Qt 编程继续为大家讲解，还是接着文章 Qt 编程点滴 初学者必看 （6） ，继续介绍，说编程那些细节。由于本话题是一节一节为大家介绍的，所以更多内容请看末尾编辑推荐。本文基本是用代码实现的效果，所以并没有太多的内容。
QPainterPath 画出的图形会闪烁的问题：
用下面的写法画出的图形会闪烁
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class MyClass: public QWidget { public: MyClass(QWidget*); private: QPainterPath* route; void paintEvent(QPaintEvent*e); }; MyClass::MyClass() { route = new QPainterPath(); } void MyClass::paintEvent( QPaintEvent*e) { QPainter *painter = new QPainter(this); //画校正图形 int insideR = 30; int outsideR = 50; QColor insideColor(237,29,12); //内圆线条颜色 QColor outSideColor(237,29,12); //外圆线条颜色 QColor lineColor(237,29,12); //直线颜色 QColor insideBrushColor(255,0,0,25);//内圆画刷颜色,最后的参数代表透明度( 0(完全透明)-100(不透明) ) QColor outsideBrushColor(255,0,0,50);//外圆画刷颜色,最后的参数代表透明度( 0(完全透明)-100(不透明) ) //QPainterPath path; route->moveTo(insideR,0); route->lineTo(outsideR,0); route->arcTo(0-outsideR,0-outsideR,outsideR*2,outsideR*2,0,180); route->lineTo(0-insideR,0); route->arcTo(0-insideR,0-insideR,insideR*2,insideR*2,0,180); route->moveTo(0-insideR,0); route->lineTo(0-outsideR,0); route->arcTo(0-outsideR,0-outsideR,outsideR*2,outsideR*2,180,180); route->lineTo(insideR,0); route->arcTo(0-insideR,0-insideR,insideR*2,insideR*2,180,180); painter->setPen(Qt::NoPen); painter->setBrush(outsideBrushColor); painter->drawPath(*route); painter->setBrush(Qt::NoBrush); painter->setPen(outSideColor); painter->drawEllipse( QPointF(0,0),outsideR,outsideR ); painter->setBrush(insideBrushColor); painter->setPen(insideColor); painter->drawEllipse( QPointF(0,0),insideR,insideR ); painter->setPen(lineColor); QPoint p1(0, 0- outsideR - 10 ); QPoint p2(0, outsideR + 10 ); painter->drawLine(p1,p2); painter->rotate(90); painter->drawLine(p1,p2); painter->rotate(-90); delete painter; }
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如下用下面的写法则不会闪烁:
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void MyClass::paintEvent( QPaintEvent*e) { QPainter *painter = new QPainter(this); //画校正图形 int insideR = 30; int outsideR = 50; QColor insideColor(237,29,12); //内圆线条颜色 QColor outSideColor(237,29,12); //外圆线条颜色 QColor lineColor(237,29,12); //直线颜色 QColor insideBrushColor(255,0,0,25);//内圆画刷颜色,最后的参数代表透明度( 0(完全透明)-100(不透明) ) QColor outsideBrushColor(255,0,0,50);//外圆画刷颜色,最后的参数代表透明度( 0(完全透明)-100(不透明) ) QPainterPath path; path.moveTo(insideR,0); path.lineTo(outsideR,0); path.arcTo(0-outsideR,0-outsideR,outsideR*2,outsideR*2,0,180); path.lineTo(0-insideR,0); path.arcTo(0-insideR,0-insideR,insideR*2,insideR*2,0,180); path.moveTo(0-insideR,0); path.lineTo(0-outsideR,0); path.arcTo(0-outsideR,0-outsideR,outsideR*2,outsideR*2,180,180); path.lineTo(insideR,0); path.arcTo(0-insideR,0-insideR,insideR*2,insideR*2,180,180); painter->setPen(Qt::NoPen); painter->setBrush(outsideBrushColor); painter->drawPath(path); painter->setBrush(Qt::NoBrush); painter->setPen(outSideColor); painter->drawEllipse( QPointF(0,0),outsideR,outsideR ); painter->setBrush(insideBrushColor); painter->setPen(insideColor); painter->drawEllipse( QPointF(0,0),insideR,insideR ); painter->setPen(lineColor); QPoint p1(0, 0- outsideR - 10 ); QPoint p2(0, outsideR + 10 ); painter->drawLine(p1,p2); painter->rotate(90); painter->drawLine(p1,p2); painter->rotate(-90); delete painter; }
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小结：本文主要介绍了在Qt 窗体的使用，通过Qt 编程点滴介绍，也给自己提高了编程过程中需要注意的细节问题，由于本话题是一节一节为大家展现的，所以更多内容，请看编辑推荐。