SystemVolume W6-10 CoInitialize CoUninitialize [MasterVolume,
MasterMute]
lazarus / 34-Windows

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RAW · 2017-02-13 02:30

Is it really necessary to use COINITIALIZE and COUNINITIALIZE ?
I remember a post where someone said that it is only necessary in
Delphi not in FreePascal.

I was playing around with this Code and everything is working as it
should.
Then I recognized that I miss those two lines...

And If so where should I put those lines ???

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i Unit
uMasterMuteW7; {$MODE OBJFPC}{$H+} Interface  USES  Classes, SysUtils,
Forms, Controls,  Windows, ComObj, ActiveX, ShellApi;   TYPE  TMyBOOL
= (myFalse = Integer(0),             myTrue  = Integer(1));  TYPE 
TwndGUI = Class(TForm)    Procedure SetMasterVolume (    sinVol:
Single );   Procedure GetMasterVolume (Out sinVol: Single ); 
 Function  GetMasterMute              : TMyBOOL;   Procedure
SetMasterMute   (     Value: TMyBOOL);    Procedure FormKeyDown    
(Sender: TObject; Var Key: Word;                              Shift :
TShiftState);  End;   // WINDOWS 7 VOLUME BEGIN TYPE 
IAudioEndpointVolumeCallback = Interface(IUnknown) 
 ['{657804FA-D6AD-4496-8A60-352752AF4F89}']  End;  
IAudioEndpointVolume = Interface(IUnknown) 
 ['{5CDF2C82-841E-4546-9722-0CF74078229A}']     Function
RegisterControlChangeNotify(              AudioEndPtVol:
IAudioEndpointVolumeCallback): HRESULT; StdCall;    Function
UnregisterControlChangeNotify(              AudioEndPtVol:
IAudioEndpointVolumeCallback): HRESULT; StdCall;    Function
GetChannelCount(Out PInteger): HRESULT; StdCall;     Function
SetMasterVolumeLevel(              fLevelDB: Single;
pguidEventContext: PGUID): HRESULT; StdCall;    Function
SetMasterVolumeLevelScalar(              fLevelDB: Single;
pguidEventContext: PGUID): HRESULT; StdCall;     Function
GetMasterVolumeLevel(              Out fLevelDB: Single): HRESULT;
StdCall;    Function GetMasterVolumeLevelScalar(              Out
fLevelDB: Single): HRESULT; StdCall;     Function
SetChannelVolumeLevel(              nChannel: Integer; fLevelDB:
Double; pguidEventContext: PGUID):             HRESULT; StdCall;   
Function SetChannelVolumeLevelScalar(              nChannel: Integer;
fLevelDB: Double; pguidEventContext: PGUID):             HRESULT;
StdCall;     Function GetChannelVolumeLevel(              nChannel:
Integer; Out fLevelDB: Double): HRESULT; StdCall;    Function
GetChannelVolumeLevelScalar(              nChannel: Integer; Out
fLevelDB: Double): HRESULT; StdCall;     Function SetMute(           
 bSetMute: Bool; pguidEventContext: PGUID): HRESULT; StdCall;   
Function GetMute(              Out bGetMute: Bool): HRESULT;
