Building with Qt depends on pkg-config, Qt 5 term doesn't work on OS X

[Mojca M. <moj...@gm...>]

Hi,

I tried to test gnuplot with Qt5, but there is one flaw in the
configure script: I need to have pkg-config installed if I want to
build with Qt 5 even if I provide QT_CFLAGS and QT_LIBS.

I have pkg-config and lots of other libraries installed via MacPorts,
but MacPorts doesn't provide Qt5. The problem is that as soon as any
given library (like libpng, libreadline, ...) comes from MacPorts that
means that -I/path/to/macports/include and -L/path/to/macports/lib
will consequently also pick Qt4 headers and libraries from MacPorts
instead of taking them from the location specified by QT_CFLAGS and
QT_LIBS, so I need to either uninstall Qt 4 from MacPorts or remove
any dependency on MacPorts.

But if I remove MacPorts from PATH completely, gnuplot refuses to
include Qt due to lack of pkg-config:

checking for QT... configure: WARNING:
The pkg-config script could not be found or is too old.  Make sure it
is in your PATH or set the PKG_CONFIG environment variable to the full
path to pkg-config.

Alternatively, you may set the environment variables QT_CFLAGS
and QT_LIBS to avoid the need to call pkg-config.
See the pkg-config man page for more details.

To get pkg-config, see <http://www.freedesktop.org/software/pkgconfig>.
checking for QT... configure: WARNING:
The pkg-config script could not be found or is too old.  Make sure it
is in your PATH or set the PKG_CONFIG environment variable to the full
path to pkg-config.

Alternatively, you may set the environment variables QT_CFLAGS
and QT_LIBS to avoid the need to call pkg-config.
See the pkg-config man page for more details.

To get pkg-config, see <http://www.freedesktop.org/software/pkgconfig>.
configure: WARNING: The Qt terminal will not be compiled.
checking that generated files are newer than configure... done


Can the configure script please be changed in such a way that
pkg-config becomes optional in the case of Qt (5)? I don't have any
simple patch ready for that, but you can see below what I needed apart
from hacking the ./configure[.in] just to get a rough idea.


There is a chance that I've screwed something up (or that there are
problems with the repository I'm using), but gnuplot with Qt 5 seems
pretty nonfunctional on Mac OS X.

It starts with

> plot sin(x)
QIODevice::write: device not open
QIODevice::write: device not open
Error: short read from gnuplot_qt socket

then nevertheress plots something, but uses the wrong dimensions and
doesn't allocate any space for fonts. The second plot works better and
uses proper dimensions (I can send screenshots if anyone is
interested). The third plot throws:

qt_processTermEvent received a GE_fontprops event. This should not have happened

Mouse events (increasing or decreasing the window) don't work at all.
Or rather: they do work in a weird way. If I try to move the second
plot around, the second plot isn't changed, but the third plot is
moved. If I increase or decrease the window, the plot doesn't change,
but the next plot adapts to those dimensions.

If I type "quit" to fast (soon after the first plot), the following is thrown:

> Event not swallowed ! 1041
############### WRONG readEvent  0 6851

I'm sorry for not testing Qt 5 earlier, but it's relatively
non-trivial to figure out how to build gnuplot against Qt 5.2 on Mac.
Here is what I eventually used:

export QT_PATH=/path/to/qt/5.2.1/clang_64

export QT_LIBS="-F$QT_PATH/lib \
-framework QtCore \
-framework QtGui \
-framework QtWidgets \
-framework QtNetwork \
-framework QtSvg \
-framework QtPrintSupport"

# NOTE: CFLAGS usually look more like
#     -framework QtCore,
# but then it would need to be used as
#     #include <QtCore/QtCore>
#
# Current use of headers requires the weird
# -I$QT_PATH/lib/QtCore.framework/Headers

export QT_CFLAGS="-F$QT_PATH/lib \
-I$QT_PATH/lib/QtCore.framework/Headers \
-I$QT_PATH/lib/QtGui.framework/Headers \
-I$QT_PATH/lib/QtWidgets.framework/Headers \
-I$QT_PATH/lib/QtNetwork.framework/Headers \
-I$QT_PATH/lib/QtSvg.framework/Headers"

export UIC=$QT_PATH/bin/uic
export MOC=$QT_PATH/bin/moc
export RCC=$QT_PATH/bin/rcc

export CC=clang
export CXX=clang++

export EMACS=no

export PATH=/usr/bin:/bin:/usr/sbin:/sbin

./configure --with-qt --prefix=$PWD/inst


I can test the latest released version to see how that behaves, but it
would be of enormous help when testing numerous patches if the
repository was using some other version control system. I'm unable to
work with CVS and I have a somewhat screwed-up GIT mirror (thanks to
bugs in "git cvsimport"). Combined with all other problems related to
non-trivial Qt5 configuration ... there are simply a lot of obstacles
preventing easy testing.

I will compare the results with the released version (with branch 4.6)
next, but really ... it would help me a lot if conversion to git was
done prior to that.

Thank you,
    Mojca