[Mod] After seeking, inform plugins about the new playback position i…

…mmediately if playback is stopped (https://bugs.openmpt.org/view.php?id=1731).

git-svn-id: https://source.openmpt.org/svn/openmpt/trunk/OpenMPT@22309 56274372-70c3-4bfc-bfc3-4c3a0b034d27

soundlib/Snd_fx.cpp

@@ -1428,6 +1428,8 @@ std::vector<GetLengthType> CSoundFile::GetLength(enmGetLengthResetMode adjustMod
 			{
 				m_MixPlugins[plug].fDryRatio = dryWetRatio;
 			}
+
+			UpdatePluginPositions();
 #endif // NO_PLUGINS
 		} else if(adjustMode != eAdjustOnSuccess)
 		{

soundlib/Sndfile.cpp

@@ -1019,6 +1019,25 @@ void CSoundFile::ResumePlugins()
 }
 
 
+void CSoundFile::UpdatePluginPositions()
+{
+#ifndef NO_PLUGINS
+	float out = 0.0f;
+	for(auto &plugin : m_MixPlugins)
+	{
+		IMixPlugin *pPlugin = plugin.pMixPlugin;
+		if(pPlugin != nullptr && !pPlugin->IsResumed())
+		{
+			pPlugin->PositionChanged();
+			pPlugin->Resume();
+			pPlugin->Process(&out, &out, 0);
+			pPlugin->Suspend();
+		}
+	}
+#endif  // NO_PLUGINS
+}
+
+
 void CSoundFile::StopAllVsti()
 {
 #ifndef NO_PLUGINS

soundlib/Sndfile.h

@@ -966,6 +966,7 @@ class CSoundFile
 	// Real-time sound functions
 	void SuspendPlugins();
 	void ResumePlugins();
+	void UpdatePluginPositions();
 	void StopAllVsti();
 	void RecalculateGainForAllPlugs();
 	void ResetChannels();