将QClipboard传递给QML

Question

我试图使剪贴板对某些QML代码可用。

传递剪贴板对象似乎有效，但是我不能调用它的方法。

下面是一个QClipboard在C++中工作良好的示例，传递给QML，而在调试输出中，它仍然是一个QClipboard对象，但失去了它的功能。

main.cpp

#include <QApplication>
#include <QClipboard>
#include <QQmlApplicationEngine>
#include <qqmlcontext.h>
#include <QtQml>


int main(int argc, char *argv[]) {
    QApplication app(argc, argv);

    QQmlApplicationEngine engine;
    engine.rootContext()->setContextProperty("clipboard", QApplication::clipboard());
    qDebug() << QApplication::clipboard()->text(); // This correctly prints the copied text
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    return app.exec();
}

main.qml

import QtQuick 2.5
import QtQuick.Controls 1.3
ApplicationWindow {
    visible: true
    MouseArea {
        acceptedButtons: Qt.MiddleButton
        anchors.fill: parent
        onClicked: {
            console.log(clipboard)
            console.log(clipboard.getText())
        }
    }
}

qml.qrc

<RCC>
    <qresource prefix="/">
        <file>main.qml</file>
    </qresource>
</RCC>

test.pro

TEMPLATE = app
VERSION = 1.0

QT += qml widgets gui
QMAKE_LFLAGS += -Wl,--as-needed

SOURCES += main.cpp
RESOURCES += qml.qrc

Answer 1

如果您想从QML调用它们，QObject的函数需要是槽。QClipboard声明没有插槽，所以不能直接调用它的函数。不过，您可以创建一个代理：

qclipboardproxy.hpp

#ifndef QCLIPBOARDPROXY_HPP
#define QCLIPBOARDPROXY_HPP

#include <QObject>

class QClipboard;

class QClipboardProxy : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QString text READ text NOTIFY textChanged)
public:
    explicit QClipboardProxy(QClipboard*);

    QString text() const;

signals:
    void textChanged();

private:
    QClipboard* clipboard;
};

#endif // QCLIPBOARDPROXY_HPP

qclipboardproxy.cpp

#include "qclipboardproxy.hpp"

#include <QClipboard>

QClipboardProxy::QClipboardProxy(QClipboard* c) : clipboard(c)
{
    connect(c, &QClipboard::dataChanged, this, QClipboardProxy::textChanged)
}

QString QClipboardProxy::text()
{
    return clipboard->text();
}

和在

main.cpp

engine.rootContext()->setContextProperty("clipboard",
    new QClipboardProxy(QGuiApplication::clipboard()));

现在你可以打电话：

console.log(clipboard.text)

甚至是

someProperty: clipboard.text

Answer 2

受@krzaq解决方案的启发，您甚至可以将代理变成可实例化的QML类型。

class ClipboardProxy : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QString text READ dataText WRITE setDataText NOTIFY dataChanged)
    Q_PROPERTY(QString selectionText READ selectionText WRITE setSelectionText NOTIFY selectionChanged)
public:
    explicit ClipboardProxy(QObject *parent = 0);

    void setDataText(const QString &text);
    QString dataText() const;

    void setSelectionText(const QString &text);
    QString selectionText() const;

signals:
    void dataChanged();
    void selectionChanged();
};

ClipboardProxy::ClipboardProxy(QObject *parent)
    : QObject(parent)
{
    QClipboard *clipboard = QGuiApplication::clipboard();
    connect(clipboard, &QClipboard::dataChanged,
            this, ClipboardProxy::dataChanged);
    connect(clipboard, &QClipboard::selectionChanged,
            this, ClipboardProxy::selectionChanged);
}

void ClipboardProxy::setDataText(const QString &text)
{
    QGuiApplication::clipboard()->setText(text, QClipboard::Clipboard);
}

QString ClipboardProxy::dataText() const
{
    return QGuiApplication::clipboard()->text(QClipboard::Clipboard);
}

void ClipboardProxy::setSelectionText(const QString &text)
{
    QGuiApplication::clipboard()->setText(text, QClipboard::Selection);
}

QString ClipboardProxy::selectionText() const
{
    return QGuiApplication::clipboard()->text(QClipboard::Selection);
}

在main()中注册为类型

qmlRegisterType<ClipboardProxy>("Clipboard", 1, 0, "Clipboard");

在QML中用作类型

import QtQuick 2.4
import Clipboard 1.0

Column {
    Clipboard {
        id: clipboard

        onDataChanged: console.log("Clipboard data changed");
        onSelectionChanged: console.log("Clipboard selection changed");
    }
    Text {
        text: clipboard.text
    }
    TextInput {
        onEditingFinished: clipboard.text = text;
    }
}