Delphi Cookbook - Second Edition - Programmer Books

Preface Every time I start to read a new book, I ask myself, "Will the author have something interesting to say?", "How much will this book change my point of view about the topics mentioned?", "Is it worth the time spent to read it?" Now, in spite of being from the other side of the river, I worked hard to put as much good quality contents in my books as possible, I hope that will match your expectations. One last note. Writing hundreds of pages about advanced programming is not an easy task. However, I am very pleased to have done it and I hope you will enjoy reading it at least how I enjoyed writing it. What this book covers Chapter 1, Delphi Basics, talks about a set of general approaches that should not be ignored by any Delphi programmer. Some topics are simple and immediate and some are not but all of them should be well understood. By the end of this chapter, the reader is able to use some of the fundamental Delphi techniques related to the RTL, to the VCL, and to the OS integration. Chapter 2, Becoming a Delphi Language Ninja, focuses on the Object Pascal language. The programming language is the way you talk to the machine, so you must be fluent and know all the possibilities offered. This chapter talks about higher-order functions, practical utilization of the extended RTTI, regular expressions, and other things useful to augment the power of your code and to lower the amount of time spent on debugging. Chapter 3, Knowing Your Friends – the Delphi RTL, focuses on the Delphi' RTL. There isn't a detailed description of all the Delphi's RTLs (you would need 10 books like this one, which will be particularly boring, I guess) but you can find some recipes that explain some of the most important RTL features and some less know but really useful classes. You'll learn how to use regular expressions, the most popular encoding format used by HTTP base applications, and how to use the built-in data de/compression-related classes. Chapter 4, Going Cross-Platform with FireMonkey, is dedicated to the FireMonkey framework in general. What you will learn from this chapter can be used in many of the platforms that FireMonkey supports. Moreover, you will learn about non-trivial LiveBindings utilizations. Chapter 5, The Thousand Faces of Multithreading, talks about thread synchronization and the mechanisms used to obtain this synchronization, such as TMonitor, thread-safe queues, and TEvent. It is also one of the most complex chapters. By the end of this chapter, the reader will be able to create and communicate with background threads, leaving your main thread free to update your GUI (or to communicate with the OS). vi

Preface Chapter 6, Putting Delphi on the Server, focuses on how well Delphi can behave when running on a server. Some people think that Delphi is a client-only tool, but it is not true. In this chapter, we'll show how to create powerful servers that offer services over a network. Then, in some recipe, we'll also implement a JavaScript client that brings the database data into the user browser. Techniques explained in this chapter open a range of possibilities, especially in the mobile and web area. Chapter 7, Riding the Mobile Revolution with FireMonkey, is dedicated to the mobile development with Delphi and FireMonkey. If you are interested in mobile development, I think that will be your favorite chapter! Mobile is everywhere, and this chapter will explain how to write software for your Android or iOS device, what are the best practices to use, how to save your data on the mobile, how to retrieve and update remote data, and how to integrate with the mobile operating system. Chapter 8, Using Specific Platform Features, shows you how to integrate your app with the underlying mobile operating systems beyond what FireMonkey offers. You will learn how to import Java and Objective C libraries in your app and how to use the SDK classes from your Object Pascal code. What you need for this book This book talks about Delphi, so you need it. Not all the recipes are available in all the Delphi editions. Typically, the mobile projects can be compiled only if you have Delphi Enterprise or higher (or Delphi Professional plus the mobile add-on, or RAD Studio professional or higher). All the projects are compiled and tested with the latest Delphi version at the time of writing, but many recipes can be compiled also on older versions. If you want to run the mobile app on a phone or a tablet, you could use the Android emulator or the iOS simulator, but we strongly suggest an actual device to see how the app really behaves. To deploy an iOS app on your device, you also need an Apple computer with MacOSX. Who this book is for This book aims to help the professional Delphi developers in their day-to-day job. This book will teach you about the newest Delphi technologies and its hidden gems. It is not a book for a newbie, but the practical approach will help you reach a new level with your Delphi skills. The experienced developer can benefit from this book because nontrivial problems are solved using best practices. Where more than one way is available or the topic is too broad to be explained in the available pages, references are provided to allow you to go deeper in that field. It is a book to have on your desk for the next few years. vii

