Introduction

Technically, Qt does not support building their Qt libraries in one location and installing them to another. This installer does allows you to pick where you install the Qt libraries and I have done quite a few nuanced tricks to make it work.

As far as I can tell, the installer produces a fully functioning Qt build that builds every complex Qt project I have thrown at it, but because of the unsupported nature of the build/relocate setup, you may run into obscure issues. Feel free to create tickets in the issue tracker of this project and we'll try to create workarounds.

Environment

The installer creates a few *.bat files to launch a Qt command prompts and visual studio with Qt variables set. These files set a QMAKESPEC variable, a QTDIR variable and adds %QTDIR%\bin to the PATH. It then calls the visual studio vcvarsall.bat file that sets up its respective variables based on the built platform.

If you installed Qt to C:\Qt\4.5.2. The QtVars.bat file would look like:

@echo off echo Setting QMAKESPEC to win32-msvc2008 set QMAKESPEC=win32-msvc2008 echo Setting QTDIR environment variable to C:\Qt\4.5.2 set QTDIR=C:\Qt\4.5.2 echo Putting Qt\bin in the current PATH environment variable. set PATH=C:\Qt\4.5.2\bin;%PATH% call "C:\Program Files\Microsoft Visual Studio 9.0\VC\vcvarsall.bat" x86 echo All done...

A QtCommandPrompt.bat is created and linked to from the start menu to pop up a command console for Qt: @echo off %COMSPEC% /k "C:\Qt\4.5.2\QtVars.bat"

And finally, QtVisualStudioStart.bat is also linked form the start menu and looks like: @echo off call QtVars.bat devenv /useenv

qt.conf

The Qt documentation for qt.conf describes how this file works to override built in directories for Qt binaries.

The trick is to create a qt.conf in the bin directory of the relocated Qt build. For example if you installed Qt to C:\Qt\4.5.2 the qt.conf in the bin directory would look like

[Paths] Prefix = C:/Qt/4.5.2 Demos = demos Examples = examples

Without the Demos and Examples lines the demo.exe program would not work properly.

Current Directory in QMAKE_INCDIR

In Qt's provided binary distributions, the pwd is included in the QMAKE_INCDIR and thus ends up in your projects include path as ".". This does not happen by default in a custom built Qt, so the installer adds the following line to mkspecs/win32-msvc2008/qmake.conf:

QMAKE_INCDIR += "."

Including Extra Qt Components

When you add a qt component to a project file (such as CONFIG+=uitools), Qt looks in %QTDIR%/lib/QtUiTools.prl to find the library dependencies of that component. These files will have the hard coded path of the directory in which Qt was configured and built.

The Install script replaces that build directory with the one in which you install it for all lib/*.prl files.

Note

I must thank the support team at Nokia Qt for helping with me figure out a few of these relocation tricks.