Add audio buffer setting and optimize overlays

AudioOutput.pas

@@ -10,7 +10,7 @@ unit AudioOutput;
   - Callback читает по одному сэмплу, обновляет outpt внутри цикла
   - Low water mark: вставляет тишину + полбуфера silence
   - High water mark: удаляет лишние сэмплы
-  - MY_AUDIO_BUFFER_SIZE = 128 frames (низкая латентность)
+  - output buffer size defaults to 128 frames (низкая латентность)
 }
 
 {$IFDEF FPC}
@@ -24,7 +24,7 @@ uses
   Classes, SysUtils, Math, SyncObjs, DynLibs;
 
 const
-  MY_AUDIO_BUFFER_SIZE = 128;          // PA frames per callback — как piHPSDR
+  MY_AUDIO_BUFFER_SIZE = 128;          // default PA frames per callback — как piHPSDR
   MY_RING_BUFFER_SIZE  = 9600;         // как piHPSDR
   MY_RING_LOW_WATER    = 512;          // как piHPSDR
   MY_RING_HIGH_WATER   = 9000;         // как piHPSDR
@@ -95,6 +95,7 @@ type
     FLibHandle:  TLibHandle;
     FStream:     TPaStream;
     FSampleRate: Integer;
+    FOutputBufferSize: Integer;
     FOpen:       Boolean;
     FPAInited:   Boolean;   // Pa_Initialize прошла
     FLastError:  string;
@@ -120,6 +121,7 @@ type
 
     function LoadLib: Boolean;
     function GetLastError: string;
+    procedure SetOutputBufferSize(V: Integer);
 
   public
     constructor Create(SampleRate: Integer = 48000);
@@ -148,6 +150,7 @@ type
     property LastError:   string  read GetLastError;
     property DeviceIndex: Integer read FDeviceIndex write FDeviceIndex;
     property SampleRate:  Integer read FSampleRate  write FSampleRate;
+    property OutputBufferSize: Integer read FOutputBufferSize write SetOutputBufferSize;
   end;
 
 // Глобальный callback (cdecl, не метод)
@@ -239,6 +242,7 @@ constructor TAudioOutput.Create(SampleRate: Integer);
 begin
   inherited Create;
   FSampleRate  := SampleRate;
+  FOutputBufferSize := MY_AUDIO_BUFFER_SIZE;
   FDeviceIndex := -1;   // -1 = default output device
   FOpen        := False;
   FPAInited    := False;
@@ -493,7 +497,7 @@ begin
     nil,                        // no input
     @OutParam,
     FSampleRate,
-    MY_AUDIO_BUFFER_SIZE,       // 128 frames как в оригинале
+    FOutputBufferSize,
     PA_NO_FLAG,
     @PaOutCallback,
     Self
@@ -531,6 +535,14 @@ begin
   Result := True;
 end;
 
+procedure TAudioOutput.SetOutputBufferSize(V: Integer);
+begin
+  if V <= 128 then V := 128
+  else if V <= 256 then V := 256
+  else V := 512;
+  FOutputBufferSize := V;
+end;
+
 procedure TAudioOutput.Close;
 begin
   if not FOpen then Exit;

MainForm.pas

@@ -660,6 +660,7 @@ type
     procedure OnModeFilterSelect(Mode: Integer; FilterBW: Integer);
     procedure OnVfoOverlayDSPChange(NRMode, NBMode: Integer; SNBOn, ANFOn: Boolean);
     procedure OnVfoOverlayAGCChange(AGCMode: Integer);
+    procedure OnVfoOverlayInvalidate(Sender: TObject);
     procedure PbSpectrumDblClick(Sender: TObject);
     procedure TrkDriveChange(Sender: TObject);
     procedure TrkVolumeChange(Sender: TObject);
@@ -702,6 +703,7 @@ type
     procedure ApplySpecViewGridFromState;
     procedure ApplyAudioDevice(DevIndex: Integer; const DevName: string);
     procedure ApplyAudioInputDevice(DevIndex: Integer; const DevName: string);
+    procedure ApplyAudioBufferSize(BufferSize: Integer);
     // TX settings: применить FTXSettings к WDSP и переслать DUC Specific
     // (mic-биты Boost/Bias/LineIn/PTT попадают в byte 50 DUCSpecific).
     procedure ApplyTXSettingsToDSP;
@@ -1321,6 +1323,7 @@ begin
   FVfoOverlay.OnSelect    := OnModeFilterSelect;
   FVfoOverlay.OnDSPChange := OnVfoOverlayDSPChange;
   FVfoOverlay.OnAGCChange := OnVfoOverlayAGCChange;
+  FVfoOverlay.OnInvalidate := OnVfoOverlayInvalidate;
   FVfoOverlay.Visible := False;
   FPanelHidden  := False;
   FShowSpectrum  := True;
@@ -1331,6 +1334,7 @@ begin
   FSplitterDrag  := False;
 