Preface Conventions In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning. Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "Style manipulation at runtime is done using the class methods of the TStyleManager class." A block of code is set as follows: procedure TMainForm.StylesListRefresh; var stylename: string; begin ListBox1.Clear; // retrieve all the styles linked in the executable for stylename in TStyleManager.StyleNames do begin ListBox1.Items.Add(stylename); end; end; When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold: begin Application.Initialize; Application.MainFormOnTaskbar : True; TStyleManager.TrySetStyle('Iceberg Classico'); Application.CreateForm(TMainForm, MainForm); Application.Run; end Any command-line input or output is written as follows: # cp /usr/src/asterisk-addons/configs/cdr mysql.conf.sample /etc/asterisk/cdr mysql.conf viii

Preface New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "Add all the columns to TDBGrid by right-clicking and selecting Columns Editor". Warnings or important notes appear in a box like this. Tips and tricks appear like this. Reader feedback Feedback from our readers is always welcome. Let us know what you think about this book— what you liked or disliked. Reader feedback is important for us as it helps us develop titles that you will really get the most out of. To send us general feedback, simply e-mail feedback@packtpub.com, and mention the book's title in the subject of your message. If there is a topic that you have expertise in and you are interested in either writing or contributing to a book, see our author guide at www.packtpub.com/authors. Customer support Now that you are the proud owner of a Packt book, we have a number of things to help you to get the most from your purchase. Downloading the example code You can download the example code files for this book from your account at http:// www.packtpub.com. If you purchased this book elsewhere, you can visit http://www. packtpub.com/support and register to have the files e-mailed directly to you. ix

Preface You can download the code files by following these steps: 1. Log in or register to our website using your e-mail address and password. 2. Hover the mouse pointer on the SUPPORT tab at the top. 3. Click on Code Downloads & Errata. 4. Enter the name of the book in the Search box. 5. Select the book for which you're looking to download the code files. 6. Choose from the drop-down menu where you purchased this book from. 7. Click on Code Download. You can also download the code files by clicking on the Code Files button on the book's webpage at the Packt Publishing website. This page can be accessed by entering the book's name in the Search box. Please note that you need to be logged in to your Packt account. Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of: ff WinRAR / 7-Zip for Windows ff Zipeg / iZip / UnRarX for Mac ff 7-Zip / PeaZip for Linux The code bundle for the book is also hosted on GitHub at https://github.com/ PacktPublishing/Delphi-Cookbook-Second-Edition. We also have other code bundles from our rich catalog of books and videos available at https://github.com/ PacktPublishing/. Check them out! Errata Although we have taken every care to ensure the accuracy of our content, mistakes do happen. If you find a mistake in one of our books—maybe a mistake in the text or the code—we would be grateful if you could report this to us. By doing so, you can save other readers from frustration and help us improve subsequent versions of this book. If you find any errata, please report them by visiting http://www.packtpub.com/submit-errata, selecting your book, clicking on the Errata Submission Form link, and entering the details of your errata. Once your errata are verified, your submission will be accepted and the errata will be uploaded to our website or added to any list of existing errata under the Errata section of that title. To view the previously submitted errata, go to https://www.packtpub.com/books/ content/support and enter the name of the book in the search field. The required information will appear under the Errata section. x

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1 Delphi Basics In this chapter, we will cover the following topics: ff Changing your application's look and feel with the VCL style and without any code ff Changing the style of your application at runtime ff Customizing TDBGrid ff Using owner draw combos and listboxes ff Making an owner draw control aware of the VCL styles ff Creating a stack of embedded forms ff Manipulating JSON ff Manipulating and transforming XML documents ff I/O in the 21st century – knowing the streams ff Creating a Windows service ff Associating a file extension with your application on Windows ff Being coherent with the Windows look and feel using TTaskDialog Introduction This chapter will explain some of the day-to-day needs of a Delphi programmer. These are ready-to-use recipes that will be useful every day and have been selected ahead of a lot of others because, although they may be obvious for some experienced users, they are still very useful. Even if there isn't specifically database-related code, many of the recipes can also be used (or sometimes, especially used) when you are dealing with data. 1

Delphi Basics Changing your application look and feel with VCL styles and no code Visual Component Library (VCL) styles are a major new entry in the latest versions of Delphi. They have been introduced in Delphi XE2 and are still one of the lesser known features for the good old Delphi developers. However, as usual, some businessmen say "looks matter" so the look and feel of your application could be one of the reasons to choose one product over another from a competitor. Consider that with a few mouse clicks, you can apply many different styles to your application to change the look and feel of your applications. So, why not to give it a try? Getting ready VCL styles can be used to revamp an old application or to create a new one with a non-standard GUI. VCL styles are a completely different beast to FireMonkey styles. They are both styles, but with completely different approaches and behavior. To get started with VCL styles, we'll use a new application. So, let's create a new VCL application and drag and drop some components onto the main form (for example, two TButton, one TListBox, one TComboBox, and a couple of TCheckBox). You can now see the resultant form that is running on my Windows 8.1 machine: Figure 1.1: A form without style 2

