qt 6.5.1 original

examples/widgets/touch/fingerpaint/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(fingerpaint LANGUAGES CXX)
+
+if(NOT DEFINED INSTALL_EXAMPLESDIR)
+    set(INSTALL_EXAMPLESDIR "examples")
+endif()
+
+set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/widgets/touch/fingerpaint")
+
+find_package(Qt6
+    REQUIRED COMPONENTS Core Gui Widgets
+    OPTIONAL_COMPONENTS PrintSupport
+)
+
+qt_standard_project_setup()
+
+qt_add_executable(fingerpaint
+    main.cpp
+    mainwindow.cpp mainwindow.h
+    scribblearea.cpp scribblearea.h
+)
+
+set_target_properties(fingerpaint PROPERTIES
+    WIN32_EXECUTABLE TRUE
+    MACOSX_BUNDLE TRUE
+)
+
+target_link_libraries(fingerpaint PRIVATE
+    Qt6::Core
+    Qt6::Gui
+    Qt6::Widgets
+)
+
+if (TARGET Qt6::PrintSupport)
+    target_link_libraries(fingerpaint PRIVATE Qt6::PrintSupport)
+endif()
+
+install(TARGETS fingerpaint
+    RUNTIME DESTINATION "${INSTALL_EXAMPLEDIR}"
+    BUNDLE DESTINATION "${INSTALL_EXAMPLEDIR}"
+    LIBRARY DESTINATION "${INSTALL_EXAMPLEDIR}"
+)

examples/widgets/touch/fingerpaint/doc/src/fingerpaint.qdoc

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+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
+
+/*!
+    \example touch/fingerpaint
+    \title Finger Paint Example
+    \ingroup touchinputexamples
+    \brief Shows the use of a touchscreen to make a simple painting application.
+
+    The Finger Paint example shows the use of a touchscreen with a custom widget
+    to create a simple painting application.
+
+    \image touch-fingerpaint-example.png
+
+    This example was specifically designed to work with a touchscreen, using
+    QTouchEvent instead of QMouseEvent to handle user input over the custom
+    widget. As a result, it is not possible to draw with the mouse cursor.
+*/

examples/widgets/touch/fingerpaint/fingerpaint.pro

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+QT += widgets
+requires(qtConfig(filedialog))
+qtHaveModule(printsupport): QT += printsupport
+
+HEADERS       = mainwindow.h \
+                scribblearea.h
+SOURCES       = main.cpp \
+                mainwindow.cpp \
+                scribblearea.cpp
+
+# install
+target.path = $$[QT_INSTALL_EXAMPLES]/widgets/touch/fingerpaint
+INSTALLS += target