   FSpecView := TSpectrumView.Create;
+  FSpecView.VfoOverlay := FVfoOverlay;
   FSpecView.VfoA           := FVfoA;
   FSpecView.VfoB           := FVfoB;
   FSpecView.ActiveVfo      := FActiveVfo;
@@ -1387,6 +1391,7 @@ begin
   // Audio output/input — создаём объекты сейчас, открываем после показа формы
   // (Pa_Initialize на Linux пишет в stderr до перехвата сигналов FPC)
   FAudioOut := TAudioOutput.Create(48000);
+  FAudioOut.OutputBufferSize := FSettings.LoadAudioBufferSize;
   FAudioIn  := TAudioInput.Create(48000);
 
   FMeterTimer := TTimer.Create(Self);
@@ -4417,22 +4422,17 @@ begin
     FNetwork.SendFullHP;
   end;
 
-  // Перерисовываем спектр всегда (маркер и полоса двигаются)
-  // Если идёт drag — не вызываем Draw напрямую, таймер подхватит
+  // Не рисуем синхронно из wheel/drag path: частые события мыши иначе
+  // забивают UI-поток и мешают аудио. Таймер подхватит ближайший кадр.
   SyncSpecViewFreq;
-  if FSpecDrag then
-    FSpectrumDirty := True
-  else
-  begin
-    FSpecView.DrawSpectrum;
+  FSpectrumDirty := True;
   PbSpectrum.Invalidate;
   if Scrolled then
   begin
-      FSpecView.DrawWaterfall;
+    FWaterfallDirty := True;
     PbWaterfall.Invalidate;
   end;
 end;
-end;
 
 // ---------------------------------------------------------------------------
 // CTUN toggle
@@ -4648,6 +4648,8 @@ end;
 procedure TMainForm.PbSpectrumMouseDown(Sender: TObject; Button: TMouseButton;
   Shift: TShiftState; X, Y: Integer);
 begin
+  if Assigned(FVfoOverlay) and
+     FVfoOverlay.HandleMouseDown(Button, X, Y) then Exit;
   if Assigned(FSampleRateOverlay) and
      FSampleRateOverlay.HandleMouseDown(Button, X, Y) then Exit;
 
@@ -4694,9 +4696,15 @@ begin
   if Assigned(FSampleRateOverlay) then
   begin
     FSampleRateOverlay.HandleMouseMove(X, Y);
-    if (FSampleRateOverlay.HotIdx >= 0) and (not FSpecDrag) then
+  end;
+  if Assigned(FVfoOverlay) then
+    FVfoOverlay.HandleMouseMove(X, Y);
+  if not FSpecDrag then
+  begin
+    if (Assigned(FVfoOverlay) and (FVfoOverlay.HotIdx >= 0)) or
+       (Assigned(FSampleRateOverlay) and (FSampleRateOverlay.HotIdx >= 0)) then
       PbSpectrum.Cursor := crHandPoint
-    else if not FSpecDrag then
+    else
       PbSpectrum.Cursor := crDefault;
   end;
 
@@ -4726,6 +4734,8 @@ procedure TMainForm.PbSpectrumMouseLeave(Sender: TObject);
 begin
   if Assigned(FSampleRateOverlay) then
     FSampleRateOverlay.HandleMouseLeave;
+  if Assigned(FVfoOverlay) then
+    FVfoOverlay.HandleMouseLeave;
   if not FSpecDrag then PbSpectrum.Cursor := crDefault;
 end;
 
@@ -5304,18 +5314,17 @@ begin
   if FPanelHidden then
   begin
     PanelLeft.Width := 0;
-    FVfoOverlay.Parent  := PanelRight;
     FVfoOverlay.Width   := 260;
     FVfoOverlay.Height  := 136;  // OVL_H_NORM — расширяется сам при открытии AGC-пикера
     FVfoOverlay.SetState(FMode, FFilterBW, FVfoA, FLastSMeter);
     FVfoOverlay.SetDSPState(BtnNR.Tag, BtnNB.Tag, BtnSNB.Tag <> 0, BtnANF.Tag <> 0, FAGCMode);
     FVfoOverlay.Visible := True;
-    FVfoOverlay.BringToFront;
     PositionVfoOverlay;
   end
   else
   begin
     PanelLeft.Width := 232;
+    FVfoOverlay.HandleMouseLeave;
     FVfoOverlay.Visible := False;
   end;
   if Assigned(FSampleRateOverlay) then
@@ -5326,20 +5335,40 @@ end;
 
