qt读取图像并且调整大小，避免撑爆qlable控件

方式

通过设置QLable的对齐方式来设置图片的对齐方式，自由的控制图片是显示在表格项的上下左右。
代码如下：

QLabel *lable = new QLabel();     					//创建lable
lable->setPixmap(QPixmap(":/image/search.png"));    //加载图片到QLable
lable->setAlignment(Qt::AlignHCenter);      		//设置QLable控件居中显示
ui->tableWidget->setCellWidget(0,5,lable);     		//显示添加QLable到控件

{
    ui->setupUi(this);
    QString StrWidth,StrHeigth;
    QString filename="F:\\Study\\junior\\Qt\\door\\1.jpg";
            QImage* img=new QImage,* scaledimg=new QImage;//分别保存原图和缩放之后的图片
            if(! ( img->load(filename) ) ) //加载图像
            {
                QMessageBox::information(this,
                                         tr("打开图像失败"),
                                         tr("打开图像失败!"));
                delete img;
                return;
            }
            int Owidth=img->width(),Oheight=img->height();
            int Fwidth,Fheight;       //缩放后的图片大小
            ui->label->setGeometry(0,0,400,300);
            int Mul;            //记录图片与label大小的比例，用于缩放图片
            if(Owidth/400>=Oheight/300)
                Mul=Owidth/400;
            else
                Mul=Oheight/300;
            Fwidth=Owidth/Mul;
            Fheight=Oheight/Mul;
            *scaledimg=img->scaled(Fwidth,Fheight,Qt::KeepAspectRatio);
            ui->label_text->setText(QString("width: ")+StrWidth.setNum(Fwidth)
                                    +QString("\nheight: ")+StrHeigth.setNum(Fheight));
            ui->label->setPixmap(QPixmap::fromImage(*scaledimg));
}

使用方式

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "login.h"
#include "QDebug"
#include "QMessageBox"
#include "QFileDialog"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    ui->label->setTextFormat(Qt::RichText);

    connect(ui->actionnew_file,&QAction::triggered,this,[=]{
                QMessageBox::information(this, "创建新项目",
                                         "成功创建项目",
                                         QMessageBox::Ok,
                                         QMessageBox::Save);
            });
    connect(ui->actionopen_file,&QAction::triggered,this,[=]{
                QMessageBox::information(this, "打开项目",
                                         "成功打开项目",
                                         QMessageBox::Ok,
                                         QMessageBox::Save);
            });
    connect(ui->actioneidt,&QAction::triggered,this,[=]{
                QMessageBox::information(this, "编辑项目",
                                         "成功编辑项目",
                                         QMessageBox::Ok,
                                         QMessageBox::Save);
            });
    connect(ui->actionbuild_all,&QAction::triggered,this,[=]{
                QMessageBox::information(this, "构建所有项目",
                                         "成功构建所有项目",
                                         QMessageBox::Ok,
                                         QMessageBox::Save);
            });
    connect(ui->actionbuile_file,&QAction::triggered,this,[=]{
                QMessageBox::information(this, "构建当前项目",
                                         "成功构建当前项目",
                                         QMessageBox::Ok,
                                         QMessageBox::Save);
            });
    connect(ui->read1,&QAction::triggered,this,[=]{
        QString fileName = QFileDialog::getOpenFileName(this,tr("Open Image"),
                                        ".",tr("Image Files (*.png *.jpg *.bmp)"));
        //this->ui->label->setPixmap(QPixmap(fileName));
        QImage* img=new QImage,* scaledimg=new QImage;//分别保存原图和缩放之后的图片
                    if(! ( img->load(fileName) ) ) //加载图像
                    {
                        QMessageBox::information(this,
                                                 tr("打开图像失败"),
                                                 tr("打开图像失败!"));
                        delete img;
                        return;
                    }
                    int Owidth=img->width(),Oheight=img->height();
                    int Fwidth,Fheight;       //缩放后的图片大小
                    ui->label->setAlignment(Qt::AlignHCenter);      		//设置QLable控件居中显示
                    //ui->label->setGeometry(0,0,100,100);
                    int Mul;            //记录图片与label大小的比例，用于缩放图片
                    if(Owidth/400>=Oheight/300)
                        Mul=Owidth/600;
                    else
                        Mul=Oheight/500;
                    Fwidth=Owidth/Mul;
                    Fheight=Oheight/Mul;
                    qDebug()<<Mul;
                    qDebug()<<Fwidth;
                    qDebug()<<Oheight;
                    *scaledimg=img->scaled(Fwidth,Fheight,Qt::KeepAspectRatio);
                    ui->label->setPixmap(QPixmap::fromImage(*scaledimg));


            });



}

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

参考1

参考2