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.