Qt Reference Documentation


Qt Development: The Steps from Challenge to Achievement

The Challenge

One day, your boss runs into your cubicle and exclaims to you, "The board blew millions on a new enterprise HelloWorld application. The new one does not work and we need a solution quickly before this disaster brings down the company! I'm putting you in charge of the whole project while I go on vacation -- see you in 2 weeks."

Brainstorming Ideas - It is time to play!

Never one to shy away from a challenge (especially when your job might be on the line), you first set out try come up with an idea about what your options are.

You ask around a bit and discover that the broken application was intended to replace one that has been living on a dusty mainframe for the past 25 years. The machine is nearing end of life and, rather than invest in replacement hardware to run a legacy HelloWorld program, the board decided to invest in new software that could be run on desktops, web, mobile devices and embedded into the company's main product line -- a pocket size device with a small LCD screen, which flashes the message "Hello World" every full moon.

The vendor that was chosen to handle this task was a well known multinational company that specialized in enterprise CRM/ERP systems. The project missed several delivery deadlines over a 2 year period, and was 500% over budget. There was not going to be much margin for error trying to fix the problem, and there would likely be no budget either.

You begin researching dozens of possible possible approaches to the problem. One of the biggest challenges is that there are very few options that will allow you to create native applications that use the same framework for targeting multiple platforms.

Some years ago you had coded a small desktop application using the Qt framework, without realizing that it also can be used for targeting the web, mobile devices and embedded devices. Since that time, Qt has added a new feature called Qt Quick, which provides the ability to easily design applications with intuitive, modern-looking, fluid user interfaces.

Creating an Objective

You quickly realize that you might need two, three, or more interfaces for your application -- one for each of the target platforms you are aiming for. Thankfully Qt has options well suited for each of them.

For your mobile application the choice seems obvious enough. The new Qt Quick technology looks very promising, but you do not know QML; the declarative language that helps define the interface in a Qt Quick program. You still want to give it a try, but worry that you might not have something complete before your boss returns from vacation in two weeks. You also wonder if Qt Quick is applicable to desktop and embedded targets -- and then of course there is the need for something targeting the web. You decide to give Qt Quick a try first and see where it takes you.

Developing Plans

One thing you realize after reading up on Qt Quick is that things are very different from the desktop when designing an interface. Qt Quick doesn't contain ready made UI 'chrome'; the widgets and other design elements that define the application interface. A new technology, called Qt Quick Components, looks like a promising solution, but the components will only be available at a later date. For now you'll have to come up with something on your own -- but you are keen to give your design skills a work out, and learning to use Qt Quick seems to be a great way to do it.

Not knowing a better place to start, you begin by taking a cue from web design and plan a wireframe, which helps define the application layout, content and user interaction. You decide on breaking the field of the screen space into three roughly equal size parts. There will be one section across the top, which will span the width of the screen, and two sections in the lower have, which will be approximately as tall as the top section is wide (when in portrait mode).

The top section will be a simple text representation of the phrase "Hello World" in English. In the lower left you would like to place some kind of audio playback feature that repeats back the phrase in the top section of the screen. Finally, in the lower right hand side of the screen will be four links to similar views for additional languages -- Mandarin Chinese, Brazilian Portuguese, Arabic, and Russian. When the user clicks one of the links the text at the top is then translated, and the playback corresponds to the appropriate language.

While the wireframe is effective in dealing with one part of the design challenge, it does not cover visual aspects other than layout and content. This means that you still need to define colours, white space, and typography (among other things). This is where a style guide would come in handy, if your company already had one that is. In the absence of one you decide to again get some inspiration from the web, and you mimic some of the company's website design into your application -- a sans-serif font for white text on a blue field across the top, black text on white for the bottom two sections, and a small company logo to the left of the "Hello World" message.

Execution: The Coding Begins!

At long last you sit down to implement your plans and designs. The first few steps go according to plan, and creating the basic layout and text goes fairly smoothly -- but you run into a few challenges quite quickly:

Devising a user friendly interface to audio playback is not as intuitive as you first thought. Since there exist a ready made component for multimedia, you remove the bottom left field and now have the screen split in two. You add textual links for each of the five target languages, and when the user clicks one of them the message text changes and the appropriate audio plays back. It is a small sacrifice to make for now, and you are sure there is a solution to be found once you have become more proficient with QML.

The next challenge you run into is that deploying the application to a Symbian phone is not as clearly understood as you expected. Again you are sure there is something you are missing, but for the time being you manually copy the .sis file to the "Installs" directory on the phone (connected to the development machine by USB) and then install it through the Application Manager.

When you finally manage to install the application on the device you notice something that looks rather peculiar, and something you had not thought of. When the phone is turned into landscape mode, your text remains at the same absolute coordinates as when it was in portrait mode. You had not realized you needed to anchor it in order to achieve the centering you wanted. There was an easy fix for this, but you were glad you saw this earlier rather than later.


After the ups and downs of learning to develop a basic application using Qt Quick, you start to see greater possibilities for using Qt technologies for your current and future projects:

The Achievement

After your boss returned from vacation you presented him with the finished Qt Quick application, demonstrating it on both a mobile device as well as desktop (it happened to work well on both with little modification). You also provided him a presentation that detailed your road map for taking things to the next level -- targeting other platforms, such as the web, as well as improving on the existing application you just completed.

Even though the final product did not turn out the way you originally planned, your boss was still sufficiently impressed. Not only was the go ahead given for future projects, but ramping up a small team of developers and designers was also suggested to help support your efforts.