Enumerating-and-Playing-System-Sounds-from-Delphi-code


            Title: Enumerating and Playing System Sounds from Delphi code
To play a system sound ("application even" or "system even" as called by MS), you can call the PlaySound API function, available in the mmsystem unit.
The PlaySound function plays a sound specified by the given filename, resource, or system event. System event are, in general, associated with a sound in the registry.
Registered system sounds are located under the "AppEvents\Apps" key under HKEY_CURRENT_USER in the Registry database.
Here's how to play the "System Question" system sound:
 uses MMSystem, ...
 
 PlaySound('SystemQuestion', 0, SND_ALIAS or SND_ASYNC) ; 
Note: Using the SND_ASYNC flag the sound is played asynchronously and PlaySound returns immediately after beginning the sound playback. SND_ALIAS tells the PlaySound function that the first parameter is a system-event alias.
Note (also): the actual sound refrences are stored in HKEY_CURRENT_USER\AppEvents\Schemes\Apps\.Default.
Listing all System/Event Sounds
Now that you know how to play a system sound, here's how to get the list of all the registered sounds in Windows:
Drop a TButton (name: "Button1") and a TListBox (name: "ListBox1") on a Delphi form (name: "SystemSoundPlayerForm"). Handle the Form's OnCreate and Button's OnClick events as:
 uses MMSystem, Registry, ... //Button1 ... OnClikc
 procedure TSystemSoundPlayerForm.Button1Click(Sender: TObject) ;
 var
 soundAlias : string;
 begin
 if ListBox1.ItemIndex = -1 then
 begin
 ShowMessage('Select a sound alias from the list...') ;
 Exit;
 end;
 
 soundAlias := ListBox1.Items[ListBox1.ItemIndex];
 
 PlaySound(PAnsiChar(soundAlias), 0, SND_ALIAS or SND_ASYNC) ;
 end;
 
 //SystemSoundPlayerForm ... OnCreate
 procedure TSystemSoundPlayerForm.FormCreate(Sender: TObject) ;
 var
 reg : TRegistry;
 begin
 reg := TRegistry.Create;
 try
 reg.RootKey := HKEY_CURRENT_USER;
 reg.OpenKeyReadOnly('\AppEvents\EventLabels') ;
 reg.GetKeyNames(ListBox1.Items) ;
 finally
 reg.Free;
 end;
 end; 
Select a sound alias from the list and hit the play button ...
System Delphi
