Newbie: Require assistance - modify existing jpeg image ,save and display on LCD

[wysota]

It is very hard to say what is wrong with your code without knowing more. I suggest you use a debugger and step through the code to make sure everything is executed correctly. You will probably encounter some oddities which will tell you where to look for errors.

[jacek]

const char *buffer = "/root/whitescreen.jpg";
QPixmap pix;
pix.load(buffer);

Does pix.load(buffer) return true? Did you compile Qt with JPEG support?

[dbugger]

Thanks for your inputs

1. Does pix.load(buffer) return true?
I checked the return value. It is zero. Does this mean the jpg format is not supported?

2. Did you compile Qt with JPEG support?
I did'nt compile Qt with jpg support
I see the following libraries in the target though- libqjpeg.so and libqjpeg.a
But any attempts to run the examples like -
/usr/local/qtopia-core/examples/itemviews/puzzle/./puzzle or any other example throws the following error: "error while loading shared libraries: libQtGui.so.4: cannot open shared object file: No such file or directory"

Does this mean that because I have built Qt with static option, I cannot link librraries dynamically.
Earlier I did try removing the static option but my application was crashing at startup giving some similar error message as the one above. So I rebuilt Qt with static option

Now, what do you suggest to rectify this. Should I try building QT without static option and with jpeg support or anything on these lines?

[wysota]

If you link against static Qt, you can't use regular plugins. Read about static plugins.

[dbugger]

Hi again ,

To statically link plugins, the doc says to do the following
- import the plugin
- make changes to the *.pro file
Having done this, I faced a compilation error of my application for which I doubted the static option. I rebuilt Qt without static opiton and with jpeg support. But, even now I get the same errors. The error is related to the jpeg library with some undefined references and also some warnings which again indicate towards static and dynamic linking

Any clues pal??

[jacek]

Any clues pal??

First you have to provide us some clues. Please post the exact error message you get. Most likely you were trying to use dynamic plugins with static Qt.

[dbugger]

Okay, so this is what I did.

My final setup will be Qt4.3.4 with static option, OS FC5

Current setup is Qt 4.3.0 without static option and with jpeg support, OS is FC5
In main.cpp file, I included the following
#include <QtPlugin>
Q_IMPORT_PLUGIN(qjpeg)
And in .pro file ,
QTPLUGIN += qjpeg

Now doing a make gives me the following errors (it is long list)

.
/home/pjain/thirdparty/qtopia/qtopia-core-commercial-src/../stage/qtopia-core/lib/libQtCore.a(qlibrary_unix.o): In function `QLibraryPrivate::load_sys()':
qlibrary_unix.cpp:[.text+0x93c]: warning: Using 'dlopen' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
/home/pjain/thirdparty/qtopia/qtopia-core-commercial-src/../stage/qtopia-core/lib/libQtCore.a[qfsfileengine_unix.o]: In function `QFSFileEngine::owner(QAbstractFileEngine::FileOwn er) const':
qfsfileengine_unix.cpp:[.text+0x2de0]: warning: Using 'getgrgid_r' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
qfsfileengine_unix.cpp:[.text+0x2e7c]: warning: Using 'getpwuid_r' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
/home/pjain/thirdparty/qtopia/qtopia-core-commercial-src/../stage/qtopia-core/lib/libQtNetwork.a(qhostinfo_unix.o): In function `QHostInfoAgent::fromName(QString const&)':
qhostinfo_unix.cpp:[.text+0x2c0]: warning: Using 'getaddrinfo' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
/home/pjain/ingenient-bsp/../ingenient-app/imedia/net/snmp/bin/libisnmp.a(snmpc.o): In function `isnmp_clientInit':
/home/pjain/ingenient-app/imedia/net/snmp/src/snmpc.c:221: warning: Using 'gethostbyname' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
/home/pjain/thirdparty/qtopia/qtopia-core-commercial-src/../stage/qtopia-core/plugins/imageformats//libqjpeg.a(qjpeghandler.o): In function `read_jpeg_image(QIODevice*, QImage*, QByteArray const&, QSize, int)':
qjpeghandler.cpp:[.text+0x156c]: undefined reference to `jpeg_CreateDecompress'
qjpeghandler.cpp:[.text+0x1580]: undefined reference to `jpeg_std_error'
qjpeghandler.cpp:[.text+0x15b8]: undefined reference to `jpeg_read_header'
qjpeghandler.cpp:[.text+0x15c0]: undefined reference to `jpeg_start_decompress'
qjpeghandler.cpp:[.text+0x1838]: undefined reference to `jpeg_destroy_decompress'
qjpeghandler.cpp:[.text+0x21c8]: undefined reference to `jpeg_read_scanlines'
qjpeghandler.cpp:[.text+0x2278]: undefined reference to `jpeg_finish_decompress'
qjpeghandler.cpp:[.text+0x22f8]: undefined reference to `jpeg_read_scanlines'
qjpeghandler.cpp:[.text+0x24b8]: undefined reference to `jpeg_resync_to_restart'
qjpeghandler.cpp:[.text+0x2510]: undefined reference to `jpeg_finish_decompress'
/home/pjain/thirdparty/qtopia/qtopia-core-commercial-src/../stage/qtopia-core/plugins/imageformats//libqjpeg.a(qjpeghandler.o): In function `write_jpeg_image(QImage const&, QIODevice*, int)':
qjpeghandler.cpp:[.text+0x2d58]: undefined reference to `jpeg_std_error'
qjpeghandler.cpp:[.text+0x2d88]: undefined reference to `jpeg_CreateCompress'
qjpeghandler.cpp:[.text+0x2e3c]: undefined reference to `jpeg_destroy_compress'
qjpeghandler.cpp:[.text+0x2ee0]: undefined reference to `jpeg_set_defaults'
qjpeghandler.cpp:[.text+0x3174]: undefined reference to `jpeg_set_quality'
qjpeghandler.cpp:[.text+0x3180]: undefined reference to `jpeg_start_compress'
qjpeghandler.cpp:[.text+0x31c8]: undefined reference to `jpeg_write_scanlines'
qjpeghandler.cpp:[.text+0x3390]: undefined reference to `jpeg_write_scanlines'
qjpeghandler.cpp:[.text+0x33ac]: undefined reference to `jpeg_finish_compress'
qjpeghandler.cpp:[.text+0x33b4]: undefined reference to `jpeg_destroy_compress'
/home/pjain/thirdparty/qtopia/qtopia-core-commercial-src/../stage/qtopia-core/plugins/imageformats//libqjpeg.a(qjpeghandler.o): In function `jpegSmoothScaler::scanLine(int, QImage const*)':
qjpeghandler.cpp:(.gnu.linkonce.t._ZN16jpegSmoothS caler8scanLineEiPK6QImage+0x28): undefined reference to `jpeg_read_scanlines'

