Qt实战案例之利用Qt实现打开最近图片功能

#include "mainwindow.h" #include<QFileDialog> #include<QMessageBox> #include<QSettings> MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) { imageLabel = new QLabel; setCentralWidget(imageLabel);//设置中心部件 //Open Action openAction = new QAction(tr("&Open..."), this);//open openAction->setShortcuts(QKeySequence::Open); //设置快捷键 connect(openAction, &QAction::triggered, this, [=]() { QString filePath = QFileDialog::getOpenFileName( this, tr("Open File"), "", tr("Images (*.png *.xpm *.jpg *.gif)")); if (!filePath.isEmpty()) loadFile(filePath); }); //recentFile Action QAction* recentFileAction = nullptr; for(auto i = 0; i < maxFileNr; ++i){ recentFileAction = new QAction(this); recentFileAction->setVisible(false); connect(recentFileAction, &QAction::triggered, this, [=]() { loadFile(recentFileAction->data().toString()); }); recentFileActionList.append(recentFileAction); } // create menus fileMenu = menuBar()->addMenu(tr("&File")); fileMenu->addAction(openAction); recentFilesMenu = fileMenu->addMenu(tr("Open Recent")); for(auto i = 0; i < maxFileNr; ++i) recentFilesMenu->addAction(recentFileActionList.at(i)); updateRecentActionList(); resize(350, 250);//调整尺寸 } MainWindow::~MainWindow() { } //加载图片 void MainWindow::loadFile(const QString &filePath){ QFile file(filePath); //如果不能打开 if (!file.open(QFile::ReadOnly)) { QMessageBox::warning(this, tr("Recent Photos"), tr("This file could not be found:\n%1.") .arg(filePath)); return; } QPixmap pMap(filePath); //如果图片为空 if (pMap.isNull()) { QMessageBox::information(this, tr("Recent Photos"), tr("Cannot load:\n%1.") .arg(filePath)); return; } imageLabel->setPixmap(pMap); //显示图像 imageLabel->setAlignment(Qt::AlignCenter); //居中对齐 adjustForCurrentFile(filePath); } //调整当前文件(使得每次新打开的文件都在最上方) void MainWindow::adjustForCurrentFile(const QString &filePath){ currentFilePath = filePath; setWindowFilePath(currentFilePath); QSettings settings("Recently", "Recent Photos1"); QStringList recentFilePaths = settings.value("recentPhotos").toStringList();//获取键对应的值 recentFilePaths.removeAll(filePath); //移除filePath recentFilePaths.prepend(filePath); //在开头增加filePath //如果尺寸超过最大尺寸，则删除最后一项 while (recentFilePaths.size() > maxFileNr) recentFilePaths.removeLast(); settings.setValue("recentPhotos", recentFilePaths);//设置键recentPhotos对应的值 updateRecentActionList(); } //更新recentFileActionList void MainWindow::updateRecentActionList(){ QSettings settings("Recently", "Recent Photos1"); QStringList recentFilePaths = settings.value("recentPhotos").toStringList();//获取键对应的值 auto itEnd = 0; if(recentFilePaths.size() <= maxFileNr) itEnd = recentFilePaths.size(); else itEnd = maxFileNr; for (auto i = 0; i < itEnd; ++i) { QString strippedName = QFileInfo(recentFilePaths.at(i)).fileName();//返回文件名(不包含路径) recentFileActionList.at(i)->setText(strippedName); //描述性文本 recentFileActionList.at(i)->setData(recentFilePaths.at(i)); //数据 recentFileActionList.at(i)->setVisible(true); } for (auto i = itEnd; i < maxFileNr; ++i) recentFileActionList.at(i)->setVisible(false); }