如何实现可拖动自定义控件

使用QT实现自定义类卡牌控件Card，使其能在父类窗口上使用鼠标进行拖动。

控件类头文件card.h

#ifndef CARD_H#define CARD_H#include <QWidget>#include <QPaintEvent>#include <QPainter>#include <QMouseEvent>class Card:public QWidget {    Q_OBJECTpublic:    explicit Card(QWidget *parent = nullptr);    ~Card();protected:    void paintEvent(QPaintEvent *event) override;    void mousePressEvent(QMouseEvent *event) override; signals:    void sendSelf(Card *w); };#endif // CARD_H

控件类头文件card.cpp

#include "card.h"Card::Card(QWidget *parent):QWidget(parent) {    this->setGeometry(0,0,200,400);       //设置控件窗口大小 } Card::~Card() { }void Card::paintEvent(QPaintEvent *event) {    QPainter painter(this);                               //创建画笔    painter.setRenderHint(QPainter::Antialiasing,true);    QBrush brush;                                         //创建笔刷    brush.setColor(Qt::yellow);                           //设置笔刷颜色    brush.setStyle(Qt::SolidPattern);                        painter.setBrush(brush);                              //设置画笔笔刷    painter.drawRoundedRect(QRectF(5,5,190,390),10,10);   //绘制圆角矩形并填充 }void Card::mousePressEvent(QMouseEvent *event) {    Q_UNUSED(event);    emit sendSelf(this);                                  //信号发送该控件地址 }

以上是基于widget类的控件类；

父窗口头文件mainwindow.h

#ifndef MAINWINDOW_H#define MAINWINDOW_H#include <QMainWindow>#include "card.h"#include <QDebug>namespace Ui {class MainWindow; }class MainWindow : public QMainWindow {    Q_OBJECTpublic:    explicit MainWindow(QWidget *parent = 0);    ~MainWindow();private:    Ui::MainWindow *ui;    Card* cd[8];    Card *temp;    QPoint startP;    QPoint yuanP;private slots:    void getObject(Card *w);protected:    void mouseMoveEvent(QMouseEvent *event) override;    void mouseReleaseEvent(QMouseEvent *event) override; };#endif // MAINWINDOW_H

父窗口头文件mainwindow.cpp

#include "mainwindow.h"#include "ui_mainwindow.h"MainWindow::MainWindow(QWidget *parent) :    QMainWindow(parent),    ui(new Ui::MainWindow) {    ui->setupUi(this);    for(int i=0;i<8;i++)    {        cd[i] = new Card(this);        connect(cd[i],&Card::sendSelf,this,&MainWindow::getObject);        cd[i]->move(i%4*200,i/4*400+20);    } } MainWindow::~MainWindow() {    delete ui; }//获取控件坐标void MainWindow::getObject(Card *w) {    temp = w;    startP = cursor().pos()-this->pos();    yuanP = temp->pos();    /*将此小部件提升到父小部件堆栈的顶部*/    temp->raise(); }//移动事件void MainWindow::mouseMoveEvent(QMouseEvent *event) {    temp->move(yuanP.x()+event->x()-startP.x(),yuanP.y()+event->y()-startP.y()); }//拖拽对象置顶，卡牌积压的时候，拖动的那张卡牌置顶void MainWindow::mouseReleaseEvent(QMouseEvent *event) {    temp->raise(); }