## 一、前言

导航按钮控件，主要用于各种漂亮精美的导航条，我们经常在web中看到导航条都非常精美，都是html+css+js实现的，还自带动画过度效果，Qt提供的qss其实也是无敌的，支持基本上所有的CSS2属性，配合QPainter这个无敌大法工具，没有什么不能绘制的。这个控件总结了大部分的导航条样式，比如左侧+右侧+顶部+底部，线条指示器，倒三角指示器等。还可以在导航条前面加上图标等，就显得更加有特色。有了此控件，再也不用担心没有精美的导航了。总之这个控件在我的很多的项目中都在用，而且很多Qt界的朋友也在用，反响很热烈很好。

主要功能：

1. 可设置文字的左侧+右侧+顶部+底部间隔

2. 可设置文字对齐方式

3. 可设置显示倒三角/倒三角边长/倒三角位置/倒三角颜色

4. 可设置显示图标/图标间隔/图标尺寸/正常状态图标/悬停状态图标/选中状态图标

5. 可设置显示边框线条/线条宽度/线条间隔/线条位置/线条颜色

6. 可设置正常背景颜色/悬停背景颜色/选中背景颜色

7. 可设置正常文字颜色/悬停文字颜色/选中文字颜色

8. 可设置背景颜色为画刷颜色

## 二、代码思路

void NavButton::paintEvent(QPaintEvent *){    //绘制准备工作,启用反锯齿    QPainter painter(this);    painter.setRenderHints(QPainter::Antialiasing | QPainter::TextAntialiasing);    //绘制背景    drawBg(&painter);    //绘制文字    drawText(&painter);    //绘制图标    drawIcon(&painter);    //绘制边框线条    drawLine(&painter);    //绘制倒三角    drawTriangle(&painter);}void NavButton::drawBg(QPainter *painter){    painter->save();    painter->setPen(Qt::NoPen);    int width = this->width();    int height = this->height();    QRect bgRect;    if (linePosition == LinePosition_Left) {        bgRect = QRect(lineSpace, 0, width - lineSpace, height);    } else if (linePosition == LinePosition_Right) {        bgRect = QRect(0, 0, width - lineSpace, height);    } else if (linePosition == LinePosition_Top) {        bgRect = QRect(0, lineSpace, width, height - lineSpace);    } else if (linePosition == LinePosition_Bottom) {        bgRect = QRect(0, 0, width, height - lineSpace);    }    //如果画刷存在则取画刷    QBrush bgBrush;    if (isChecked()) {        bgBrush = checkBgBrush;    } else if (hover) {        bgBrush = hoverBgBrush;    } else {        bgBrush = normalBgBrush;    }    if (bgBrush != Qt::NoBrush) {        painter->setBrush(bgBrush);    } else {        //根据当前状态选择对应颜色        QColor bgColor;        if (isChecked()) {            bgColor = checkBgColor;        } else if (hover) {            bgColor = hoverBgColor;        } else {            bgColor = normalBgColor;        }        painter->setBrush(bgColor);    }    painter->drawRect(bgRect);    painter->restore();}void NavButton::drawText(QPainter *painter){    painter->save();    painter->setBrush(Qt::NoBrush);    //根据当前状态选择对应颜色    QColor textColor;    if (isChecked()) {        textColor = checkTextColor;    } else if (hover) {        textColor = hoverTextColor;    } else {        textColor = normalTextColor;    }    QRect textRect = QRect(paddingLeft, paddingTop, width() - paddingLeft - paddingRight, height() - paddingTop - paddingBottom);    painter->setPen(textColor);    painter->drawText(textRect, textAlign | Qt::AlignVCenter, text());    painter->restore();}void NavButton::drawIcon(QPainter *painter){    if (!showIcon) {        return;    }    painter->save();    QPixmap pix;    if (isChecked()) {        pix = iconCheck;    } else if (hover) {        pix = iconHover;    } else {        pix = iconNormal;    }    if (!pix.isNull()) {        //等比例平滑缩放图标        pix = pix.scaled(iconSize, Qt::KeepAspectRatio, Qt::SmoothTransformation);        painter->drawPixmap(iconSpace, (height() - iconSize.height()) / 2, pix);    }    painter->restore();}void NavButton::drawLine(QPainter *painter){    if (!showLine) {        return;    }    if (!isChecked()) {        return;    }    painter->save();    QPen pen;    pen.setWidth(lineWidth);    pen.setColor(lineColor);    painter->setPen(pen);    //根据线条位置设置线条坐标    QPoint pointStart, pointEnd;    if (linePosition == LinePosition_Left) {        pointStart = QPoint(0, 0);        pointEnd = QPoint(0, height());    } else if (linePosition == LinePosition_Right) {        pointStart = QPoint(width(), 0);        pointEnd = QPoint(width(), height());    } else if (linePosition == LinePosition_Top) {        pointStart = QPoint(0, 0);        pointEnd = QPoint(width(), 0);    } else if (linePosition == LinePosition_Bottom) {        pointStart = QPoint(0, height());        pointEnd = QPoint(width(), height());    }    painter->drawLine(pointStart, pointEnd);    painter->restore();}void NavButton::drawTriangle(QPainter *painter){    if (!showTriangle) {        return;    }    //选中或者悬停显示    if (!hover && !isChecked()) {        return;    }    painter->save();    painter->setPen(Qt::NoPen);    painter->setBrush(triangleColor);    //绘制在右侧中间,根据设定的倒三角的边长设定三个点位置    int width = this->width();    int height = this->height();    int midWidth = width / 2;    int midHeight = height / 2;    QPolygon pts;    if (trianglePosition == TrianglePosition_Left) {        pts.setPoints(3, triangleLen, midHeight, 0, midHeight - triangleLen, 0, midHeight + triangleLen);    } else if (trianglePosition == TrianglePosition_Right) {        pts.setPoints(3, width - triangleLen, midHeight, width, midHeight - triangleLen, width, midHeight + triangleLen);    } else if (trianglePosition == TrianglePosition_Top) {        pts.setPoints(3, midWidth, triangleLen, midWidth - triangleLen, 0, midWidth + triangleLen, 0);    } else if (trianglePosition == TrianglePosition_Bottom) {        pts.setPoints(3, midWidth, height - triangleLen, midWidth - triangleLen, height, midWidth + triangleLen, height);    }    painter->drawPolygon(pts);    painter->restore();}

## 三、效果图

## 四、开源主页

**以上作品完整源码下载都在开源主页，会持续不断更新作品数量和质量，欢迎各位关注。**

1. 国内站点：[https://gitee.com/feiyangqingyun/QWidgetDemo](https://gitee.com/feiyangqingyun/QWidgetDemo)

2. 国际站点：[https://github.com/feiyangqingyun/QWidgetDemo](https://github.com/feiyangqingyun/QWidgetDemo)

3. 个人主页：[https://blog.csdn.net/feiyangqingyun](https://blog.csdn.net/feiyangqingyun)

4. 知乎主页：[https://www.zhihu.com/people/feiyangqingyun/](https://www.zhihu.com/people/feiyangqingyun/)