Qt绘制指南针（仪表盘绘制封装使用示例）
资源内容介绍
本示例是在Qt中绘制一个指南针，通过继承QWidget类，并重写其paintEvent函数来实现。并对仪表盘绘制进行封装。 #include "qcgaugewidget.h"QcGaugeWidget::QcGaugeWidget(QWidget *parent) : QWidget(parent){ setMinimumSize(250,250);}QcBackgroundItem *QcGaugeWidget::addBackground(float position){ QcBackgroundItem * item = new QcBackgroundItem(this); item->setPosition(position); mItems.append(item); return item;}QcDegreesItem *QcGaugeWidget::addDegrees(float position){ QcDegreesItem * item = new QcDegreesItem(this); item->setPosition(position); mItems.append(item); return item;}QcValuesItem *QcGaugeWidget::addValues(float position){ QcValuesItem * item = new QcValuesItem(this); item->setPosition(position); mItems.append(item); return item;}QcArcItem *QcGaugeWidget::addArc(float position){ QcArcItem * item = new QcArcItem(this); item->setPosition(position); mItems.append(item); return item;}QcColorBand *QcGaugeWidget::addColorBand(float position){ QcColorBand * item = new QcColorBand(this); item->setPosition(position); mItems.append(item); return item;}QcNeedleItem *QcGaugeWidget::addNeedle(float position){ QcNeedleItem * item = new QcNeedleItem(this); item->setPosition(position); mItems.append(item); return item;}QcLabelItem *QcGaugeWidget::addLabel(float position){ QcLabelItem * item = new QcLabelItem(this); item->setPosition(position); mItems.append(item); return item;}QcGlassItem *QcGaugeWidget::addGlass(float position){ QcGlassItem * item = new QcGlassItem(this); item->setPosition(position); mItems.append(item); return item;}QcAttitudeMeter *QcGaugeWidget::addAttitudeMeter(float position){ QcAttitudeMeter * item = new QcAttitudeMeter(this); item->setPosition(position); mItems.append(item); return item;}void QcGaugeWidget::addItem(QcItem *item,float position){ // takes parentship of the item item->setParent(this); item->setPosition(position); mItems.append(item);}int QcGaugeWidget::removeItem(QcItem *item){ return mItems.removeAll(item);}QList<QcItem *> QcGaugeWidget::items(){ return mItems;}void QcGaugeWidget::paintEvent(QPaintEvent *){ QPainter painter(this); painter.setRenderHint(QPainter::Antialiasing); foreach (QcItem * item, mItems) { item->draw(&painter); }}///////////////////////////////////////////////////////////////////////////////////////////QcItem::QcItem(QObject *parent) : QObject(parent){ parentWidget = qobject_cast<QWidget*>(parent); mPosition = 50;}int QcItem::type(){ return 50;}void QcItem::update(){ parentWidget->update();}float QcItem::position(){ return mPosition;}QRectF QcItem::rect(){ return mRect;}void QcItem::setPosition(float position){ if(position>100) mPosition = 100; else if(position<0) mPosition = 0; else mPosition = position; update();}QRectF QcItem::adjustRect(float percentage){ float r = getRadius(mRect); float offset = r-(percentage*r)/100.0; QRectF tmpRect = mRect.adjusted(offset,offset,-offset,-offset); return tmpRect;}float QcItem::getRadius(const QRectF &tmpRect){ float r = 0; if(tmpRect.width()<tmpRect.height()) r = tmpRect.width()/2.0; else r = tmpRect.height()/2.0; return r;}QRectF QcItem::resetRect(){ mRect = parentWidget->rect(); float r = getRadius(mRect); mRect.setWidth(2.0*r); mRect.setHeight(2.0*r); mRect.moveCenter(parentWidget->rect().center()); return mRect;}QPointF QcItem::getPoint(float deg,const QRectF &tmpRect){ float r = getRadius(tmpRect); float xx=cos(qDegreesToRadians(deg))*r; float yy=sin(qDegreesToRadians(deg))*r; QPointF pt; xx=tmpRect.center().x()-xx; yy=tmpRect.center().y()-yy; pt.setX(xx); pt.setY(yy); return pt;}float QcItem::getAngle(const QPointF&pt, const QRectF &tmpRect){ float xx=tmpRect.center().x()-pt.x(); float yy=tmpRect.center().y()-pt.y(); return qRadiansToDegrees( atan2(yy,xx));}///////////////////////////////////////////////////////////////////////////////////////////QcScaleItem::QcScaleItem(QObject *parent) : QcItem(parent){ mMinDegree = -45; mMaxDegree = 225; mMinValue = 0; mMaxValue = 100;}void QcScaleItem::setValueRange(float minValue, float maxValue){ if(!