qt 6.5.1 original

examples/widgets/tools/plugandpaint/app/CMakeLists.txt

@@ -0,0 +1,36 @@
+# Copyright (C) 2022 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+qt_add_executable(plugandpaint
+    interfaces.h
+    main.cpp
+    mainwindow.cpp mainwindow.h
+    paintarea.cpp paintarea.h
+    plugindialog.cpp plugindialog.h
+)
+
+set_target_properties(plugandpaint PROPERTIES
+    WIN32_EXECUTABLE TRUE
+    MACOSX_BUNDLE TRUE
+)
+
+target_link_libraries(plugandpaint PRIVATE
+    Qt6::Widgets
+    pnp_basictools
+)
+
+if(QT6_IS_SHARED_LIBS_BUILD)
+    # Build the shared plugin too when building this example target.
+    add_dependencies(plugandpaint pnp_extrafilters)
+else()
+    # Link the extrafilters plugin if Qt is built statically.
+    target_link_libraries(plugandpaint PRIVATE
+        pnp_extrafilters
+    )
+endif()
+
+install(TARGETS plugandpaint
+    RUNTIME DESTINATION "${INSTALL_EXAMPLEDIR}"
+    BUNDLE DESTINATION "${INSTALL_EXAMPLEDIR}"
+    LIBRARY DESTINATION "${INSTALL_EXAMPLEDIR}"
+)

examples/widgets/tools/plugandpaint/app/app.pro

@@ -0,0 +1,37 @@
+#! [0]
+TARGET = plugandpaint
+DESTDIR = ..
+
+QT += widgets
+
+HEADERS        = interfaces.h \
+                 mainwindow.h \
+                 paintarea.h \
+                 plugindialog.h
+SOURCES        = main.cpp \
+                 mainwindow.cpp \
+                 paintarea.cpp \
+                 plugindialog.cpp
+
+LIBS           = -L../plugins
+
+macx-xcode {
+    LIBS += -lpnp_basictools$($${QMAKE_XCODE_LIBRARY_SUFFIX_SETTING})
+} else {
+    android {
+        LIBS += -lpnp_basictools_$${QT_ARCH}
+    } else {
+        LIBS += -lpnp_basictools
+    }
+    if(!debug_and_release|build_pass):CONFIG(debug, debug|release) {
+        mac:LIBS = $$member(LIBS, 0) $$member(LIBS, 1)_debug
+        win32:LIBS = $$member(LIBS, 0) $$member(LIBS, 1)d
+    }
+}
+#! [0]
+
+# install
+target.path = $$[QT_INSTALL_EXAMPLES]/widgets/tools/plugandpaint
+INSTALLS += target
+
+CONFIG += install_ok  # Do not cargo-cult this!

examples/widgets/tools/plugandpaint/app/interfaces.h

@@ -0,0 +1,76 @@
+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#ifndef INTERFACES_H
+#define INTERFACES_H
+
+#include <QtPlugin>
+
+QT_BEGIN_NAMESPACE
+class QImage;
+class QPainter;
+class QWidget;
+class QPainterPath;
+class QPoint;
+class QRect;
+class QString;
+QT_END_NAMESPACE
+
+//! [0]
+class BrushInterface
+{
+public:
+    virtual ~BrushInterface() = default;
+
+    virtual QStringList brushes() const = 0;
+    virtual QRect mousePress(const QString &brush, QPainter &painter,
+                             const QPoint &pos) = 0;
+    virtual QRect mouseMove(const QString &brush, QPainter &painter,
+                            const QPoint &oldPos, const QPoint &newPos) = 0;
+    virtual QRect mouseRelease(const QString &brush, QPainter &painter,
+                               const QPoint &pos) = 0;
+};
+//! [0]
+
+//! [1]
+class ShapeInterface
+{
+public:
+    virtual ~ShapeInterface() = default;
+
+    virtual QStringList shapes() const = 0;
+    virtual QPainterPath generateShape(const QString &shape,
+                                       QWidget *parent) = 0;
+};
+//! [1]
+
+//! [2]
+class FilterInterface
+{
+public:
+    virtual ~FilterInterface() = default;
+
+    virtual QStringList filters() const = 0;
+    virtual QImage filterImage(const QString &filter, const QImage &image,
+                               QWidget *parent) = 0;
+};
+//! [2]
+
+QT_BEGIN_NAMESPACE
+//! [3] //! [4]
+#define BrushInterface_iid "org.qt-project.Qt.Examples.PlugAndPaint.BrushInterface/1.0"
+
+Q_DECLARE_INTERFACE(BrushInterface, BrushInterface_iid)
+//! [3]
+
+#define ShapeInterface_iid  "org.qt-project.Qt.Examples.PlugAndPaint.ShapeInterface/1.0"
+
+Q_DECLARE_INTERFACE(ShapeInterface, ShapeInterface_iid)
+//! [5]
+#define FilterInterface_iid "org.qt-project.Qt.Examples.PlugAndPaint.FilterInterface/1.0"
+
+Q_DECLARE_INTERFACE(FilterInterface, FilterInterface_iid)
+//! [4] //! [5]
+QT_END_NAMESPACE
+
+#endif

