosition, mTotalCount-mBufferSize);
+ resetBuffer(mBufferPosition, mTotalCount);
+ }
+ // Check buffer higher limit
+ else if (start <= lastBufferItem && end > lastBufferItem) {
+ mTotalCount = mTotalCount-(end-lastBufferItem);
+ simpleRemoveItems(lastBufferItem+1, end);
+ mTotalCount = mTotalCount-(lastBufferItem-start+1);
+ simpleRemoveItems(start, lastBufferItem);
+ // Order does matter
+ mTotalCount = mTotalCount-(end-lastBufferItem);
+ simpleRemoveItems(lastBufferItem+1, end);
+ mTotalCount = mTotalCount-(lastBufferItem-start+1);
+ simpleRemoveItems(start, lastBufferItem);
+ }
+ // Check buffer lower limit
+ else if (start < mBufferPosition && end >= mBufferPosition) {
+ // Order does matter
+ mTotalCount = mTotalCount-(end-mBufferPosition+1);
+ simpleRemoveItems(mBufferPosition, end);
+ mTotalCount = mTotalCount-(mBufferPosition-start);
+ simpleRemoveItems(start, mBufferPosition-1);
+ }
+ else {
+ mTotalCount = mTotalCount-removedItemCount;
+ simpleRemoveItems(start, end);
+ }
+}
+
+void HgScrollBufferManager::moveItems(int start, int end, int target)
+{
+ int lastBufferItem = mBufferPosition+mBufferSize-1;
+
+ INFO("Move" << start << "-" << end << "to" << target << ",buffer:" << mBufferPosition << "-" << lastBufferItem << "total count:" << mTotalCount);
+
+ if (mTotalCount < mBufferSize) {
+ // Do nothing
+ }
+ else if (start < mBufferPosition && end > lastBufferItem) {
+ resetBuffer(mBufferPosition, mTotalCount);
+ }
+ else if (start > lastBufferItem && target > lastBufferItem) {
+ // Do nothing
+ }
+ else if (start > lastBufferItem && target < mBufferPosition) {
+ simpleAddItems(start, end);
+ }
+ else if (end < mBufferPosition && target < mBufferPosition) {
+ // Do nothing
+ }
+ else if (end < mBufferPosition && target > lastBufferItem) {
+ simpleRemoveItems(start, end);
+ }
+ else if (start >= mBufferPosition && end <= lastBufferItem &&
+ target >= mBufferPosition && target <= lastBufferItem) {
+ // Do nothing
+ }
+ else {
+ // Rare and complicated use cases: reset the whole buffer
+ resetBuffer(mBufferPosition, mTotalCount);
+ }
+}
+
+void HgScrollBufferManager::flushRequestBuffers()
+{
+ FUNC_LOG;
+
+ qSort(mReleaseBuffer);
+ int releaseCount = mReleaseBuffer.count();
+ int lastReleased = -1;
+ for (int i = 0; i < releaseCount; i++) {
+ UpdatePair update = mReleaseBuffer.at(i);
+ emit releaseItems(qMax(lastReleased+1, update.start()), update.end());
+ lastReleased = update.end();
+ }
+ mReleaseBuffer.clear();
+
+ qSort(mRequestBuffer);
+ int requestCount = mRequestBuffer.count();
+ int lastRequested = -1;
+ for (int i = 0; i < requestCount; i++) {
+ UpdatePair update = mRequestBuffer.at(i);
+ emit requestItems(qMax(lastRequested+1, update.start()), update.end());
+ lastRequested = update.end();
+ }
+ mRequestBuffer.clear();
+}
+
+int HgScrollBufferManager::changeBufferPosition(int newPos)
+{
+ FUNC_LOG;
+ INFO("Change buffer position to" << newPos << "total count:" << mTotalCount);
+ HANDLE_ERROR_BOOL((newPos >= 0));
+ HANDLE_ERROR_BOOL((newPos+mBufferSize <= mTotalCount));
+
+ int bufferShift = newPos-mBufferPosition;
+ if (bufferShift > 0) {
+ mRequestBuffer.shiftRight(mBufferPosition, bufferShift);
+ mReleaseBuffer.shiftRight(mBufferPosition, bufferShift);
+ }
+ else if (bufferShift < 0) {
+ mRequestBuffer.shiftLeft(mBufferPosition, -bufferShift);
+ mReleaseBuffer.shiftLeft(mBufferPosition, -bufferShift);
+ }
+ mBufferPosition = newPos;
+ return bufferShift;
+}
+
+/**
+ This function manages only simple item additions: all items are either
+ outside the buffer or inside it.
+ Firs call prepare, then update model, then call fecth.
+*/
+void HgScrollBufferManager::simpleAddItems(int start, int end)
+{
+ FUNC_LOG;
+
+ int lastBufferItem = mBufferPosition+mBufferSize-1;
+ int numAddedItems = end-start+1; // [start, end] inclusive
+
+ if (mTotalCount < mBufferSize) {
+ appendRequestBuffer(start, numAddedItems);
+ }
+ else if (start > lastBufferItem) {
+ // Do nothing
+ }
+ else if (start <= mBufferPosition) {
+ changeBufferPosition(mBufferPosition+numAddedItems);
+ // No need to fetch items, the indexes just change
+ }
+ else {
+ // free from end
+ appendReleaseBuffer(lastBufferItem+1-numAddedItems, numAddedItems);
+ mReleaseBuffer.shiftRight(start, numAddedItems);
+ mRequestBuffer.shiftRight(start, numAddedItems);
+ appendRequestBuffer(start, numAddedItems);
+ }
+}
+
+/**
+ This function manages only simple item removals: all items are either
+ outside the buffer or inside it.