(minValue<maxValue)) throw( InvalidValueRange); mMinValue = minValue; mMaxValue = maxValue;}void QcScaleItem::setDgereeRange(float minDegree, float maxDegree){ if(!(minDegree<maxDegree)) throw( InvalidValueRange); mMinDegree = minDegree; mMaxDegree = maxDegree;}float QcScaleItem::getDegFromValue(float v){ float a = (mMaxDegree-mMinDegree)/(mMaxValue-mMinValue); float b = -a*mMinValue+mMinDegree; return a*v+b;}void QcScaleItem::setMinValue(float minValue){ if(minValue>mMaxValue) throw (InvalidValueRange); mMinValue = minValue; update();}void QcScaleItem::setMaxValue(float maxValue){ if(maxValue<mMinValue ) throw (InvalidValueRange); mMaxValue = maxValue; update();}void QcScaleItem::setMinDegree(float minDegree){ if(minDegree>mMaxDegree) throw (InvalidDegreeRange); mMinDegree = minDegree; update();}void QcScaleItem::setMaxDegree(float maxDegree){ if(maxDegree<mMinDegree) throw (InvalidDegreeRange); mMaxDegree = maxDegree; update();}///////////////////////////////////////////////////////////////////////////////////////////QcBackgroundItem::QcBackgroundItem(QObject *parent) : QcItem(parent){ setPosition(88); mPen = Qt::NoPen; setPosition(88); addColor(0.4,Qt::darkGray); addColor(0.8,Qt::black);}void QcBackgroundItem::draw(QPainter* painter){ QRectF tmpRect = resetRect(); painter->setBrush(Qt::NoBrush); QLinearGradient linearGrad(tmpRect.topLeft(), tmpRect.bottomRight()); for(int i = 0;i<mColors.size();i++){ linearGrad.setColorAt(mColors[i].first,mColors[i].second); } painter->setPen(mPen); painter->setBrush(linearGrad); painter->drawEllipse(adjustRect(position()));}void QcBackgroundItem::addColor(float position, const QColor &color){ if(position<0||position>1) return; QPair<float,QColor> pair; pair.first = position; pair.second = color; mColors.append(pair); update();}void QcBackgroundItem::clearrColors(){ mColors.clear();}///////////////////////////////////////////////////////////////////////////////////////////QcGlassItem::QcGlassItem(QObject *parent) : QcItem(parent){ setPosition(88);}void QcGlassItem::draw(QPainter *painter){ resetRect(); QRectF tmpRect1 = adjustRect(position()); QRectF tmpRect2 = tmpRect1; float r = getRadius(tmpRect1); tmpRect2.setHeight(r/2.0); painter->setPen(Qt::NoPen); QColor clr1 = Qt::gray ; QColor clr2 = Qt::white; clr1.setAlphaF(0.2); clr2.setAlphaF(0.4); QLinearGradient linearGrad1(tmpRect1.topLeft(), tmpRect1.bottomRight()); linearGrad1.setColorAt(0.1, clr1); linearGrad1.setColorAt(0.5, clr2); painter->setBrush(linearGrad1); painter->drawPie(tmpRect1,0,16*180); tmpRect2.moveCenter(rect().center()); painter->drawPie(tmpRect2,0,-16*180);}///////////////////////////////////////////////////////////////////////////////////////////QcLabelItem::QcLabelItem(QObject *parent) : QcItem(parent){ setPosition(50); mAngle = 270; mText = "%"; mColor = Qt::black;}void QcLabelItem::draw(QPainter *painter){ resetRect(); QRectF tmpRect = adjustRect(position()); float r = getRadius(rect()); QFont font("Meiryo UI", r/10.0, QFont::Bold); painter->setFont(font); painter->setPen(QPen(mColor)); QPointF txtCenter = getPoint(mAngle,tmpRect); QFontMetrics fMetrics = painter->fo