From 8e223c396b8f4f15401ff9b2c417b2930067d46f Mon Sep 17 00:00:00 2001
From: maxim <maxim@lazarus-ide.org>
Date: Fri, 18 Oct 2019 22:05:33 +0000
Subject: [PATCH] Merged revision(s) 62003 #d3daac07ac, 62020 #690b7498e7,
 62062 #c164409c0a from trunk: LCL-GTK2: Improve logic for loading
 LibAppIndicator3 for TrayIcon. Based on research by D.Bannon. Issue #35723.
 ........ LCL-GTK2: Add Debian to the list of distros that need the
 AppIndicator lib. Optimize a little. Issue #35723. ........ LCL-GTK2: Improve
 the logic for loading LibAppIndicator3 lib. Support an environment variable
 LAZUSEAPPIND. Issue #35723, patch from David. ........

git-svn-id: branches/fixes_2_0@62083 -
---
 lcl/interfaces/gtk2/unitywsctrls.pas | 86 ++++++++++++++++++++++------
 1 file changed, 69 insertions(+), 17 deletions(-)

diff --git a/lcl/interfaces/gtk2/unitywsctrls.pas b/lcl/interfaces/gtk2/unitywsctrls.pas
index 1dc7e805a8..5f0fc8a2a0 100644
--- a/lcl/interfaces/gtk2/unitywsctrls.pas
+++ b/lcl/interfaces/gtk2/unitywsctrls.pas
@@ -10,14 +10,21 @@ interface
 uses
   GLib2, Gtk2, Gdk2Pixbuf,
   Classes, SysUtils, dynlibs,
-  Graphics, Controls, Forms, ExtCtrls, WSExtCtrls, LCLType, LazUTF8;
+  Graphics, Controls, Forms, ExtCtrls, WSExtCtrls, LCLType, LazUTF8,
+  FileUtil;
 
-{ Changed priority, now use libappindicator_3 if available.  ~_3 is, nominally
-  a Unity thing but Ubuntu and several other distros ship it (and support it) with
-  Gnome desktops.
+{ Changed October 2019, we now try and identify those Linux distributions that
+  need to use LibAppIndicator3 and allow the remainder to use the older and
+  more functional SystemTray. Only a few old distributions can use LibAppIndicator_1
+  so don't bother to try it, rely, here on LibAppIndicator3
 
-  As of U19.04, libappindicator_1, even if present, does not seem to work.
+  The 'look up table' in NeedAppIndicator() can be overridden.
+  Introduce an optional env var, LAZUSEAPPIND that can be unset or set to
+  YES, NO or INFO - YES forces an attempt to use LibAppIndicator3, NO prevents
+  an attempt, any non blank value (eg INFO) displays to std out what is happening.
 
+  Note we assume this env var will only be used in Linux were its always safe to
+  write to stdout.
   DRB
 }
 
@@ -253,9 +260,40 @@ var
   Initialized: Boolean;
 
 function UnityAppIndicatorInit: Boolean;
-var
-  Module: HModule;
-  DeskTop: String;
+  var
+    Module: HModule;
+    UseAppInd : string;
+
+    function NeedAppIndicator: boolean;
+    var
+      DeskTop,  VersionSt : String;
+      ProcFile: TextFile;
+    begin
+      DeskTop := GetEnvironmentVariableUTF8('XDG_CURRENT_DESKTOP');
+      // See the wiki for details of what extras these desktops require !!
+      if (DeskTop = 'Unity')
+         or (Desktop = 'Enlightenment')
+            then exit(True);
+      if (DeskTop = 'GNOME') then begin
+          {$PUSH}
+          {$IOChecks off}
+          AssignFile(ProcFile, '/proc/version');
+          reset(ProcFile);
+          if IOResult<>0 then exit(false);
+          {$POP}
+          readln(ProcFile, VersionSt);
+          CloseFile(ProcFile);
+          if ( (pos('mageia', VersionSt) > 0) or
+            (pos('Debian', VersionSt) > 0) or
+            (pos('Red Hat', VersionSt) > 0) or
+            (pos('SUSE', VersionSt) > 0) )
+            // 19.04 and earlier Ubuntu Gnome does not need LibAppIndicator3
+            then exit(True);
+      end;
+      Result := False;
+    end;
+
+
 
   function TryLoad(const ProcName: string; var Proc: Pointer): Boolean;
   begin
@@ -268,17 +306,29 @@ begin
   if Loaded then
     Exit(Initialized);
   Loaded := True;
-  DeskTop := GetEnvironmentVariableUTF8('XDG_CURRENT_DESKTOP');
-  if (DeskTop = 'KDE') or (DeskTop = 'X-Cinnamon') then
-  begin
-    Initialized := False;
-    Exit;
-  end;
   if Initialized then
     Exit(True);
-  Module := LoadLibrary(libappindicator_3);        // thats the one we want here.
-  if Module = 0 then                               // no libappindicator_3
-     Exit;                                         // hope libappindicator_1 can help you ....
+  UseAppInd := getEnvironmentVariable('LAZUSEAPPIND');
+  if UseAppInd = 'NO' then
+    begin
+    Initialized := False;
+    writeln('APPIND Debug : Choosing to not try AppIndicator3');
+    Exit;
+  end;
+  if (UseAppInd <> 'YES') and (not NeedAppIndicator()) then    // ie its NO or blank or INFO
+  begin
+    Initialized := False;
+    if UseAppInd <> '' then
+       writeln('APPIND Debug : Will not use AppIndicator3');
+    Exit;
+  end;
+  if UseAppInd = 'YES' then                                    // either a YES or OS needs it
+     writeln('APPIND Debug : Will try to force AppIndicator3')
+  else
+     if UseAppInd <> '' then writeln('APPIND Debug : OS and Desktop request AppIndicator3');
+  Module := LoadLibrary(libappindicator_3);        // might have several package names, see wiki
+  if Module = 0 then
+     Exit;
   Result :=
     TryLoad('app_indicator_get_type', @app_indicator_get_type) and
     TryLoad('app_indicator_new', @app_indicator_new) and
@@ -300,6 +350,8 @@ begin
     TryLoad('app_indicator_get_label', @app_indicator_get_label) and
     TryLoad('app_indicator_get_label_guide', @app_indicator_get_label_guide) and
     TryLoad('app_indicator_get_ordering_index', @app_indicator_get_ordering_index);
+  if UseAppInd <> '' then
+     writeln('APPIND Debug : AppIndicator3 has loaded ' + booltostr(Result, True));
   Initialized := Result;
 end;