Getting Started With Using Qt 4 and QDevelop

Qt is a toolkit made by Trolltech that mainly is focused on graphical user interface (GUI) programming. It is not just a GUI toolkit, though, containing classes for network programming, database programming, and primitive graphics.

It is also unique in the way that it kind of adds its own "extensions" to C++, which are then processed by the meta-object compiler. These extensions generally make programming Qt easy and fast. Unfortunately, this also makes Qt not work with a lot of integrated development environments (IDEs). QDevelop, specifically designed to be used with Qt 4, works with Qt well, so that's what we'll be using.

Qt comes in two main editions: a commercial edition, which costs money, which allows it to be used in the development of proprietary, or non-open source and free, software, and an open source edition, which is free, and it is what you use if you are developing open source applications - this is the one we're interested in.

Installing Qt and Qt Basics

You can download Qt for the Windows, Mac, and X11 platforms here. If you're using Linux, or another Unix-based operating system besides Mac OS, then the X11 version is for you. In addition, if you're using Linux, you can probably more easily install Qt through repositories - most likely, the ones enabled by default. The packages you'll need will probably be under the names "qt4" and "qt4-devel," and any dependencies will automatically be handled if you're using a decent operating system (just kidding, Slackware and other "stable" operating system users ;)). You'll probably only need to install qt4-devel, and qt4 will automatically be installed, being a dependency.

