將格式化文本從 QML 傳遞到 C++

Question

I have a simple pdf generator in my QML app, which uses C++ to receive a signal and write my PDF document to the device - when using a sample TestHtml.html document in the resources prints as intended, but I'm struggling to be able直接從 QML 頁面發送自定義 HTML 格式的文本。

我想做的事

我的reportPage.qml顯示不同的數據/信息，當我單擊“下載”按鈕時，它會將這些格式化的數據發送到 C++ 以打印到 PDF，（C++不是我的強項）

我試過的

• 使用QIODevice write .html文件，根據需要有效刪除/重寫數據
• 使用 QString 將我的文本從reportPage.qml作為字符串傳遞
• 使用 QVariant 將我的 html 存儲為數組並從reportPage.qml

我唯一的問題是，c++ 不是我的強項，我得到的只是我的pdf.cpp中的錯誤，例如未聲明的標識符，沒有匹配的成員 ZC1C425268E68385D1AB5074C17A94F14 等等

我的問題是

What is the best way to pass formatted html text using signals/slots form QML to C++ to print as a pdf using my pdf printer shown in the code below?

目前，我的代碼的簡化部分是：

reportPage.qml

import Felgo 3.0
import com.allbookd.pdf 1.0
import QtQuick.Controls 1.2

Page {
    id: reportPage

    MyPdf {
        id: pdf
    }
    AppButton {
        text: "download"
        var htmlData = "<b>Hello</b> World 
                        <ul>
                            <li>Coffee</li>
                            <li>Tea</li>
                            <li>Milk</li>
                        </ul>"
        onClicked: { pdf.saveInvoice(htmlData); }
    }
}

pdf.h

#ifndef PDF_H
#define PDF_H

#include <QObject>
#include <QDebug>
#include <QPainter>
#include <QTextDocument>
#include <QPdfWriter>
#include <QDate>
#include <QStandardPaths>
#include <QPrinter>
#include <QFile>

class pdf : public QObject
{
    Q_OBJECT
public:
    explicit pdf(QObject *parent = nullptr);

    void setCurrentDate();
    QString getCurrentDate() const;

signals:

    void invoiceSaved(int error);

public slots:
    QString getPdfPath() const;
    void saveInvoice();

private:
    QString currentDate;
    QString pdfPath;
};

#endif // PDF_H

pdf.cpp

pdf::pdf(QObject *parent) : QObject(parent)
{
    setCurrentDate();
    QString path = QStandardPaths::writableLocation(QStandardPaths::DocumentsLocation);
    pdfPath = path + "/invoice_" + getCurrentDate() + ".pdf";
}

void pdf::setCurrentDate()
{
    QDate date(QDate::currentDate());
    int day = date.day();
    int month = date.month();
    int year =  date.year();

    currentDate = QString::number(day) + "_" + QString::number(month) + "_" + QString::number(year);
}

QString pdf::getCurrentDate() const
{
    return currentDate;
}

QString pdf::getPdfPath() const
{
    return pdfPath;
}


void pdf::saveInvoice(QString htmlData)
{
    int error = 0;
    QPdfWriter pdfWriter(getPdfPath());

    pdfWriter.setPageSize(QPageSize(QPageSize::A4));

    QPainter painter(&pdfWriter);

    painter.scale(15.0, 15.0);

    QFile file(":/htmlcode.html");    //the HTML file from resources

    if(file.open(QIODevice::ReadWrite)) {
        QByteArray temp = file.readAll();   //read it all

        QString html = temp;                //convert it to QString
        QTextDocument doc;
        doc.setHtml(html);                  //set it as HTML

        doc.drawContents(&painter);         

    } else {
        qDebug() << "error: " << file.error();
        error = 1;
    }
    emit invoiceSaved(error);

}

Answer 1

您可以將pdf class 暴露給 QML。 使函數 Q_INVOKABLE 能夠直接從 QML 調用它們，甚至更好地使用 Q_PROPERTY

Q_INVOKABLE的文檔Q_PROPERTY的文檔

這是一個例子：

在main.cpp中注冊/公開您的 pdf class 到 qml

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include "pdf.h"

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    QGuiApplication app(argc, argv);

    qmlRegisterType<pdf>("com.allbookd.pdf", 1, 0, "PdfPrinter");
    QQmlApplicationEngine engine;    
    ............

    return app.exec();
}

使saveInvoice function 在pdf.h中可調用：

#include <QObject>

class pdf : public QObject
{
    Q_OBJECT
public:
    explicit pdf(QObject *parent = nullptr);

    void setCurrentDate();
    QString getCurrentDate() const;

    Q_INVOKABLE void saveInvoice(QString htmlData);

    ..............

並使用 QPdfWriter 將htmlData保存到 pdf：

void pdf::saveInvoice(QString htmlData)
{
    int error = 0;
    QPdfWriter pdfWriter(getPdfPath());

    pdfWriter.setPageSize(QPageSize(QPageSize::A4));

    QPainter painter(&pdfWriter);
    painter.scale(15.0, 15.0);

    QTextDocument doc;
    doc.setHtml(htmlData);
    doc.drawContents(&painter);

    emit invoiceSaved(error);
}

您的 QML 可能看起來像這樣：

import Felgo 3.0
import com.allbookd.pdf 1.0
import QtQuick.Controls 1.2

Page {
    id: reportPage
    property PdfPrinter pdf: PdfPrinter{}

    AppButton {
        text: "download"
        var htmlData = "<b>Hello</b> World 
                        <ul>
                            <li>Coffee</li>
                            <li>Tea</li>
                            <li>Milk</li>
                        </ul>"
        onClicked: { pdf.saveInvoice(htmlData); }
    }
}