正确的方法来复制QMimeData对象 [英] Proper way to copy a QMimeData object

问题描述

我正在开发一个Qt应用程序，以存储剪贴板中的所有内容，以便以后恢复.我的方法是从 QApplication:中检索 QMimeData :剪贴板()并将其存储在 QList< QMimeData *> 中.由于剪贴板中的数据易变，因此我必须复制 QClipboard :: mimeData()返回的QMimeData.没有QMimeData的复制构造函数，所以我认为我会像这样复制它:

I am developing a Qt application to store whatever goes through the clipboard so I can restore it later. My approach was to retrieve the QMimeData from the QApplication::clipboard() and store it in a QList<QMimeData *>. As the data in the clipboard is volatile, I have to copy the QMimeData returned by QClipboard::mimeData(). There is no copy constructor for QMimeData so I figured that I would copy it like this :

const QMimeData * clipboardData = _clipboard->mimeData();
QMimeData * mimeCopy = new QMimeData();

foreach(const QString & format, clipboardData->formats())
    mimeCopy->setData(format, clipboardData->data(format))

其中 _clipboard 是 QApplication :: clipboard().

除了某些特定于应用程序的MIME类型之外，此方法工作得还不错.例如，我注意到当我在Skype对话中复制，还原然后粘贴Skype消息时，该消息不再被引用".这是否证明我的副本有缺陷?有没有更好，更准确的方法来复制QMimeData?

This works relatively fine except for some application-specific MIME types. For example, I noticed that when I copy, restore and then paste a Skype message in a Skype conversation, the message is not "quoted" anymore. Does This proves that my copy is flawed ? Is there a better, more accurate way to copy QMimeData ?

经过一些调试，我发现Skype消息mimedata中有两种格式.包含消息本身文本的 Text/Plain 类型和包含一些类似xml的 application/x-qt-windows-mime; value ="SkypeMessageFragment" 类型数据. Qt关于MIME类型的文档指示 value ="..." 描述数据的编码方式.为了使QMimeData的副本有效，我是否必须在某些时候进行编码或解码?

After some debugging, I found out that there are two formats in a Skype message mimedata. A Text/Plain type containing the text of the message itself and a application/x-qt-windows-mime;value="SkypeMessageFragment" type which contains some xml-like data. Qt's documentation on MIME types indicates that the value="..." describes how the data is encoded. Do I have to encode or decode something at some point to make my QMimeData's copy valid ?

推荐答案

对于自定义MIME类型(例如 application/x-qt-windows-mime; value ="SomeValue" )，实际格式名称为实际上是 SomeValue (在两个引号之间 value = 之后是什么).

For custom MIME types like application/x-qt-windows-mime;value="SomeValue", the real format name is in fact SomeValue (what is after value=, between the two quotes).

复制QMimeData对象的更准确方法如下:

A more accurate way to copy a QMimeData object would then be something like this :

QMimeData * copyMimeData(const QMimeData * mimeReference)
{
    QMimeData * mimeCopy = new QMimeData();

    foreach(QString format, mimeReference->formats())
    {
        // Retrieving data
        QByteArray data = mimeReference->data(format);
        // Checking for custom MIME types
        if(format.startsWith("application/x-qt"))
        {
            // Retrieving true format name
            int indexBegin = format.indexOf('"') + 1;
            int indexEnd = format.indexOf('"', indexBegin);
            format = format.mid(indexBegin, indexEnd - indexBegin);
        }
        mimeCopy->setData(format, data);
    }

    return mimeCopy;
}

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