Remove echo plugin

Remove echo plugin code and documentation.

Fixes: QTBUG-119981
Change-Id: I4083ac6cdb768facaed041241af2c5ee6e28df50
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit 01bf423d67d5e6f8de5ec51a6b85178492681ca9)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

examples/widgets/doc/src/echoplugin.qdoc

@@ -1,180 +0,0 @@
-// Copyright (C) 2016 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
-
-/*!
-    \example tools/echoplugin
-    \title Echo Plugin Example
-    \examplecategory {Data Processing & I/O}
-    \ingroup examples-widgets-tools
-    \ingroup examples-layout
-
-    \brief This example shows how to create a Qt plugin.
-
-    \image echopluginexample.png
-
-    There are two kinds of plugins in Qt: plugins that extend Qt
-    itself and plugins that extend applications written in Qt. In this
-    example, we show the procedure of implementing plugins that extend
-    applications. When you create a plugin you declare an interface,
-    which is a class with only pure virtual functions. This interface
-    is inherited by the class that implements the plugin. The class is
-    stored in a shared library and can therefore be loaded by
-    applications at run-time. When loaded, the plugin is dynamically
-    cast to the interface using Qt's \l{Meta-Object
-    System}{meta-object system}. The plugin \l{How to Create Qt
-    Plugins}{overview document} gives a high-level introduction to
-    plugins.
-
-    We have implemented a plugin, the \c EchoPlugin, which implements
-    the \c EchoInterface. The interface consists of \c echo(), which
-    takes a QString as argument. The \c EchoPlugin returns the string
-    unaltered (i.e., it works as the familiar echo command found in
-    both Unix and Windows).
-
-    We test the plugin in \c EchoWindow: when you push the QPushButton
-    (as seen in the image above), the application sends the text in
-    the QLineEdit to the plugin, which echoes it back to the
-    application. The answer from the plugin is displayed in the
-    QLabel.
-
-
-    \section1 EchoWindow Class Definition
-
-    The \c EchoWindow class lets us test the \c EchoPlugin through a
-    GUI.
-
-    \snippet tools/echoplugin/echowindow/echowindow.h 0
-
-    We load the plugin in \c loadPlugin() and cast it to \c
-    EchoInterface. When the user clicks the \c button we take the
-    text in \c lineEdit and call the interface's \c echo() with it.
-
-
-    \section1 EchoWindow Class Implementation
-
-    We start with a look at the constructor:
-
-    \snippet tools/echoplugin/echowindow/echowindow.cpp 0
-
-    We create the widgets and set a title for the window. We then load
-    the plugin. \c loadPlugin() returns false if the plugin could not
-    be loaded, in which case we disable the widgets. If you wish a
-    more detailed error message, you can use
-    \l{QPluginLoader::}{errorString()}; we will look more closely at
-    QPluginLoader later.
-
-    Here is the implementation of \c sendEcho():
-
-    \snippet tools/echoplugin/echowindow/echowindow.cpp 1
-
-    This slot is called when the user pushes \c button or presses
-    enter in \c lineEdit. We call \c echo() of the echo interface. In
-    our example this is the \c EchoPlugin, but it could be any plugin
-    that inherit the \c EchoInterface. We take the QString returned
-    from \c echo() and display it in the \c label.
-
-    Here is the implementation of \c createGUI():
-
-    \snippet tools/echoplugin/echowindow/echowindow.cpp 2
-
-    We create the widgets and lay them out in a grid layout. We
-    connect the label and line edit to our \c sendEcho() slot.
-
-    Here is the \c loadPlugin() function:
-
-    \snippet tools/echoplugin/echowindow/echowindow.cpp 3
-
-    Access to plugins at run-time is provided by QPluginLoader. You
-    supply it with the filename of the shared library the plugin is