examples/widgets/tools/plugandpaint/app/main.cpp

@@ -0,0 +1,19 @@
+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+//! [0]
+#include "mainwindow.h"
+
+#include <QApplication>
+#include <QtPlugin>
+
+Q_IMPORT_PLUGIN(BasicToolsPlugin)
+
+int main(int argc, char *argv[])
+{
+    QApplication app(argc, argv);
+    MainWindow window;
+    window.show();
+    return app.exec();
+}
+//! [0]

examples/widgets/tools/plugandpaint/app/mainwindow.cpp

@@ -0,0 +1,282 @@
+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+
+#include "mainwindow.h"
+#include "interfaces.h"
+#include "paintarea.h"
+#include "plugindialog.h"
+
+#include <QAction>
+#include <QActionGroup>
+#include <QApplication>
+#include <QColorDialog>
+#include <QFileDialog>
+#include <QInputDialog>
+#include <QMenu>
+#include <QMenuBar>
+#include <QMessageBox>
+#include <QPluginLoader>
+#include <QScrollArea>
+#include <QTimer>
+
+MainWindow::MainWindow() : paintArea(new PaintArea)
+    , scrollArea(new QScrollArea)
+{
+    scrollArea->setBackgroundRole(QPalette::Dark);
+    scrollArea->setWidget(paintArea);
+    setCentralWidget(scrollArea);
+
+    createActions();
+    createMenus();
+    loadPlugins();
+
+    setWindowTitle(tr("Plug & Paint"));
+
+    if (!brushActionGroup->actions().isEmpty())
+        brushActionGroup->actions().first()->trigger();
+
+    QTimer::singleShot(500, this, &MainWindow::aboutPlugins);
+}
+
+void MainWindow::open()
+{
+    const QString fileName = QFileDialog::getOpenFileName(this,
+                                                          tr("Open File"),
+                                                          QDir::currentPath());
+    if (!fileName.isEmpty()) {
+        if (!paintArea->openImage(fileName)) {
+            QMessageBox::information(this, tr("Plug & Paint"),
+                                     tr("Cannot load %1.").arg(fileName));
+            return;
+        }
+        paintArea->adjustSize();
+    }
+}
+
+bool MainWindow::saveAs()
+{
+    const QString initialPath = QDir::currentPath() + "/untitled.png";
+
+    const QString fileName = QFileDialog::getSaveFileName(this, tr("Save As"),
+                                                          initialPath);
+    if (fileName.isEmpty())
+        return false;
+
+    return paintArea->saveImage(fileName, "png");
+}
+
+void MainWindow::brushColor()
+{
+    const QColor newColor = QColorDialog::getColor(paintArea->brushColor());
+    if (newColor.isValid())
+        paintArea->setBrushColor(newColor);
+}
+
+void MainWindow::brushWidth()
+{
+    bool ok;
+    const int newWidth = QInputDialog::getInt(this, tr("Plug & Paint"),
+                                              tr("Select brush width:"),
+                                              paintArea->brushWidth(),
+                                              1, 50, 1, &ok);
+    if (ok)
+        paintArea->setBrushWidth(newWidth);
+}
+
+//! [0]
+void MainWindow::changeBrush()
+{
+    auto action = qobject_cast<QAction *>(sender());
+    if (!action)
+      return;
+    auto iBrush = qobject_cast<BrushInterface *>(action->parent());
+    if (!iBrush)
+      return;
+    const QString brush = action->text();
+
+    paintArea->setBrush(iBrush, brush);
+}
+//! [0]
+
+//! [1]
+void MainWindow::insertShape()
+{
+    auto action = qobject_cast<QAction *>(sender());
+    if (!action)
+      return;
+    auto iShape = qobject_cast<ShapeInterface *>(action->parent());
+    if (!iShape)
+      return;
+
+    const QPainterPath path = iShape->generateShape(action->text(), this);
+    if (!path.isEmpty())
+        paintArea->insertShape(path);
+}
+//! [1]
+
+//! [2]
+void MainWindow::applyFilter()
+{
+    auto action = qobject_cast<QAction *>(sender());
+    if (!action)
+      return;
+    auto iFilter = qobject_cast<FilterInterface *>(action->parent());
+    if (!iFilter)
+      return;
+
+    const QImage image = iFilter->filterImage(action->text(), paintArea->image(),
+                                              this);
+    paintArea->setImage(image);
+}
+//! [2]
+
+void MainWindow::about()
+{
+   QMessageBox::about(this, tr("About Plug & Paint"),
+            tr("The <b>Plug & Paint</b> example demonstrates how to write Qt "
+               "applications that can be extended through plugins."));
+}
+
+//! [3]
+void MainWindow::aboutPlugins()
+{
+    PluginDialog dialog(pluginsDir.path(), pluginFileNames, this);