StdCall;     Function GetVolumeStepInfo(              pnStep: Integer;
Out pnStepCount: Integer): HRESULT; StdCall;    Function
VolumeStepUp(              pguidEventContext: PGUID): HRESULT;
StdCall;    Function VolumeStepDown(              pguidEventContext:
PGUID): HRESULT; StdCall;    Function GetVolumeRange(              Out
pflVolumeMindB: Double; Out pflVolumeMaxdB: Double;              Out
pflVolumeIncrementdB: Double): HRESULT; StdCall;    Function
QueryHardwareSupport(              Out pdwHardwareSupportMask):
HRESULT; StdCall;  End;   IAudioMeterInformation =
Interface(IUnknown)   ['{C02216F6-8C67-4B5B-9D00-D008E73E0064}'] 
End;   IPropertyStore = Interface(IUnknown)  End;   IMMDevice =
Interface(IUnknown)   ['{D666063F-1587-4E43-81F1-B948E807363F}']   
Function Activate(              Const refId: TGUID; dwClsCtx: DWORD;
pActivationParams: PInteger;              Out pEndpointVolume:
IAudioEndpointVolume): HRESULT; StdCall;    Function
OpenPropertyStore(              stgmAccess: DWORD; Out ppProperties:
IPropertyStore):             HRESULT; StdCall;    Function GetId  
(Out ppstrId: PLPWSTR): HRESULT; StdCall;    Function GetState(Out
State: Integer):   HRESULT; StdCall;  End;   IMMDeviceCollection =
interface(IUnknown)   ['{0BD7A1BE-7A1A-44DB-8397-CC5392387B5E}'] 
End;   IMMNotificationClient = interface(IUnknown) 
 ['{7991EEC9-7E89-4D85-8390-6C703CEC60C0}']  End;  
IMMDeviceEnumerator = interface(IUnknown) 
 ['{A95664D2-9614-4F35-A746-DE8DB63617E6}']    Function
EnumAudioEndpoints(              dataFlow: TOleEnum; deviceState:
SYSUINT; DevCollection:              IMMDeviceCollection): HRESULT;
StdCall;    Function GetDefaultAudioEndpoint(              EDF:
SYSUINT; ER: SYSUINT; Out Dev: IMMDevice): HRESULT; StdCall;   
Function GetDevice(pwstrId: Pointer; Out Dev: IMMDevice): HRESULT;
StdCall;    Function RegisterEndpointNotificationCallback(           
 pClient: IMMNotificationClient): HRESULT; StdCall;  End;  CONST 
CLASS_IMMDeviceEnumerator: TGUID =
'{BCDE0395-E52F-467C-8E3D-C4579291692E}';  IID_IMMDeviceEnumerator  :
TGUID = '{A95664D2-9614-4F35-A746-DE8DB63617E6}'; 
IID_IAudioEndpointVolume : TGUID =
'{5CDF2C82-841E-4546-9722-0CF74078229A}'; // WINDOWS 7 VOLUME
END  VAR  wndGUI: TwndGUI; Implementation {$R *.LFM}  Procedure
TwndGUI.FormKeyDown(Sender: TObject; Var Key: Word;                  
          Shift : TShiftState);  Var   myMute: TMyBOOL;   sinVol:
Single; Begin  // MIXER  If Key = Ord('V')  Then ShellExecute(0, Nil,
PChar('sndvol.exe'), '', '', SW_SHOWNORMAL);   // MUTE  If Key =
Ord('M')  Then   Begin    myMute:= GetMasterMute;     If myMute =
myTrue    Then SetMasterMute(myFalse)    Else SetMasterMute(myTrue); 
