JPEG support in Android

[m_andrej]

Hi,
QImageReader::supportedImageFormats() prints on Android "bmp", "pbm", "pgm", "png", "ppm", "xbm", "xpm" while on Desktop it also includes jpg. Due to this, QImage::loadFormData() fails. How can I enable jpg support in Android?

[SGaist]

Hi,

Plugin not deployed ?

[m_andrej]

@SGaist I added QTPLUGIN += qjpeg in the *.pro file, if that's what you mean. Didn't help.

[m_andrej]

I have some more information.
I run androiddeployqt with --verbose option and it shows that libqjpeg.so is copied to *.apk:

-- Copied /home/andrej/programovanie/build-trance-Android_for_armeabi_v7a_GCC_4_9_Qt_5_4_2-Release/android-build//libs/armeabi-v7a/libplugins_imageformats_libqjpeg.so

The file is also present in bundled_in_lib section of res/values/libs.xml.
However, at runtime the application output doesn't show any error loading the library.

[SGaist]

What do you get if you set QT_DEBUG_PLUGINS ?

[m_andrej]

@SGaist How can I set environment variables on Android?

[m_andrej]

I went back to older revisions of my code and realized that JPEG plugin was working before. By trying various revisions I was able to locate the change in code that prevented the plugin from loading. It was in my server communicator class:

class CServerCommunicator : public QObject
{
...
private:	
	static QNetworkAccessManager *m_netManager;
	static QString m_sessionID;
	QNetworkReply *m_reply;
};

This line in CServerCommunicator.cpp was actually the problem:

QNetworkAccessManager *CServerCommunicator::m_netManager = new QNetworkAccessManager();

Instead of static member m_netManager, I made a method which creates network manager as static local variable and returns its address. Now the JPEG plugin works fine on Android.

This is clearly some bug, so I will make a bug report from this.

[gyll]

Can you please add the bug report's URL here, i'd like to monitor the progress too

[m_andrej]

@gyll https://bugreports.qt.io/browse/QTBUG-46901

[SGaist]

Out of curiosity, why a static QNetworkAccessManager ?

[m_andrej]

Because you should have only one network manager in the entire application. AFAIK this is in the official docs.

[SGaist]

You misunderstood that part. The doc says that one should be enough, not that you should only have one.