+    dialog.exec();
+}
+//! [3]
+
+void MainWindow::createActions()
+{
+    openAct = new QAction(tr("&Open..."), this);
+    openAct->setShortcuts(QKeySequence::Open);
+    connect(openAct, &QAction::triggered, this, &MainWindow::open);
+
+    saveAsAct = new QAction(tr("&Save As..."), this);
+    saveAsAct->setShortcuts(QKeySequence::SaveAs);
+    connect(saveAsAct, &QAction::triggered, this, &MainWindow::saveAs);
+
+    exitAct = new QAction(tr("E&xit"), this);
+    exitAct->setShortcuts(QKeySequence::Quit);
+    connect(exitAct, &QAction::triggered, this, &MainWindow::close);
+
+    brushColorAct = new QAction(tr("&Brush Color..."), this);
+    connect(brushColorAct, &QAction::triggered, this, &MainWindow::brushColor);
+
+    brushWidthAct = new QAction(tr("&Brush Width..."), this);
+    connect(brushWidthAct, &QAction::triggered, this, &MainWindow::brushWidth);
+
+    brushActionGroup = new QActionGroup(this);
+
+    aboutAct = new QAction(tr("&About"), this);
+    connect(aboutAct, &QAction::triggered, this, &MainWindow::about);
+
+    aboutQtAct = new QAction(tr("About &Qt"), this);
+    connect(aboutQtAct, &QAction::triggered, qApp, &QApplication::aboutQt);
+
+    aboutPluginsAct = new QAction(tr("About &Plugins"), this);
+    connect(aboutPluginsAct, &QAction::triggered, this, &MainWindow::aboutPlugins);
+}
+
+void MainWindow::createMenus()
+{
+    fileMenu = menuBar()->addMenu(tr("&File"));
+    fileMenu->addAction(openAct);
+    fileMenu->addAction(saveAsAct);
+    fileMenu->addSeparator();
+    fileMenu->addAction(exitAct);
+
+    brushMenu = menuBar()->addMenu(tr("&Brush"));
+    brushMenu->addAction(brushColorAct);
+    brushMenu->addAction(brushWidthAct);
+    brushMenu->addSeparator();
+
+    shapesMenu = menuBar()->addMenu(tr("&Shapes"));
+
+    filterMenu = menuBar()->addMenu(tr("&Filter"));
+
+    menuBar()->addSeparator();
+
+    helpMenu = menuBar()->addMenu(tr("&Help"));
+    helpMenu->addAction(aboutAct);
+    helpMenu->addAction(aboutQtAct);
+    helpMenu->addAction(aboutPluginsAct);
+}
+
+//! [4]
+void MainWindow::loadPlugins()
+{
+    const auto staticInstances = QPluginLoader::staticInstances();
+    for (QObject *plugin : staticInstances)
+        populateMenus(plugin);
+//! [4] //! [5]
+
+    pluginsDir = QDir(QCoreApplication::applicationDirPath());
+
+#if defined(Q_OS_WIN)
+    if (pluginsDir.dirName().toLower() == "debug" || pluginsDir.dirName().toLower() == "release")
+        pluginsDir.cdUp();
+#elif defined(Q_OS_MAC)
+    if (pluginsDir.dirName() == "MacOS") {
+        pluginsDir.cdUp();
+        pluginsDir.cdUp();
+        pluginsDir.cdUp();
+    }
+#endif
+    pluginsDir.cd("plugins");
+//! [5]
+
+//! [6]
+    const auto entryList = pluginsDir.entryList(QDir::Files);
+    for (const QString &fileName : entryList) {
+        QPluginLoader loader(pluginsDir.absoluteFilePath(fileName));
+        QObject *plugin = loader.instance();
+        if (plugin) {
+            populateMenus(plugin);
+            pluginFileNames += fileName;
+//! [6] //! [7]
+        }
+//! [7] //! [8]
+    }
+//! [8]
+
+//! [9]
+    brushMenu->setEnabled(!brushActionGroup->actions().isEmpty());
+    shapesMenu->setEnabled(!shapesMenu->actions().isEmpty());
+    filterMenu->setEnabled(!filterMenu->actions().isEmpty());
+}
+//! [9]
+
+//! [10]
+void MainWindow::populateMenus(QObject *plugin)
+{
+    auto iBrush = qobject_cast<BrushInterface *>(plugin);
+    if (iBrush)
+        addToMenu(plugin, iBrush->brushes(), brushMenu, &MainWindow::changeBrush,
+                  brushActionGroup);
+
+    auto iShape = qobject_cast<ShapeInterface *>(plugin);
+    if (iShape)
+        addToMenu(plugin, iShape->shapes(), shapesMenu, &MainWindow::insertShape);
+
+    auto iFilter = qobject_cast<FilterInterface *>(plugin);
+    if (iFilter)
+        addToMenu(plugin, iFilter->filters(), filterMenu, &MainWindow::applyFilter);
+}
+//! [10]
+
+void MainWindow::addToMenu(QObject *plugin, const QStringList &texts,
+                           QMenu *menu, Member member,
+                           QActionGroup *actionGroup)
+{
+    for (const QString &text : texts) {
+        auto action = new QAction(text, plugin);
+        connect(action, &QAction::triggered, this, member);
+        menu->addAction(action);
+
+        if (actionGroup) {
+            action->setCheckable(true);
+            actionGroup->addAction(action);
+        }
+    }
+}