 End;   // MAX VOLUME  If Key = Ord('F')  Then   Begin    myMute:=
GetMasterMute;     If myMute = myTrue    Then
SetMasterMute(myFalse);     SetMasterVolume(1.0);   End;   // VOLUME
UP 1%  If Key = VK_UP  Then   Begin    GetMasterVolume(sinVol);    
sinVol:= sinVol+0.01;     If sinVol   > 1.0    Then sinVol:= 1.0;    
SetMasterVolume(sinVol);   End;   // VOLUME DOWN 1%  If Key = VK_DOWN 
Then   Begin    GetMasterVolume(sinVol);     sinVol:= sinVol-0.01;   
If sinVol   < 0.0    Then sinVol:= 0.0;     SetMasterVolume(sinVol); 
 End; End;  Procedure TwndGUI.SetMasterVolume(sinVol: Single);  Var 
 EndpointVolume  : IAudioEndpointVolume;   DeviceEnumerator:
IMMDeviceEnumerator;   Device          : IMMDevice; Begin 
CoCreateInstance(   CLASS_IMMDeviceEnumerator, Nil,
CLSCTX_INPROC_SERVER,   IID_IMMDeviceEnumerator, DeviceEnumerator); 
DeviceEnumerator.GetDefaultAudioEndpoint($00000000, $00000000,
Device);  Device.Activate(   IID_IAudioEndpointVolume,
CLSCTX_INPROC_SERVER, Nil, EndpointVolume); 
EndpointVolume.SetMasterVolumeLevelScalar(sinVol,
Nil); End;  Procedure TwndGUI.GetMasterVolume(Out sinVol: Single); 
Var   EndpointVolume  : IAudioEndpointVolume;   DeviceEnumerator:
IMMDeviceEnumerator;   Device          : IMMDevice; Begin 
CoCreateInstance(   CLASS_IMMDeviceEnumerator, Nil,
CLSCTX_INPROC_SERVER,   IID_IMMDeviceEnumerator, DeviceEnumerator); 
DeviceEnumerator.GetDefaultAudioEndpoint($00000000, $00000000,
Device);  Device.Activate(   IID_IAudioEndpointVolume,
CLSCTX_INPROC_SERVER, Nil, EndpointVolume); 
EndpointVolume.GetMasterVolumeLevelScalar(sinVol); End;  Function
TwndGUI.GetMasterMute: TMyBOOL;  Var   EndpointVolume  :
IAudioEndpointVolume;   DeviceEnumerator: IMMDeviceEnumerator; 
 Device          : IMMDevice;    hrRes: HResult;   bRes : BOOL; Begin 
CoCreateInstance(   CLASS_IMMDeviceEnumerator, Nil,
CLSCTX_INPROC_SERVER,   IID_IMMDeviceEnumerator, DeviceEnumerator); 
DeviceEnumerator.GetDefaultAudioEndpoint($00000000, $00000000,
Device);  Device.Activate(   IID_IAudioEndpointVolume,
CLSCTX_INPROC_SERVER, Nil, EndpointVolume);   hrRes:=
EndpointVolume.GetMute(bRes);    If FAILED(hrRes)   Then
OleCheck(hrRes);   Result:= TMyBOOL(bRes); End;  Procedure
TwndGUI.SetMasterMute(Value: TMyBOOL);  Var   EndpointVolume  :
IAudioEndpointVolume;   DeviceEnumerator: IMMDeviceEnumerator; 
 Device          : IMMDevice;    hrRes: HResult; Begin 
CoCreateInstance(   CLASS_IMMDeviceEnumerator, Nil,
CLSCTX_INPROC_SERVER,   IID_IMMDeviceEnumerator, DeviceEnumerator); 
DeviceEnumerator.GetDefaultAudioEndpoint($00000000, $00000000,
Device);  Device.Activate(   IID_IAudioEndpointVolume,
CLSCTX_INPROC_SERVER, Nil, EndpointVolume);   hrRes:=
EndpointVolume.SetMute(BOOL(Value), Nil);   OleCheck(hrRes); End; End.

