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;
}
