拖动音量滑块来显示音量的百分比

Question

大家有做人做过这样的功能？

Answer 1

给你一段调节音量的代码供参考：
unit   Volume;     
    
  interface     
    
  uses   windows,mmsystem;     
    
  type   
          Tvolume=record   
                left,right:word;   //   取值范围   0--65535   
          end;     
    
  procedure   fillstruct(control:PMixerControl;var   Cdetails:tMIXERCONTROLDETAILS);     
  function   getpeak(control:PMixerControl;var   peak:integer):boolean;     
  function   setvolume(control:Pmixercontrol;   volume:Tvolume):boolean;     
  function   getvolume(control:Pmixercontrol;   volume:Tvolume):boolean;     
    
  var   
          mcontrols:array   of   array   of   array   of   PMixerControl;   //mixer的数组,单声卡可以不用   
          fmixerhandle:HMIXER;   //mixer的句柄     
    
  implementation     
    
  procedure   fillstruct(control:PMixerControl;var   Cdetails:tMIXERCONTROLDETAILS);     
  begin   
          Cdetails.cbStruct:=sizeof(cdetails);   
          cdetails.dwControlID:=Control.dwControlID;   
          cdetails.cbDetails:=sizeof(integer);   
          cdetails.hwndOwner:=0;     
  end;     
    
  function   getpeak(control:PMixerControl;var   peak:integer):boolean;     
  var   
        details:TMixerControlDetailsSigned;   
        cdetails:tMIXERCONTROLDETAILS;     
  begin   
          Result:=false;   
          if   control.dwControlType<>   mixercontrol_controltype_peakmeter   then   exit;   
          cdetails.cChannels:=1;   
          cdetails.paDetails:=@details;   
          fillstruct(control,cdetails);   
          result:=mixerGetControlDetails(fmixerhandle,@cdetails,MIXER_GETCONTROLDETAILSF_VALUE)=0;     
  end;     
    
  function   setvolume(control:Pmixercontrol;   volume:Tvolume):boolean;     
  var   
          details:array[0..30]   of   integer;   
          cdetails:tMIXERCONTROLDETAILS;     
  begin   
          fillstruct(control,cdetails);   
          cdetails.cChannels:=2;   
          cdetails.paDetails:=@details;   
          details[0]:=volume.left;   
          details[1]:=volume.right;   
          result:=mixerSetControlDetails(fmixerhandle,@cdetails,MIXER_GETCONTROLDETAILSF_VALUE)=0;   
          volume.left:=details[0];   
          volume.right:=details[1];     
  end;     
    
  function   getvolume(control:Pmixercontrol;   volume:Tvolume):boolean;     
  var   
          details:array[0..30]   of   integer;   
          cdetails:tMIXERCONTROLDETAILS;     
  begin   
          fillstruct(control,cdetails);   
          cdetails.cChannels:=2;   
          cdetails.paDetails:=@details;   
          result:=mixerGetControlDetails(fmixerhandle,@cdetails,MIXER_GETCONTROLDETAILSF_VALUE)=0;   
          volume.left:=details[0];   
          volume.right:=details[1];     
  end;     
    
  end.     
    
  //   调用方法:     
  procedure   TForm1.Button1Click(Sender:   TObject);     
  var   s   :   Tvolume;   
            kz   :   Pmixercontrol;     
  begin   
          new(kz);   //<------------   此处一定要分配内存     
  kz.dwControlID   :=   0;     
  s.left   :=   0;     
  s.right   :=   0;     
  try     
  setvolume(kz,s);     
  except     
  end;     
  freemem(kz);     
  end;