Invisible text in QTextEdit

jsulm

@Alp-Hancioglu Does it work if you don't set any font? Do other Qt apps work (like VCL)?
Also: how did you install Qt?

Alp Hancioglu

It doesn't work if I don't set any font.
Do you mean VLC media player? I just installed VLC and it also doesn't display any text. It only displays window headers and menu items.
I built qt from source as I said in my post.

karlheinzreichel

Hmm.. according to your code:
When you do not set a text in the QTextEdit-Control (textEdit.setPlainText)
there will be no visible text in the control!

Alp Hancioglu

@karlheinzreichel I don't understand what you mean exactly but textEdit.append("some"); call doesn't display any text either. It moves the cursor but no text is shown.

karlheinzreichel

@Alp-Hancioglu
in your code above there is no append (or did I miss something ?)

Alp Hancioglu

@karlheinzreichel I tried the append call at some point but forgot to add it to the post. The issue seems much more bigger than QTextEdit though as there is also no text shown in VLC media player.

karlheinzreichel

As you build qt from scratch, the question :
Have you installed the libconfig libraries before ... ?

(probably not)

regards
karl-heinz

Alp Hancioglu

@karlheinzreichel I didn't explicitly install libconfig library myself. I don't know if other program installed it as prerequisite.
In order to build, I downloaded qt-everywhere-opensource-src-5.9.1.tar.xz file and extracted it.
Then called ./configure and make on bash.

karlheinzreichel

So I would reccomend to check the build requierments for QT
(see http://doc.qt.io/qt-5/linux-requirements.html)
before building the qt libs

regards
Karl-Heinz

jsulm

@Alp-Hancioglu Try to start your app with QT_DEBUG_PLUGINS environment variable set and check the output in the console. Looks like something is wrong with your system.

Alp Hancioglu

@jsulm I set the env variable and there are no errors listed. Just a bunch of plugin metadata loads. Should I look for something?

jsulm

@Alp-Hancioglu Are there any errors/warnings?

Alp Hancioglu

@jsulm There are no errors or warnings.

Alp Hancioglu

@karlheinzreichel I checked every package and its dev version listed in requirements list and they are all installed and at newest version so there is no need to install or upgrade any of them. Some packages don't have the exact same name on my machine: libfontconfig is listed as libfontconfig1 on mine, libfreetype is listed as libfreetype6 on mine but the descriptions match.
I built Qt a week ago so they were most probably at newest version at time of compilation so I don't think they are related to the issue I have.

jsulm

@Alp-Hancioglu If you execute configure script before building Qt you will get a summary what was found and enabled. You can execute configure again with -v parameter and see whether fontconfig was really enabled.

Alp Hancioglu

@jsulm Thanks for the continued support jsulm.

I used ./configure -v and saw that fontconfig is disabled in build options:

Qt Gui:
  Accessibility .......................... yes
  FreeType ............................... yes
    Using system FreeType ................ no
  HarfBuzz ............................... yes
    Using system HarfBuzz ................ no
  Fontconfig ............................. no

Then I used ./configure -v -fontconfig to enable it but it didn't work with error:

ERROR: Feature 'fontconfig' was enabled, but the pre-condition '!config.win32 && !config.darwin && features.system-freetype && libs.fontconfig' failed.

Then I run following to make sure libfontconfig is installed:

sudo apt install libfontconfig1
[sudo] password for alp: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
libfontconfig1 is already the newest version (2.11.94-0ubuntu1.1).
0 upgraded, 0 newly installed, 0 to remove and 39 not upgraded.

I also run ./configure -system-freetype -fontconfig but it doesn't make a difference with resulting errors:

ERROR: Feature 'system-freetype' was enabled, but the pre-condition 'features.freetype && libs.freetype' failed.

ERROR: Feature 'fontconfig' was enabled, but the pre-condition '!config.win32 && !config.darwin && features.system-freetype && libs.fontconfig' failed.