----------------------------------------------------------------------
Thaddy · 2017-02-13 06:12

Quote from: RAW on February 13, 2017, 03:30:26 amIs it really
necessary to use COINITIALIZE and COUNINITIALIZE ?
I remember a post where someone said that it is only necessary in
Delphi not in FreePascal.
That's only the case if you use the comobj unit, which is not
necessary to use com in general. So that information is .... not
correct...
That would be highly gambling to rely on. comobj needs only to be
pulled in if you write your own com objects.
ActiveX is the one you want if you use third party com code, like in
your case.
Every COM using program needs to initialize and uninitialize the COM
sub-system in any language.
You only have to do it once so  do it in the initialization and
finalization section of the main unit and/or in the unit above. There
is no harm to do it in more than one unit though. May even be
practical.
There is a refcount on it, so for every call to coInitialize you have
to call a corresponding coUninitialize. Hence the initialization and
finalization sections are the right place to call them.

so before  the end of your code add:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
initialization   coInitialize(nil);finalization  coUnInitialize;end.
To summarize:

If you have comobj somewhere in the uses clause it is not necessary to
call coInitialize/coUnInitialize.
If you use just external com objects and need just ActiveX to work
with it, you need to call coInitialize and coUnInitialize.
Don't pull in comobj if you do not need it, i.e.: if you don't write
com objects yourself.
There's no real harm in adding comobj to the uses clause, but your
code will be much larger.
Com code from comobj can not be always eliminated by the
compiler/linker if you do not use it due to its run-time callable
nature.

----------------------------------------------------------------------
RAW · 2017-02-13 21:17

Thank you very much for your explanation...
So the first code doesn't need coInitialize and coUninitialize because
of COMOBJ, but if I don't need OLECHECK (it's optional), then I can
use only ACTIVEX in combination with coInitialize and coUninitialize
and eliminate COMOBJ. Sounds good...

