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chart/chartform_canvas.cpp Example File

#include "canvastext.h"
#include "chartform.h"

#include <qbrush.h>
#include <qcanvas.h>

#include <math.h> // sin, cos

#ifndef M_PI
#define M_PI 3.1415
#endif

void ChartForm::drawElements()
{
    QCanvasItemList list = m_canvas->allItems();
    for ( QCanvasItemList::iterator it = list.begin(); it != list.end(); ++it )
        delete *it;

        // 360 * 16 for pies; Qt works with 16ths of degrees
    int scaleFactor = m_chartType == PIE ? 5760 :
                        m_chartType == VERTICAL_BAR ? m_canvas->height() :
                            m_canvas->width();
    double biggest = 0.0;
    int count = 0;
    double total = 0.0;
    static double scales[MAX_ELEMENTS];

    for ( int i = 0; i < MAX_ELEMENTS; ++i ) {
        if ( m_elements[i].isValid() ) {
            double value = m_elements[i].value();
            count++;
            total += value;
            if ( value > biggest )
                biggest = value;
            scales[i] = m_elements[i].value() * scaleFactor;
        }
    }

    if ( count ) {
            // 2nd loop because of total and biggest
        for ( int i = 0; i < MAX_ELEMENTS; ++i )
            if ( m_elements[i].isValid() )
                if ( m_chartType == PIE )
                    scales[i] = (m_elements[i].value() * scaleFactor) / total;
                else
                    scales[i] = (m_elements[i].value() * scaleFactor) / biggest;

        switch ( m_chartType ) {
            case PIE:
                drawPieChart( scales, total, count );
                break;
            case VERTICAL_BAR:
                drawVerticalBarChart( scales, total, count );
                break;
            case HORIZONTAL_BAR:
                drawHorizontalBarChart( scales, total, count );
                break;
        }
    }

    m_canvas->update();
}


void ChartForm::drawPieChart( const double scales[], double total, int )
{
    double width = m_canvas->width();
    double height = m_canvas->height();
    int size = int(width > height ? height : width);
    int x = int(width / 2);
    int y = int(height / 2);
    int angle = 0;

    for ( int i = 0; i < MAX_ELEMENTS; ++i ) {
        if ( m_elements[i].isValid() ) {
            int extent = int(scales[i]);
            QCanvasEllipse *arc = new QCanvasEllipse(
                                            size, size, angle, extent, m_canvas );
            arc->setX( x );
            arc->setY( y );
            arc->setZ( 0 );
            arc->setBrush( QBrush( m_elements[i].valueColor(),
                                   BrushStyle(m_elements[i].valuePattern()) ) );
            arc->show();
            angle += extent;
            QString label = m_elements[i].label();
            if ( !label.isEmpty() || m_addValues != NO ) {
                label = valueLabel( label, m_elements[i].value(), total );
                CanvasText *text = new CanvasText( i, label, m_font, m_canvas );
                double proX = m_elements[i].proX( PIE );
                double proY = m_elements[i].proY( PIE );
                if ( proX < 0 || proY < 0 ) {
                    // Find the centre of the pie segment
                    QRect rect = arc->boundingRect();
                    proX = ( rect.width() / 2 ) + rect.x();
                    proY = ( rect.height() / 2 ) + rect.y();
                    // Centre text over the centre of the pie segment
                    rect = text->boundingRect();
                    proX -= ( rect.width() / 2 );
                    proY -= ( rect.height() / 2 );
                    // Make proportional
                    proX /= width;
                    proY /= height;
                }
                text->setColor( m_elements[i].labelColor() );
                text->setX( proX * width );
                text->setY( proY * height );
                text->setZ( 1 );
                text->show();
                m_elements[i].setProX( PIE, proX );
                m_elements[i].setProY( PIE, proY );
            }
        }
    }
}


