1.自定义按钮类

效果：

(1)仅当未选中，未悬浮时

 (2)其他三种情况，均如图

#ifndef BTN_H
#define BTN_H#include <QPushButton>
class btn : public QPushButton
{Q_OBJECT
public:btn(QWidget * parent = nullptr);void set_normal_icon(QString icon);void set_checked_icon(QString icon);void init();
protected:void paintEvent(QPaintEvent *) override;void enterEvent(QEvent *event);void leaveEvent(QEvent *event);
private:QString normal_icon,checked_icon;//选中，悬浮bool hover;
};#endif // BTN_H

#include "btn.h"
#include <QDebug>
#include <QPainter>
#pragma execution_character_set("utf-8")
btn::btn(QWidget * parent ): QPushButton(parent)
{//正常时，无边框//被选中时，背景变换+圆角矩形init();
}void btn::set_normal_icon(QString icon)
{normal_icon=icon;
}void btn::set_checked_icon(QString icon)
{checked_icon=icon;
}void btn::init()
{QSizePolicy sizePolicy1(QSizePolicy::Fixed, QSizePolicy::Fixed);sizePolicy1.setHorizontalStretch(0);sizePolicy1.setVerticalStretch(0);sizePolicy1.setHeightForWidth(this->sizePolicy().hasHeightForWidth());this->setSizePolicy(sizePolicy1);//宽高this->setMinimumSize(QSize(75, 75));this->setMaximumSize(QSize(75, 75));//可选中this->setCheckable(true);hover=false;
}void btn::enterEvent(QEvent *event)
{qDebug()<<"进入事件发生";hover=true;
}void btn::leaveEvent(QEvent *event)
{qDebug()<<"离开事件发生";hover=false;
}void btn::paintEvent(QPaintEvent *)
{QPainter painter(this);painter.setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform | QPainter::TextAntialiasing, true);if(!hover && !this->isChecked()){//画黑图标QPixmap pix(normal_icon);pix=pix.scaled(40,40,Qt::IgnoreAspectRatio);//75*75,40*40//(75-40)/2=12.5QRectF target(12.5, 12.5, 52.5, 52.5);QRectF source(0.0, 0.0, 40.0, 40.0);painter.drawPixmap(target,pix,source);}else{//画圆角矩形QRect rect(0,0,75,75);painter.setPen(Qt::NoPen);painter.setBrush(QBrush(QColor(255,255,255)));painter.drawRoundedRect(rect,10,10,Qt::AbsoluteSize);//画蓝图标QPixmap pix(checked_icon);pix=pix.scaled(40,40,Qt::IgnoreAspectRatio);//75*75,40*40//(75-40)/2=12.5QRectF target(12.5, 12.5, 52.5, 52.5);QRectF source(0.0, 0.0, 40.0, 40.0);painter.drawPixmap(target,pix,source);}
}

2.实验：

label与widget平级，label在widget上面，label显示完全

label在widget里面，label局部显示：

3.自定义按钮类2： 

效果：

#ifndef BTN2_H
#define BTN2_H#include <QPushButton>
class btn2 : public QPushButton
{Q_OBJECT
public:btn2(QWidget * parent =nullptr);void get_icon(QString path);
protected:void paintEvent(QPaintEvent *) override;
private:QString icon;
};#endif // BTN2_H

#include "btn2.h"
#include <QPainter>
#include <QDebug>
#pragma execution_character_set("utf-8")
btn2::btn2(QWidget *parent):QPushButton(parent)
{}void btn2::get_icon(QString path)
{icon=path;
}void btn2::paintEvent(QPaintEvent *)
{QPainter painter(this);painter.setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform | QPainter::TextAntialiasing, true);//圆角边框QRect rect(0,0,200,75);QPen pen;pen.setColor(QColor(244,244,244));pen.setWidth(3);pen.setStyle(Qt::SolidLine);painter.setPen(pen);painter.setBrush(QBrush(QColor(255,255,255)));painter.drawRoundedRect(rect,10,10,Qt::AbsoluteSize);//蓝色图标QPixmap pix(icon);pix=pix.scaled(40,40,Qt::IgnoreAspectRatio);//75*75,40*40//(75-40)/2=12.5QRectF target(12.5, 12.5, 52.5, 52.5);QRectF source(0.0, 0.0, 40.0, 40.0);painter.drawPixmap(target,pix,source);//文字QFont font;font.setPointSize(12);font.setFamily("隶书");painter.setFont(font);painter.setPen(QColor(0,0,0));painter.drawText(52.5,0,200-52.5,75,Qt::AlignCenter,this->text());}

4.实验：

目标：得到这个蓝色矩形左上角的坐标信息： 

pos : QPoint

它返回的是相对于父窗口的偏移位置，而不是最外面的窗口的。

QPoint Form::get_pos(QWidget * w)
{QWidget * p=qobject_cast<QWidget *>(w->parent());if(p == this){return w->pos();}else{return w->pos()+get_pos(p);}
}

    timer.singleShot(100,this,[=](){//这样就可以解决输出为0的问题了for(int i=0;i<btn1.count();++i){btn * one=btn1.at(i);one->set_absolute_pos(get_pos(one));qDebug()<<one->get_absolute_pos();}});

    group=new QButtonGroup(this);for(int i=0;i<btn1.count();++i){QAbstractButton * b=qobject_cast<QAbstractButton *>(btn1.at(i));group->addButton(b,i+1);}

#ifndef MOVABLE_WIDGET_H
#define MOVABLE_WIDGET_H#include <QWidget>class movable_widget:public QWidget
{
public:movable_widget(QWidget * parent=0);
protected:void mouseMoveEvent(QMouseEvent *event);void mousePressEvent(QMouseEvent *event);void mouseReleaseEvent(QMouseEvent *event);void paintEvent(QPaintEvent *event);
private:QPoint Pos;bool ismoving;
};#endif // MOVABLE_WIDGET_H

#include "movable_widget.h"
#include <QMouseEvent>
#include <QPainter>
movable_widget::movable_widget(QWidget * parent):QWidget(parent)
{setWindowFlag(Qt::FramelessWindowHint);setAttribute(Qt::WA_TranslucentBackground);}
void movable_widget::mouseMoveEvent(QMouseEvent *event)
{if(ismoving){QPoint now=event->globalPos()-Pos;move(now);}QWidget::mouseMoveEvent(event);
}void movable_widget::mousePressEvent(QMouseEvent *event)
{if(event->button()==Qt::LeftButton){ismoving=true;Pos=event->globalPos()-pos();}QWidget::mousePressEvent(event);
}void movable_widget::mouseReleaseEvent(QMouseEvent *event)
{ismoving=false;QWidget::mouseReleaseEvent(event);
}
void movable_widget::paintEvent(QPaintEvent *event)
{QPainter painter(this);painter.setRenderHint(QPainter::Antialiasing);	// 反锯齿;painter.setBrush(QBrush(Qt::red));painter.setPen(Qt::transparent);QRect rect = this->rect();rect.setWidth(rect.width() - 1);rect.setHeight(rect.height() - 1);painter.drawRoundedRect(rect, 15, 15);QWidget::paintEvent(event);
}