拖动事件 dragEnterEvent、放置事件 dropEvent、resize事件resizeEvent的实现

拖动事件 dragEnterEvent

放置事件 dropEvent

resize事件resizeEvent

 

 DragFileExample.h

#ifndef DRAGFILEEXAMPLE_H
#define DRAGFILEEXAMPLE_H

#include <QWidget>
#include <QDragEnterEvent>
#include <QResizeEvent>
#include <QDropEvent>

namespace Ui {
class DragFileExample;
}

class DragFileExample : public QWidget
{
    Q_OBJECT
protected:
    void dragEnterEvent(QDragEnterEvent *event);
    void resizeEvent(QResizeEvent *event);
    void dropEvent(QDropEvent *event);


public:
    explicit DragFileExample(QWidget *parent = nullptr);
    ~DragFileExample();

private:
    Ui::DragFileExample *ui;
};

#endif // DRAGFILEEXAMPLE_H

DragFileExample.cpp

#include "dragfileexample.h"
#include "ui_dragfileexample.h"

#include <QMimeData>
#include <QFileInfo>

DragFileExample::DragFileExample(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::DragFileExample)
{
    ui->setupUi(this);
    ui->labPic->setScaledContents(true);//图片自适应大小
    this->setAcceptDrops(true);//窗体统一接受drop
    ui->labPic->setAcceptDrops(false);//labPic不接受drop
    ui->plainTextEdit->setAcceptDrops(false);//
}



DragFileExample::~DragFileExample()
{
    delete ui;
}

void DragFileExample::dragEnterEvent(QDragEnterEvent *event)
{
    ui->plainTextEdit->clear();
    ui->plainTextEdit->appendPlainText("dragEnterEvent事件开始");
    for(int i=0;i<event->mimeData()->urls().size();i++)
    {//选中的拖动的文档的列表 通过event->mimeData() 来遍历
        QUrl url = event->mimeData()->urls().at(i);
        ui->plainTextEdit->appendPlainText(url.path());
    }

    if(event->mimeData()->hasUrls())
    {
        QString fileName = event->mimeData()->urls().at(0).fileName();
        QFileInfo fileinfo(fileName);
        QString ext = fileinfo.suffix().toUpper();
        if(ext=="JPG")
            event->acceptProposedAction();
        else
            event->ignore();
    }
    else
        event->ignore();
}

void DragFileExample::resizeEvent(QResizeEvent *event)
{//窗口大小变化的时候，改变文本框的宽度，和图片框的宽度和高度
    QSize sz= ui->plainTextEdit->size();
    ui->plainTextEdit->resize(this->width()-10,sz.height());
    ui->labPic->resize(this->width()-10,this->height()-sz.height()-20);
    event->accept();
}

void DragFileExample::dropEvent(QDropEvent *event)
{
    QString filename = event->mimeData()->urls().at(0).path();
    filename = filename.right(filename.length()-1);
    QPixmap pixmap(filename);
    ui->labPic->setPixmap(pixmap);
    event->accept();
}

总结

1. 按下鼠标mousePressEnter，然后拖动鼠标mouserMove到目标控件触发dragEnterEvent，最后放置触发dropEvent的过程

2.拖动的文件 通过event->mimeData()获取到文件的路径，然后通过QFileInfo获取文件的具体信息

QString fileName = event->mimeData()->urls().at(0).fileName();
        QFileInfo fileinfo(fileName);