qt 6.5.1 original

examples/widgets/itemviews/fetchmore/CMakeLists.txt

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+# Copyright (C) 2022 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+cmake_minimum_required(VERSION 3.16)
+project(fetchmore LANGUAGES CXX)
+
+if(NOT DEFINED INSTALL_EXAMPLESDIR)
+    set(INSTALL_EXAMPLESDIR "examples")
+endif()
+
+set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/widgets/itemviews/fetchmore")
+
+find_package(Qt6 REQUIRED COMPONENTS Core Gui Widgets)
+
+qt_standard_project_setup()
+
+qt_add_executable(fetchmore
+    filelistmodel.cpp filelistmodel.h
+    main.cpp
+    window.cpp window.h
+)
+
+set_target_properties(fetchmore PROPERTIES
+    WIN32_EXECUTABLE TRUE
+    MACOSX_BUNDLE TRUE
+)
+
+target_link_libraries(fetchmore PRIVATE
+    Qt6::Core
+    Qt6::Gui
+    Qt6::Widgets
+)
+
+install(TARGETS fetchmore
+    RUNTIME DESTINATION "${INSTALL_EXAMPLEDIR}"
+    BUNDLE DESTINATION "${INSTALL_EXAMPLEDIR}"
+    LIBRARY DESTINATION "${INSTALL_EXAMPLEDIR}"
+)

examples/widgets/itemviews/fetchmore/fetchmore.pro

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+QT += widgets
+requires(qtConfig(listview))
+
+HEADERS   = filelistmodel.h \
+            window.h
+SOURCES   = filelistmodel.cpp \
+            main.cpp \
+            window.cpp
+
+# install
+target.path = $$[QT_INSTALL_EXAMPLES]/widgets/itemviews/fetchmore
+INSTALLS += target

examples/widgets/itemviews/fetchmore/filelistmodel.cpp

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+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include "filelistmodel.h"
+
+#include <QGuiApplication>
+#include <QDir>
+#include <QPalette>
+
+static const int batchSize = 100;
+
+FileListModel::FileListModel(QObject *parent)
+    : QAbstractListModel(parent)
+{}
+
+//![4]
+int FileListModel::rowCount(const QModelIndex &parent) const
+{
+    return parent.isValid() ? 0 : fileCount;
+}
+
+QVariant FileListModel::data(const QModelIndex &index, int role) const
+{
+    if (!index.isValid())
+        return {};
+
+    const int row = index.row();
+    if (row >= fileList.size() || row < 0)
+        return {};
+
+    switch (role) {
+    case Qt::DisplayRole:
+        return fileList.at(row).fileName();
+    case Qt::BackgroundRole: {
+        const int batch = row / batchSize;
+        const QPalette &palette = QGuiApplication::palette();
+        return (batch % 2) != 0 ? palette.alternateBase() : palette.base();
+    }
+    case Qt::DecorationRole:
+        return iconProvider.icon(fileList.at(row));
+    }
+    return {};
+}
+
+//![4]
+
+QFileInfo FileListModel::fileInfoAt(const QModelIndex &index) const
+{
+    return fileList.at(index.row());
+}
+
+//![1]
+bool FileListModel::canFetchMore(const QModelIndex &parent) const
+{
+    if (parent.isValid())
+        return false;
+    return (fileCount < fileList.size());
+}
+//![1]
+
+//![2]
+void FileListModel::fetchMore(const QModelIndex &parent)
+{
+    if (parent.isValid())
+        return;
+    const int start = fileCount;
+    const int remainder = int(fileList.size()) - start;
+    const int itemsToFetch = qMin(batchSize, remainder);
+
+    if (itemsToFetch <= 0)
+        return;
+
+    beginInsertRows(QModelIndex(), start, start + itemsToFetch - 1);
+
+    fileCount += itemsToFetch;
+
+    endInsertRows();
+
+    emit numberPopulated(path, start, itemsToFetch, int(fileList.size()));
+}
+//![2]
+
+//![0]
+void FileListModel::setDirPath(const QString &path)
+{
+    QDir dir(path);
+
+    beginResetModel();
+    this->path = path;
+    fileList = dir.entryInfoList(QDir::NoDot | QDir::AllEntries, QDir::Name);
+    fileCount = 0;
+    endResetModel();
+}
+//![0]
+

