From 3f0e4204c262c5dd1b0f3a237023a2e5cceceb96 Mon Sep 17 00:00:00 2001
From: Vladimir <i@vladimir.cc>
Date: Mon, 22 Jun 2026 22:06:44 +0300
Subject: [PATCH] fix: unify beacon decoder filter marker (CPU matches GL)
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The narrow beacon decoder filter marker rendered differently in the two
spectrum views: CPU drew a translucent filled band (BlendBand) plus a centre
line, while OpenGL drew three plain vertical lines (both edges + centre), so
it looked like one band on CPU and "two parts" on GL.

Make the CPU path draw the same three lines as GL — consistent look and
cheaper (drops the per-frame per-pixel alpha blend for this marker; BlendBand
is kept for the RX/TX passband shading).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 SpectrumView.pas | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/SpectrumView.pas b/SpectrumView.pas
index 5e3f9fa..f729828 100644
--- a/SpectrumView.pas
+++ b/SpectrumView.pas
@@ -526,23 +526,19 @@ procedure TSpectrumView.DrawBeaconMarkers(C: TCanvas; W, H: Integer);
     C.Pen.Color := Col; C.Pen.Width := 1; C.Pen.Style := Style;
     C.MoveTo(x, 0); C.LineTo(x, H);
   end;
-var
-  xc, x1, x2: Integer;
 begin
   if FBeaconMarkActive then
   begin
     Vline(FBeaconRefFreq, clLime,            psDot);     // где маяк ДОЛЖЕН быть
     Vline(FBeaconTrkFreq, TColor($000AA5FF), psSolid);   // отслеживаемый центроид (оранж)
   end;
-  // Узкий фильтр-маркер декодера: жёлтые грани полосы + центральная линия.
+  // Узкий фильтр-маркер декодера: грани полосы + центральная линия. Три линии без
+  // полупрозрачной заливки (как в GL-рендере) — единый вид и дешевле для CPU.
   if FBeaconDecActive and (FSpanHz > 0) then
   begin
-    xc := Round((FBeaconDecFreq - (FCenterFreq - FSpanHz / 2)) / FSpanHz * W);
-    x1 := Round((FBeaconDecFreq - FBeaconDecHalf - (FCenterFreq - FSpanHz / 2)) / FSpanHz * W);
-    x2 := Round((FBeaconDecFreq + FBeaconDecHalf - (FCenterFreq - FSpanHz / 2)) / FSpanHz * W);
-    BlendBand(x1, x2, H, $FF, $D0, $20, 48);              // полупрозрачная полоса
-    C.Pen.Color := TColor($0020D0FF); C.Pen.Width := 1; C.Pen.Style := psSolid;
-    if (xc >= 0) and (xc < W) then begin C.MoveTo(xc, 0); C.LineTo(xc, H); end;
+    Vline(FBeaconDecFreq - FBeaconDecHalf, TColor($0020D0FF), psSolid);  // грань фильтра
+    Vline(FBeaconDecFreq + FBeaconDecHalf, TColor($0020D0FF), psSolid);
+    Vline(FBeaconDecFreq,                  TColor($0020D0FF), psSolid);  // центр наведения
   end;
   C.Pen.Style := psSolid;
 end;