I’ve learned a number of small things in the recent days. None of them is interesting enough to fly solo, so I’m combining them into a single post. Maybe one will tickle your fancy.
Quazip
I’ve moved from JSZip to QuaZIP, for better performance and stability in opening zip files. (Side effects include exposure to C++.) Here’s how you open a file in a zip file in QuaZIP.
QuaZip* zip = new QuaZip("file.zip");
if (!zip->open(QuaZip::mdUnzip))
return;
zip->setCurrentFile("file_within_zip.ext");
QuaZipFile zfile(zip);
if (!zfile.open(QIODevice::ReadOnly))
return;
QByteArray data = zfile.readAll();That’s … not what I would have expected. Note that a QuaZipFile acts as a QIODevice, so you can use it as a stream source, for example. However, only one QuaZipFile can be opened at a time per QuaZip. You can open a second and read from that just fine, but you’ll no longer be able to read from the first.
QString vs. QByteArray
If you pass a QByteArray from a C++ plugin to QML, it will be treated as something of type QVariant. It will not act stringy in QML, even though it often does in C++. (Arguably, QML is doing this correctly; as we’ve learned from Python, you should always know whether your dealing with a string or bytes.)
This distinction persists even after you stuff the data into a text column in a database and pull it back out again. So make sure your plugins return QStrings if you actually want strings.
Mimetypes and WebKit
If you don’t set the Content-Type header when serving Javascript files to WebKit, you’ll all manner of subtle and indecipherable Javascript errors. Because that’s so much better than nothing working and a clear error message.
And why does it care, anyway?
Arguments to qmlscene
The Ubuntu SDK provides an Arguments class to give you access to the command line arguments. But when you run your program with qmlscene, you end up with the arguments intended for qmlscene as well. And in some cases qmlscene will try to interpret the arguments meant for your program.
I have trouble believing that this is how it’s supposed to work, but my question about this remains unanswered.