QML C++插件dll引用

插件的创建非常简单，但是它可以复用，并且为不同的应用程序扩展类型。使用创建的插件是非常灵活的
解决方案。关于插件一个很好的例子见QmlBook-In-Chinese 中最后一章介绍的例子。

本文主要备忘生成插件dll，怎么引用。

1.创建插件 ，Library->Qt Quick 2 Extension Plugin

#ifndef MYITEM_H
#define MYITEM_H

#include <QQuickItem>

class MyItem : public QQuickItem
{
    Q_OBJECT
    Q_DISABLE_COPY(MyItem)

public:
    MyItem(QQuickItem *parent = );
    ~MyItem();    

     Q_INVOKABLE void read();

};

#endif // MYITEM_H

#include "myitem.h"
#include <QDebug>
MyItem::MyItem(QQuickItem *parent):
    QQuickItem(parent)
{
    // By default, QQuickItem does not draw anything. If you subclass
    // QQuickItem to create a visual item, you will need to uncomment the
    // following line and re-implement updatePaintNode()

    // setFlag(ItemHasContents, true);
}

MyItem::~MyItem()
{
}

void MyItem::read()
{

    qWarning() << "qml cpp plugin ";
}

#pragma once

#include <QQmlExtensionPlugin>

class QMLCPPPluginPlugin : public QQmlExtensionPlugin
{
    Q_OBJECT
    Q_PLUGIN_METADATA(IID "org.qt-project.Qt.QQmlExtensionInterface")

public:
    void registerTypes(const char *uri);
};

#include "qmlcppplugin_plugin.h"
#include "myitem.h"

#include <qqml.h>

void QMLCPPPluginPlugin::registerTypes(const char *uri)
{
    // @uri com.mycompany.qmlcomponents
    qmlRegisterType<MyItem>(uri, , , "MyItem");
}

qmldir 文件

module MyPlugin

plugin QMLCPPPlugin

编译，生成release和debug   QMLCPPPlugin.dll 和 QMLCPPPlugind.dll

2.应用

Application->Qt Quick Application

在应用程序新建文件夹DLL(DLL文件夹和QMLCPPPluginApp.pro同级目录),在DLL新建文件夹MyPlugin(此MyPlugin是qmldir文件中module).

把QMLCPPPlugin.dll ,QMLCPPPlugind.dll和qmldir复制到MyPlugin文件夹内。（D:\Test1\QMLCPPPluginApp\QMLCPPPluginApp\DLL\MyPlugin）

指定插件DLL的路径

engine.addImportPath("D:/Test1/QMLCPPPluginApp/QMLCPPPluginApp/DLL/");

如果不指定，在Qt安装文件D:\ProgramFiles\Qt\Qt580\5.8\mingw53_32\qml目录新建文件夹MyPlugin,把QMLCPPPlugin.dll ,QMLCPPPlugind.dll和qmldir复制到MyPlugin文件夹内。

#include <QGuiApplication>
#include <QQmlApplicationEngine>

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

    QQmlApplicationEngine engine;
    engine.addImportPath("D:/Test1/QMLCPPPluginApp/QMLCPPPluginApp/DLL/");
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

    return app.exec();
}

import QtQuick 2.6
import QtQuick.Window 2.2
import MyPlugin 1.0
Window {
    visible: true
    width:
    height:
    title: qsTr("Hello World")

    MainForm {
        anchors.fill: parent
        mouseArea.onClicked: {
            cppPlugin.read()
            console.log(qsTr('Clicked on background. Text: "' + textEdit.text + '"'))
        }

    }

    MyItem{
        id:cppPlugin
    }
}