Delphi Fundamentals

Introduction

Delphi offers a practical and easy means of creating computer applications. It uses Object Pascal as its core syntax and programming logic. There are various ways you can launch the program. The most common way consists of clicking.

To create a shortcut on the desktop, in Microsoft Windows higher than Win95, you can click Start -> (All) Programs -> Embarcadero RAD Studio 2010, and right-click Delphi 2010. You can click Pin To Start Menu to permanently add it to the Start Menu in the same group with Internet Explorer. You can click Send To -> Desktop (Create Shortcut), which would create a Delphi shortcut on the desktop.

• To start Delphi, click Start -> (All) Programs -> Embarcadero RAD Studio 2010 -> Delphi 2010
   
  

An Integrated Development Environment (IDE) is an application that provides a friendly interface for creating computer programs. Delphi’s IDE is structurally a classic application. On top, there is a title bar that displays the name of the application and the program currently running. The title bar itself is made of three sections.

To create a computer application in Delphi, you start with a project. A project is a collection of files that, when put together, represent an object that can be executed on various computers (including those that don't have Delphi). There are different types of applications you can create and thus different ways to start a project.

To create a Windows application, on the main menu, you would click File -> New -> VCL Forms Application - Delphi:

This action starts a project and displays a rectangular object called a form.

• On the main menu, click File -> New -> VCL Forms Application - Delphi

A new type of application becoming popular and wholly supported in the VCL involves touch screens. There is no formal application for a touch screen. This means that, if you are developing for Microsoft Windows 7,  any type of VCL Forms Application you create has full support for touch screen. Normally, there is nothing much you have to do for your application to be usable on a touch screen: it is simply ready by virtue of creating a VCL Forms Application. Still, there are details you should pay attention to.

If you want to create applications for the touch screen, you must first have a touch screen. The prices of touch screens are coming down but like every time a new hardware product is getting in the industry, it starts with high prices. In most cases, 15 inches touch screen monitors currently cost as much as 22 inches regular monitors. With some luck and microscopic searching, you can find a good touch screen monitor at a resonable price. For example, we were able to get a 23" ACER touch screen monitor for less than $390 and it works fine. When purchasing a touch screen, the size is one of the first details you will pay attention to. In some cases, small monitors can be fine for such businesses as department stores or supermarkets. In such bunisses, employees use their fingers that they directly apply to the screen. Employees on those businesses also usually have clean hands. There are other categories of businesses where touch screens are welcome such as car repair stores and warehouses. Employees in those businesses tend to wear gloses while using the touch screen. If you are purchasing touch screen monitors for such businesses, the bigger the screen the better.

Delphi allows you to create an "experimental" application that would disappear when you close Embarcadero RAD Studio. To use such an experimental application, start by creating a project, do whatever you want with it, including adding other items and resources as we will see throughout our lessons. While using the project, don't save it.

If you want to keep everything you have done in a project and continue it another time, you must save the project. Also, if you want to be able to distribute your application to other computers, you must save it.

To save a project, on the main menu, you can click File -> Save All or File -> Save Project As... An alternative is to click the Save All button from the Standard toolbar. When saving a project, you must specify (or create) a folder for the project. You must specify a name for the project and you must name each file used in your application.

1. On the Standard toolbar, click Save All
2. Type Exercise to replace the name of the Unit1
3. Click the Create New Folder button
4. Type Exercise01 and press Enter
5. Double-click Exercise01 to display it in the Save In combo box
6. Click Save to save Exercise.cpp
7. Type Exercise1 to replace the name of the project
8. Click Save

A program would not mean much unless it accomplishes the desired purpose. To examine how your development is proceeding, you should regularly ask Delphi to show you the result.

There are three ways you can execute a program in Delphi. To execute a program:

• You can press F9
• You can use the main menu where you would click Run -> Run
• On the toolbar, you can click the Run button

Remember that you can do almost anything without, or before, saving a project. This means that you can execute a project even if it has not been saved already.

• On the Debug toolbar, click the Run button

If you had used early versions of Delphi (<= 6), you may be familiar with its thoughtful style that used independent objects. That is, each window of the programming environment was not connected to the other. Each window could be dragged from one side to another without any effect on the other window. This was an unusual design that presented many options. If you want, you can get that interface.

To get the classic view, on the main menu, click View -> Desktop -> Classic Undocked:

The title bar is a horizontal bar that signals the application to the operating system:

The title bar displays the system icon . The system icon is used to identify the application you are using. Almost every application has its own system icon. The system icon holds its own list of actions. For example, it can be used to move, minimize, maximize or close (when double-clicked) a window. These actions are available through a menu that displays when you click the system icon:

The main section of the title bar displays Embarcadero RAD Studio 2010. On the right section of the title bar, there are three system buttons with the following roles:

Button			Role
			Minimizes the window
			Maximizes the window
			Restores the window
			Closes the window

Under the title bar, the main menu displays its various groups of menu items.

In our lessons, the word "Main Menu" refers to the menu on top of the IDE

There are four main types of menu items you will encounter:

• When clicked, the behavior of a menu that stands alone depends on the actions prior to clicking it. Under the File menu, examples include Save, Close, Close All, or Exit. For example, if you click Close All, Delphi will find out whether the project had been saved already. If it was, the project would be closed; otherwise, you would be asked whether you want to save it
• A menu that is disabled is not accessible at the moment. This kind of menu depends on another action or the availability of something else
• A menu with three dots means an action is required in order to apply its setting(s). Usually, this menu would call a dialog box where the user would have to make a decision.
  