examples/widgets/tools/plugandpaint/app/mainwindow.h

@@ -0,0 +1,68 @@
+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#ifndef MAINWINDOW_H
+#define MAINWINDOW_H
+
+#include <QDir>
+#include <QMainWindow>
+#include <QStringList>
+
+QT_BEGIN_NAMESPACE
+class QAction;
+class QActionGroup;
+class QMenu;
+class QScrollArea;
+QT_END_NAMESPACE
+class PaintArea;
+
+class MainWindow : public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    MainWindow();
+
+private slots:
+    void open();
+    bool saveAs();
+    void brushColor();
+    void brushWidth();
+    void changeBrush();
+    void insertShape();
+    void applyFilter();
+    void about();
+    void aboutPlugins();
+
+private:
+    typedef void (MainWindow::*Member)();
+
+    void createActions();
+    void createMenus();
+    void loadPlugins();
+    void populateMenus(QObject *plugin);
+    void addToMenu(QObject *plugin, const QStringList &texts, QMenu *menu,
+                   Member member, QActionGroup *actionGroup = nullptr);
+
+    PaintArea *paintArea = nullptr;
+    QScrollArea *scrollArea = nullptr;
+    QDir pluginsDir;
+    QStringList pluginFileNames;
+
+    QMenu *fileMenu = nullptr;
+    QMenu *brushMenu = nullptr;
+    QMenu *shapesMenu = nullptr;
+    QMenu *filterMenu = nullptr;
+    QMenu *helpMenu = nullptr;
+    QActionGroup *brushActionGroup = nullptr;
+    QAction *openAct = nullptr;
+    QAction *saveAsAct = nullptr;
+    QAction *exitAct = nullptr;
+    QAction *brushWidthAct = nullptr;
+    QAction *brushColorAct = nullptr;
+    QAction *aboutAct = nullptr;
+    QAction *aboutQtAct = nullptr;
+    QAction *aboutPluginsAct = nullptr;
+};
+
+#endif