Chapter 1 How to do it Now, we've got to apply a set of nice styles by following these steps: 1. Go to Project Options from the menu. Then, in the resultant dialog, go to Application Appearance and select all the styles that we want to include in our application. 2. Using the Preview button, the IDE shows a simple demo form with some controls, and we can get an idea about the final result of our styled form. Feel free to experiment and choose the style—or set of styles—that you like. Only one style at a time will be used, but we can link the necessary resources into the executable and select the proper one at runtime. 3. After selecting all the required styles from the list, we've got to select one in the combo box at the bottom. This style will be the default style for our form and will be loaded as soon as the application starts. You can delay this choice and make it at runtime using code if you prefer. 4. Click on OK, hit F9 (or go to Run Run), and your application is styled: Figure 1.2: The same form as Figure 1.1 but with the Iceberg Classico style applied 3

Delphi Basics How it works Selecting one or more styles from Project Options Application Appearance will cause the Delphi linker to link the style resource into your executable. It is possible to link many styles into your executable, but you can use only one style at a time. So, how does Delphi know which style you want to use when there are more than one? If you check the Project file (the file with the .dpr extension) by going to Project View Source Menu, you can see where and how this little magic happens. The following lines are the interesting section: begin Application.Initialize; Application.MainFormOnTaskbar : True; TStyleManager.TrySetStyle('Iceberg Classico'); Application.CreateForm(TMainForm, MainForm); Application.Run; end When we've selected the Iceberg Classico style as the default style, the Delphi IDE added a line just before the creation of the main form, setting the default style for all the applications using TStyleManager.TrySetStyle static methods. TStyleManager is very important class when dealing with VCL styles. We'll see more about it in the upcoming recipe, where you'll learn how to change styles at runtime. There's more Delphi and C Builder 10.1 Berlin come with 36 VCL styles available in the folder (with a standard installation): C:\Program Files (x86)\Embarcadero\Studio\18.0\Redist\styles\vcl\ Moreover, it is possible to create your own styles or modify the existing ones using the Bitmap Style Designer. You can access it by going to Tools Bitmap Style Designer Menu. For more details on how to create or customize a VCL style, visit http://docwiki. embarcadero.com/RADStudio/en/Creating a Style using the Bitmap Style Designer. The Bitmap Style Designer also provides test applications to test VCL styles. 4

Chapter 1 Changing the style of your VCL application at runtime VCL styles are a powerful way to change the appearance of your application. One of the main features of VCL styles is the ability to change the style while the application is running. Getting ready Because a VCL Style is simply a particular kind of binary file, we can allow our users to load their preferred styles at runtime. We could even provide new styles by publishing them on a website or sending them by e-mail to our customers. In this recipe, we'll change the style while the application is running using a style already linked at design time, or let the user choose between a set of styles deployed inside a folder. How to do it Style manipulation at runtime is done using the class methods of the TStyleManager class. Follow these steps to change the style of your VCL application at runtime: 1. Create a brand new VCL application and add the Vcl.Themes and Vcl.Styles units to the implementation main form uses section. These units are required to use VCL styles at runtime. 2. Drop on the form a TListBox, two TButton, and a TOpenDialog. Leave the default component names. 3. Go to Project Appearance and select eight styles of your choice from the list. Leave the Default style to Windows. 4. The TStyleManager.StyleNames property contains names of all the available styles. In the FormCreate event handler, we have to load the already linked styles present in the executable into the listbox to let the user choose one of them. So, create a new procedure called StylesListRefresh with the following code and call it from the FormCreate event handler: procedure TMainForm.StylesListRefresh; var stylename: string; begin ListBox1.Clear; // retrieve all the styles linked in the executable for stylename in TStyleManager.StyleNames do begin ListBox1.Items.Add(stylename); end; end; 5

Delphi Basics 5. In the Button1Click event handler, we've to set the current style according to the one selected from the ListBox1 using the code as follows: mIndex]); 6. The Butt

Roman Yankovsky is a long time Delphi developer who has been working with Delphi since Delphi 2. He has developed and maintained various applications in different industries. Currently he is working with ShareBike, developing a public bike sharing system. Roman is an Embarcadero MVP and a frequent speaker at developer conferences.