examples/widgets/itemviews/fetchmore/filelistmodel.h

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+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#ifndef FILELISTMODEL_H
+#define FILELISTMODEL_H
+
+#include <QAbstractListModel>
+#include <QFileInfoList>
+#include <QFileIconProvider>
+
+//![0]
+class FileListModel : public QAbstractListModel
+{
+    Q_OBJECT
+
+public:
+    FileListModel(QObject *parent = nullptr);
+
+    int rowCount(const QModelIndex &parent = QModelIndex()) const override;
+    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
+
+    QFileInfo fileInfoAt(const QModelIndex &) const;
+
+signals:
+    void numberPopulated(const QString &path, int start, int number, int total);
+
+public slots:
+    void setDirPath(const QString &path);
+
+protected:
+    bool canFetchMore(const QModelIndex &parent) const override;
+    void fetchMore(const QModelIndex &parent) override;
+
+private:
+    QFileInfoList fileList;
+    QString path;
+    QFileIconProvider iconProvider;
+    int fileCount = 0;
+};
+//![0]
+
+#endif // FILELISTMODEL_H

examples/widgets/itemviews/fetchmore/main.cpp

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+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include "window.h"
+
+#include <QApplication>
+
+int main(int argc, char *argv[])
+{
+    QApplication app(argc, argv);
+    Window window;
+    window.show();
+    return app.exec();
+}

examples/widgets/itemviews/fetchmore/window.cpp

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+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include "window.h"
+#include "filelistmodel.h"
+
+#include <QtWidgets>
+
+Window::Window(QWidget *parent)
+    : QWidget(parent)
+{
+    model = new FileListModel(this);
+    model->setDirPath(QDir::rootPath());
+
+    view = new QListView;
+    view->setModel(model);
+
+    logViewer = new QPlainTextEdit(this);
+    logViewer->setReadOnly(true);
+    logViewer->setSizePolicy(QSizePolicy(QSizePolicy::Preferred,
+                                         QSizePolicy::Preferred));
+
+    connect(model, &FileListModel::numberPopulated,
+            this, &Window::updateLog);
+    connect(view, &QAbstractItemView::activated,
+            this, &Window::activated);
+
+    auto *layout = new QVBoxLayout(this);
+    layout->addWidget(view);
+    layout->addWidget(logViewer);
+
+    setWindowTitle(tr("Fetch More Example"));
+}
+
+void Window::updateLog(const QString &path, int start, int number, int total)
+{
+    const int last = start + number - 1;
+    const QString nativePath = QDir::toNativeSeparators(path);
+    const QString message = tr("%1..%2/%3 items from \"%4\" added.")
+                            .arg(start).arg(last).arg(total).arg(nativePath);
+    logViewer->appendPlainText(message);
+}
+
+void Window::activated(const QModelIndex &index)
+{
+    const QFileInfo fi = model->fileInfoAt(index);
+    if (fi.isDir()) {
+        logViewer->clear();
+        model->setDirPath(fi.absoluteFilePath());
+    }
+}

examples/widgets/itemviews/fetchmore/window.h

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+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#ifndef WINDOW_H
+#define WINDOW_H
+
+#include <QWidget>
+
+QT_BEGIN_NAMESPACE
+class QModelIndex;
+class QListView;
+class QPlainTextEdit;
+QT_END_NAMESPACE
+
+class FileListModel;
+
+class Window : public QWidget
+{
+    Q_OBJECT
+
+public:
+    Window(QWidget *parent = nullptr);
+
+public slots:
+    void updateLog(const QString &path, int start, int number, int total);
+    void activated(const QModelIndex &);
+
+private:
+    QPlainTextEdit *logViewer;
+    FileListModel *model;
+    QListView *view;
+};
+
+#endif // WINDOW_H