examples/widgets/tools/plugandpaint/app/paintarea.cpp

@@ -0,0 +1,152 @@
+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+
+#include "paintarea.h"
+#include "interfaces.h"
+
+#include <QMouseEvent>
+#include <QPainter>
+
+PaintArea::PaintArea(QWidget *parent) : QWidget(parent)
+{
+    setAttribute(Qt::WA_StaticContents);
+    setAttribute(Qt::WA_OpaquePaintEvent);
+
+    theImage.fill(qRgb(255, 255, 255));
+}
+
+bool PaintArea::openImage(const QString &fileName)
+{
+    QImage image;
+    if (!image.load(fileName))
+        return false;
+
+    setImage(image);
+    return true;
+}
+
+bool PaintArea::saveImage(const QString &fileName, const char *fileFormat)
+{
+    return theImage.save(fileName, fileFormat);
+}
+
+void PaintArea::setImage(const QImage &image)
+{
+    theImage = image.convertToFormat(QImage::Format_RGB32);
+    update();
+    updateGeometry();
+}
+
+void PaintArea::insertShape(const QPainterPath &path)
+{
+    pendingPath = path;
+#ifndef QT_NO_CURSOR
+    setCursor(Qt::CrossCursor);
+#endif
+}
+
+void PaintArea::setBrushColor(const QColor &color)
+{
+    this->color = color;
+}
+
+void PaintArea::setBrushWidth(int width)
+{
+    thickness = width;
+}
+
+//! [0]
+void PaintArea::setBrush(BrushInterface *brushInterface, const QString &brush)
+{
+    this->brushInterface = brushInterface;
+    this->brush = brush;
+}
+//! [0]
+
+QSize PaintArea::sizeHint() const
+{
+    return theImage.size();
+}
+
+void PaintArea::paintEvent(QPaintEvent * /* event */)
+{
+    QPainter painter(this);
+    painter.drawImage(QPoint(0, 0), theImage);
+}
+
+void PaintArea::mousePressEvent(QMouseEvent *event)
+{
+    if (event->button() == Qt::LeftButton) {
+        if (!pendingPath.isEmpty()) {
+            QPainter painter(&theImage);
+            setupPainter(painter);
+
+            const QRectF boundingRect = pendingPath.boundingRect();
+            QLinearGradient gradient(boundingRect.topRight(),
+                                     boundingRect.bottomLeft());
+            gradient.setColorAt(0.0, QColor(color.red(), color.green(),
+                                            color.blue(), 63));
+            gradient.setColorAt(1.0, QColor(color.red(), color.green(),
+                                            color.blue(), 191));
+            painter.setBrush(gradient);
+            painter.translate(event->position().toPoint() - boundingRect.center());
+            painter.drawPath(pendingPath);
+
+            pendingPath = QPainterPath();
+#ifndef QT_NO_CURSOR
+            unsetCursor();
+#endif
+            update();
+        } else {
+            if (brushInterface) {
+                QPainter painter(&theImage);
+                setupPainter(painter);
+                const QRect rect = brushInterface->mousePress(brush, painter,
+                                                              event->position().toPoint());
+                update(rect);
+            }
+
+            lastPos = event->position().toPoint();
+        }
+    }
+}
+
+//! [1]
+void PaintArea::mouseMoveEvent(QMouseEvent *event)
+{
+    if ((event->buttons() & Qt::LeftButton) && lastPos != QPoint(-1, -1)) {
+        if (brushInterface) {
+            QPainter painter(&theImage);
+            setupPainter(painter);
+            const QRect rect = brushInterface->mouseMove(brush, painter, lastPos,
+                                                         event->position().toPoint());
+            update(rect);
+        }
+
+        lastPos = event->position().toPoint();
+    }
+}
+//! [1]
+
+void PaintArea::mouseReleaseEvent(QMouseEvent *event)
+{
+    if (event->button() == Qt::LeftButton && lastPos != QPoint(-1, -1)) {
+        if (brushInterface) {
+            QPainter painter(&theImage);
+            setupPainter(painter);
+            QRect rect = brushInterface->mouseRelease(brush, painter,
+                                                      event->position().toPoint());
+            update(rect);
+        }
+
+        lastPos = QPoint(-1, -1);
+    }
+}
+
+void PaintArea::setupPainter(QPainter &painter)
+{
+    painter.setRenderHint(QPainter::Antialiasing, true);
+    painter.setPen(QPen(color, thickness, Qt::SolidLine, Qt::RoundCap,
+                   Qt::RoundJoin));
+}

