Struct to bytearray and vice versa?
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I have the following structure. While drag and drop, I've to pass this struct to another widget. How can I do this?
@struct ImageData {
QString imageOption;
QImage fullImage;
QImage mirrorImage;
QImage tileImage;
QImage displayImage;
int width;
int height;
};@ -
Hi,
Qt: Make it a typedef, add the struct typedef to the Qt known variables list and (qRegisterMetaType() in the QMetaType class) past in signal/slot.
Basic C++: Typedef the type and use as a function parameter. -
so, code example accomplish this:
@struct ImageData
{
..
};Q_DECLARE_METATYPE( ImageData) //Done in the same file as the struct definition@
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This has to be handled using "QMimeData":http://qt-project.org/doc/qt-4.8/qmimedata.html . For more information about mime data and drag and drop have a look at this "article about drag and drop in Qt":http://qt-project.org/doc/qt-4.8/dnd.html#adding-new-drag-and-drop-types .
If you still have questions after reading those docs please ask them.Edit: to convert your struct to/from a bytearray you can use "QDataStream":http://qt-project.org/doc/qt-4.8/qdatastream.html . QDataStream supports QImage, QString, int and many other types ( "here":http://qt-project.org/doc/qt-4.8/datastreamformat.html is a list of all supported types ).
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[quote author="Gowtam" date="1380514057"]I solved it using Qdatastream by appending each member of struct. But, isn't there anyway to pass the complete struct directly?[/quote]
Who should know how to store the data beside you? The compiler can't do it without magic ;)
Since the struct name may not be unique and also may change over versions you also may want to store a version number with your struct to be backwards compatible for example.
You see that there can't be a auto feature such a "simple" task. -
Within your program, indeed you can.
A QByteArray can contain all the information you want. You could use it to pass it something like an index to a data structure that is accessible by everyone involved in the drag & drop operation, or you can use it to contain a quintptr. You cast a pointer to the struct instance to the quintptr, put it in your QByteArray, and on the other side of the D&D operation, you do it the other way around.
I would not, within my own application, serialize a set of images into a QByteArray just to support D&D. That seems rather wastefull.
