C++ QValueStack::count方法代码示例

//.........这里部分代码省略.........
    }

    // If there was no value at all, bail out, to avoid endless loops
    // later on (e.g. in findPieAt()).
    if( !atLeastOneValue )
        return;


    // Find the backmost pie which is at +90° and needs to be drawn
    // first
    int backmostpie = findPieAt( 90 * 16 );
    // Find the frontmost pie (at -90°/+270°) that should be drawn last
    int frontmostpie = findPieAt( 270 * 16 );
    // and put the backmost pie on the TODO stack to initialize it,
    // but only if it is not the frontmostpie
    QValueStack < int > todostack;
    if ( backmostpie != frontmostpie )
        todostack.push( backmostpie );
    else {
        // Otherwise, try to find something else
        int leftOfCurrent = findLeftPie( backmostpie );
        if ( leftOfCurrent != frontmostpie ) {
            todostack.push( leftOfCurrent );
        } else {
            int rightOfCurrent = findRightPie( backmostpie );
            if ( rightOfCurrent != frontmostpie ) {
                todostack.push( rightOfCurrent );
            }
        }
        // If we get here, there was nothing else, and we will bail
        // out of the while loop below.
    }

    // The list with pies that have already been drawn

    QValueList < int > donelist;

    // Draw pies until the todostack is empty or only the frontmost
    // pie is there
    while ( !todostack.isEmpty() &&
            !( ( todostack.count() == 1 ) &&
                ( ( todostack.top() == frontmostpie ) ) ) ) {
        // The while loop cannot be cancelled if frontmostpie is on
        // top of the stack, but this is also backmostpie (can happen
        // when one of the pies covers more than 1/2 of the circle. In
        // this case, we need to find something else to put on the
        // stack to get things going.

        // take one pie from the stack
        int currentpie = todostack.pop();
        // if this pie was already drawn, ignore it
        if ( donelist.find( currentpie ) != donelist.end() )
            continue;

        // If this pie is the frontmost pie, put it back, but at the
        // second position (otherwise, there would be an endless
        // loop). If this pie is the frontmost pie, there must be at
        // least one other pie, otherwise the loop would already have
        // been terminated by the loop condition.
        if ( currentpie == frontmostpie ) {
            Q_ASSERT( !todostack.isEmpty() );
            // QValueStack::exchange() would be nice here...
            int secondpie = todostack.pop();
            if ( currentpie == secondpie )
                // no need to have the second pie twice on the stack,
                // forget about one instance and take the third
                // instead
                if ( todostack.isEmpty() )
                    break; // done anyway
                else
                    secondpie = todostack.pop();
            todostack.push( currentpie );
            todostack.push( secondpie );
            continue;
        }

        // When we get here, we can just draw the pie and proceed.
        drawOnePie( painter, data, dataset, currentpie, chart,
                sizeFor3DEffect,
                regions );

        // Mark the pie just drawn as done.
        donelist.append( currentpie );

        // Now take the pie to the left and to the right, check
        // whether these have not been painted already, and put them
        // on the stack.
        int leftOfCurrent = findLeftPie( currentpie );
        if ( donelist.find( leftOfCurrent ) == donelist.end() )
            todostack.push( leftOfCurrent );
        int rightOfCurrent = findRightPie( currentpie );
        if ( donelist.find( rightOfCurrent ) == donelist.end() )
            todostack.push( rightOfCurrent );
    }

    // now only the frontmost pie is left to draw
    drawOnePie( painter, data, dataset, frontmostpie, chart,
            sizeFor3DEffect,
            regions );
}