examples/widgets/tools/plugandpaint/app/paintarea.h

@@ -0,0 +1,54 @@
+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#ifndef PAINTAREA_H
+#define PAINTAREA_H
+
+#include <QColor>
+#include <QImage>
+#include <QPainterPath>
+#include <QWidget>
+
+class BrushInterface;
+
+class PaintArea : public QWidget
+{
+    Q_OBJECT
+
+public:
+    PaintArea(QWidget *parent = nullptr);
+
+    bool openImage(const QString &fileName);
+    bool saveImage(const QString &fileName, const char *fileFormat);
+    void setImage(const QImage &image);
+    void insertShape(const QPainterPath &path);
+    void setBrushColor(const QColor &color);
+    void setBrushWidth(int width);
+    void setBrush(BrushInterface *brushInterface, const QString &brush);
+
+    QImage image() const { return theImage; }
+    QColor brushColor() const { return color; }
+    int brushWidth() const { return thickness; }
+    QSize sizeHint() const override;
+
+protected:
+    void paintEvent(QPaintEvent *event) override;
+    void mousePressEvent(QMouseEvent *event) override;
+    void mouseMoveEvent(QMouseEvent *event) override;
+    void mouseReleaseEvent(QMouseEvent *event) override;
+
+private:
+    void setupPainter(QPainter &painter);
+
+    QImage theImage = {500, 400, QImage::Format_RGB32};
+    QColor color = Qt::blue;
+    int thickness = 3;
+
+    BrushInterface *brushInterface = nullptr;
+    QString brush;
+    QPoint lastPos = {-1, -1};
+
+    QPainterPath pendingPath;
+};
+
+#endif

