Example #1
0
/*! \reimp
 */
void TextDocumentLayout::documentChanged(int from, int /*charsRemoved*/, int charsAdded)
{
    QTextDocument *doc = document();
    int newBlockCount = doc->blockCount();

    QTextBlock changeStartBlock = doc->findBlock(from);
    QTextBlock changeEndBlock = doc->findBlock(qMax(0, from + charsAdded - 1));

    if (changeStartBlock == changeEndBlock && newBlockCount == d->blockCount) {
        QTextBlock block = changeStartBlock;
        if (block.isValid()  && block.layout()->lineCount()) {
            QRectF oldBr = blockBoundingRect(block);
            layoutBlock(block);
            QRectF newBr = blockBoundingRect(block);
            if (newBr.height() == oldBr.height()) {
                if (!d->blockUpdate)
                    emit updateBlock(block);
                return;
            }
        }
    } else {
        QTextBlock block = changeStartBlock;
        do {
            block.clearLayout();
            if (block == changeEndBlock)
                break;
            block = block.next();
        } while(block.isValid());
    }

    if (newBlockCount != d->blockCount) {

        int changeEnd = changeEndBlock.blockNumber();
        int blockDiff = newBlockCount - d->blockCount;
        int oldChangeEnd = changeEnd - blockDiff;

        if (d->maximumWidthBlockNumber > oldChangeEnd)
            d->maximumWidthBlockNumber += blockDiff;

        d->blockCount = newBlockCount;
        if (d->blockCount == 1)
            d->maximumWidth = blockWidth(doc->firstBlock());

        if (!d->blockDocumentSizeChanged)
            emit documentSizeChanged(documentSize());

        if (blockDiff == 1 && changeEnd == newBlockCount -1 ) {
            if (!d->blockUpdate)
            {
                QTextBlock b = changeStartBlock;
                for(;;) {
                    emit updateBlock(b);
                    if (b == changeEndBlock)
                        break;
                    b = b.next();
                }
            }
            return;
        }
    }
    if (!d->blockUpdate)
        emit update(QRectF(0., -doc->documentMargin(), 1000000000., 1000000000.)); // optimization potential
}