Book Image

Delphi GUI Programming with FireMonkey

By : Andrea Magni
4 (1)
Book Image

Delphi GUI Programming with FireMonkey

4 (1)
By: Andrea Magni

Overview of this book

FireMonkey (FMX) is a cross-platform application framework that allows developers to create exciting user interfaces and deliver applications on multiple operating systems (OS). This book will help you learn visual programming with Delphi and FMX. Starting with an overview of the FMX framework, including a general discussion of the underlying philosophy and approach, you’ll then move on to the fundamentals and architectural details of FMX. You’ll also cover a significant comparison between Delphi and the Visual Component Library (VCL). Next, you’ll focus on the main FMX components, data access/data binding, and style concepts, in addition to understanding how to deliver visually responsive UIs. To address modern application development, the book takes you through topics such as animations and effects, and provides you with a general introduction to parallel programming, specifically targeting UI-related aspects, including application responsiveness. Later, you’ll explore the most important cross-platform services in the FMX framework, which are essential for delivering your application on multiple platforms while retaining the single codebase approach. Finally, you’ll learn about FMX’s built-in 3D functionalities. By the end of this book, you’ll be familiar with the FMX framework and be able to build effective cross-platform apps.
Table of Contents (18 chapters)
Section 1: Delphi GUI Programming Frameworks
Section 2: The FMX Framework in Depth
Section 3: Pushing to The Top: Advanced Topics

Playing with the form's OnTouch event

Especially on mobile platforms, devices have multi-touch support. Basically, the user can interact with the screen of the device using one or more fingers. FMX provides a simple way to handle touches on the screen, that is, the OnTouch event exposed by TForm descendants.

The event handler you can provide has the following signature:

procedure TMainForm.FormTouch(Sender: TObject; const Touches: TTouches;
const Action: TTouchAction);

Arguments include Touches and Action parameters. The first is an array of TTouch structures (records) basically representing the point the touch has happened at. Given the multi-touch support, you'll have an entry in the array for each finger actually detected on the device. The Action argument will help you discriminate which kind of event is happening among the None, Up, Down, Move, and Cancel possibilities.

You can easily keep track of the number of fingers currently on the active surface by...