TCheckGroup

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A TCheckGroup is a control that comprises a group of TCheckBox items physically and logically grouped together on a container component.

Usage

To use a TCheckGroup on a form, you can simply select it on the Standard tab of the Component Palette and place it by clicking on the form.

Small example

It changes the background color of a form. This color is determined by adding the individual color components:

• create a new application and place a TCheckGroup on your form
• in the object inspector change the property Name of CheckGroup1 to cgRed and the caption to Red
• add the checkboxes for cgRed:
  • in the object inspector select the property Items of cgRed
  • click on the button [...], the character chain editor opens
  • write among one another 1 2 4 8 16 32 64 128 and complete the entry with the OK button
• copy this TCheckGroup by right click cgRed in the form and click on Copy
• right-click the form and click on Insert, which creates TCheckGroup named cgRed1
• now change the Name of cgRed1 to cgGreen and the Caption to Green
• insert even a TCheckGroup and change the name to cgBlue and the caption to Blue
• whenever a CheckBox is clicked, the color will change:
  • in the object inspector create the OnItemClick event handler of cgRed by clicking the button [...] next to the event OnItemClick
  • select for cgGreen and cgBlue also this event handler, by choosing each next to the event OnItemClick ComboBox cgRedItemClick
  • write following code in the event handler:

procedure TForm1.cgRedItemClick(Sender: TObject; Index: integer);
var
  i, c: Integer;
begin
  c := $000000;                                          // first the color is black
  for i:=0 to 7 do begin                                 // test Items 0..7 of all Checkgroups
    if cgRed.Checked[i]   then c := c + 1 shl i;         // amount of red   $000000..$0000FF
    if cgGreen.Checked[i] then c := c + 1 shl (i + 8);   // amount of green $000000..$00FF00
    if cgBlue.Checked[i]  then c := c + 1 shl (i + 16);  // amount of blue  $000000..$FF0000
  end;
  Color := c;
end;

• start your program, it could look like:

Accessing the Check Boxes

Each item in the TCheckGroup has a Checked property, to set them all to checked do

for i := 0 to MyCheckGroup.items.Count-1 do   // check all the categories we found.
    MyCheckGroup.Checked[i] := true;

You can add items at run time by using TCheckGroup.Items, its a TStrings list. To add an new checkbox to the set, just do MyCheckGroup.Items.add('CheckThis'); Similarly, to remove all items, clear the list, MyCheckGroup.Items.clear;

See also

• TCheckGroup doc
• TCheckBox
• TGroupBox