qt 6.5.1 original

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

examples/widgets/touch/knobs/doc/src/touch-knobs.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/knobs
+    \title Touch Knobs Example
+    \ingroup touchinputexamples
+    \brief Shows how to create custom controls that accept touch input.
+
+    The Touch Knobs example shows how to create custom controls that
+    accept touch input.
+
+    \image touch-knobs-example.png
+*/

examples/widgets/touch/knobs/knob.cpp

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+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include "knob.h"
+
+#include <QBrush>
+#include <QTouchEvent>
+
+Knob::Knob()
+    : QGraphicsEllipseItem(-50, -50, 100, 100)
+{
+    setAcceptTouchEvents(true);
+    setBrush(Qt::lightGray);
+
+    QGraphicsEllipseItem *leftItem = new QGraphicsEllipseItem(0, 0, 20, 20, this);
+    leftItem->setPos(-40, -10);
+    leftItem->setBrush(Qt::darkGreen);
+
+    QGraphicsEllipseItem *rightItem = new QGraphicsEllipseItem(0, 0, 20, 20, this);
+    rightItem->setPos(20, -10);
+    rightItem->setBrush(Qt::darkRed);
+}
+
+bool Knob::sceneEvent(QEvent *event)
+{
+    switch (event->type()) {
+    case QEvent::TouchBegin:
+    case QEvent::TouchUpdate:
+    case QEvent::TouchEnd:
+    {
+        QTouchEvent *touchEvent = static_cast<QTouchEvent *>(event);
+
+        if (touchEvent->points().count() == 2) {
+            const QEventPoint &touchPoint1 = touchEvent->points().first();
+            const QEventPoint &touchPoint2 = touchEvent->points().last();
+
+            QLineF line1(touchPoint1.sceneLastPosition(), touchPoint2.sceneLastPosition());
+            QLineF line2(touchPoint1.scenePosition(), touchPoint2.scenePosition());
+
+            setTransform(QTransform().rotate(line2.angleTo(line1)), true);
+        }
+
+        break;
+    }
+
+    default:
+        return QGraphicsItem::sceneEvent(event);
+    }
+
+    return true;
+}

examples/widgets/touch/knobs/knob.h

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+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#ifndef KNOB_H
+#define KNOB_H
+
+#include <QGraphicsItem>
+
+class Knob : public QGraphicsEllipseItem
+{
+public:
+    Knob();
+
+    bool sceneEvent(QEvent *event) override;
+};
+
+#endif // KNOB_H

examples/widgets/touch/knobs/knobs.pro

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+QT += widgets
+
+HEADERS = knob.h
+SOURCES = main.cpp knob.cpp
+
+# install
+target.path = $$[QT_INSTALL_EXAMPLES]/widgets/touch/knobs
+INSTALLS += target

examples/widgets/touch/knobs/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 <QGraphicsView>
+
+#include "knob.h"
+
+int main(int argc, char **argv)
+{
+    QApplication app(argc, argv);
+
+    QGraphicsScene scene;
+    QGraphicsView view(&scene);
+
+    Knob *knob1 = new Knob;
+    knob1->setPos(-110, 0);
+    Knob *knob2 = new Knob;
+
+    scene.addItem(knob1);
+    scene.addItem(knob2);
+
+    view.showMaximized();
+    view.fitInView(scene.sceneRect().adjusted(-20, -20, 20, 20), Qt::KeepAspectRatio);
+
+    return app.exec();
+}