 procedure TMainForm.PositionVfoOverlay;
 var
-  VfoX, OW, SpTop: Integer;
+  VfoX, FilterEndX, OW, NewLeft, NewTop: Integer;
+  HiHz: Double;
 begin
   if not Assigned(FVfoOverlay) or not FVfoOverlay.Visible then Exit;
   OW    := FVfoOverlay.Width;
-  SpTop := PbSpectrum.Top;   // смещение PbSpectrum внутри PanelRight
 
-  if PbSpectrum.Width > 0 then
+  if (PbSpectrum.Width > 0) and (FSpanHz > 0) then
+  begin
     VfoX := Round((FVfoA - FCenterFreq + FSpanHz / 2) / FSpanHz * PbSpectrum.Width)
+  end
   else
     VfoX := PbSpectrum.Width div 2;
 
-  // Всегда справа от VFO-линии
-  FVfoOverlay.Left := Min(PanelRight.Width - OW - 4, VfoX + 6);
-  FVfoOverlay.Top  := SpTop + 6;
+  case FMode of
+    MODE_LSB: HiHz := -100;
+    MODE_USB: HiHz := FFilterBW;
+  else
+    HiHz := FFilterBW / 2;
+  end;
+  if (PbSpectrum.Width > 0) and (FSpanHz > 0) then
+    FilterEndX := VfoX + Round(HiHz / FSpanHz * PbSpectrum.Width)
+  else
+    FilterEndX := VfoX;
+  FilterEndX := Max(0, Min(PbSpectrum.Width - 1, FilterEndX));
+
+  // Всегда справа от правого края полосы фильтра.
+  NewLeft := Max(4, Min(PbSpectrum.Width - OW - 4, FilterEndX + 6));
+  NewTop := 16;
+  if (FVfoOverlay.Left <> NewLeft) or (FVfoOverlay.Top <> NewTop) then
+  begin
+    FVfoOverlay.Left := NewLeft;
+    FVfoOverlay.Top := NewTop;
+    OnVfoOverlayInvalidate(FVfoOverlay);
+  end;
 end;
 
 procedure TMainForm.PbSpectrumDblClick(Sender: TObject);
@@ -5400,6 +5429,13 @@ begin
   FBandCache[FCurrentBand].AGCMode := FAGCMode;
 end;
 
+procedure TMainForm.OnVfoOverlayInvalidate(Sender: TObject);
+begin
+  FSpectrumDirty := True;
+  if Assigned(FSpecView) then FSpecView.SpectrumDirty := True;
+  if Assigned(PbSpectrum) then PbSpectrum.Invalidate;
+end;
+
 procedure TMainForm.OnSampleRateSelect(SampleRate: Integer);
 var
   NewRate: Integer;
@@ -6731,6 +6767,29 @@ begin
   end;
 end;
 
+procedure TMainForm.ApplyAudioBufferSize(BufferSize: Integer);
+var
+  WasOpen: Boolean;
+begin
+  if BufferSize <= 128 then BufferSize := 128
+  else if BufferSize <= 256 then BufferSize := 256
+  else BufferSize := 512;
+  if FAudioOut.OutputBufferSize = BufferSize then Exit;
+
+  WasOpen := FAudioOut.IsOpen;
+  if WasOpen then FAudioOut.Close;
+  FAudioOut.OutputBufferSize := BufferSize;
+  if WasOpen then
+  begin
+    try
+      FAudioOut.Open;
+    except
+    end;
+  end;
+  FSettings.SaveAudioBufferSize(BufferSize);
+  FSettings.Save;
+end;
+
 procedure TMainForm.ApplyVisibility(ShowSpectrum, ShowWaterfall: Boolean);
 begin
   FShowSpectrum  := ShowSpectrum;
@@ -6781,6 +6840,7 @@ begin
     SF.OnGridChange       := ApplyGridParams;
     SF.OnAudioDevChange   := ApplyAudioDevice;
     SF.OnAudioInDevChange := ApplyAudioInputDevice;
+    SF.OnAudioBufferChange := ApplyAudioBufferSize;
     SF.OnVisibilityChange := ApplyVisibility;
     SF.OnFPSChange        := ApplyFPS;
     SF.OnPAChange         := OnPASettingsChange;
@@ -6821,6 +6881,7 @@ begin
   SF.LoadFPS(FDisplayFPS);
   SF.LoadLightTheme(FLightTheme);
   SF.LoadFreqMhzDigits(FFreqMhzDigits);
+  SF.LoadAudioBufferSize(FAudioOut.OutputBufferSize);
   // Загружаем текущие значения
   if FWDSPReady then
     SF.LoadValues(

