Styjun

The problem is that the coordinates of the window are not set correctly. Therefore, the window is moved incorrectly and errors appear:

QWindowsWindow::setGeometry: Unable to set geometry 400x400+62998+32284 on QQuickApplicationWindow_QML_0/''...

I don't know how to fix this. Here's the code:

main.qml

import QtQuick 2.12
import QtQuick.Controls 2.3
import QtQuick.Layouts 1.3

ApplicationWindow Qt.FramelessWindowHint

 Rectangle 
 width: parent.width
 height: 40
 color: "gold"

 anchors.top: parent.top

 Text 
 anchors.verticalCenter: parent.verticalCenter
 leftPadding: 8
 text: window.title
 color: "white"
 

 MouseArea 
 anchors.fill: parent

 property real lastMouseX: 0
 property real lastMouseY: 0

 onPressed: 
 lastMouseX = mouse.x
 lastMouseY = mouse.y
 
 onMouseXChanged: window.x += (mouse.x - lastMouseX)
 onMouseYChanged: window.y += (mouse.y- lastMouseY)
 
 

main.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>


int main(int argc, char *argv[])

 QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

 QGuiApplication app(argc, argv);

 QQmlApplicationEngine engine;

 engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
 if (engine.rootObjects().isEmpty())
 return -1;

 return app.exec();

Even if you manage to solve this using QML you will see that the window will move with a LOT of jitter. It's mainly because of how bindings work (asynchronously). A better approach is asking C++ for QCursor::pos()


Here's a brief way on how to do that:


In your main.qml create a MouseArea:

MouseArea 
 property var clickPos
 anchors.fill: parent
 onPressed: 
 clickPos = x: mouse.x, y: mouse.y 
 
 onPositionChanged: 
 window.x = cpp_helper_class.cursorPos().x - clickPos.x
 window.y = cpp_helper_class.cursorPos().y - clickPos.y
 

In your c++ cpp_helper_class you should have the following method:

Q_INVOKABLE QPointF cursorPos() return QCursor::pos(); 

The Q_INVOKALBE makes sure your C++ code is accessible from QML.


Also your main.cpp should contain the following:

context->setContextProperty("cpp_helper_class", &helper_class_instance);