-    stored in and call \l{QPluginLoader::}{instance()}, which loads
-    and returns the root component of the plugin (i.e., it resolves
-    the type of the plugin and creates a QObject instance of it). If
-    the plugin was not successfully loaded, it will be null, so we
-    return false. If it was loaded correctly, we can cast the plugin
-    to our \c EchoInterface and return true. In the case that the
-    plugin loaded does not implement the \c EchoInterface, \c
-    instance() will return null, but this cannot happen in our
-    example. Notice that the location of the plugin is not the same
-    for all platforms.
-
-
-    \section1 EchoInterface Class Definition
-
-    The \c EchoInterface defines the functions that the plugin will
-    provide. An interface is a class that only consists of pure
-    virtual functions. If non virtual functions were present in the
-    class you would get misleading compile errors in the moc files.
-
-    \snippet tools/echoplugin/echowindow/echointerface.h 0
-
-    We declare \c echo(). In our \c EchoPlugin we use this method to
-    return, or echo, \a message.
-
-    We use the Q_DECLARE_INTERFACE macro to let \l{Meta-Object
-    System}{Qt's meta object system} aware of the interface. We do
-    this so that it will be possible to identify plugins that
-    implements the interface at run-time. The second argument is a
-    string that must identify the interface in a unique way.
-
-
-    \section1 EchoPlugin Class Definition
-
-    We inherit both QObject and \c EchoInterface to make this class a
-    plugin. The Q_INTERFACES macro tells Qt which interfaces the class
-    implements. In our case we only implement the \c EchoInterface.
-    If a class implements more than one interface, they are given as
-    a space separated list. The Q_PLUGIN_METADATA macro is included next
-    to the Q_OBJECT macro. It contains the plugins IID and a filename
-    pointing to a json file containing the metadata for the plugin.
-    The json file is compiled into the plugin and does not need to be installed.
-
-    \snippet tools/echoplugin/plugin/echoplugin.h 0
-
-    \section1 EchoPlugin Class Implementation
-
-    Here is the implementation of \c echo():
-
-    \snippet tools/echoplugin/plugin/echoplugin.cpp 0
-
-    We simply return the functions parameter.
-
-    \section1 The \c main() function
-
-    \snippet tools/echoplugin/echowindow/main.cpp 0
-
-    We create an \c EchoWindow and display it as a top-level window.
-
-    \section1 The Profiles
-
-    When creating plugins the profiles need to be adjusted.
-    We show here what changes need to be done.
-
-    The profile in the echoplugin directory uses the \c subdirs
-    template and simply includes includes to directories in which
-    the echo window and echo plugin lives:
-
-    \snippet tools/echoplugin/echoplugin.pro 0
-
-    The profile for the echo window does not need any plugin specific
-    settings. We move on to the plugin profile:
-
-    \snippet tools/echoplugin/plugin/plugin.pro 0
-
-    We need to set the TEMPLATE as we now want to make a library
-    instead of an executable. We also need to tell qmake that we are
-    creating a plugin. The \c EchoInterface that the plugin implements
-    lives in the \c echowindow directory, so we need to add that
-    directory to the include path. We set the TARGET of the project,
-    which is the name of the library file in which the plugin will be
-    stored; qmake appends the appropriate file extension depending on
-    the platform. By convention the target should have the same name
-    as the plugin (set with Q_EXPORT_PLUGIN2)
-
-    \section1 Further Reading and Examples
-
-    The \l {qtplugin-defining-plugins}{Defining Plugins} page presents an overview of the macros needed to
-    create plugins.
-
-    We give an example of a plugin that extends Qt in the \l{Style
-    Plugin Example}{style plugin} example.
-*/