• A menu with an arrow holds submenu. To use such a menu, position the mouse on it to display its submenu

If you press F10, the main menu receives focus and a letter becomes underlined on each word of the menu. Examples would be F in File, E in Edit, etc. The underlined letter is called an access key. It allows you to access the same menu item using the keyboard. In order to use an access key, the menu should have focus first. The menu is given focus by pressing either the Alt or the F10 keys.

When the menu has focus and you want to dismiss it, press Esc.

On some menu items, there is a combination of keys we call a shortcut. This key or this combination allows you to perform the same action on that menu using the keyboard.
If the shortcut is made of one key only, you can just press it. If the shortcut is made of two keys, press and hold the first one, while you are holding the first, press the second key once and release the first key. Some shortcuts are a combination of three keys.

The About dialog box allows you to get some information about Delphi and the operating system. To access the About dialog box, on the main menu, you can click Help -> About Embarcadero® Delphi®. Alternatively, on the right side of the main menu, there is a Delphi button . If you click the button, the About dialog box would display:

From now on, in our lessons,

A toolbar is an object made of buttons. These buttons provide the same features you would get from the menu. Under the menu, the IDE is equipped with various toolbars. To see the list of available toolbars, you can right-click the one under the main menu:

You can move a toolbar from its default position to another area on the screen. To do this, you can click and drag it away. To position the toolbar back or to somewhere else, you can drag its title bar to the desired location

In our lessons, every toolbar is referred to by its name
 

Toolbar Name	Illustration
Standard
Debug
Desktop
Browser
View
Custom

A toolbar is equipped with buttons that could be unpredictable. Just looking at one is not obvious. The solution to knowing what a button is used for is to position the mouse on top of it. A tool tip also called a hint will come up and display for a few seconds:

Besides designing applications, one of your most regular jobs will consist of writing code that directs the computer as to what to do, when, and how to do it. This is done in an appropriate window called the Code Editor.

The Code Editor is a feature-rich text editor adapted for coding purposes. It is programmed to recognize the parts of a program that belong to Pascal or not. To access the Code Editor, if you have a form opened, you can press F12. The Code Editor manages your jobs by organizing its files into property pages (also called tabs). If your project contains more than one file, you can click the desired tab to access one of the files.

The basic building block of a program is called a code file. Whenever you create a new project, the Delphi programming environment creates a Pascal file called Unit1 while the project is called Project1. If you want, you can change these names by saving the project.

To display the code file of the form, you can click the Design tab. To change the displaying of the form and its code, on the main menu, you can click View -> Toggle Form/Unit. At any time, for example if the programming environment is displaying something other than the form, to display the form, on the main menu, you can click View -> Forms... This would display the list of forms of the application. You can then click the desired form and click OK.

1. To toggle between the form and its unit, press F12
2. To bring back the Code Editor, press F12
3. To bring back the form, press F12

The Welcome Page is the first wide area that appears when Delphi comes up. The section displays a title as Recent Projects. At any time, to display the Welcome Page:

• You can click the Welcome Page button in the middle-upper side of the IDE
• On the main menu, you can click View -> Welcome Page

If you have just installed Delphi or have not previously opened a project, the Recent Projects section would be empty. Once you start creating and using projects, they display in the Recent Projects section by their names.

When you start or open a project, Delphi makes some windows available. These are the most regularly used windows. If you think that one of them is not regularly used in your types of assignments, you can remove it from the screen. To hide a window, you can click its Close button .

All of the windows you can use are listed in the View menu. Therefore, if a window is not displaying, you can click View on the main menu and click a window of your choice.

When creating your applications, you will use a set of windows that each accomplishes a specific purpose. Some windows are represented with an icon but hide the rest of the body. To display such a window, you can position the mouse on it. This would expand the window:

If you expand a window, it would display a title bar with two buttons. One is called Auto Hide and the other is the Close button:

If you expand a window but find out you don't need it any more, you can just move the mouse away from it. The window would return to its previous state. Based on this functionality, if you are working with a window and move the mouse away from it, it would retract. If you need it again, you would have to reopen it using the same technique. If you are going to work with a certain window for a while, you can keep it open even if you move the mouse away. To do this, you can click the Auto Hide button. If clicked, the Auto Hide button changes from pointing left to pointing down:

By default, Delphi installs some windows to the left and some others to the right of the screen. You can change this arrangement if you want. To do this, expand a window, then click its title bar and start dragging. To position a window on one side of the screen, drag its title bar to that side. When you get to a side, a transparent blue rectangle would be drawn to indicate the possible position:

OR

OR

You can dock a window only if it is dockable. This means that some windows, such as the Code Editor, are not dockable. To find out whether a certain window is currently docked, right-click its body and notice that the Dockable option is checked:

If a window is dockable but you want to prevent yourself from (accidentally) docking it, right-click its body and click Dockable. The check box would be removed from the Dockable option and then, if you drag the window to another location, it cannot be docked.

Most of the windows you will use are positioned on one side of the screen. If you want, you can have a window that stays on top of other windows but cannot  be "glued" to one side. Such a window is said to float. To float a window, drag its title bar and release it somewhere in the middle of the screen but not on a side because, while dragging, if you release the mouse on one of the sides, and if the window is dockable, it would assume the position of where you released the mouse.

You can make two or more windows share one side of the screen or to share an area. To do this, first expand and fix the window that you will use as foundation (or reference). Then, drag the title bar of the window that will share the area:

This

Produces

Or this

Produces

Or this

Produces

 In the same way, you can make two or more windows share the same area.