examples/widgets/touch/fingerpaint/main.cpp

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

examples/widgets/touch/fingerpaint/mainwindow.cpp

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+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include <QtWidgets>
+
+#include "mainwindow.h"
+#include "scribblearea.h"
+
+//! [0]
+MainWindow::MainWindow()
+{
+    scribbleArea = new ScribbleArea;
+    setCentralWidget(scribbleArea);
+
+    createActions();
+    createMenus();
+
+    setWindowTitle(tr("Finger Paint"));
+    resize(500, 500);
+}
+//! [0]
+
+//! [1]
+void MainWindow::closeEvent(QCloseEvent *event)
+//! [1] //! [2]
+{
+    if (maybeSave()) {
+        event->accept();
+    } else {
+        event->ignore();
+    }
+}
+//! [2]
+
+//! [3]
+void MainWindow::open()
+//! [3] //! [4]
+{
+    if (maybeSave()) {
+        QString fileName = QFileDialog::getOpenFileName(this,
+                                   tr("Open File"), QDir::currentPath());
+        if (!fileName.isEmpty())
+            scribbleArea->openImage(fileName);
+    }
+}
+//! [4]
+
+//! [5]
+void MainWindow::save()
+//! [5] //! [6]
+{
+    QAction *action = qobject_cast<QAction *>(sender());
+    QByteArray fileFormat = action->data().toByteArray();
+    saveFile(fileFormat);
+}
+//! [6]
+
+//! [11]
+void MainWindow::about()
+//! [11] //! [12]
+{
+    QMessageBox::about(this, tr("About Scribble"),
+            tr("<p>The <b>Scribble</b> example shows how to use QMainWindow as the "
+               "base widget for an application, and how to reimplement some of "
+               "QWidget's event handlers to receive the events generated for "
+               "the application's widgets:</p><p> We reimplement the mouse event "
+               "handlers to facilitate drawing, the paint event handler to "
+               "update the application and the resize event handler to optimize "
+               "the application's appearance. In addition we reimplement the "
+               "close event handler to intercept the close events before "
+               "terminating the application.</p><p> The example also demonstrates "
+               "how to use QPainter to draw an image in real time, as well as "
+               "to repaint widgets.</p>"));
+}
+//! [12]
+
+//! [13]
+void MainWindow::createActions()
+//! [13] //! [14]
+{
+    openAct = new QAction(tr("&Open..."), this);
+    openAct->setShortcut(tr("Ctrl+O"));
+    connect(openAct, &QAction::triggered, this, &MainWindow::open);
+
+    const QList<QByteArray> imageFormats = QImageWriter::supportedImageFormats();
+    for (const QByteArray &format : imageFormats) {
+        QString text = tr("%1...").arg(QString(format).toUpper());
+
+        QAction *action = new QAction(text, this);
+        action->setData(format);
+        connect(action, &QAction::triggered, this, &MainWindow::save);
+        saveAsActs.append(action);
+    }
+
+    printAct = new QAction(tr("&Print..."), this);
+    connect(printAct, &QAction::triggered, scribbleArea, &ScribbleArea::print);
+
+    exitAct = new QAction(tr("E&xit"), this);
+    exitAct->setShortcut(tr("Ctrl+Q"));
+    connect(exitAct, &QAction::triggered, this, &QWidget::close);
+
+    clearScreenAct = new QAction(tr("&Clear Screen"), this);
+    clearScreenAct->setShortcut(tr("Ctrl+L"));
+    connect(clearScreenAct, &QAction::triggered,
+            scribbleArea, &ScribbleArea::clearImage);
+
+    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);
+}
+//! [14]
+
+//! [15]
+void MainWindow::createMenus()
+//! [15] //! [16]
+{
+    saveAsMenu = new QMenu(tr("&Save As"), this);
+    saveAsMenu->addActions(saveAsActs);
+
+    fileMenu = new QMenu(tr("&File"), this);
+    fileMenu->addAction(openAct);
+    fileMenu->addMenu(saveAsMenu);
+    fileMenu->addAction(printAct);
+    fileMenu->addSeparator();
+    fileMenu->addAction(exitAct);
+
+    optionMenu = new QMenu(tr("&Options"), this);
+    optionMenu->addAction(clearScreenAct);
+
+    helpMenu = new QMenu(tr("&Help"), this);
+    helpMenu->addAction(aboutAct);
+    helpMenu->addAction(aboutQtAct);
+
+    menuBar()->addMenu(fileMenu);
+    menuBar()->addMenu(optionMenu);
+    menuBar()->addMenu(helpMenu);
+}
+//! [16]
+
+//! [17]
+bool MainWindow::maybeSave()
+//! [17] //! [18]
+{
+    if (scribbleArea->isModified()) {
+       QMessageBox::StandardButton ret;
+       ret = QMessageBox::warning(this, tr("Scribble"),
+                          tr("The image has been modified.\n"
+                             "Do you want to save your changes?"),
+                          QMessageBox::Save | QMessageBox::Discard
+                          | QMessageBox::Cancel);
+        if (ret == QMessageBox::Save) {
+            return saveFile("png");
+        } else if (ret == QMessageBox::Cancel) {
+            return false;
+        }
+    }
+    return true;
+}
+//! [18]
+
+//! [19]
+bool MainWindow::saveFile(const QByteArray &fileFormat)
+//! [19] //! [20]
+{
+    QString initialPath = QDir::currentPath() + "/untitled." + fileFormat;
+
+    QString fileName = QFileDialog::getSaveFileName(this, tr("Save As"),
+                               initialPath,
+                               tr("%1 Files (*.%2);;All Files (*)")
+                               .arg(QString::fromLatin1(fileFormat.toUpper()))
+                               .arg(QString::fromLatin1(fileFormat)));
+    if (fileName.isEmpty()) {
+        return false;
+    } else {
+        return scribbleArea->saveImage(fileName, fileFormat.constData());
+    }
+}
+//! [20]