Make sure freetype is installed:

sudo apt install libfreetype6
Reading package lists... Done
Building dependency tree       
Reading state information... Done
libfreetype6 is already the newest version (2.6.1-0.1ubuntu2.3).
0 upgraded, 0 newly installed, 0 to remove and 39 not upgraded.

jsulm

@Alp-Hancioglu You need to install the dev package for fontconfig. Something like libfontconfig1-dev.

Alp Hancioglu

@jsulm It is already installed:

sudo apt install libfontconfig1-dev
[sudo] password for alp: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
libfontconfig1-dev is already the newest version (2.11.94-0ubuntu1.1).
0 upgraded, 0 newly installed, 0 to remove and 39 not upgraded.

I checked every dev package in the requirements list and they are all installed with newest versions

jsulm

@Alp-Hancioglu If you execute configure with -v you should get more output. Can you post it here?

Alp Hancioglu

I uninstalled Qt build with make uninstall and then fonts in VLC appeared. I am guessing Qt code in VLC was referencing Qt build libs in /usr/local/Qt-5.9.1/lib directory, which are deleted after uninstall, and this was causing the missing font in VLC. After uninstall VLC started referencing libs in /usr/lib/x86_64-linux-gnu/ which work and fonts appeared.

I tried compiling against headers and libs in qt-everywhere-opensource-src-5.9.1 directory, which is downloaded from qt website:

g++ -Wall -fPIC -c -g -I/home/alp/Downloads/qt-everywhere-opensource-src-5.9.1/qtbase/include -I/home/alp/Downloads/qt-everywhere-opensource-src-5.9.1/qtbase/include/QtWidgets main.cpp -o main.o
g++ -g -Wl,--trace main.o ext/printer.o -o main -L/home/alp/Downloads/qt-everywhere-opensource-src-5.9.1/qtbase/lib -lQt5Gui -lQt5Core -lQt5Widgets
/usr/bin/ld: mode elf_x86_64
/usr/lib/gcc/x86_64-linux-gnu/6/../../../x86_64-linux-gnu/crt1.o
/usr/lib/gcc/x86_64-linux-gnu/6/../../../x86_64-linux-gnu/crti.o
/usr/lib/gcc/x86_64-linux-gnu/6/crtbegin.o
main.o
ext/printer.o
-lQt5Gui (/home/alp/Downloads/qt-everywhere-opensource-src-5.9.1/qtbase/lib/libQt5Gui.so)
-lQt5Core (/home/alp/Downloads/qt-everywhere-opensource-src-5.9.1/qtbase/lib/libQt5Core.so)
-lQt5Widgets (/home/alp/Downloads/qt-everywhere-opensource-src-5.9.1/qtbase/lib/libQt5Widgets.so)
-lstdc++ (/usr/lib/gcc/x86_64-linux-gnu/6/libstdc++.so)
/lib/x86_64-linux-gnu/libm.so.6
/lib/x86_64-linux-gnu/libmvec.so.1
libgcc_s.so.1 (/usr/lib/gcc/x86_64-linux-gnu/6/libgcc_s.so.1)
/lib/x86_64-linux-gnu/libc.so.6
(/usr/lib/x86_64-linux-gnu/libc_nonshared.a)elf-init.oS
/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
libgcc_s.so.1 (/usr/lib/gcc/x86_64-linux-gnu/6/libgcc_s.so.1)
/usr/lib/gcc/x86_64-linux-gnu/6/crtend.o
/usr/lib/gcc/x86_64-linux-gnu/6/../../../x86_64-linux-gnu/crtn.o

When I run with ./main following errors appear:

./main: /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5: version Qt_5' not found (required by ./main) ./main: /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5: version Qt_5' not found (required by ./main)
./main: /usr/lib/x86_64-linux-gnu/libQt5Core.so.5: version Qt_5.9' not found (required by ./main) ./main: /usr/lib/x86_64-linux-gnu/libQt5Core.so.5: version Qt_5' not found (required by ./main)

which makes me guess that libs in qt-everywhere-opensource-src-5.9.1 are empty and g++ references the libs in x86_64-linux-gnu which are not the latest version 5.9 as expected.