+ Firs call prepare, then update model, then call fecth.
+*/
+void HgScrollBufferManager::simpleRemoveItems(int start, int end)
+{
+ FUNC_LOG;
+
+ int lastBufferItem = mBufferPosition+mBufferSize-1;
+ int numRemovedItems = end-start+1; // [start, end] inclusive
+
+ if (start > lastBufferItem) {
+ // Do nothing
+ }
+ else if (end < mBufferPosition) {
+ changeBufferPosition(qMax(0, mBufferPosition-numRemovedItems));
+ // No need to fetch items, the indexes just change
+ }
+ else {
+ if (mTotalCount < mBufferPosition+mBufferSize) {
+ // Buffer is at the end of items
+ int bufferShift = changeBufferPosition(qMax(0, mTotalCount-mBufferSize));
+ // Fetch from beginning
+ // Releasing removed items has been done outside this class
+ appendRequestBuffer(mBufferPosition, qAbs(bufferShift));
+ }
+ else {
+ // Fetch from end
+ appendRequestBuffer(lastBufferItem+1-numRemovedItems, numRemovedItems);
+ }
+ }
+}
+
+void HgScrollBufferManager::appendRequestBuffer(int start, int count)
+{
+ FUNC_LOG;
+ INFO("Request items" << start << ":" << count)
+
+ mRequestBuffer.add(start, count);
+ mReleaseBuffer.remove(start, count);
+}
+
+void HgScrollBufferManager::appendReleaseBuffer(int start, int count)
+{
+ FUNC_LOG;
+ INFO("Release items" << start << ":" << count)
+
+ mReleaseBuffer.add(start, count);
+ mRequestBuffer.remove(start, count);
+}
+
+UpdatePair::UpdatePair(int start, int count) : mStart(start), mCount(count)
+{
+ HANDLE_ERROR_BOOL(mCount > 0);
+}
+
+int UpdatePair::start() const
+{
+ return mStart;
+}
+
+int UpdatePair::end() const
+{
+ return mStart+mCount-1;
+}
+
+bool UpdatePair::adjacent(int start, int count) const
+{
+ if (start+count < mStart) return false;
+ if (start > mStart+mCount) return false;
+ return true;
+}
+
+bool UpdatePair::contains(const UpdatePair &other) const
+{
+ if (other.mStart+other.mCount-1 < mStart) return false;
+ if (other.mStart > mStart+mCount-1) return false;
+ return true;
+}
+
+void UpdatePair::extend(int start, int count)
+{
+ int end = qMax(mStart+mCount, start+count);
+ mStart = qMin(mStart, start);
+ mCount = end-mStart;
+ INFO("Pair extended to:" << mStart << ":" << mCount);
+}
+
+void UpdatePair::subtract(int start, int count)
+{
+ int end = qMin(mStart+mCount, start+count);
+ mStart = qMax(mStart, start);
+ mCount = end-mStart;
+ INFO("Pair reduced to:" << mStart << ":" << mCount);
+}
+
+void UpdatePair::shiftRight(int count)
+{
+ mStart += count;
+ INFO("Pair shifted to:" << mStart << ":" << mCount);
+}
+
+void UpdatePair::shiftLeft(int count)
+{
+ mStart -= count;
+ HANDLE_ERROR_BOOL((mStart >= 0));
+ INFO("Pair shifted to:" << mStart << ":" << mCount);
+}
+
+bool UpdatePair::operator== (const UpdatePair &other) const
+{
+ return mStart == other.mStart && mCount == other.mCount;
+}
+
+bool UpdatePair::operator< (const UpdatePair &other) const
+{
+ return (mStart < other.mStart || mStart == other.mStart && mCount < other.mCount);
+}
+
+UpdateBuffer::UpdateBuffer()
+{
+ FUNC_LOG;
+}
+
+void UpdateBuffer::add(int start, int count)
+{
+ FUNC_LOG;
+
+ int itemCount = this->count();
+ for (int i = 0; i < itemCount; i++) {
+ if (at(i).contains(UpdatePair(start, count))) {
+ // It is already there
+ return;
+ }
+ if (at(i).adjacent(start, count)) {
+ (*this)[i].extend(start, count);
+ return;
+ }
+ }
+ append(UpdatePair(start, count));
+}
+
+void UpdateBuffer::remove(int start, int count)
+{
+ FUNC_LOG;
+
+ int itemCount = this->count();
+ for (int i = itemCount-1; i >= 0; i--) {
+ UpdatePair pair = at(i);
+ UpdatePair comp = UpdatePair(start, count);
+ if (comp.contains(pair)) {
+ INFO("Removing pair" << pair.start() << "-" << pair.end());
+ removeAt(i);
+ }
+ else if (pair.contains(comp)) {
+ // Subtraction from middle is not applicable in mediawall use cases
+ (*this)[i].subtract(start, count);
+ }
+ // Item may be present in multiple pairs.
+ }
+}
+
+void UpdateBuffer::shiftRight(int startingFrom, int amount)
+{
+ FUNC_LOG;
+
+ int itemCount = this->count();
+ for (int i = 0; i < itemCount; i++) {
+ if (at(i).start() >= startingFrom) {
+ (*this)[i].shiftRight(amount);
+ }
+ }
+}
+
+void UpdateBuffer::shiftLeft(int startingFrom, int amount)
+{
+ FUNC_LOG;
+
+ int itemCount = this->count();
+ for (int i = 0; i < itemCount; i++) {
+ if (at(i).start() >= startingFrom) {
+ (*this)[i].shiftLeft(amount);
+ }
+ }
+}