Delphi is a powerful programming language used for building Windows desktop applications. One of the most powerful features of Delphi is the ability to create custom components that can be used in your applications. In this post, we'll show you how to create a custom component and use it in Delphi.
Step 1: Create a new component
To create a new component in Delphi, go to File > New > Other and select "Component" from the list of options.
This will open the "New Component" wizard. In this wizard, you can specify the name of your component, as well as other properties such as the unit name and the class name.
For this example, we'll create a simple component called "TMyButton". This component will be a custom button control that will display a message when clicked.
Step 2: Add properties and methods
Once you've created your component, you can add properties and methods to it. In this example, we'll add a property called "Message" that will allow the user to specify the message to be displayed when the button is clicked.
To add a property, open the source code for your component by clicking on the "Edit" button in the "New Component" wizard. Then, add the following code:
private
FMessage: string;
published
property Message: string read FMessage write FMessage;
This code defines a private field called "FMessage" and a published property called "Message". The "read" and "write" keywords indicate that this property can be both read and written.
Next, we'll add a method called "" that will display the message when the button is clicked. Add the following code to your component's source code:
procedure Click; override;
procedure TMyButton.Click;
begin
ShowMessage(FMessage);
inherited;
end;
This code defines the "Click" method and overrides the existing "Click" method of the TButton component. The "ShowMessage" function displays the message specified by the "Message" property.
Step 3: Install the component
Now that you've created your component, you need to install it in Delphi so that it can be used in your applications.
To install the component, go to Component > Install Component. In the "Install Component" wizard, select the "Into new package" option and specify a package name and description.
In the "Units" page of the wizard, select the unit that contains your component's source code. Then, click "Compile" to compile the package.
Once the package is compiled, click "Install" to install the component. This will add your component to the "Tool Palette" in Delphi.
Step 4: Use the component in your application
To use your new component in a Delphi application, simply drag and drop it from the "Tool Palette" onto your form. Then, set the "Message" property to the message you want to display when the button is clicked.
Here's an example of how to use the TMyButton component in a Delphi application:
procedure TForm1.FormCreate(Sender: TObject);
begin
MyButton1.Message := 'Hello, world!';
end;
This code sets the "Message" property of the MyButton1 instance to "Hello, world!". When the button is clicked, the message will be displayed.
That's it! You've just created a custom component in Delphi and used it in your application. With this knowledge, you can create a wide range of custom components to enhance your Delphi applications.