无法构建多部件QtDesigner插件

Question

我试图创建一个包含两个QtDesigner插件的单一DLL "CustomPlugins"。通过复制WorldClockPlugin示例，我能够让每个插件单独工作。但是，当我试图将它们都包含在一个DLL中时，我得到以下构建错误:

LNK2005: _qt_plugin_instance already defined in moc_qledplugin.obj

在我看来，通过使我的插件包装小部件都继承QDesignerCustomWidgetInterface，它导致_qt_plugin_instance函数的多重定义。我已经查看了moc文件和customwidget头文件(由QDesignerCustomWidgetInterface包含)，但找不到对该函数的任何引用。

QDesignerExportWidget包含在两个插件头中，QDESIGNER_WIDGET_EXPORT包含在两个小部件声明中。

是根本不可能包装两个插件在同一个DLL?还是我错过了什么?

谢谢。

代码如下:qdragabletoolboxplugin。*文件(未显示)几乎与qledplugin*文件相同。此外，qdragabletoolbox(也没有显示)的声明方式与qled相同，但显然做了一些非常不同的事情。为了节省空间，我省略了这些文件，并用省略号替换了一些函数定义。

。支持文件:

QT          += widgets designer
QMAKE_LFLAGS += /INCREMENTAL:NO
TARGET      = $$qtLibraryTarget($$TARGET)
CONFIG     += plugin
TEMPLATE    = lib
target.path = $$[QT_INSTALL_PLUGINS]/designer
INSTALLS += target
HEADERS     = qled.h 
              qledplugin.h 
              qdragabletoolbox.h 
              qdragabletoolboxplugin.h
SOURCES     = qled.cpp 
              qledplugin.cpp 
              qdragabletoolbox.cpp 
              qdragabletoolboxplugin.cpp
RESOURCES += CustomDesignerPlugins.qrc

qled.h:

#ifndef QLED_H
#define QLED_H
#include <QWidget>
#include <QPaintEvent>
#include <QPainter>
#include <QList>
#include <QColor>
#include <QGradient>
#include <QtDesigner/QDesignerExportWidget>
class QDESIGNER_WIDGET_EXPORT QLED : public QWidget
{
    Q_OBJECT
    Q_ENUMS(ledColor)
    Q_ENUMS(ledShape)
    Q_PROPERTY(ledColor offColor READ offColor WRITE setOffColor)
    Q_PROPERTY(ledColor onColor READ onColor WRITE setOnColor)
    Q_PROPERTY(bool shadow READ shadow WRITE setShadow)
    Q_PROPERTY(ledShape shape READ shape WRITE setShape)
    Q_PROPERTY(bool value READ value WRITE setValue)
public:
    enum ledColor { Red = 0, Orange, Yellow, Green, Blue, Indigo, Violet, Black, Gray, DarkGray };
    enum ledShape { Ellipse = 0, Rectangle, Circle, Square };
    explicit QLED(QWidget *parent = NULL);
    virtual ~QLED() { /*empty*/ }
    bool value() const { return mValue; }
    ledColor onColor() const { return mOnColor; }
    ledColor offColor() const { return mOffColor; }
    ledShape shape() const { return mShape; }
    bool shadow() const { return mShadow; }
signals:
public slots:
    void setValue(bool value) { mValue = value; update(); }
    void setShape(ledShape shape) { mShape = shape; update(); }
    void setOnColor(ledColor color) { mOnColor = color; update(); }
    void setOffColor(ledColor color) { mOffColor = color; update(); }
    void setShadow(bool b) { mShadow = b; update(); }
    void toggle() { mValue = !mValue; update(); }
protected:
    void paintEvent(QPaintEvent *event);
private:
    void drawBezel(QPainter *painter);
    void drawFace(QPainter *painter);
    void drawShadow(QPainter *painter);
private:
    bool mValue;
    ledColor mOnColor;
    ledColor mOffColor;
    bool mBezel;
    float  mBezelWidth;
    ledColor mBezelColor;
    bool mShadow;
    ledShape mShape;
    QList<QColor> colors;
};
#endif

qled.cpp

#include "qled.h"
QLED::QLED(QWidget *parent)
    : QWidget(parent)
{
    ...
}
void QLED::paintEvent(QPaintEvent *event)
{
    ...
}
void QLED::drawBezel(QPainter *painter)
{
    ...
}
void QLED::drawFace(QPainter *painter)
{
    ...
}
void QLED::drawShadow(QPainter *painter)
{
    ...
}

qledplugin.h

#ifndef QLEDPLUGIN_H
#define QLEDPLUGIN_H
#include <QDesignerCustomWidgetInterface>
class QLEDPlugin : public QObject, public QDesignerCustomWidgetInterface
{
    Q_OBJECT
    Q_PLUGIN_METADATA(IID "org.qt-project.Qt.QDesignerCustomWidgetInterface" FILE "qled.json")
    Q_INTERFACES(QDesignerCustomWidgetInterface)
public:
    QLEDPlugin(QObject *parent = 0);
    bool isContainer() const;
    bool isInitialized() const;
    QIcon icon() const;
    QString domXml() const;
    QString group() const;
    QString includeFile() const;
    QString name() const;
    QString toolTip() const;
    QString whatsThis() const;
    QWidget *createWidget(QWidget *parent);
    void initialize(QDesignerFormEditorInterface *core);
private:
    bool initialized;
};
#endif

qledplugin.cpp

#include "qled.h"
#include "qledplugin.h"
#include <QtPlugin>
QLEDPlugin::QLEDPlugin(QObject *parent)
    : QObject(parent)
{
    initialized = false;
}
void QLEDPlugin::initialize(QDesignerFormEditorInterface *core)
{
    Q_UNUSED(core);
    if (initialized)
        return;
    else
        initialized = true;
}
bool QLEDPlugin::isInitialized() const
{
    return initialized;
}
QWidget *QLEDPlugin::createWidget(QWidget *parent)
{
    return new QLED(parent);
}
QString QLEDPlugin::name() const
{
    return QLatin1String("QLED");
}
QString QLEDPlugin::group() const
{
    return QLatin1String("Display Widgets");
}
QIcon QLEDPlugin::icon() const
{
    return QIcon(QLatin1String(":/QLED/LEDIcon.png"));
}
QString QLEDPlugin::toolTip() const
{
    return "Binary status indicator";
}
QString QLEDPlugin::whatsThis() const
{
    return "";
}
bool QLEDPlugin::isContainer() const
{
    return false;
}
QString QLEDPlugin::domXml() const
{
    return "<ui language="c++">n"
            " <widget class="QLED" name="qLed">n"
            "  <property name="geometry">n"
            "   <rect>n"
            "    <x>0</x>n"
            "    <y>0</y>n"
            "    <width>25</width>n"
            "    <height>25</height>n"
            "   </rect>n"
            "  </property>n"
            " </widget>n"
            "</ui>";;
}
QString QLEDPlugin::includeFile() const
{
    return QLatin1String("QtWidgets/QLED.h");
}

Answer 1

编译器错误信息给了你所有你需要的信息:你有两个小部件，但你只需要一个插件。

不实现QDesignerCustomWidgetInterface，实现QDesignerCustomWidgetCollectionInterface