Changing your application look and feel with VCL styles and no code

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

Now, we've got to apply a set of nice styles by following these steps:

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.

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.