Fix spectrum invisible on win32 and mask WDSP FPU exceptions

SpectrumView: rewrite DrawSpectrumGradient to blend directly into
FSpectrumBitmap via ScanLine instead of TLazIntfImage+BitBlt (stale DC
on win32). Add alpha=$FF fixup pass so pf32bit Canvas.Draw renders via
StretchBlt not AlphaBlend. Remove FSpecGradImg/FSpecGradBmp fields.

MainForm: mask exZeroDivide/exInvalidOp in FormCreate so WDSP DLL
divide-by-zero does not crash the DSP thread on win32 (Qt6 already
masks FPU exceptions globally).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

MainForm.pas

@@ -1160,6 +1160,7 @@ var
   WebCfg: TWebSettings;
   StartupVfoA, StartupVfoB: Double;
 begin
+  SetExceptionMask(GetExceptionMask + [exZeroDivide, exInvalidOp]);
   FVfoA      := 14200000;
   FVfoB      := 7100000;
   FActiveVfo := 0;
@@ -1933,6 +1934,7 @@ begin
   PanelRight.Parent     := Self;
   PanelRight.Align      := alClient;
   PanelRight.BevelOuter     := bvNone;
+  PanelRight.DoubleBuffered := True;
   PanelRight.OnResize   := RightPanelResize;
 
   FSampleRateOverlay := TSampleRateOverlay.Create(Self);

SpectrumView.pas

@@ -19,7 +19,7 @@ interface
 
 uses
   Classes, SysUtils, Graphics, ExtCtrls, Controls, Math,
-  IntfGraphics, FPImage, LCLIntf, LCLType, GraphType, AppTheme,
+  LCLIntf, LCLType, AppTheme,
   AlertOverlay, SampleRateOverlay, VfoOverlay,
   WaterfallView, SMeterView, RulerView;
 
@@ -37,8 +37,6 @@ type
     FFMGridLastCenter: Double;
     FFMGridLastStepHz: Double;
     FFMGridLastSpan:   Double;
-    FSpecGradImg:     TLazIntfImage;
-    FSpecGradBmp:     TBitmap;
     FSpPts:           array of TPoint;
     FSpPtsLen:        Integer;
     // ── Тема ─────────────────────────────────────────────────────────────────
@@ -248,23 +246,6 @@ begin
   Result := Format('%d.%3.3d.%3.3d', [Mhz, KHz, Rest]);
 end;
 
-procedure InitRawDesc32(var Desc: TRawImageDescription; AWidth, AHeight: Integer);
-begin
-  FillChar(Desc, SizeOf(Desc), 0);
-  Desc.Format       := ricfRGBA;
-  Desc.Width        := AWidth;
-  Desc.Height       := AHeight;
-  Desc.Depth        := 32;
-  Desc.BitOrder     := riboBitsInOrder;
-  Desc.ByteOrder    := riboLSBFirst;
-  Desc.LineOrder    := riloTopToBottom;
-  Desc.BitsPerPixel := 32;
-  Desc.LineEnd      := rileDWordBoundary;
-  Desc.BlueShift    := 0;  Desc.BluePrec  := 8;
-  Desc.GreenShift   := 8;  Desc.GreenPrec := 8;
-  Desc.RedShift     := 16; Desc.RedPrec   := 8;
-  Desc.AlphaShift   := 24; Desc.AlphaPrec := 8;
-end;
 
 function MixColorBGR(C1, C2: TColor; T: Double): TColor;
 var
@@ -301,8 +282,6 @@ begin
   FSpectrumBitmap  := TBitmap.Create;
   FSpectrumBitmap.PixelFormat := pf32bit;
   FGridBitmap      := TBitmap.Create;
-  FSpecGradBmp     := TBitmap.Create;
-  FSpecGradImg     := nil;
   FGridBitmapW     := 0; FGridBitmapH := 0;
   FFMGridLastCenter := -1.0; FFMGridLastStepHz := -1.0; FFMGridLastSpan := -1.0;
   FFMGridStepHz    := 0.0;
@@ -334,8 +313,6 @@ destructor TSpectrumView.Destroy;
 begin
   FSpectrumBitmap.Free;
   FGridBitmap.Free;
-  FSpecGradBmp.Free;
-  FreeAndNil(FSpecGradImg);
   FWaterfall.Free;
   FSMeter.Free;
   FRuler.Free;
@@ -550,9 +527,9 @@ end;
 
