Remove: [Video] no longer draw in a thread

Drawing in a thread is a bit odd, and often leads to surprising
issues. For example, OpenGL would only allow it if you move the
full context to the thread. Which is not always easily done on
all OSes.
In general, the advise is to handle system events and drawing
from the main thread, and do everything else in other threads.
So, let's be more like other games.

Additionally, putting the drawing routine in a thread was only
done for a few targets.

Upcoming commit will move the GameLoop in a thread, which will
work for all targets.

1 files changed, 1 insertions, 109 deletions

diff --git a/src/video/win32_v.cpp b/src/video/win32_v.cpp
index 30729ead6..d8841671a 100644
--- a/src/video/win32_v.cpp
+++ b/src/video/win32_v.cpp
@@ -225,11 +225,6 @@ bool VideoDriver_Win32Base::MakeWindow(bool full_screen)
 	return true;
 }
 
-/* static */ void VideoDriver_Win32Base::PaintThreadThunk(VideoDriver_Win32Base *drv)
-{
-	drv->PaintThread();
-}
-
 /** Forward key presses to the window system. */
 static LRESULT HandleCharMsg(uint keycode, WChar charcode)
 {
@@ -868,70 +863,12 @@ bool VideoDriver_Win32Base::PollEvent()
 
 void VideoDriver_Win32Base::MainLoop()
 {
-	std::thread draw_thread;
-
-	if (this->draw_threaded) {
-		/* Initialise the mutex first, because that's the thing we *need*
-		 * directly in the newly created thread. */
-		try {
-			this->draw_signal = new std::condition_variable_any();
-			this->draw_mutex = new std::recursive_mutex();
-		} catch (...) {
-			this->draw_threaded = false;
-		}
-
-		if (this->draw_threaded) {
-			this->draw_lock = std::unique_lock<std::recursive_mutex>(*this->draw_mutex);
-
-			this->draw_continue = true;
-			this->draw_threaded = StartNewThread(&draw_thread, "ottd:draw-win32", &VideoDriver_Win32Base::PaintThreadThunk, this);
-
-			/* Free the mutex if we won't be able to use it. */
-			if (!this->draw_threaded) {
-				this->draw_lock.unlock();
-				this->draw_lock.release();
-				delete this->draw_mutex;
-				delete this->draw_signal;
-				this->draw_mutex = nullptr;
-				this->draw_signal = nullptr;
-			} else {
-				DEBUG(driver, 1, "Threaded drawing enabled");
-				/* Wait till the draw thread has started itself. */
-				this->draw_signal->wait(*this->draw_mutex);
-			}
-		}
-	}
-
 	for (;;) {
 		if (_exit_game) break;
 
-		/* Flush GDI buffer to ensure we don't conflict with the drawing thread. */
-		GdiFlush();
-
-		if (this->Tick()) {
-			if (this->draw_mutex != nullptr && !HasModalProgress()) {
-				this->draw_signal->notify_one();
-			} else {
-				this->Paint();
-			}
-		}
+		this->Tick();
 		this->SleepTillNextTick();
 	}
-
-	if (this->draw_threaded) {
-		this->draw_continue = false;
-		/* Sending signal if there is no thread blocked
-		 * is very valid and results in noop */
-		this->draw_signal->notify_all();
-		if (this->draw_lock.owns_lock()) this->draw_lock.unlock();
-		this->draw_lock.release();
-		draw_thread.join();
-
-		delete this->draw_mutex;
-		delete this->draw_signal;
-
-		this->draw_mutex = nullptr;
-	}
 }
 
 void VideoDriver_Win32Base::ClientSizeChanged(int w, int h, bool force)
@@ -951,9 +888,6 @@ void VideoDriver_Win32Base::ClientSizeChanged(int w, int h, bool force)
 
