From 762fad420e6dbc139c4d8949bd7b2263ef3891aa Mon Sep 17 00:00:00 2001
From: Uladzimir Karpenka <i@vladimir.cc>
Date: Tue, 26 May 2026 11:06:55 +0300
Subject: [PATCH] Guard OpenGL mode on native Wayland

---
 MainForm.pas      | 17 +++++++++++++++++
 PlatformUtils.pas | 42 ++++++++++++++++++++++++++++++++++++++++++
 ewsdr.lpi         |  4 ++++
 3 files changed, 63 insertions(+)
 create mode 100644 PlatformUtils.pas

diff --git a/MainForm.pas b/MainForm.pas
index dbe7be8..866779c 100644
--- a/MainForm.pas
+++ b/MainForm.pas
@@ -35,6 +35,7 @@ uses
   CATEngine, CATSerial, CATTcp,
   SpectrumView, SpectrumViewOpengl,
   StatusBar,
+  PlatformUtils,
   WinFirewall;
 
 const
@@ -1469,6 +1470,22 @@ begin
   FSplitterDrag  := False;
 
   FUseOpenGLSpectrum := HasOpenGLSpectrumSwitch;
+  if FUseOpenGLSpectrum and (not QtPlatformAllowsOpenGLControls) then
+  begin
+    MessageDlg('OpenGL rendering disabled',
+      'OpenGL rendering is not available in the current Qt Wayland mode.' + LineEnding +
+      LineEnding +
+      'The Lazarus/LCL Qt6 OpenGL control used by EWSDR requires an X11 display handle, ' +
+      'but the native Wayland backend does not provide one. Using it here can cause an access violation during startup.' +
+      LineEnding +
+      LineEnding +
+      'To run EWSDR with OpenGL rendering, start it through XWayland:' + LineEnding +
+      'QT_QPA_PLATFORM=xcb ./ewsdr --opengl' + LineEnding +
+      LineEnding +
+      'OpenGL rendering will be disabled for this session.',
+      mtWarning, [mbOK], 0);
+    FUseOpenGLSpectrum := False;
+  end;
   if FUseOpenGLSpectrum then
     FWaterfallFrameInterval := 1;
   if FUseOpenGLSpectrum then
diff --git a/PlatformUtils.pas b/PlatformUtils.pas
new file mode 100644
index 0000000..0ab1404
--- /dev/null
+++ b/PlatformUtils.pas
@@ -0,0 +1,42 @@
+unit PlatformUtils;
+
+{
+  PlatformUtils.pas - small helpers for desktop/runtime platform checks.
+}
+
+{$IFDEF FPC}
+  {$MODE Delphi}
+{$ENDIF}
+
+interface
+
+function QtPlatformAllowsOpenGLControls: Boolean;
+
+implementation
+
+uses
+  SysUtils;
+
+function QtPlatformAllowsOpenGLControls: Boolean;
+var
+  Qpa, FirstQpa, SessionType: string;
+  Sep: Integer;
+begin
+  Result := True;
+  Qpa := LowerCase(Trim(GetEnvironmentVariable('QT_QPA_PLATFORM')));
+  SessionType := LowerCase(Trim(GetEnvironmentVariable('XDG_SESSION_TYPE')));
+
+  if Qpa <> '' then
+  begin
+    FirstQpa := Qpa;
+    Sep := Pos(';', FirstQpa);
+    if Sep > 0 then
+      FirstQpa := Copy(FirstQpa, 1, Sep - 1);
+    Result := FirstQpa <> 'wayland';
+    Exit;
+  end;
+
+  Result := SessionType <> 'wayland';
+end;
+
+end.
diff --git a/ewsdr.lpi b/ewsdr.lpi
index f094009..55ed8f9 100644
--- a/ewsdr.lpi
+++ b/ewsdr.lpi
@@ -210,6 +210,10 @@
         <Filename Value="SpectrumView.pas"/>
         <IsPartOfProject Value="True"/>
       </Unit>
+      <Unit>
+        <Filename Value="PlatformUtils.pas"/>
+        <IsPartOfProject Value="True"/>
+      </Unit>
       <Unit>
         <Filename Value="SpectrumViewOpengl.pas"/>
         <IsPartOfProject Value="True"/>