[Jtdx-improved-community] Building JTDX-Improved on a slightly older platform

[Jon K. <jo...@kr...>]

Dear JTDX-Improved users and developers,

I tried to compile JTDX-Improved and JTDX-Improved-JTDX-GUI (v2.2.159 
improved, 2022-10-07) on a older computer with the youngest Ubuntu that 
can still be installed on that machine.  That is Ubuntu 18.04.6 LTS, a 
release that is still supported with regular updates.  On that platform, 
the current QT has version 5.9.5

Both variants of JTDX-Improved use a feature of QT5 that only appeared 
in QT v5.12, namely: "QPalette::PlaceholderText".  A feature that is 
nice, but not really important for the functioning of JTDX.

This feature shows up in the C++ header file "ui_mainwindow.h" and 
breaks the compilation.

That header file is created by the "Qt User Interface Compiler" from the 
QT-XML source file "mainwindow.ui"

This header is (obviously) created before make calls on the C++ 
compiler; so once this compiler fails one can edit the header file.

It is enough to just comment-out (or even remove) the six lines that 
refer to "QPalette::PlaceholderText" and call on "make" again. This then 
compiles (on my platform) a perfect version of JTDX-Improved.

A possibly nicer way to "comment-out" these 6 occurrences in a portable 
way would be with a "#if", e.g.:

#if QT_VERSION >= QT_VERSION_CHECK(5, 12, 0)
         palette2.setBrush(QPalette::Active, QPalette::PlaceholderText, 
brush6);
#endif

But that's hardly worth it, since this file will likely be overwritten 
by the next full re-build.

In the hope that this useful to someone else with older hardware,

73, Jon
PE1AQP/DK1AQP