examples/widgets/doc/src/styleplugin.qdoc

@@ -130,8 +130,4 @@
     In addition to the plugin \l{How to Create Qt Plugins}{overview
     document}, we have other examples and articles that concern
     plugins.
-
-    In the \l{Echo Plugin Example}{echo plugin example} we show how to
-    implement plugins that extends Qt applications rather than Qt
-    itself, which is the case with the style plugin of this example.
 */

examples/widgets/tools/CMakeLists.txt

@@ -7,7 +7,3 @@ qt_internal_add_example(regularexpression)
 qt_internal_add_example(styleplugin)
 qt_internal_add_example(treemodelcompleter)
 qt_internal_add_example(undoframework)
-
-if(QT_FEATURE_library)
-    qt_internal_add_example(echoplugin)
-endif()

examples/widgets/tools/echoplugin/CMakeLists.txt

@@ -1,18 +0,0 @@
-# Copyright (C) 2022 The Qt Company Ltd.
-# SPDX-License-Identifier: BSD-3-Clause
-
-cmake_minimum_required(VERSION 3.16)
-project(echoplugin LANGUAGES CXX)
-
-if(NOT DEFINED INSTALL_EXAMPLESDIR)
-    set(INSTALL_EXAMPLESDIR "examples")
-endif()
-
-set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/widgets/tools/echoplugin")
-
-find_package(Qt6 REQUIRED COMPONENTS Core Gui Widgets)
-
-qt_standard_project_setup()
-
-add_subdirectory(plugin)
-add_subdirectory(echowindow)

examples/widgets/tools/echoplugin/echoplugin.pro

@@ -1,5 +0,0 @@
-#! [0]
-TEMPLATE    = subdirs
-SUBDIRS	    = echowindow \
-	      plugin
-#! [0]

examples/widgets/tools/echoplugin/echowindow/CMakeLists.txt

@@ -1,35 +0,0 @@
-# Copyright (C) 2022 The Qt Company Ltd.
-# SPDX-License-Identifier: BSD-3-Clause
-
-qt_add_executable(echopluginwindow
-    echointerface.h
-    echowindow.cpp echowindow.h
-    main.cpp
-)
-
-set_target_properties(echopluginwindow PROPERTIES
-    WIN32_EXECUTABLE TRUE
-    MACOSX_BUNDLE TRUE
-)
-
-target_link_libraries(echopluginwindow PRIVATE
-    Qt6::Core
-    Qt6::Gui
-    Qt6::Widgets
-)
-
-if(QT6_IS_SHARED_LIBS_BUILD)
-    # Build the shared plugin too when building this example target.
-    add_dependencies(echopluginwindow echoplugin)
-else()
-    # Link the echoplugin if Qt is built statically.
-    target_link_libraries(echopluginwindow PRIVATE
-        echoplugin
-    )
-endif()
-
-install(TARGETS echopluginwindow
-    RUNTIME DESTINATION "${INSTALL_EXAMPLEDIR}"
-    BUNDLE DESTINATION "${INSTALL_EXAMPLEDIR}"
-    LIBRARY DESTINATION "${INSTALL_EXAMPLEDIR}"
-)

examples/widgets/tools/echoplugin/echowindow/echointerface.h

@@ -1,27 +0,0 @@
-// Copyright (C) 2016 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
-
-#ifndef ECHOINTERFACE_H
-#define ECHOINTERFACE_H
-
-#include <QObject>
-#include <QString>
-
-//! [0]
-class EchoInterface
-{
-public:
-    virtual ~EchoInterface() = default;
-    virtual QString echo(const QString &message) = 0;
-};
-
-
-QT_BEGIN_NAMESPACE
-
-#define EchoInterface_iid "org.qt-project.Qt.Examples.EchoInterface"
-
-Q_DECLARE_INTERFACE(EchoInterface, EchoInterface_iid)
-QT_END_NAMESPACE
-
-//! [0]
-#endif