examples/widgets/touch/fingerpaint/mainwindow.h

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+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#ifndef MAINWINDOW_H
+#define MAINWINDOW_H
+
+#include <QList>
+#include <QMainWindow>
+
+class ScribbleArea;
+
+//! [0]
+class MainWindow : public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    MainWindow();
+
+protected:
+    void closeEvent(QCloseEvent *event) override;
+
+private slots:
+    void open();
+    void save();
+    void about();
+
+private:
+    void createActions();
+    void createMenus();
+    bool maybeSave();
+    bool saveFile(const QByteArray &fileFormat);
+
+    ScribbleArea *scribbleArea;
+
+    QMenu *saveAsMenu;
+    QMenu *fileMenu;
+    QMenu *optionMenu;
+    QMenu *helpMenu;
+
+    QAction *openAct;
+    QList<QAction *> saveAsActs;
+    QAction *exitAct;
+    QAction *printAct;
+    QAction *clearScreenAct;
+    QAction *aboutAct;
+    QAction *aboutQtAct;
+};
+//! [0]
+
+#endif

examples/widgets/touch/fingerpaint/scribblearea.cpp

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+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include <QtWidgets>
+#if defined(QT_PRINTSUPPORT_LIB)
+#include <QtPrintSupport/qtprintsupportglobal.h>
+#if QT_CONFIG(printdialog)
+#include <QPrinter>
+#include <QPrintDialog>
+#endif
+#endif
+
+#include "scribblearea.h"
+
+static const qreal MinimumDiameter = 3.0;
+static const qreal MaximumDiameter = 50.0;
+
+//! [0]
+ScribbleArea::ScribbleArea(QWidget *parent)
+    : QWidget(parent)
+{
+    setAttribute(Qt::WA_AcceptTouchEvents);
+    setAttribute(Qt::WA_StaticContents);
+    modified = false;
+
+    myPenColors
+            << QColor("green")
+            << QColor("purple")
+            << QColor("red")
+            << QColor("blue")
+            << QColor("yellow")
+
+            << QColor("pink")
+            << QColor("orange")
+            << QColor("brown")
+            << QColor("grey")
+            << QColor("black");
+}
+//! [0]
+
+//! [1]
+bool ScribbleArea::openImage(const QString &fileName)
+//! [1] //! [2]
+{
+    QImage loadedImage;
+    if (!loadedImage.load(fileName))
+        return false;
+
+    QSize newSize = loadedImage.size().expandedTo(size());
+    resizeImage(&loadedImage, newSize);
+    image = loadedImage;
+    modified = false;
+    update();
+    return true;
+}
+//! [2]
+
+//! [3]
+bool ScribbleArea::saveImage(const QString &fileName, const char *fileFormat)
+//! [3] //! [4]
+{
+    QImage visibleImage = image;
+    resizeImage(&visibleImage, size());
+
+    if (visibleImage.save(fileName, fileFormat)) {
+        modified = false;
+        return true;
+    } else {
+        return false;
+    }
+}
+//! [4]
+
+//! [9]
+void ScribbleArea::clearImage()
+//! [9] //! [10]
+{
+    image.fill(qRgb(255, 255, 255));
+    modified = true;
+    update();
+}
+//! [10]
+
+//! [12] //! [13]
+void ScribbleArea::paintEvent(QPaintEvent *event)
+//! [13] //! [14]
+{
+    QPainter painter(this);
+    const QRect rect = event->rect();
+    painter.drawImage(rect.topLeft(), image, rect);
+}
+//! [14]
+
+//! [15]
+void ScribbleArea::resizeEvent(QResizeEvent *event)
+//! [15] //! [16]
+{
+    if (width() > image.width() || height() > image.height()) {
+        int newWidth = qMax(width() + 128, image.width());
+        int newHeight = qMax(height() + 128, image.height());
+        resizeImage(&image, QSize(newWidth, newHeight));
+        update();
+    }
+    QWidget::resizeEvent(event);
+}
+//! [16]
+
+//! [19]
+void ScribbleArea::resizeImage(QImage *image, const QSize &newSize)
+//! [19] //! [20]
+{
+    if (image->size() == newSize)
+        return;
+
+    QImage newImage(newSize, QImage::Format_RGB32);