Settings.pas

@@ -286,6 +286,8 @@ type
     procedure LoadWindowBounds(out L, T, W, H: Integer);
     procedure SaveStartupPreview(VfoA, VfoB: Double; SampleRate: Integer);
     function  LoadStartupPreview(out VfoA, VfoB: Double; out SampleRate: Integer): Boolean;
+    procedure SaveAudioBufferSize(BufferSize: Integer);
+    function  LoadAudioBufferSize: Integer;
     // CAT settings — не привязаны к MAC, хранятся в корне JSON (доступны до подключения)
     procedure SaveCATSettings(const G: TGlobalSettings);
     procedure LoadCATSettings(var G: TGlobalSettings);
@@ -798,6 +800,27 @@ begin
   SampleRate := JI(O, 'sample_rate', 192000);
 end;
 
+procedure TSettingsManager.SaveAudioBufferSize(BufferSize: Integer);
+var O: TJSONObject;
+begin
+  if BufferSize <= 128 then BufferSize := 128
+  else if BufferSize <= 256 then BufferSize := 256
+  else BufferSize := 512;
+  O := EnsureObj(FRoot, 'audio');
+  JW(O, 'output_buffer_size', BufferSize);
+end;
+
+function TSettingsManager.LoadAudioBufferSize: Integer;
+var O: TJSONObject;
+begin
+  if FRoot.Find('audio') = nil then Exit(128);
+  O := EnsureObj(FRoot, 'audio');
+  Result := JI(O, 'output_buffer_size', 128);
+  if Result <= 128 then Result := 128
+  else if Result <= 256 then Result := 256
+  else Result := 512;
+end;
+
 procedure TSettingsManager.SaveCATSettings(const G: TGlobalSettings);
 var O: TJSONObject; i: Integer;
 begin

SettingsForm.pas

@@ -46,6 +46,7 @@ type
   TOnGridParamChange = procedure(RefLevel, Range, GridStep: Double) of object;
   TOnAudioDevChange = procedure(DevIndex: Integer; const DevName: string) of object;
   TOnAudioInDevChange = procedure(DevIndex: Integer; const DevName: string) of object;
+  TOnAudioBufferChange = procedure(BufferSize: Integer) of object;
   TOnVisibilityChange = procedure(ShowSpectrum, ShowWaterfall: Boolean) of object;
   TOnFPSChange = procedure(FPS: Integer) of object;
   TOnThemeChange = procedure(LightTheme: Boolean) of object;
@@ -94,6 +95,7 @@ type
     FCmbTXDev:       TComboBox;
     FTXDevIndices:   array[0..63] of Integer;
     FTXDevCount:     Integer;
+    FCmbAudioBuffer: TComboBox;
 
     // ---- RX1 sub-tab controls ----
     FCmbFFTSize:     TComboBox;
@@ -263,6 +265,7 @@ type
     FOnGridChange:       TOnGridParamChange;
     FOnAudioDevChange:   TOnAudioDevChange;
     FOnAudioInDevChange: TOnAudioInDevChange;
+    FOnAudioBufferChange: TOnAudioBufferChange;
     FOnVisibilityChange: TOnVisibilityChange;
     FOnFPSChange:        TOnFPSChange;
     FOnThemeChange:            TOnThemeChange;
@@ -325,6 +328,7 @@ type
     procedure OnGridStepChange(Sender: TObject);
     procedure OnRXDevChange(Sender: TObject);
     procedure OnTXDevChange(Sender: TObject);
+    procedure OnAudioBufferCmbChange(Sender: TObject);
     procedure OnVisibilityChkChange(Sender: TObject);
     procedure OnFPSCmbChange(Sender: TObject);
     procedure OnLightThemeChkChange(Sender: TObject);
@@ -364,6 +368,7 @@ type
       const AudioInDevName: string);
 
