unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  ComCtrls, StdCtrls, AMixer;

type
  TForm1 = class(TForm)
    ComboBox1: TComboBox;
    ComboBox2: TComboBox;
    TrackBar: TTrackBar;
    CheckBox: TCheckBox;
    Label1: TLabel;
    Label2: TLabel;
    Mixer: TAudioMixer;
    Label3: TLabel;
    Label4: TLabel;
    procedure FormCreate(Sender: TObject);
    procedure ComboBox1Change(Sender: TObject);
    procedure ComboBox2Change(Sender: TObject);
    procedure MixerControlChange(Sender: TObject; MixerH, ID: Integer);
    procedure TrackBarChange(Sender: TObject);
    procedure CheckBoxClick(Sender: TObject);
  private
    { Private declarations }
    Setting:Boolean;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.FormCreate(Sender: TObject);
var A:Integer;
begin
  If Mixer.MixerCount>0 then
  begin
    For A:=0 to Mixer.Destinations.Count-1 do
      ComboBox1.Items.Add (Mixer.Destinations[A].Data.szName);
    If ComboBox1.Items.Count>0 then
    begin
      ComboBox1.ItemIndex:=0;
      ComboBox1Change (Self);
    end;
  end
  else
  begin
    ComboBox1.OnChange:=nil;
    ComboBox2.OnChange:=nil;
    TrackBar.OnChange:=nil;
    CheckBox.OnClick:=nil;
    MessageDlg ('No mixer present in the system !',mtError,[mbOK],0);
  end;
  Setting:=False;
end;

procedure TForm1.ComboBox1Change(Sender: TObject);
var A:Integer;
begin
  ComboBox2.Items.Clear;
  ComboBox2.Items.Add (Mixer.Destinations[ComboBox1.ItemIndex].Data.szName);
  For A:=0 to Mixer.Destinations[ComboBox1.ItemIndex].Connections.Count-1 do
    ComboBox2.Items.Add(Mixer.Destinations[ComboBox1.ItemIndex].Connections[A].Data.szName);
  If ComboBox2.Items.Count>0 then
  begin
    ComboBox2.ItemIndex:=0;
    ComboBox2Change (Self);
  end;
end;

procedure TForm1.ComboBox2Change(Sender: TObject);
var L,R,M:Integer;
    VD,MD:Boolean;
begin
  Mixer.GetVolume (ComboBox1.ItemIndex,ComboBox2.ItemIndex-1,L,R,M,VD,MD);
  Setting:=True;
  TrackBar.Enabled:=L<>-1;
  Label3.Visible:=not VD;
  If TrackBar.Enabled then
    TrackBar.Position:=L;
  CheckBox.Enabled:=M<>-1;
  Label4.Visible:=not MD;
  If CheckBox.Enabled then
    CheckBox.Checked:=M<>0;
  Setting:=False;
end;

procedure TForm1.MixerControlChange(Sender: TObject; MixerH, ID: Integer);
begin
  ComboBox2Change (Self);
end;

procedure TForm1.TrackBarChange(Sender: TObject);
begin
  Setting:=True;
  Mixer.SetVolume (ComboBox1.ItemIndex,ComboBox2.ItemIndex-1,TrackBar.Position,-1,Integer(CheckBox.Checked));
  Setting:=False;
end;

procedure TForm1.CheckBoxClick(Sender: TObject);
begin
  If not Setting then
    TrackBarChange (Self);
end;

end.