void ChartForm::drawVerticalBarChart(
        const double scales[], double total, int count )
{
    double width = m_canvas->width();
    double height = m_canvas->height();
    int prowidth = int(width / count);
    int x = 0;
    QPen pen;
    pen.setStyle( NoPen );

    for ( int i = 0; i < MAX_ELEMENTS; ++i ) {
        if ( m_elements[i].isValid() ) {
            int extent = int(scales[i]);
            int y = int(height - extent);
            QCanvasRectangle *rect = new QCanvasRectangle(
                                            x, y, prowidth, extent, m_canvas );
            rect->setBrush( QBrush( m_elements[i].valueColor(),
                                    BrushStyle(m_elements[i].valuePattern()) ) );
            rect->setPen( pen );
            rect->setZ( 0 );
            rect->show();
            QString label = m_elements[i].label();
            if ( !label.isEmpty() || m_addValues != NO ) {
                double proX = m_elements[i].proX( VERTICAL_BAR );
                double proY = m_elements[i].proY( VERTICAL_BAR );
                if ( proX < 0 || proY < 0 ) {
                    proX = x / width;
                    proY = y / height;
                }
                label = valueLabel( label, m_elements[i].value(), total );
                CanvasText *text = new CanvasText( i, label, m_font, m_canvas );
                text->setColor( m_elements[i].labelColor() );
                text->setX( proX * width );
                text->setY( proY * height );
                text->setZ( 1 );
                text->show();
                m_elements[i].setProX( VERTICAL_BAR, proX );
                m_elements[i].setProY( VERTICAL_BAR, proY );
            }
            x += prowidth;
        }
    }
}


void ChartForm::drawHorizontalBarChart(
        const double scales[], double total, int count )
{
    double width = m_canvas->width();
    double height = m_canvas->height();
    int proheight = int(height / count);
    int y = 0;
    QPen pen;
    pen.setStyle( NoPen );

    for ( int i = 0; i < MAX_ELEMENTS; ++i ) {
        if ( m_elements[i].isValid() ) {
            int extent = int(scales[i]);
            QCanvasRectangle *rect = new QCanvasRectangle(
                                            0, y, extent, proheight, m_canvas );
            rect->setBrush( QBrush( m_elements[i].valueColor(),
                                    BrushStyle(m_elements[i].valuePattern()) ) );
            rect->setPen( pen );
            rect->setZ( 0 );
            rect->show();
            QString label = m_elements[i].label();
            if ( !label.isEmpty() || m_addValues != NO ) {
                double proX = m_elements[i].proX( HORIZONTAL_BAR );
                double proY = m_elements[i].proY( HORIZONTAL_BAR );
                if ( proX < 0 || proY < 0 ) {
                    proX = 0;
                    proY = y / height;
                }
                label = valueLabel( label, m_elements[i].value(), total );
                CanvasText *text = new CanvasText( i, label, m_font, m_canvas );
                text->setColor( m_elements[i].labelColor() );
                text->setX( proX * width );
                text->setY( proY * height );
                text->setZ( 1 );
                text->show();
                m_elements[i].setProX( HORIZONTAL_BAR, proX );
                m_elements[i].setProY( HORIZONTAL_BAR, proY );
            }
            y += proheight;
        }
    }
}


QString ChartForm::valueLabel(
            const QString& label, double value, double total )
{
    if ( m_addValues == NO )
        return label;

    QString newLabel = label;
    if ( !label.isEmpty() )
        if ( m_chartType == VERTICAL_BAR )
            newLabel += '\n';
        else
            newLabel += ' ';
    if ( m_addValues == YES )
        newLabel += QString::number( value, 'f', m_decimalPlaces );
    else if ( m_addValues == AS_PERCENTAGE )
        newLabel += QString::number( (value / total) * 100, 'f', m_decimalPlaces )
                    + '%';
    return newLabel;
}


Copyright © 2005 TrolltechTrademarks
Qt 3.3.7