     procedure RefreshAudioDevices(AudioOut: TAudioOutput; AudioIn: TAudioInput);
+    procedure LoadAudioBufferSize(BufferSize: Integer);
     procedure LoadVisibility(ShowSpectrum, ShowWaterfall: Boolean);
     procedure LoadFPS(FPS: Integer);
     procedure LoadLightTheme(ALight: Boolean);
@@ -393,6 +398,7 @@ type
     property OnGridChange:       TOnGridParamChange      read FOnGridChange      write FOnGridChange;
     property OnAudioDevChange:   TOnAudioDevChange       read FOnAudioDevChange  write FOnAudioDevChange;
     property OnAudioInDevChange: TOnAudioInDevChange     read FOnAudioInDevChange write FOnAudioInDevChange;
+    property OnAudioBufferChange: TOnAudioBufferChange    read FOnAudioBufferChange write FOnAudioBufferChange;
     property OnVisibilityChange: TOnVisibilityChange     read FOnVisibilityChange write FOnVisibilityChange;
     property OnFPSChange:        TOnFPSChange            read FOnFPSChange       write FOnFPSChange;
     property OnThemeChange:      TOnThemeChange          read FOnThemeChange     write FOnThemeChange;
@@ -737,7 +743,7 @@ begin
     Font.Color := CLR_TEXTDIM;
   end;
 
-  Grp := MakeGroupPanel(FPageAudio, 'Audio Devices', MARGIN, 86, 650, 142);
+  Grp := MakeGroupPanel(FPageAudio, 'Audio Devices', MARGIN, 86, 650, 184);
 
   MakeLbl(Grp, 'TX input device', PAD, R1 + 5, LW);
   FCmbTXDev := MakeCombo(Grp, CX, R1, CMB_W, OnTXDevChange);
@@ -746,6 +752,13 @@ begin
   MakeLbl(Grp, 'RX output device', PAD, R1 + STEP + 5, LW);
   FCmbRXDev := MakeCombo(Grp, CX, R1 + STEP, CMB_W, OnRXDevChange);
   FCmbRXDev.Items.Add('Default');
+
+  MakeLbl(Grp, 'Output buffer', PAD, R1 + STEP * 2 + 5, LW);
+  FCmbAudioBuffer := MakeCombo(Grp, CX, R1 + STEP * 2, 160, OnAudioBufferCmbChange);
+  FCmbAudioBuffer.Items.Add('128 frames');
+  FCmbAudioBuffer.Items.Add('256 frames');
+  FCmbAudioBuffer.Items.Add('512 frames');
+  FCmbAudioBuffer.ItemIndex := 0;
 end;
 
 // ---------------------------------------------------------------------------
@@ -1972,6 +1985,25 @@ begin
   end;
 end;
 
+// ---------------------------------------------------------------------------
+// LoadAudioBufferSize
+// ---------------------------------------------------------------------------
+
+procedure TSettingsForm.LoadAudioBufferSize(BufferSize: Integer);
+begin
+  FLoading := True;
+  try
+    case BufferSize of
+      256: FCmbAudioBuffer.ItemIndex := 1;
+      512: FCmbAudioBuffer.ItemIndex := 2;
+    else
+      FCmbAudioBuffer.ItemIndex := 0;
+    end;
+  finally
+    FLoading := False;
+  end;
+end;
+
 // ---------------------------------------------------------------------------
 // RefreshAudioDevices
 // ---------------------------------------------------------------------------
@@ -2243,6 +2275,21 @@ begin
   end;
 end;
 
+procedure TSettingsForm.OnAudioBufferCmbChange(Sender: TObject);
+var
+  BufferSize: Integer;
+begin
+  if FLoading then Exit;
+  if not Assigned(FOnAudioBufferChange) then Exit;
+  case FCmbAudioBuffer.ItemIndex of
+    1: BufferSize := 256;
+    2: BufferSize := 512;
+  else
+    BufferSize := 128;
+  end;
+  FOnAudioBufferChange(BufferSize);
+end;
+
 procedure TSettingsForm.LoadVisibility(ShowSpectrum, ShowWaterfall: Boolean);
 begin
   FLoading := True;

SpectrumView.pas

@@ -20,7 +20,7 @@ interface
 uses
   Classes, SysUtils, Graphics, ExtCtrls, Controls, Math,
   IntfGraphics, FPImage, LCLIntf, LCLType, GraphType, AppTheme,
-  AlertOverlay, SampleRateOverlay,
+  AlertOverlay, SampleRateOverlay, VfoOverlay,
   WaterfallView, SMeterView, RulerView;
 
 const
@@ -70,6 +70,7 @@ type
     // ── ADC overload overlay ─────────────────────────────────────────────────
     FADCOverloadVisible: Boolean;
     FSampleRateOverlay: TSampleRateOverlay;
+    FVfoOverlay: TVfoOverlay;
     // ── Marker ────────────────────────────────────────────────────────────────
     FMarkerActive:  Boolean;
     FMarkerX:       Integer;
@@ -199,6 +200,7 @@ type
     property PbRuler:       TPaintBox write SetPbRuler;
     property PbSMeterRight: TPaintBox write SetPbSMeterRight;
     property SampleRateOverlay: TSampleRateOverlay read FSampleRateOverlay write FSampleRateOverlay;
+    property VfoOverlay: TVfoOverlay read FVfoOverlay write FVfoOverlay;
 