 procedure TSpectrumView.DrawSpectrumGradient(const SpPts: array of TPoint; W, H: Integer);
 var
-  Row, Col: Integer; YMin, Alpha: Integer;
+  Row, Col, Alpha, YMin, Off: Integer;
-  RowPtr: PByte; BPPg: Integer; RG, GG: Byte;
+  RowPtr: PByte;
-  Desc: TRawImageDescription;
+  GradB, GradG, GradR: Byte;
 begin
   if FSpectrumBitmap = nil then Exit;
   if (W <= 0) or (H <= 0) then Exit;
@@ -560,45 +537,27 @@ begin
   for Col := 0 to W - 1 do
     if SpPts[Col].Y < YMin then YMin := SpPts[Col].Y;
   if YMin >= H then Exit;
-  if (FSpecGradImg = nil) or (FSpecGradImg.Width <> W) or (FSpecGradImg.Height <> H) then
+
-  begin
+  FSpectrumBitmap.BeginUpdate(False);
-    FreeAndNil(FSpecGradImg);
-    FSpecGradImg := TLazIntfImage.Create(W, H);
-    InitRawDesc32(Desc, W, H);
-    FSpecGradImg.DataDescription := Desc;
-    FSpecGradImg.CreateData;
-  end;
-  if FSpecGradImg.PixelData <> nil then
-    FillChar(FSpecGradImg.PixelData^, W * H * 4, 0);
-  BPPg := FSpecGradImg.DataDescription.BitsPerPixel div 8;
-  if BPPg < 3 then BPPg := 4;
   for Row := YMin to H - 1 do
   begin
     Alpha := Round((1.0 - Sqr((Row - YMin) / Max(1.0, H - YMin - 1.0))) * 200);
     if Alpha <= 0 then Continue;
     if Alpha > 200 then Alpha := 200;
-    GG := Byte(FTheme.SpecGradB * Alpha div 200);
+    GradB := Byte(FTheme.SpecGradB * Alpha div 200);
-    RG := Byte(FTheme.SpecGradG * Alpha div 200);
+    GradG := Byte(FTheme.SpecGradG * Alpha div 200);
-    RowPtr := FSpecGradImg.GetDataLineStart(Row);
+    GradR := Byte(FTheme.SpecGradR * Alpha div 200);
-    if RowPtr = nil then Continue;
+    RowPtr := PByte(FSpectrumBitmap.ScanLine[Row]);
     for Col := 0 to W - 1 do
-    begin
       if SpPts[Col].Y <= Row then
       begin
-        RowPtr[0] := GG;
+        Off := Col * 4;
-        RowPtr[1] := RG;
+        RowPtr[Off]   := (GradB * Alpha + RowPtr[Off]   * (200 - Alpha)) div 200;
-        RowPtr[2] := Byte(FTheme.SpecGradR * Alpha div 200);
+        RowPtr[Off+1] := (GradG * Alpha + RowPtr[Off+1] * (200 - Alpha)) div 200;
-        if BPPg >= 4 then RowPtr[3] := Byte(Alpha);
+        RowPtr[Off+2] := (GradR * Alpha + RowPtr[Off+2] * (200 - Alpha)) div 200;
-      end else begin
-        RowPtr[0] := 0; RowPtr[1] := 0; RowPtr[2] := 0;
-        if BPPg >= 4 then RowPtr[3] := 0;
-      end;
-      Inc(RowPtr, BPPg);
       end;
   end;
-  FSpecGradBmp.LoadFromIntfImage(FSpecGradImg);
+  FSpectrumBitmap.EndUpdate(False);
-  LCLIntf.BitBlt(FSpectrumBitmap.Canvas.Handle, 0, 0, W, H,
-                 FSpecGradBmp.Canvas.Handle, 0, 0, $CC0020);
 end;
 
 // ────────────────────────────────────────────────────────────────────────────
@@ -629,7 +588,6 @@ begin
   FSpectrumBitmap.SetSize(W, H);
   FSpectrumBitmap.Canvas.Brush.Color := FTheme.BG;
   FSpectrumBitmap.Canvas.FillRect(Rect(0, 0, W, H));
-  FreeAndNil(FSpecGradImg);
   InvalidateGridCache;
   FSpPtsLen := 0;
 end;
@@ -663,7 +621,6 @@ procedure TSpectrumView.SetTheme(const T: TAppTheme);
 begin
   FTheme      := T;
   FLightTheme := T.BG > TColor($00808080);
-  FreeAndNil(FSpecGradImg);
   InvalidateGridCache;
   FWaterfall.SetTheme(T);
   FSMeter.SetTheme(T);
@@ -716,6 +673,7 @@ procedure TSpectrumView.DrawSpectrum;
 var
   C, GC: TCanvas;
   i, Yp, W, H, GX: Integer;
+  AlphaRow: PCardinal;
   DBmin, DBmax, dB: Double;
   VfoX, X1, X2: Integer;
   TXVfoX, TXX1, TXX2: Integer;
@@ -922,6 +880,15 @@ begin
     FSampleRateOverlay.DrawOverlay(FSpectrumBitmap, C, W, H);
   if Assigned(FVfoOverlay) then
     FVfoOverlay.DrawOverlay(FSpectrumBitmap, W, H);
+
+  FSpectrumBitmap.BeginUpdate(False);
+  for i := 0 to H - 1 do
+  begin
+    AlphaRow := PCardinal(FSpectrumBitmap.ScanLine[i]);
+    for Yp := 0 to W - 1 do
+      AlphaRow[Yp] := AlphaRow[Yp] or $FF000000;
+  end;
+  FSpectrumBitmap.EndUpdate(False);
 end;
 
 // ────────────────────────────────────────────────────────────────────────────
@@ -946,12 +913,7 @@ procedure TSpectrumView.PaintSpectrum(Sender: TObject);
 var PB: TPaintBox;
 begin
   PB := TPaintBox(Sender);
-  if (FSpectrumBitmap.Width > 0) and (FSpectrumBitmap.Height > 0) then
+  PB.Canvas.Draw(0, 0, FSpectrumBitmap);
-    PB.Canvas.Draw(0, 0, FSpectrumBitmap)
-  else begin
-    PB.Canvas.Brush.Color := SV_CLR_BG;
-    PB.Canvas.FillRect(Rect(0, 0, PB.Width, PB.Height));
-  end;
 end;
 
 procedure TSpectrumView.PaintWaterfall(Sender: TObject);