Qt

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Uses

Download of 4.x and 5.x version

http://download.qt-project.org/official_releases/

For example, the source code for 5.0.1 can be downloaded from http://download.qt-project.org/official_releases/qt/5.0/5.0.1/single/

Qt 4.8.5 mingw

Got an error of 'Only versions with W32API 3.13 are supported'. See https://bugreports.qt-project.org/browse/QTBUG-26137. I am using MinGW-get-setup.exe to install MinGW. The gcc version is 4.7.2-1.

Some suggestions are to install old versions of GCC. http://qt-project.org/forums/viewthread/22352 and http://qt-project.org/wiki/MinGW.

Download gcc 4.4.0 (mingw-gcc440_1.zip) from search google.

Although Qt can be installed without any errors, when I try some examples, some of them will give an error "The program has unexpectedly finished". Update: the error was caused by previous build residue. Just delete the build directory (Debug/Release) and re-build again. Things works well. However, remember the executable file can only be run through Qt Creator. It does not work by just double clicking the executable file.

Transition of Qt 4.x to 5

http://qt-project.org/wiki/Transition_from_Qt_4.x_to_Qt5


How to Build static Qt on Windows

General resource:

Why do we need to

Using the VS2010 version of Qt to build an app has a problem when it is time to distribute the application. In my first example of GUI with button & label, I need to put the following 7 dll files in the same exe directory in order to run the exe file from Windows Command Prompt instead of Qt Creator.

  • icudt49.dll (17MB)
  • icuin49.dll (1.3MB)
  • icuuc49.dll (1MB)
  • Qt5Cored.dll (7MB)
  • Qt5Guid.dll (5.5MB)
  • Qt5Widgets.dll (4MB)
  • Qt5Widgetsd.dll (7.5MB)

Google: how to reploy application on windows, how to build qt contains all dll static on windows

My experience based on Qt 4.8.4

  • Download and install Perl (no need for python, ruby for Qt 4.8).
  • Unzip source file in zip format and put it under C:\Qt
  • Rename C:\Qt\qt-everywhere-opensource-src-4.8.4 to C:\Qt\4.8.4
  • Open c:\Qt\4.8.4\mkspecs\win32-msvc2010\qmake.conf and change QMAKE_CFLAGS_RELEASE according to the page ?
  • Change PATH variable and add C:\Qt\4.8.4\bin.
  • Open Visual Studio command prompt and
cd C:\Qt\4.8.4
configure -platform win32-msvc2010 -static -release
nmake sub-src

My experience based on Qt 5.0.2

  • See the instruction on Git
  • read ReadME file to download Perl, Python and Ruby. Make sure the executable path in in PATH env variable.
  • Download/Install Windows SDK 7.1 (for Windows 7) or 8 (for Windows 8).
  • OpenGL (NOT optional): DirectX SDK The 6/7/2010 version is about 572MB. This will be installed to C:\Program Files (x86)\Microsoft DirectX SDK(June 2010) directory. (The precompiled Qt is built against ANGLE which provides OpenGL ES 2.0 support. ANGLE allows Windows users to run OpenGL ES 2.0 content by translating OpenGL ES 2.0 API calls to DirectX 9 API calls) I actually got an error of Error code S1023 when I installed DirectX SDK. See the solution here/Basically uninstall x86 & x64 VC2010 Redistr and install DirectX SDK and then re-install x86 & x64 VC2010 Redistr.
  • modify mkspecs by searching qmake.conf. It was found in C:\Qt\qt-everwhere-opensource-src-5.0.2\qtbase\mkspecs\win32-msvc2010
  • configure -static -release -platform win32-msvc2010 -opengl desktop

Install Qt on Ubuntu

It is also necessary to follow qt-project.org/wiki/install_Qt_5_on_Ubuntu to install g++ and OpenGL libraries. Note the last one is what I added to resolve the error of cannot finding -lGL; check Compile Qt 4.7 on Ubuntu 10.10. 

sudo apt-get install build-essential
sudo apt-get install libgl1-mesa-dev

If Qt Creator was installed (eg from binary installer of Qt 5.1.0), then it can be launched by 

~/Qt5.1.0/Tools/QtCreator/bin/qtcreator

Qt 5.1.0

Straight forward. Just use 'chmod +x' to make the download file executable and then run the executable file. 