     // ── Данные от DSP ─────────────────────────────────────────────────────────
     procedure SetSpectrumData(const Pixels: array of Single; Count: Integer);
@@ -918,6 +920,8 @@ begin
   DrawADCOverloadOverlay(C, W, H);
   if Assigned(FSampleRateOverlay) then
     FSampleRateOverlay.DrawOverlay(FSpectrumBitmap, C, W, H);
+  if Assigned(FVfoOverlay) then
+    FVfoOverlay.DrawOverlay(FSpectrumBitmap, W, H);
 end;
 
 // ────────────────────────────────────────────────────────────────────────────

VfoOverlay.pas

@@ -21,6 +21,7 @@ type
     FOnSelect:    TModeFilterEvent;
     FOnDSPChange: TDSPChangeEvent;
     FOnAGCChange: TAGCChangeEvent;
+    FOnInvalidate: TNotifyEvent;
     FModeFilter: array[0..7] of Integer;
 
     FNRMode: Integer;   // 0=off, 1..4=NR/NR2/NR3/NR4
@@ -34,6 +35,8 @@ type
     FHitActions: array[0..24] of Integer;
     FHitCount:   Integer;
     FHotIdx:     Integer;
+    FCacheBitmap: TBitmap;
+    FCacheDirty: Boolean;
 
     procedure DrawSelf(C: TCanvas; W, H: Integer);
     procedure DrawSMeterBar(C: TCanvas; X, Y, BW, BH: Integer);
@@ -47,6 +50,7 @@ type
     function  GetFilterBWForMode(ModeIdx, FilterIdx: Integer): Integer;
     function  GetFilterLblForMode(ModeIdx, FilterIdx: Integer): string;
     function  GetFilterCountForMode(ModeIdx: Integer): Integer;
+    procedure RequestInvalidate;
 
   protected
     procedure Paint; override;
@@ -57,19 +61,28 @@ type
 
   public
     constructor Create(AOwner: TComponent); override;
+    destructor Destroy; override;
+    procedure DrawOverlay(Target: TBitmap; W, H: Integer);
+    function HandleMouseDown(Button: TMouseButton; X, Y: Integer): Boolean;
+    function HandleMouseMove(X, Y: Integer): Boolean;
+    function HandleMouseLeave: Boolean;
     procedure SetState(AMode, ABW: Integer; AVfoHz, ASMeterDB: Double);
     procedure SetDSPState(ANRMode, ANBMode: Integer; ASNBOn, AANFOn: Boolean;
                           AAGCMode: Integer);
     procedure UpdateSMeter(DB: Double);
     procedure UpdateVfo(AVfoHz: Double);
+    property HotIdx: Integer read FHotIdx;
     property OnSelect:    TModeFilterEvent read FOnSelect    write FOnSelect;
     property OnDSPChange: TDSPChangeEvent  read FOnDSPChange write FOnDSPChange;
     property OnAGCChange: TAGCChangeEvent  read FOnAGCChange write FOnAGCChange;
+    property OnInvalidate: TNotifyEvent read FOnInvalidate write FOnInvalidate;
   end;
 
 implementation
 
 const
+  KEY_COLOR = TColor($00FF00FF);
+
   HIT_NR  = -9;
   HIT_NB  = -10;
   HIT_SNB = -11;
@@ -126,6 +139,53 @@ const
   // S-шкала: S1..S9
   DB_S: array[1..9] of Double = (-121,-115,-109,-103,-97,-91,-85,-79,-73);
 