If you're using Windows, Qt 4 will probably be installed in C:t\\.\*\.\*\ \(replace\ each\ \"\*\"\ with\ a\ version\ number\,\ for\ example\:\ C\:t\\\\\\.2\\\.3\\\)\\\.\\\ \\\ If\\\ you\\\'re\\\ using\\\ Linux\\\ and\\\ have\\\ installed\\\ Qt\\\ from\\\ a\\\ repository\\\,\\\ it\\\ will\\\ probably\\\ be\\\ installed\\\ in\\\ \\\/usr\\\/lib\\\/qt4\\\ or\\\ \\\/usr\\\/lib64\\\/qt4\\\.\\\ \\\ If\\\ you\\\'re\\\ on\\\ Mac\\\ OS\\\,\\\ then\\\.\\\.\\\.well\\\,\\\ I\\\'m\\\ not\\\ sure\\\.\\\.\\\.I\\\ don\\\'t\\\ know\\\ much\\\ about\\\ Macs\\\.\\\.\\\.but\\\ whatever\\\ the\\\ installation\\\ directory\\\ is\\\,\\\ it\\\ should\\\ probably\\\ be\\\ intuitive\\\.\\\ \\\ \\\;\\\)\\\ \\\ Anyway\\\,\\\ navigate\\\ to\\\ wherever\\\ Qt\\\ 4\\\ was\\\ installed\\\.\\\ \\\ In\\\ the\\\ \\\"bin\\\"\\\ folder\\\,\\\ you\\\'ll\\\ notice\\\ several\\\ programs\\\.\\\ \\\ The\\\ ones\\\ that\\\ you\\\ should\\\ probably\\\ be\\\ most\\\ concerned\\\ about\\\ at\\\ this\\\ point\\\ are\\\ \\\"qtdemo\\\,\\\"\\\ \\\"assistant\\\,\\\"\\\ \\\"designer\\\,\\\"\\\ and\\\ \\\"qmake\\\.\\\"\\\ \\\ \\\"qtdemo\\\"\\\ lets\\\ you\\\ try\\\ some\\\ interesting\\\ and\\\ helpful\\\ demonstration\\\ programs\\\,\\\ and\\\ it\\\ also\\\ comes\\\ with\\\ links\\\ to\\\ their\\\ source\\\ code\\\ and\\\ documentation\\\.\\\ \\\ \\\"assistant\\\"\\\ is\\\ a\\\ very\\\ useful\\\ program\\\,\\\ providing\\\ extensive\\\ information\\\ about\\\ Qt\\\,\\\ and\\\ essentially\\\ being\\\ an\\\ easy\\\-to\\\-use\\\ right\\\-there\\\-when\\\-you\\\-need\\\-it\\\ form\\\ of\\\ the\\\ Qt\\\ documentation\\\ \\\-\\\ I\\\ highly\\\ recommend\\\ checking\\\ it\\\ out\\\ sometime\\\.\\\ \\\ \\\"designer\\\"\\\ is\\\ a\\\ visual\\\ What\\\-You\\\-See\\\-Is\\\-What\\\-You\\\-Get\\\ \\\(WYSIWYG\\\)\\\ editor\\\ for\\\ Qt\\\ \\\-\\\ you\\\ may\\\ not\\\ be\\\ using\\\ this\\\ directly\\\ much\\\ because\\\ QDevelop\\\ kind\\\ of\\\ intergrates\\\ with\\\ it\\\.\\\.\\\.you\\\'ll\\\ see\\\.\\\ \\\ \\\:\\\)\\\ \\\ And\\\ lastly\\\,\\\ there\\\ is\\\ \\\"qmake\\\.\\\"\\\ \\\ Although\\\ you\\\ probably\\\ won\\\'t\\\ be\\\ using\\\ this\\\ directly\\\ much\\\,\\\ I\\\ thought\\\ you\\\ should\\\ know\\\ a\\\ bit\\\ about\\\ it\\\.\\\ \\\ It\\\'s\\\ a\\\ tool\\\ that\\\ generates\\\ a\\\ Makefile\\\ for\\\ you\\\ based\\\ off\\\ of\\\ information\\\ from\\\ a\\\ Qt\\\ project\\\ file\\\ \\\(which\\\ has\\\ a\\\ file\\\ extension\\\ of\\\ \\\"\\\.pro\\\"\\\)\\\,\\\ simplifing\\\ matters\\\ grealtly\\\ \\\-\\\ especially\\\ development\\\ across\\\ multiple\\\ platforms\\\.\\\<\\\/p\\\>\\\ \\\\\\About\\\ QDevelop\\\<\\\/b\\\>\\\<\\\/p\\\>\\\ \\\QDevelop\\\ is\\\ a\\\ free\\\ cross\\\-platform\\\ IDE\\\ for\\\ Qt\\\ programming\\\ with\\\ C\\\+\\\+\\\.\\\ \\\ It\\\ integrates\\\ well\\\ with\\\ the\\\ components\\\ of\\\ Qt\\\ and\\\ is\\\ easy\\\ to\\\ use\\\.\\\ \\\ Once\\\ you\\\ get\\\ more\\\ advanced\\\ at\\\ programming\\\ in\\\ C\\\+\\\+\\\ with\\\ Qt\\\,\\\ you\\\ might\\\ want\\\ to\\\ switch\\\ to\\\ using\\\ a\\\ plain\\\ text\\\ editor\\\ and\\\ a\\\ command\\\ prompt\\\.\\\ \\\ This\\\ is\\\ because\\\ QDevelop\\\ likes\\\ things\\\ its\\\ way\\\,\\\ and\\\ if\\\ you\\\ decide\\\ to\\\ make\\\ a\\\ very\\\ complicated\\\ Qt\\\ project\\\ file\\\ with\\\ a\\\ bunch\\\ of\\\ odd\\\ dependencies\\\ or\\\ something\\\ like\\\ that\\\,\\\ QDevelop\\\ will\\\ likely\\\ either\\\ mess\\\ up\\\ you\\\'re\\\ Qt\\\ project\\\ file\\\ or\\\ crash\\\,\\\ unfortunately\\\ \\\(although\\\ it\\\ is\\\ radidly\\\ improving\\\ its\\\ stability\\\)\\\.\\\ \\\ For\\\ now\\\,\\\ and\\\ quite\\\ some\\\ time\\\,\\\ though\\\,\\\ QDevelop\\\ should\\\ be\\\ fine\\\.\\\<\\\/p\\\>\\\ \\\\\\Installing\\\ QDevelop\\\<\\\/b\\\>\\\<\\\/p\\\>\\\ \\\Go\\\ to\\\ \\\http\\\:\\\/\\\/www\\\.qdevelop\\\.org\\\/\\\<\\\/a\\\>\\\ and\\\ click\\\ on\\\ \\\"Download\\\.