 bool VideoDriver_Win32Base::ChangeResolution(int w, int h)
 {
-	std::unique_lock<std::recursive_mutex> lock;
-	if (this->draw_mutex != nullptr) lock = std::unique_lock<std::recursive_mutex>(*this->draw_mutex);
-
 	if (_window_maximize) ShowWindow(this->main_wnd, SW_SHOWNORMAL);
 
 	this->width = this->width_org = w;
@@ -964,30 +898,14 @@ bool VideoDriver_Win32Base::ChangeResolution(int w, int h)
 
 bool VideoDriver_Win32Base::ToggleFullscreen(bool full_screen)
 {
-	std::unique_lock<std::recursive_mutex> lock;
-	if (this->draw_mutex != nullptr) lock = std::unique_lock<std::recursive_mutex>(*this->draw_mutex);
-
 	bool res = this->MakeWindow(full_screen);
 
 	InvalidateWindowClassesData(WC_GAME_OPTIONS, 3);
 	return res;
 }
 
-void VideoDriver_Win32Base::AcquireBlitterLock()
-{
-	if (this->draw_mutex != nullptr) this->draw_mutex->lock();
-}
-
-void VideoDriver_Win32Base::ReleaseBlitterLock()
-{
-	if (this->draw_mutex != nullptr) this->draw_mutex->unlock();
-}
-
 void VideoDriver_Win32Base::EditBoxLostFocus()
 {
-	std::unique_lock<std::recursive_mutex> lock;
-	if (this->draw_mutex != nullptr) lock = std::unique_lock<std::recursive_mutex>(*this->draw_mutex);
-
 	CancelIMEComposition(this->main_wnd);
 	SetCompositionPos(this->main_wnd);
 	SetCandidatePos(this->main_wnd);
@@ -1043,8 +961,6 @@ bool VideoDriver_Win32Base::LockVideoBuffer()
 	if (this->buffer_locked) return false;
 	this->buffer_locked = true;
 
-	if (this->draw_threaded) this->draw_lock.lock();
-
 	_screen.dst_ptr = this->GetVideoPointer();
 	assert(_screen.dst_ptr != nullptr);
 
@@ -1060,7 +976,6 @@ void VideoDriver_Win32Base::UnlockVideoBuffer()
 		_screen.dst_ptr = nullptr;
 	}
 
-	if (this->draw_threaded) this->draw_lock.unlock();
 	this->buffer_locked = false;
 }
 
@@ -1079,8 +994,6 @@ const char *VideoDriver_Win32GDI::Start(const StringList &param)
 
 	MarkWholeScreenDirty();
 
-	this->draw_threaded = !GetDriverParam(param, "no_threads") && !GetDriverParam(param, "no_thread") && std::thread::hardware_concurrency() > 1;
-
 	return nullptr;
 }
 
@@ -1230,26 +1143,6 @@ void VideoDriver_Win32GDI::Paint()
 	this->dirty_rect = {};
 }
 
-void VideoDriver_Win32GDI::PaintThread()
-{
-	/* First tell the main thread we're started */
-	std::unique_lock<std::recursive_mutex> lock(*this->draw_mutex);
-	this->draw_signal->notify_one();
-
-	/* Now wait for the first thing to draw! */
-	this->draw_signal->wait(*this->draw_mutex);
-
-	while (this->draw_continue) {
-		this->Paint();
-
-		/* Flush GDI buffer to ensure drawing here doesn't conflict with any GDI usage in the main WndProc. */
-		GdiFlush();
-
-		this->draw_signal->wait(*this->draw_mutex);
-	}
-}
-
-
 #ifdef _DEBUG
 /* Keep this function here..
  * It allows you to redraw the screen from within the MSVC debugger */
@@ -1395,7 +1288,6 @@ const char *VideoDriver_Win32OpenGL::Start(const StringList &param)
 
 	this->ClientSizeChanged(this->width, this->height, true);
 
-	this->draw_threaded = false;
 	MarkWholeScreenDirty();
 
 	return nullptr;