Now commenting the Q_IMPORT_PLUGIN(qjpeg), solves the compilation problem. But, then the return value for pix.load is still zero

Now, the errors are the same incase of QT built with static option

So, I am not sure what is the problem here!!
Is there any other information that you require?

Thanks for your support

[dbugger]

plz ignore the emoticons....got generated!!

[jacek]

Current setup is Qt 4.3.0 without static option and with jpeg support, OS is FC5

You can't use static plugins (i.e. Q_IMPORT_PLUGIN(xxx) and QTPLUGIN += xxx) with non-static Qt.

qjpeghandler.cpp:[.text+0x156c]: undefined reference to `jpeg_CreateDecompress'

This means that linker has problems in finding jpeg library. What commands did you exactly issue?

[dbugger]

Let me clear the confusion

"You can't use static plugins (i.e. Q_IMPORT_PLUGIN(xxx) and QTPLUGIN += xxx) with non-static Qt."
Dbugger: Precisely, initially my Qt was with static support. When I imported the plugins, I got meassages that I posted in the earlier reply. This made me doubt that importing of plugins may not always work when Qt is built statically. So, I reconfigured Qt without static support and with jpeg support. When I tested the code, the return value (pix.load) was zero. So I tried importing the plugin, just to check if there is any change, but the error messages were the same. So, I am not sure what needs to be done

"What commands did you exactly issue?"
Dbugger: I think you mean here the import plugin commands
In my main.cpp file, I did the following
#include <QtPlugin>
Q_IMPORT_PLUGIN(qjpeg)
And in .pro file ,
QTPLUGIN += qjpeg-
The above two are the only changes that I did

As mentioned, even building Qt with jpeg support and without static option, still I am not able to succeed

[jacek]

"What commands did you exactly issue?"
Dbugger: I think you mean here the import plugin commands

I meant the commands you have entered on the console to get that error messages. Where do you run make exactly? What parameters did you pass to configure?

[dbugger]

"I meant the commands you have entered on the console to get that error messages. Where do you run make exactly? What parameters did you pass to configure?"
Dbugger: This image code is part of another screen in which I have a button, which when clicked is supposed to show the image that I want to see on the LCD.
My application is cross compiled.
So, by doing a make of my application, I get the binary of the entire application on the target

I hope I am clear!!

[dbugger]

Sorry, I missed the configure options. The following are my configuration options
./configure -v \
-prefix "${STAGE_DIR}" \
-prefix-install \
-no-rpath \
-embedded arm \
-little-endian \
-release \
-no-mouse-pc \
-no-kbd-tty \
-no-kbd-usb \
-no-kbd-sl5000 \
-no-kbd-yopy \
-no-kbd-vr41xx \
-no-kbd-qvfb \
-no-mouse-bus \
-no-mouse-linuxtp \
-no-mouse-yopy \
-no-mouse-vr41xx \
-no-mouse-tslib \
-no-mouse-qvfb \
-no-accessibility \
-no-largefile \
-no-stl \
-no-nis \
-no-cups \
-no-iconv \
-no-qt3support \
-no-freetype \
-qt-libjpeg \ ...
the above is the current config options. earlier ther was "-static" and no support for jpeg

Thanks!!