Creating the Application

The simplest static control is considered a label. It consists of a simple object that displays text. The user cannot directly change this text unless you programmatically allow it. This form of the static control is the simplest control you can use in a VCL application.

To add a simple label to a dialog box, you can click the Label button on the Standard tab of the Component Palette. The only thing you need to do is to change the Caption property on the Object Inspector window.

If you cannot add a label to the dialog box when designing it, you can programmatically create one. This is done using the TLabel class and calling its constructor.

Practical Learning: Starting the Exercise

1. Start Borland C++ Builder and create a new application
2. To start saving the application, on the Standard toolbar, click the Save All button. Create a new folder named ColorChanger1 and display it in the Save In combo box
3. Save the unit as Main and save the project as ColorChanger
4. Design the dialog box as follows:
    

   Control Name Caption Additional Properties Form   frmMain Color Changer BorderStyle: bsDialog Position: poScreenCenter Panel pnlPreview None Color: clSilver TrackBar trcRed   Frequency: 20 Max: 255 Orientation: trVertical Position: 63 TickMarks: tmBoth TrackBar trcGreen   Frequency: 20 Max: 255 Orientation: trVertical Position: 63 TickMarks: tmBoth TrackBar trcBlue   Frequency: 20 Max: 255 Orientation: trVertical Position: 63 TickMarks: tmBoth BitBtn     Kind: bkClose Label lblRed 192 Alignment: taCenter Label lblGreen 192 Alignment: taCenter Label lblBlue 192 Alignment: taCenter

5. Save All
6. On the form, double-click the left track bar and implement its OnChange event as follows:
    

   //--------------------------------------------------------------------------- void __fastcall TfrmMain::trcRedChange(TObject *Sender) { int iRed = 255 - trcRed->Position; int iGreen = 255 - trcGreen->Position; int iBlue = 255 - trcBlue->Position; pnlPreview->Color = TColor(RGB(iRed, iGreen, iBlue)); lblRed->Caption = IntToStr(iRed); } //---------------------------------------------------------------------------

7. On the form, double-click the middle track bar and implement its OnChange event as follows:
    

   //--------------------------------------------------------------------------- void __fastcall TForm1::trcGreenChange(TObject *Sender) { int iRed = 255 - trcRed->Position; int iGreen = 255 - trcGreen->Position; int iBlue = 255 - trcBlue->Position; pnlPreview->Color = TColor(RGB(iRed, iGreen, iBlue)); lblGreen->Caption = IntToStr(iGreen); } //---------------------------------------------------------------------------

8. On the form, double-click the right track bar and implement its OnChange event as follows:
    

   //--------------------------------------------------------------------------- void __fastcall TfrmMain::trcBlueChange(TObject *Sender) { int iRed = 255 - trcRed->Position; int iGreen = 255 - trcGreen->Position; int iBlue = 255 - trcBlue->Position; pnlPreview->Color = TColor(RGB(iRed, iGreen, iBlue)); lblBlue->Caption = IntToStr(iBlue); } //---------------------------------------------------------------------------

9. Test the application
10. After using it, close it and return to your programming environment.