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i Unit
uMasterMuteW7; {$MODE OBJFPC}{$H+} Interface  USES  Classes, SysUtils,
Forms, Controls,  Windows, ActiveX,  ShellApi;  TYPE  TMyBOOL =
(myFalse = Integer(0),             myTrue  = Integer(1));  TYPE 
TwndGUI = Class(TForm)    Procedure SetMasterVolume (    sinVol:
Single );   Procedure GetMasterVolume (Out sinVol: Single ); 
 Function  GetMasterMute              : TMyBOOL;   Procedure
SetMasterMute   (     Value: TMyBOOL);    Procedure FormKeyDown    
(Sender: TObject; Var Key: Word;                              Shift :
TShiftState);  End;  // WINDOWS 7 VOLUME BEGIN TYPE 
IAudioEndpointVolumeCallback = Interface(IUnknown) 
 ['{657804FA-D6AD-4496-8A60-352752AF4F89}']  End;  
IAudioEndpointVolume = Interface(IUnknown) 
 ['{5CDF2C82-841E-4546-9722-0CF74078229A}']     Function
RegisterControlChangeNotify(              AudioEndPtVol:
IAudioEndpointVolumeCallback): HRESULT; StdCall;    Function
UnregisterControlChangeNotify(              AudioEndPtVol:
IAudioEndpointVolumeCallback): HRESULT; StdCall;    Function
GetChannelCount(Out PInteger): HRESULT; StdCall;     Function
SetMasterVolumeLevel(              fLevelDB: Single;
pguidEventContext: PGUID): HRESULT; StdCall;    Function
SetMasterVolumeLevelScalar(              fLevelDB: Single;
pguidEventContext: PGUID): HRESULT; StdCall;     Function
GetMasterVolumeLevel(              Out fLevelDB: Single): HRESULT;
StdCall;    Function GetMasterVolumeLevelScalar(              Out
fLevelDB: Single): HRESULT; StdCall;     Function
SetChannelVolumeLevel(              nChannel: Integer; fLevelDB:
Double; pguidEventContext: PGUID):             HRESULT; StdCall;   
Function SetChannelVolumeLevelScalar(              nChannel: Integer;
fLevelDB: Double; pguidEventContext: PGUID):             HRESULT;
StdCall;     Function GetChannelVolumeLevel(              nChannel:
Integer; Out fLevelDB: Double): HRESULT; StdCall;    Function
GetChannelVolumeLevelScalar(              nChannel: Integer; Out
fLevelDB: Double): HRESULT; StdCall;     Function SetMute(           
 bSetMute: Bool; pguidEventContext: PGUID): HRESULT; StdCall;   
Function GetMute(              Out bGetMute: Bool): HRESULT;
StdCall;     Function GetVolumeStepInfo(              pnStep: Integer;
Out pnStepCount: Integer): HRESULT; StdCall;    Function
VolumeStepUp(              pguidEventContext: PGUID): HRESULT;
StdCall;    Function VolumeStepDown(              pguidEventContext:
PGUID): HRESULT; StdCall;    Function GetVolumeRange(              Out
pflVolumeMindB: Double; Out pflVolumeMaxdB: Double;              Out
pflVolumeIncrementdB: Double): HRESULT; StdCall;    Function
QueryHardwareSupport(              Out pdwHardwareSupportMask):
HRESULT; StdCall;  End;   IAudioMeterInformation =
Interface(IUnknown)   ['{C02216F6-8C67-4B5B-9D00-D008E73E0064}'] 
End;   IPropertyStore = Interface(IUnknown)  End;   IMMDevice =
Interface(IUnknown)   ['{D666063F-1587-4E43-81F1-B948E807363F}']   
Function Activate(              Const refId: TGUID; dwClsCtx: DWORD;
pActivationParams: PInteger;              Out pEndpointVolume:
IAudioEndpointVolume): HRESULT; StdCall;    Function
OpenPropertyStore(              stgmAccess: DWORD; Out ppProperties:
IPropertyStore):             HRESULT; StdCall;    Function GetId  
(Out ppstrId: PLPWSTR): HRESULT; StdCall;    Function GetState(Out
State: Integer):   HRESULT; StdCall;  End;   IMMDeviceCollection =
interface(IUnknown)   ['{0BD7A1BE-7A1A-44DB-8397-CC5392387B5E}'] 
End;   IMMNotificationClient = interface(IUnknown) 
 ['{7991EEC9-7E89-4D85-8390-6C703CEC60C0}']  End;  
IMMDeviceEnumerator = interface(IUnknown) 
 ['{A95664D2-9614-4F35-A746-DE8DB63617E6}']    Function
EnumAudioEndpoints(              dataFlow: TOleEnum; deviceState:
SYSUINT; DevCollection:              IMMDeviceCollection): HRESULT;
StdCall;    Function GetDefaultAudioEndpoint(              EDF:
SYSUINT; ER: SYSUINT; Out Dev: IMMDevice): HRESULT; StdCall;   