./qt-linux-opensource-5.1.0-x86_64-offline.run

At the end, the qmake program is available under ~/Qt5.1.0/5.1.0/gcc_64/bin/qmake.

Qt 4.x.x

Method 1. Use apt-get install approach. See http://www.wikihow.com/Install-Qt-SDK-on-Ubuntu-Linux 

sudo apt-get install qt4-dev-tools

At the time of writing (tested on Linux Mint 15), the qmake is 4.5.2 (the Qt website offers 4.8.5).

Method 2. Manually compile it. First we download Linux/X11 one from qt-project.org (230MB). The INSTALL file points to http://qt-project.org/doc/qt-4.8/install-x11.html. We also need to do 'apt-get install libxext-dev' to resolve an error that 'basic XLib functionality test failed'. 

tar xzvf qt-everywhere-opensource-src-4.8.5.tar.gz
./configure
make
make install

Note that the last step make install is required; if this is skipped, Qt Creator won't let you to add 4.8.5 as a Kit.

In .profile (if your shell is bash, ksh, zsh or sh), add the following lines: 

 PATH=/usr/local/Trolltech/Qt-4.8.5/bin:$PATH
 export PATH

Qt Creator

  • Multiple version of Qt library
  • Keyboard shortcuts:
    • Ctrl + Click the symbol - move to the definition or the declaration of a symbol.
    • Click a symbol + Right click + Follow the symbol under cursor - move to the definition
  • The default build directory is parallel to the folder of source code which is a pain if there is a same project name. A better default build directory should be under the source code folder. To change the default setting, go to Tools -> Options -> Build and Run -> Remove "../" from the Default build directory value "../build-%{CurrentProject:Name}-%{CurrentKit:FileSystemName}-%{CurrentBuild:Name}". The project name is determined by Qt project file XXXX.pro.

Qt Tutorial

Qt forum

http://www.qtcentre.org/forum

Simple Test

To quickly test whether the Qt was built successfully, we can 

cd c:\Qt
mkdir example
cd example
notepad test.cpp
set PATH=%PATH%;C:\QT\4.8.4\bin
qmake -project
qmake
nmake

If everything went well, we will obtain the executable file under release folder. That is, we can run the executable file by 

release\example.exe

Qt-Apps.org

http://qt-apps.org/ is a good source to find open source projects based on Qt.

Graphics

Scientific

Qt Widget

Qt games

C++ basics

See C++ tutorial.

  • Use dot (.) to refer to any public member of a class.
  • Use the arrow operator (->) to refer to a member of an object pointed by a pointer. The label below is a pointer rather than an object but *label is an object.
QLabel *label = new QLabel("ABCDE");
label->show();
// (*label).show();
  • Use the operator of scope (::) to set a definition of a class's member function or call a function from some class. For example,
QObject::connect();

means to use connect() function from QObject class.

  • The this pointer passed on to the EditDialog sets the parent of the dlg to the list dialog.
EditDialog dlg( this );

Here explains: The keyword this identifies a special type of pointer. Suppose that you create an object named x of class A, and class A has a nonstatic member function f(). If you call the function x.f(), the keyword this in the body of f() stores the address of x..

Qt Basic

  • To run Qt from command line, I use
# Open command prompt from Visual Studio 2010
set PATH=C:\Qt\Qt5.0.2\5.0.2\msvc2010_opengl\bin;%PATH%

Now we can build the project by for example 

cd C:\Qt\FQD\Chapter01\plain-cpp
qmake -project
qmake
nmake

The executable will be located under release subfolder.

Qt Tricks

QT += widgets

to your .pro file.

  • Use QCoreApplication::applicationDirPath() to get the current working path or QFile::absolutePath() to get the absolute path from relative one.
  • Pop up a help file.
    • QMessageBox: no maximize button on top-right corner. Cannot resize (old Qheatmap)
    • QTextBrowser: the html file cannot be part of C++ (Qtextbrowser)
    • QLabel: No scroll bar (Qt07_BasicApplication)
    • QTextEdit: Good (new Qheatmap)
    • QWebkit
    • QTextDocument: no scroll bar (Qt79_drawText)
  • Not yet.
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