\\\"\\\ \\\ Downloading\\\ the\\\ correct\\\ version\\\ should\\\ be\\\ easy\\\ enough\\\.\\\.\\\.except\\\ for\\\ a\\\ few\\\ exceptions\\\.\\\ \\\ If\\\ you\\\'re\\\ using\\\ Linux\\\,\\\ first\\\ check\\\ if\\\ QDevelop\\\ is\\\ in\\\ your\\\ repositories\\\,\\\ and\\\ if\\\ it\\\ is\\\,\\\ you\\\ should\\\ probably\\\ download\\\ it\\\ from\\\ there\\\.\\\ \\\ If\\\ not\\\,\\\ download\\\ the\\\ appropriate\\\ package\\\ from\\\ the\\\ QDevelop\\\ website\\\,\\\ and\\\ if\\\ there\\\ are\\\ no\\\ packages\\\ available\\\ for\\\ your\\\ distribution\\\,\\\ then\\\ just\\\ download\\\ the\\\ \\\"Linux\\\ dynamic\\\ version\\\ with\\\ plugins\\\.\\\"\\\<\\\/p\\\>\\\ \\\ \\\Installation\\\ should\\\ be\\\ easy\\\ enough\\\.\\\ \\\ If\\\ you\\\'re\\\ building\\\ from\\\ the\\\ source\\\,\\\ make\\\ sure\\\ you\\\ have\\\ the\\\ necessary\\\ dependencies\\\ \\\(such\\\ as\\\ Qt\\\ 4\\\,\\\ which\\\ you\\\ should\\\ already\\\ have\\\)\\\.\\\<\\\/p\\\>\\\ \\\\\\Using\\\ QDevelop\\\<\\\/b\\\>\\\<\\\/p\\\>\\\ \\\When\\\ you\\\ first\\\ open\\\ QDevelop\\\,\\\ you\\\'ll\\\ be\\\ prompted\\\ for\\\ some\\\ the\\\ paths\\\ to\\\ the\\\ external\\\ tools\\\ it\\\ uses\\\.\\\ \\\ \\\"gdb\\\,\\\"\\\ a\\\ debugger\\\,\\\ and\\\ \\\"ctags\\\,\\\"\\\ which\\\ can\\\ further\\\ assist\\\ you\\\ while\\\ programming\\\,\\\ are\\\ both\\\ handy\\\,\\\ but\\\ not\\\ necessary\\\.\\\ \\\ And\\\ if\\\ you\\\'re\\\ Qt\\\ installation\\\ was\\\ successful\\\,\\\ you\\\ should\\\ be\\\ able\\\ to\\\ fill\\\ in\\\ most\\\,\\\ if\\\ not\\\ all\\\,\\\ of\\\ the\\\ other\\\ fields\\\ \\\(except\\\ \\\"make\\\"\\\)\\\.\\\ \\\ If\\\ you\\\ don\\\'t\\\ have\\\ \\\"make\\\"\\\ already\\\ I\\\ recommend\\\ getting\\\ it\\\ from\\\ \\\here\\\<\\\/a\\\>\\\.\\\<\\\/p\\\>\\\ \\\From\\\ there\\\.\\\.\\\.feel\\\ free\\\ to\\\ experiment\\\.\\\ \\\:\\\)\\\ A\\\ few\\\ things\\\ to\\\ note\\\:\\\<\\\/p\\\>\\\ \\\\\\-\\\ If\\\ you\\\ click\\\ on\\\ a\\\ \\\.ui\\\ file\\\,\\\ or\\\ a\\\ file\\\ that\\\ is\\\ under\\\ the\\\ \\\"Dialogs\\\"\\\ menu\\\,\\\ it\\\ will\\\ most\\\ likely\\\ be\\\ opened\\\ with\\\ Qt\\\ Designer\\\.\\\ \\\ If\\\ you\\\ want\\\ to\\\ view\\\ the\\\ actual\\\ contents\\\ of\\\ the\\\ file\\\ with\\\ QDevelop\\\,\\\ you\\\ can\\\ simply\\\ open\\\ it\\\ with\\\ File\\\-\\\>\\\;Open\\\.\\\<\\\/p\\\>\\\ \\\\\\-\\\ If\\\ you\\\ need\\\ to\\\ use\\\ any\\\ of\\\ Qt\\\'s\\\ non\\\-GUI\\\ features\\\,\\\ you\\\ can\\\ enable\\\ them\\\ through\\\ Project\\\-\\\>\\\;Properties\\\ of\\\ \\\[project\\\ name\\\]\\\.pro\\\.\\\<\\\/p\\\>\\\ \\\\\\-\\\ Most\\\ of\\\ the\\\ time\\\,\\\ you\\\'ll\\\ probably\\\ want\\\ to\\\ create\\\ a\\\ Qt\\\ application\\\ that\\\ uses\\\ a\\\ main\\\ window\\\ and\\\ not\\\ a\\\ dialog\\\.\\\ \\\ The\\\ default\\\ option\\\ in\\\ QDevelop\\\ is\\\ to\\\ create\\\ a\\\ Qt\\\ project\\\ with\\\ a\\\ dialog\\\,\\\ though\\\.\\\ \\\ When\\\ creating\\\ a\\\ new\\\ project\\\,\\\ in\\\ the\\\ \\\"New\\\ project\\\ creation\\\"\\\ window\\\,\\\ simply\\\ select\\\ the\\\ \\\"Application\\\ with\\\ Main\\\ Window\\\"\\\ option\\\.\\\<\\\/p\\\>\\\ \\\ \\\\\\Where\\\ to\\\ Go\\\ From\\\ Here\\\<\\\/b\\\>\\\<\\\/p\\\>\\\ \\\I\\\ recommend\\\ reading\\\ through\\\ the\\\ Qt\\\ documentation\\\,\\\ either\\\ online\\\ \\\(\\\http\\\:\\\/\\\/doc\\\.trolltech\\\.com\\\/4\\\.3\\\/\\\<\\\/a\\\>\\\ contains\\\ documentation\\\ for\\\ the\\\ current\\\ stable\\\ release\\\ of\\\ Qt\\\)\\\ or\\\ through\\\ the\\\ Qt\\\ Assistant\\\.\\\ \\\ There\\\'s\\\ a\\\ good\\\ Qt\\\ tutorial\\\ included\\\ within\\\ the\\\ documentation\\\ \\\here\\\<\\\/a\\\>\\\,\\\ which\\\ I\\\ particularly\\\ suggest\\\ you\\\ go\\\ to\\\.\\\<\\\/p\\\>\\\ \\\\\\ Last\\\ updated\\\ \\\?\\\ \\\<\\\/p\\\>\\\ \\\