View-graph-applets-QT.rar_绘图

#include <QtGui> #include "Histogram.h" Histogram::Histogram( void ) { m_VecItems.clear( ); } void Histogram::AddItem( QString name, qreal value, QColor pillarColor ) { HistogramItem item; item.m_Name = name; item.m_Value = value; item.m_PillarColor = pillarColor; item.m_PillarRect = QRect( ); m_VecItems.push_back( item ); } void Histogram::SetMaxValue( quint32 maxValue ) { m_MaxValue = maxValue; } void Histogram::Paint( QPaintDevice* pDevice ) { QPainter painter( pDevice ); DrawAxis( pDevice, &painter ); DrawPillars( pDevice, &painter ); DrawText( &painter ); DrawScale( pDevice, &painter ); } void Histogram::DrawAxis( QPaintDevice* pDevice, QPainter* pPainter ) { pPainter->drawLine( yAxisOffset, 0, yAxisOffset, pDevice->height( ) ); pPainter->drawLine( 0, pDevice->height( ) - xAxisOffset, pDevice->width( ), pDevice->height( ) - xAxisOffset ); } void Histogram::DrawPillars( QPaintDevice* pDevice, QPainter* pPainter ) // 绘制柱子 { if ( m_VecItems.size( ) == 0 ) return; //const quint32 blankWidth = 64; // 柱子间空格宽 quint32 pillarWidth = ( pDevice->width( ) - yAxisOffset - pillarIndent - quint32( m_VecItems.size( ) - 1 ) * blankWidth ) / m_VecItems.size( ); // 柱子的宽 // 绘制因子。绘制因子在绘制柱子的时候起着重要作用。 // 根据比例公式： // pDevice->width( ) - xAxisOffset pillarHeight // --------------------------------- = -------------------- // MaxValue m_VecItem[0].value // 求出pillarHeight的值，但是左边的部分我们可以看作是一个绘制因子heightFact记录下来。 // 计算时可以节约时间。 qreal heightFact = qreal( pDevice->height( ) - xAxisOffset ) / m_MaxValue; for ( int i = 0; i < m_VecItems.size( ); ++i ) { quint32 pillarHeight = m_VecItems[i].m_Value * heightFact; int leftUpX = yAxisOffset + pillarIndent + i * ( pillarWidth + blankWidth ); int leftUpY = pDevice->height( ) - xAxisOffset - pillarHeight; QRect& rect = m_VecItems[i].m_PillarRect; rect.setRect( leftUpX, leftUpY, pillarWidth, pillarHeight ); pPainter->setPen( QPen( m_VecItems[i].m_PillarColor ) ); pPainter->setBrush( QBrush( m_VecItems[i].m_PillarColor ) ); pPainter->drawRect( rect ); } } void Histogram::DrawText( QPainter* pPainter ) // 绘制文字 { // 已经可以保证m_VecItems.[i].m_Rect.isNull( )为假 // 即柱子所在的矩形框是一个有效的矩形框 pPainter->setPen( QPen( QColor( 0, 0, 0 ) ) ); for ( int i = 0; i < m_VecItems.size( ); ++i ) { QRect rect( m_VecItems[i].m_PillarRect.left( ) - blankWidth / 2, m_VecItems[i].m_PillarRect.top( ) - textRectHeight, m_VecItems[i].m_PillarRect.width( ) + blankWidth, textRectHeight ); const QString& text = QString( "%1(%2)" ) .arg( m_VecItems[i].m_Name ).arg( m_VecItems[i].m_Value ); pPainter->drawText( rect, Qt::AlignCenter, text ); } } void Histogram::DrawScale( QPaintDevice *pDevice, QPainter *pPainter ) // 绘制刻度 { // 名词解释 MSWidth = Marked Scale Width，刻度宽 // MSHeight = Marked Scale Height 刻度高 const quint32 MSWidth = 100; const quint32 MSHeight = textRectHeight; const quint32 heightInterval = ( pDevice->height( ) - xAxisOffset ) / 4; for ( int i = 0; i < 4; ++i ) { QRect rect( 0, i * heightInterval, MSWidth, MSHeight ); pPainter->drawLine( yAxisOffset - 2, i * heightInterval, yAxisOffset + 2, i * heightInterval ); pPainter->drawText( rect, Qt::AlignLeft, QString( "%1" ) .arg( m_MaxValue * ( 4 - i ) / 4 ) ); } }