examples/widgets/tools/echoplugin/echowindow/echowindow.cpp

@@ -1,90 +0,0 @@
-// Copyright (C) 2016 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
-
-#include "echowindow.h"
-
-#include <QCoreApplication>
-#include <QDir>
-#include <QLabel>
-#include <QLayout>
-#include <QLineEdit>
-#include <QMessageBox>
-#include <QPluginLoader>
-#include <QPushButton>
-
-//! [0]
-EchoWindow::EchoWindow()
-{
-    createGUI();
-    setLayout(layout);
-    setWindowTitle("Echo Plugin Example");
-
-    if (!loadPlugin()) {
-        QMessageBox::information(this, "Error", "Could not load the plugin");
-        lineEdit->setEnabled(false);
-        button->setEnabled(false);
-    }
-}
-//! [0]
-
-//! [1]
-void EchoWindow::sendEcho()
-{
-    QString text = echoInterface->echo(lineEdit->text());
-    label->setText(text);
-}
-//! [1]
-
-//! [2]
-void EchoWindow::createGUI()
-{
-    lineEdit = new QLineEdit;
-    label = new QLabel;
-    label->setFrameStyle(QFrame::Box | QFrame::Plain);
-    button = new QPushButton(tr("Send Message"));
-
-    connect(lineEdit, &QLineEdit::editingFinished,
-            this, &EchoWindow::sendEcho);
-    connect(button, &QPushButton::clicked,
-            this, &EchoWindow::sendEcho);
-
-    layout = new QGridLayout;
-    layout->addWidget(new QLabel(tr("Message:")), 0, 0);
-    layout->addWidget(lineEdit, 0, 1);
-    layout->addWidget(new QLabel(tr("Answer:")), 1, 0);
-    layout->addWidget(label, 1, 1);
-    layout->addWidget(button, 2, 1, Qt::AlignRight);
-    layout->setSizeConstraint(QLayout::SetFixedSize);
-}
-//! [2]
-
-//! [3]
-bool EchoWindow::loadPlugin()
-{
-    QDir pluginsDir(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");
-    const QStringList entries = pluginsDir.entryList(QDir::Files);
-    for (const QString &fileName : entries) {
-        QPluginLoader pluginLoader(pluginsDir.absoluteFilePath(fileName));
-        QObject *plugin = pluginLoader.instance();
-        if (plugin) {
-            echoInterface = qobject_cast<EchoInterface *>(plugin);
-            if (echoInterface)
-                return true;
-            pluginLoader.unload();
-        }
-    }
-
-    return false;
-}
-//! [3]

examples/widgets/tools/echoplugin/echowindow/echowindow.h

@@ -1,42 +0,0 @@
-// Copyright (C) 2016 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
-
-#ifndef ECHODIALOG_H
-#define ECHODIALOG_H
-
-#include <QWidget>
-
-#include "echointerface.h"
-
-QT_BEGIN_NAMESPACE
-class QString;
-class QLineEdit;
-class QLabel;
-class QPushButton;
-class QGridLayout;
-QT_END_NAMESPACE
-
-//! [0]
-class EchoWindow : public QWidget
-{
-    Q_OBJECT
-
-public:
-    EchoWindow();
-
-private slots:
-    void sendEcho();
-
-private:
-    void createGUI();
-    bool loadPlugin();
-
-    EchoInterface *echoInterface;
-    QLineEdit *lineEdit;
-    QLabel *label;
-    QPushButton *button;
-    QGridLayout *layout;
-};
-//! [0]
-
-#endif

examples/widgets/tools/echoplugin/echowindow/echowindow.pro

@@ -1,21 +0,0 @@
-QT += widgets
-
-HEADERS    = echowindow.h \
-             echointerface.h
-SOURCES    = echowindow.cpp \
-             main.cpp
-
-TARGET     = echoplugin
-QMAKE_PROJECT_NAME = echopluginwindow
-win32 {
-    CONFIG(debug, release|debug):DESTDIR = ../debug/
-    CONFIG(release, release|debug):DESTDIR = ../release/
-} else {
-    DESTDIR    = ../
-}
-
-# install
-target.path = $$[QT_INSTALL_EXAMPLES]/widgets/tools/echoplugin
-INSTALLS += target
-
-CONFIG += install_ok  # Do not cargo-cult this!