+procedure BlendBitmapKey(Target, Source: TBitmap; DstX, DstY: Integer; Alpha: Byte);
+var
+  Y, X, SX0, SY0, SX1, SY1, TY, InvA: Integer;
+  SrcRow, DstRow: PByte;
+begin
+  if (Target = nil) or (Source = nil) or (Alpha = 0) then Exit;
+  SX0 := 0;
+  SY0 := 0;
+  SX1 := Source.Width;
+  SY1 := Source.Height;
+  if DstX < 0 then begin SX0 := -DstX; DstX := 0; end;
+  if DstY < 0 then begin SY0 := -DstY; DstY := 0; end;
+  if DstX + (SX1 - SX0) > Target.Width then SX1 := SX0 + Target.Width - DstX;
+  if DstY + (SY1 - SY0) > Target.Height then SY1 := SY0 + Target.Height - DstY;
+  if (SX1 <= SX0) or (SY1 <= SY0) then Exit;
+
+  InvA := 255 - Alpha;
+  Target.BeginUpdate(False);
+  Source.BeginUpdate(False);
+  try
+    for Y := SY0 to SY1 - 1 do
+    begin
+      TY := DstY + (Y - SY0);
+      SrcRow := PByte(Source.ScanLine[Y]);
+      DstRow := PByte(Target.ScanLine[TY]);
+      if (SrcRow = nil) or (DstRow = nil) then Continue;
+      Inc(SrcRow, SX0 * 4);
+      Inc(DstRow, DstX * 4);
+      for X := SX0 to SX1 - 1 do
+      begin
+        // KEY_COLOR is clFuchsia in pf32bit B,G,R order.
+        if not ((SrcRow[0] = $FF) and (SrcRow[1] = $00) and (SrcRow[2] = $FF)) then
+        begin
+          DstRow[0] := Byte((Alpha * SrcRow[0] + InvA * DstRow[0]) div 255);
+          DstRow[1] := Byte((Alpha * SrcRow[1] + InvA * DstRow[1]) div 255);
+          DstRow[2] := Byte((Alpha * SrcRow[2] + InvA * DstRow[2]) div 255);
+        end;
+        Inc(SrcRow, 4);
+        Inc(DstRow, 4);
+      end;
+    end;
+  finally
+    Source.EndUpdate(False);
+    Target.EndUpdate(False);
+  end;
+end;
+
 function TVfoOverlay.GetFilterBWForMode(ModeIdx, FilterIdx: Integer): Integer;
 begin
   case ModeIdx of
@@ -206,11 +266,20 @@ begin
   FANFOn         := False;
   FAGCMode       := 0;
   FAGCPickerOpen := False;
+  FCacheBitmap := TBitmap.Create;
+  FCacheBitmap.PixelFormat := pf32bit;
+  FCacheDirty := True;
   Width  := 260;
   Height := OVL_H_NORM;
   Cursor     := crHandPoint;
 end;
 
+destructor TVfoOverlay.Destroy;
+begin
+  FCacheBitmap.Free;
+  inherited Destroy;
+end;
+
 procedure TVfoOverlay.RegisterHit(HR: TRect; HV: Integer);
 begin
   if FHitCount > High(FHitRects) then Exit;
@@ -219,6 +288,13 @@ begin
   Inc(FHitCount);
 end;
 
+procedure TVfoOverlay.RequestInvalidate;
+begin
+  FCacheDirty := True;
+  inherited Invalidate;
+  if Assigned(FOnInvalidate) then FOnInvalidate(Self);
+end;
+
 function TVfoOverlay.FormatFreq(Hz: Double): string;
 var
   iM, iK, iH: Integer;
@@ -534,6 +610,72 @@ begin
   DrawSelf(Canvas, Width, Height);
 end;
 