examples/widgets/tools/plugandpaint/app/plugindialog.cpp

@@ -0,0 +1,118 @@
+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+
+#include "plugindialog.h"
+#include "interfaces.h"
+
+#include <QDir>
+#include <QGridLayout>
+#include <QHeaderView>
+#include <QLabel>
+#include <QPluginLoader>
+#include <QPushButton>
+#include <QStringList>
+#include <QTreeWidget>
+#include <QTreeWidgetItem>
+
+PluginDialog::PluginDialog(const QString &path, const QStringList &fileNames,
+                           QWidget *parent) :
+    QDialog(parent),
+    label(new QLabel),
+    treeWidget(new QTreeWidget),
+    okButton(new QPushButton(tr("OK")))
+{
+    treeWidget->setAlternatingRowColors(false);
+    treeWidget->setSelectionMode(QAbstractItemView::NoSelection);
+    treeWidget->setColumnCount(1);
+    treeWidget->header()->hide();
+
+    okButton->setDefault(true);
+
+    connect(okButton, &QAbstractButton::clicked, this, &QWidget::close);
+
+    QGridLayout *mainLayout = new QGridLayout;
+    mainLayout->setColumnStretch(0, 1);
+    mainLayout->setColumnStretch(2, 1);
+    mainLayout->addWidget(label, 0, 0, 1, 3);
+    mainLayout->addWidget(treeWidget, 1, 0, 1, 3);
+    mainLayout->addWidget(okButton, 2, 1);
+    setLayout(mainLayout);
+
+    interfaceIcon.addPixmap(style()->standardPixmap(QStyle::SP_DirOpenIcon),
+                            QIcon::Normal, QIcon::On);
+    interfaceIcon.addPixmap(style()->standardPixmap(QStyle::SP_DirClosedIcon),
+                            QIcon::Normal, QIcon::Off);
+    featureIcon.addPixmap(style()->standardPixmap(QStyle::SP_FileIcon));
+
+    setWindowTitle(tr("Plugin Information"));
+    findPlugins(path, fileNames);
+}
+
+//! [0]
+void PluginDialog::findPlugins(const QString &path,
+                               const QStringList &fileNames)
+{
+    label->setText(tr("Plug & Paint found the following plugins\n"
+                      "(looked in %1):")
+                   .arg(QDir::toNativeSeparators(path)));
+
+    const QDir dir(path);
+
+    const auto staticInstances = QPluginLoader::staticInstances();
+    for (QObject *plugin : staticInstances)
+        populateTreeWidget(plugin, tr("%1 (Static Plugin)")
+                                   .arg(plugin->metaObject()->className()));
+
+    for (const QString &fileName : fileNames) {
+        QPluginLoader loader(dir.absoluteFilePath(fileName));
+        QObject *plugin = loader.instance();
+        if (plugin)
+            populateTreeWidget(plugin, fileName);
+    }
+}
+//! [0]
+
+//! [1]
+void PluginDialog::populateTreeWidget(QObject *plugin, const QString &text)
+{
+    auto pluginItem = new QTreeWidgetItem(treeWidget);
+    pluginItem->setText(0, text);
+    pluginItem->setExpanded(true);
+
+    QFont boldFont = pluginItem->font(0);
+    boldFont.setBold(true);
+    pluginItem->setFont(0, boldFont);
+
+    if (plugin) {
+        auto iBrush = qobject_cast<BrushInterface *>(plugin);
+        if (iBrush)
+            addItems(pluginItem, "BrushInterface", iBrush->brushes());
+
+        auto iShape = qobject_cast<ShapeInterface *>(plugin);
+        if (iShape)
+            addItems(pluginItem, "ShapeInterface", iShape->shapes());
+
+        auto iFilter = qobject_cast<FilterInterface *>(plugin);
+        if (iFilter)
+            addItems(pluginItem, "FilterInterface", iFilter->filters());
+    }
+}
+//! [1]
+
+void PluginDialog::addItems(QTreeWidgetItem *pluginItem,
+                            const char *interfaceName,
+                            const QStringList &features)
+{
+    auto interfaceItem = new QTreeWidgetItem(pluginItem);
+    interfaceItem->setText(0, interfaceName);
+    interfaceItem->setIcon(0, interfaceIcon);
+
+    for (QString feature : features) {
+        if (feature.endsWith("..."))
+            feature.chop(3);
+        auto featureItem = new QTreeWidgetItem(interfaceItem);
+        featureItem->setText(0, feature);
+        featureItem->setIcon(0, featureIcon);
+    }
+}

examples/widgets/tools/plugandpaint/app/plugindialog.h

@@ -0,0 +1,38 @@
+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#ifndef PLUGINDIALOG_H
+#define PLUGINDIALOG_H
+
+#include <QDialog>
+#include <QIcon>
+
+QT_BEGIN_NAMESPACE
+class QLabel;
+class QPushButton;
+class QTreeWidget;
+class QTreeWidgetItem;
+QT_END_NAMESPACE
+
+class PluginDialog : public QDialog
+{
+    Q_OBJECT
+
+public:
+    PluginDialog(const QString &path, const QStringList &fileNames,
+                 QWidget *parent = nullptr);
+
+private:
+    void findPlugins(const QString &path, const QStringList &fileNames);
+    void populateTreeWidget(QObject *plugin, const QString &text);
+    void addItems(QTreeWidgetItem *pluginItem, const char *interfaceName,
+                  const QStringList &features);
+
+    QLabel *label = nullptr;
+    QTreeWidget *treeWidget = nullptr;
+    QPushButton *okButton = nullptr;
+    QIcon interfaceIcon;
+    QIcon featureIcon;
+};
+
+#endif