Function GetDevice(pwstrId: Pointer; Out Dev: IMMDevice): HRESULT;
StdCall;    Function RegisterEndpointNotificationCallback(           
 pClient: IMMNotificationClient): HRESULT; StdCall;  End;  CONST 
CLASS_IMMDeviceEnumerator: TGUID =
'{BCDE0395-E52F-467C-8E3D-C4579291692E}';  IID_IMMDeviceEnumerator  :
TGUID = '{A95664D2-9614-4F35-A746-DE8DB63617E6}'; 
IID_IAudioEndpointVolume : TGUID =
'{5CDF2C82-841E-4546-9722-0CF74078229A}'; // WINDOWS 7 VOLUME
END  VAR  wndGUI: TwndGUI; Implementation {$R *.LFM}  Procedure
TwndGUI.FormKeyDown(Sender: TObject; Var Key: Word;                  
          Shift : TShiftState);  Var   myMute: TMyBOOL;   sinVol:
Single; Begin  // MIXER  If Key = Ord('V')  Then ShellExecute(0, Nil,
PChar('sndvol.exe'), '', '', SW_SHOWNORMAL);   // MUTE  If Key =
Ord('M')  Then   Begin    myMute:= GetMasterMute;     If myMute =
myTrue    Then SetMasterMute(myFalse)    Else SetMasterMute(myTrue); 
 End;   // MAX VOLUME  If Key = Ord('F')  Then   Begin    myMute:=
GetMasterMute;     If myMute = myTrue    Then
SetMasterMute(myFalse);     SetMasterVolume(1.0);   End;   // VOLUME
UP 1%  If Key = VK_UP  Then   Begin    GetMasterVolume(sinVol);      
If (1-sinVol) < 0.01    Then sinVol:= 1    Else sinVol:=
sinVol+0.01;     SetMasterVolume(sinVol);   End;   // VOLUME DOWN 1% 
If Key = VK_DOWN  Then   Begin    GetMasterVolume(sinVol);     If
(sinVol-0.01) < 0    Then sinVol:= 0    Else sinVol:= sinVol-0.01;   
SetMasterVolume(sinVol);   End; End;  Procedure
TwndGUI.SetMasterVolume(sinVol: Single);  Var   EndpointVolume  :
IAudioEndpointVolume;   DeviceEnumerator: IMMDeviceEnumerator; 
 Device          : IMMDevice; Begin  CoCreateInstance( 
 CLASS_IMMDeviceEnumerator, Nil, CLSCTX_INPROC_SERVER, 
 IID_IMMDeviceEnumerator, DeviceEnumerator); 
DeviceEnumerator.GetDefaultAudioEndpoint($00000000, $00000000,
Device);  Device.Activate(   IID_IAudioEndpointVolume,
CLSCTX_INPROC_SERVER, Nil, EndpointVolume); 
EndpointVolume.SetMasterVolumeLevelScalar(sinVol,
Nil); End;  Procedure TwndGUI.GetMasterVolume(Out sinVol: Single); 
Var   EndpointVolume  : IAudioEndpointVolume;   DeviceEnumerator:
IMMDeviceEnumerator;   Device          : IMMDevice; Begin 
CoCreateInstance(   CLASS_IMMDeviceEnumerator, Nil,
CLSCTX_INPROC_SERVER,   IID_IMMDeviceEnumerator, DeviceEnumerator); 
DeviceEnumerator.GetDefaultAudioEndpoint($00000000, $00000000,
Device);  Device.Activate(   IID_IAudioEndpointVolume,
CLSCTX_INPROC_SERVER, Nil, EndpointVolume); 
EndpointVolume.GetMasterVolumeLevelScalar(sinVol); End;  Function
TwndGUI.GetMasterMute: TMyBOOL;  Var   EndpointVolume  :
IAudioEndpointVolume;   DeviceEnumerator: IMMDeviceEnumerator; 
 Device          : IMMDevice;    bRes: BOOL; Begin  CoCreateInstance( 
 CLASS_IMMDeviceEnumerator, Nil, CLSCTX_INPROC_SERVER, 
 IID_IMMDeviceEnumerator, DeviceEnumerator); 
DeviceEnumerator.GetDefaultAudioEndpoint($00000000, $00000000,
Device);  Device.Activate(   IID_IAudioEndpointVolume,
CLSCTX_INPROC_SERVER, Nil, EndpointVolume); 
EndpointVolume.GetMute(bRes);   Result:=
TMyBOOL(bRes); End;  Procedure TwndGUI.SetMasterMute(Value: TMyBOOL); 
Var   EndpointVolume  : IAudioEndpointVolume;   DeviceEnumerator:
IMMDeviceEnumerator;   Device          : IMMDevice; Begin 
CoCreateInstance(   CLASS_IMMDeviceEnumerator, Nil,
CLSCTX_INPROC_SERVER,   IID_IMMDeviceEnumerator, DeviceEnumerator); 
DeviceEnumerator.GetDefaultAudioEndpoint($00000000, $00000000,
Device);  Device.Activate(   IID_IAudioEndpointVolume,
CLSCTX_INPROC_SERVER, Nil, EndpointVolume); 
EndpointVolume.SetMute(BOOL(Value), Nil); End; Initialization coInitia
lize(Nil);Finalization coUnInitialize; End. 
I was a little bit confused, because if I don't use COMOBJ and don't
use coInitialize and coUninitialize then it's still working.
Normally when I miss something, then I expect an error or any kind of
exception or at least that the code is not working.

----------------------------------------------------------------------
majid.ebru · 2017-10-28 22:55

Hi
is it possible put your sample program , here?