+procedure TVfoOverlay.DrawOverlay(Target: TBitmap; W, H: Integer);
+begin
+  if (not Visible) or (Target = nil) or (Width <= 0) or (Height <= 0) then Exit;
+  if (Left >= W) or (Top >= H) then Exit;
+
+  if (FCacheBitmap.Width <> Width) or (FCacheBitmap.Height <> Height) then
+  begin
+    FCacheBitmap.SetSize(Width, Height);
+    FCacheDirty := True;
+  end;
+  if FCacheDirty then
+  begin
+    FCacheBitmap.Canvas.Brush.Color := KEY_COLOR;
+    FCacheBitmap.Canvas.Brush.Style := bsSolid;
+    FCacheBitmap.Canvas.Pen.Style := psClear;
+    FCacheBitmap.Canvas.FillRect(Rect(0, 0, Width, Height));
+    DrawSelf(FCacheBitmap.Canvas, Width, Height);
+    FCacheDirty := False;
+  end;
+  BlendBitmapKey(Target, FCacheBitmap, Left, Top, 218);
+end;
+
+function TVfoOverlay.HandleMouseDown(Button: TMouseButton; X, Y: Integer): Boolean;
+begin
+  Result := False;
+  if not Visible then Exit;
+  if (X < Left) or (Y < Top) or (X >= Left + Width) or (Y >= Top + Height) then Exit;
+  MouseDown(Button, [], X - Left, Y - Top);
+  Result := True;
+end;
+
+function TVfoOverlay.HandleMouseMove(X, Y: Integer): Boolean;
+var
+  I, OldHot, LX, LY: Integer;
+begin
+  Result := False;
+  if not Visible then Exit;
+  LX := X - Left;
+  LY := Y - Top;
+  OldHot := FHotIdx;
+  FHotIdx := -1;
+  if (LX >= 0) and (LY >= 0) and (LX < Width) and (LY < Height) then
+    for I := 0 to FHitCount - 1 do
+      if PtInRect(FHitRects[I], Point(LX, LY)) then
+      begin
+        FHotIdx := I;
+        Break;
+      end;
+  if FHotIdx <> OldHot then
+  begin
+    RequestInvalidate;
+    Result := True;
+  end;
+end;
+
+function TVfoOverlay.HandleMouseLeave: Boolean;
+begin
+  Result := False;
+  if FHotIdx >= 0 then
+  begin
+    FHotIdx := -1;
+    RequestInvalidate;
+    Result := True;
+  end;
+end;
+
 procedure TVfoOverlay.MouseDown(Button: TMouseButton; Shift: TShiftState;
   X, Y: Integer);
 var
@@ -556,7 +698,7 @@ begin
             FModeFilter[FMode] := FFilterBW;
             FMode := NewMode;
             FFilterBW := FModeFilter[FMode];
-            Invalidate;
+            RequestInvalidate;
             if Assigned(FOnSelect) then FOnSelect(FMode, FFilterBW);
           end;
         end
@@ -568,7 +710,7 @@ begin
             FAGCPickerOpen := not FAGCPickerOpen;
             if FAGCPickerOpen then Height := OVL_H_AGC
             else                   Height := OVL_H_NORM;
-            Invalidate;
+            RequestInvalidate;
           end
           else
           begin
@@ -578,7 +720,7 @@ begin
               HIT_SNB: FSNBOn  := not FSNBOn;
               HIT_ANF: FANFOn  := not FANFOn;
             end;
-            Invalidate;
+            RequestInvalidate;
             if Assigned(FOnDSPChange) then
               FOnDSPChange(FNRMode, FNBMode, FSNBOn, FANFOn);
           end;
@@ -590,7 +732,7 @@ begin
         FAGCMode       := HV - HIT_AGC_PICK_BASE;
         FAGCPickerOpen := False;
         Height         := OVL_H_NORM;
-        Invalidate;
+        RequestInvalidate;
         if Assigned(FOnAGCChange) then FOnAGCChange(FAGCMode);
       end
       else if HV > 0 then
@@ -600,7 +742,7 @@ begin
         begin
           FFilterBW := NewBW;
           FModeFilter[FMode] := FFilterBW;
-          Invalidate;
+          RequestInvalidate;
           if Assigned(FOnSelect) then FOnSelect(FMode, FFilterBW);
         end;
       end;
@@ -617,13 +759,13 @@ begin
   for I := 0 to FHitCount - 1 do
     if PtInRect(FHitRects[I], Point(X, Y)) then
     begin FHotIdx := I; Break; end;
-  if FHotIdx <> OldHot then Invalidate;
+  if FHotIdx <> OldHot then RequestInvalidate;
 end;
 
 procedure TVfoOverlay.MouseLeave;
 begin
   inherited;
-  if FHotIdx >= 0 then begin FHotIdx := -1; Invalidate; end;
+  if FHotIdx >= 0 then begin FHotIdx := -1; RequestInvalidate; end;
 end;
 
 procedure TVfoOverlay.SetState(AMode, ABW: Integer; AVfoHz, ASMeterDB: Double);
@@ -634,7 +776,7 @@ begin
   FModeFilter[FMode] := ABW;
   FVfoHz    := AVfoHz;
   FSMeterDB := ASMeterDB;
-  Invalidate;
+  RequestInvalidate;
 end;
 
 procedure TVfoOverlay.SetDSPState(ANRMode, ANBMode: Integer; ASNBOn, AANFOn: Boolean;
@@ -645,7 +787,7 @@ begin
   FSNBOn   := ASNBOn;
   FANFOn   := AANFOn;
   FAGCMode := AAGCMode;
-  Invalidate;
+  RequestInvalidate;
 end;
 
 procedure TVfoOverlay.UpdateSMeter(DB: Double);
@@ -654,7 +796,7 @@ begin
   if Abs(DB - FSMeterDB) > 0.4 then
   begin
     FSMeterDB := DB;
-    Invalidate;
+    RequestInvalidate;
   end;
 end;
 
@@ -663,7 +805,7 @@ begin
   if FVfoHz <> AVfoHz then
   begin
     FVfoHz := AVfoHz;
-    Invalidate;
+    RequestInvalidate;
   end;
 end;