+    newImage.fill(qRgb(255, 255, 255));
+    QPainter painter(&newImage);
+    painter.drawImage(QPoint(0, 0), *image);
+    *image = newImage;
+}
+//! [20]
+
+//! [21]
+void ScribbleArea::print()
+{
+#if defined(QT_PRINTSUPPORT_LIB) && QT_CONFIG(printdialog)
+    QPrinter printer(QPrinter::HighResolution);
+
+    QPrintDialog printDialog(&printer, this);
+//! [21] //! [22]
+    if (printDialog.exec() == QDialog::Accepted) {
+        QPainter painter(&printer);
+        QRect rect = painter.viewport();
+        QSize size = image.size();
+        size.scale(rect.size(), Qt::KeepAspectRatio);
+        painter.setViewport(rect.x(), rect.y(), size.width(), size.height());
+        painter.setWindow(image.rect());
+        painter.drawImage(0, 0, image);
+    }
+#endif // QT_CONFIG(printdialog)
+}
+//! [22]
+
+bool ScribbleArea::event(QEvent *event)
+{
+    switch (event->type()) {
+    case QEvent::TouchBegin:
+    case QEvent::TouchUpdate:
+    case QEvent::TouchEnd:
+    {
+        const QTouchEvent *touch = static_cast<QTouchEvent *>(event);
+        const auto touchPoints = static_cast<QTouchEvent *>(event)->points();
+        for (const QTouchEvent::TouchPoint &touchPoint : touchPoints) {
+            switch (touchPoint.state()) {
+            case QEventPoint::Stationary:
+            case QEventPoint::Released:
+                // don't do anything if this touch point hasn't moved or has been released
+                continue;
+            default:
+                {
+                    QSizeF diams = touchPoint.ellipseDiameters();
+                    if (diams.isEmpty()) {
+                        qreal diameter = MaximumDiameter;
+                        if (touch->pointingDevice()->capabilities().testFlag(QPointingDevice::Capability::Pressure))
+                            diameter = MinimumDiameter + (MaximumDiameter - MinimumDiameter) * touchPoint.pressure();
+                        diams = QSizeF(diameter, diameter);
+                    }
+
+                    QPainter painter(&image);
+                    painter.setPen(Qt::NoPen);
+                    painter.setBrush(myPenColors.at(touchPoint.id() % myPenColors.count()));
+                    painter.drawEllipse(touchPoint.position(), diams.width() / 2, diams.height() / 2);
+                    painter.end();
+
+                    modified = true;
+                    const int rad = 2;
+                    QRectF rect(QPointF(), diams);
+                    rect.moveCenter(touchPoint.position());
+                    update(rect.toRect().adjusted(-rad,-rad, +rad, +rad));
+                }
+                break;
+            }
+        }
+        break;
+    }
+    default:
+        return QWidget::event(event);
+    }
+    return true;
+}

examples/widgets/touch/fingerpaint/scribblearea.h

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+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#ifndef SCRIBBLEAREA_H
+#define SCRIBBLEAREA_H
+
+#include <QColor>
+#include <QImage>
+#include <QPoint>
+#include <QWidget>
+
+//! [0]
+class ScribbleArea : public QWidget
+{
+    Q_OBJECT
+
+public:
+    ScribbleArea(QWidget *parent = nullptr);
+
+    bool openImage(const QString &fileName);
+    bool saveImage(const QString &fileName, const char *fileFormat);
+
+    bool isModified() const { return modified; }
+
+public slots:
+    void clearImage();
+    void print();
+
+protected:
+    void paintEvent(QPaintEvent *event) override;
+    void resizeEvent(QResizeEvent *event) override;
+    bool event(QEvent *event) override;
+
+private:
+    void resizeImage(QImage *image, const QSize &newSize);
+
+    bool modified;
+    QList<QColor> myPenColors;
+    QImage image;
+};
+//! [0]
+
+#endif