examples/widgets/tools/echoplugin/echowindow/main.cpp

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

examples/widgets/tools/echoplugin/plugin/CMakeLists.txt

@@ -1,26 +0,0 @@
-# Copyright (C) 2022 The Qt Company Ltd.
-# SPDX-License-Identifier: BSD-3-Clause
-
-qt_add_plugin(echoplugin
-    CLASS_NAME EchoPlugin
-    echoplugin.cpp echoplugin.h
-)
-
-set_target_properties(echoplugin PROPERTIES
-    LIBRARY_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/echowindow"
-)
-
-target_include_directories(echoplugin PRIVATE
-    ../echowindow
-)
-
-target_link_libraries(echoplugin PRIVATE
-    Qt6::Core
-    Qt6::Gui
-    Qt6::Widgets
-)
-
-install(TARGETS echoplugin
-    RUNTIME DESTINATION "${INSTALL_EXAMPLEDIR}"
-    LIBRARY DESTINATION "${INSTALL_EXAMPLEDIR}"
-)

examples/widgets/tools/echoplugin/plugin/echoplugin.cpp

@@ -1,11 +0,0 @@
-// Copyright (C) 2016 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
-
-#include "echoplugin.h"
-
-//! [0]
-QString EchoPlugin::echo(const QString &message)
-{
-    return message;
-}
-//! [0]

examples/widgets/tools/echoplugin/plugin/echoplugin.h

@@ -1,23 +0,0 @@
-// Copyright (C) 2016 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
-
-#ifndef ECHOPLUGIN_H
-#define ECHOPLUGIN_H
-
-#include <QObject>
-#include <QtPlugin>
-#include "echointerface.h"
-
-//! [0]
-class EchoPlugin : public QObject, EchoInterface
-{
-    Q_OBJECT
-    Q_PLUGIN_METADATA(IID "org.qt-project.Qt.Examples.EchoInterface" FILE "echoplugin.json")
-    Q_INTERFACES(EchoInterface)
-
-public:
-    QString echo(const QString &message) override;
-};
-//! [0]
-
-#endif

examples/widgets/tools/echoplugin/plugin/echoplugin.json

@@ -1 +0,0 @@
-{}

examples/widgets/tools/echoplugin/plugin/plugin.pro

@@ -1,18 +0,0 @@
-#! [0]
-TEMPLATE        = lib
-CONFIG         += plugin
-QT             += widgets
-INCLUDEPATH    += ../echowindow
-HEADERS         = echoplugin.h
-SOURCES         = echoplugin.cpp
-TARGET          = $$qtLibraryTarget(echoplugin)
-DESTDIR         = ../plugins
-#! [0]
-
-EXAMPLE_FILES = echoplugin.json
-
-# install
-target.path = $$[QT_INSTALL_EXAMPLES]/widgets/tools/echoplugin/plugins
-INSTALLS += target
-
-CONFIG += install_ok  # Do not cargo-cult this!

examples/widgets/tools/tools.pro

@@ -2,13 +2,8 @@ TEMPLATE      = subdirs
 SUBDIRS       = \
                 completer \
                 customcompleter \
-                echoplugin \
                 regularexpression \
                 styleplugin \
                 treemodelcompleter \
                 undoframework
 
-!qtConfig(library) {
-    SUBDIRS -= \
-        echoplugin
-}

src/corelib/plugin/qpluginloader.cpp

@@ -71,7 +71,7 @@ using namespace Qt::StringLiterals;
     link to plugins statically. You can use QLibrary if you need to
     load dynamic libraries in a statically linked application.
 
-    \sa QLibrary, {Echo Plugin Example}
+    \sa QLibrary
 */
 
 static constexpr QLibrary::LoadHints defaultLoadHints = QLibrary::PreventUnloadHint;