[doc] faq: Correct misinformed question about mouse warp issue

This change not only exposes and allows use of NtDelayExecution, but
also moves the code to set the system timer resolution.

client/displayservers/Wayland/input.c

@@ -444,7 +444,7 @@ void waylandWarpPointer(int x, int y, bool exiting)
 
   INTERLOCKED_SECTION(wlWm.confineLock,
   {
-    if (!wlWm.lockedPointer)
+    if (wlWm.lockedPointer)
     {
       LG_UNLOCK(wlWm.confineLock);
       return;

doc/build.rst

@@ -59,14 +59,12 @@ Required Dependencies
 -  libgl-dev
 -  libfontconfig1-dev
 -  libgmp-dev
--  libsdl2-dev
--  libsdl2-ttf-dev
 -  libspice-protocol-dev
 -  make
 -  nettle-dev
 -  pkg-config
 
-.. _may_be_disabled:
+.. _client_deps_may_be_disabled:
 
 May be disabled
 <<<<<<<<<<<<<<<
@@ -83,6 +81,7 @@ feature is disabled when running :ref:`cmake <client_building>`.
    -  libx11-dev
    -  libxfixes-dev
    -  libxi-dev
+   -  libxinerama-dev
    -  libxss-dev
 
 -  Disable with ``cmake -DENABLE_WAYLAND=no ..``
@@ -91,11 +90,33 @@ feature is disabled when running :ref:`cmake <client_building>`.
    -  libwayland-dev
    -  wayland-protocols
 
-You can fetch these dependencies on Debian systems with the following command:
+.. _client_deps_deprecated:
+
+Deprecated
+<<<<<<<<<<
+
+These dependencies may be used, but are not required, and will be removed
+in the future.
+
+-  Enable with ``cmake -DENABLE_SDL=yes ..``
+
+   -  libsdl2-dev
+   -  libsdl2-ttf-dev
+
+.. _client_fetching_with_apt:
+
+Fetching with APT
+^^^^^^^^^^^^^^^^^
+
+You can fetch these dependencies with the following command:
 
 ``apt-get install binutils-dev cmake fonts-freefont-ttf libfontconfig1-dev
-libsdl2-dev libsdl2-ttf-dev libspice-protocol-dev libx11-dev nettle-dev
+libegl-dev libspice-protocol-dev nettle-dev libx11-dev libxi-dev libxinerama-dev
-wayland-protocols``
+libxss-dev libwayland-dev wayland-protocols``
+
+You may omit some dependencies, if you disable the feature which requires them
+when running :ref:`cmake <client_building>`.
+(See :ref:`client_deps_may_be_disabled`)
 
 
 .. _client_building:

doc/faq.rst

@@ -88,13 +88,20 @@ The mouse is jumpy, slow, laggy when using SPICE
 Please be sure to install the SPICE guest tools from
 https://www.spice-space.org/download.html#windows-binaries.
 
-.. _the_mouse_doesnt_stay_aligned_with_the_host.:
+.. _mouse_desync_when_entering:
 
-The mouse doesn't stay aligned with the host.
+The mouse position is wrong when entering the window
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-This is intentional. The host's mouse no longer interacts with your operating
+This is due to windows mouse acceleration, it can be disabled by
-system, and is completely captured by Looking Glass.
+following one of these methods:
+
+-  Disabling pointer precision (Control Panel > Mouse > Pointer Options
+   > Uncheck Enhance pointer precision)
+-  By changing the acceleration behavior with the following registry
+   magic:
+   http://donewmouseaccel.blogspot.com.au/2010/03/markc-windows-7-mouse-acceleration-fix.html
+   (Contrary to the title this works just fine on Windows 10)
 
 .. _the_cursor_position_doesnt_update_until_i_click:
 

host/platform/Windows/CMakeLists.txt

@@ -10,6 +10,7 @@ add_library(platform_Windows STATIC
 	src/service.c
 	src/mousehook.c
 	src/force_compose.c
+	src/delay.c
 )
 
 # allow use of functions for Windows Vista or later

host/platform/Windows/include/windows/delay.h

@@ -0,0 +1,34 @@
+/**
+ * Looking Glass
+ * Copyright (C) 2017-2021 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <windows.h>
+
+typedef NTSTATUS (__stdcall *ZwSetTimerResolution_t)(ULONG RequestedResolution,
+    BOOLEAN Set, PULONG ActualResolution);
+extern ZwSetTimerResolution_t ZwSetTimerResolution;
+
+typedef NTSTATUS (__stdcall *NtDelayExecution_t)(BOOL Alertable,
+    PLARGE_INTEGER DelayInterval);
+extern NtDelayExecution_t NtDelayExecution;
+
+void delayInit(void);
+
+// like sleep but more accurate
+void delayExecution(float ms);

host/platform/Windows/src/delay.c

@@ -0,0 +1,49 @@
+/**
+ * Looking Glass
+ * Copyright (C) 2017-2021 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include "windows/delay.h"
+#include "common/debug.h"
+
+NtDelayExecution_t NtDelayExecution;
+ZwSetTimerResolution_t ZwSetTimerResolution;
+
+void delayInit(void)
+{
+  HMODULE ntdll = GetModuleHandle("ntdll.dll");
+  NtDelayExecution = (NtDelayExecution_t)
+    GetProcAddress(ntdll, "NtDelayExecution");
+
+  // Increase the timer resolution
+  ZwSetTimerResolution = (ZwSetTimerResolution_t)
+    GetProcAddress(ntdll, "ZwSetTimerResolution");
+
+  if (ZwSetTimerResolution)
+  {
+    ULONG actualResolution;
+    ZwSetTimerResolution(1, true, &actualResolution);
+    DEBUG_INFO("System timer resolution: %lu ns", actualResolution * 100);
+  }
+}
+
+void delayExecution(float ms)
+{
+  LARGE_INTEGER interval = { .QuadPart = -1 * (int)(ms * 10000.0f) };
+  NtDelayExecution(FALSE, &interval);
+}

host/platform/Windows/src/mousehook.c

@@ -19,6 +19,7 @@
  */
 
 #include "windows/mousehook.h"
+#include "windows/delay.h"
 #include "common/windebug.h"
 #include "platform.h"
 
@@ -31,8 +32,8 @@ struct mouseHook
   HHOOK       hook;
   MouseHookFn callback;
   int         x, y;
-  HANDLE      event;
+  HANDLE      event , updateEvent;
-  HANDLE      thread;
+  HANDLE      thread, updateThread;
 };
 
 static struct mouseHook mouseHook = { 0 };
@@ -85,6 +86,31 @@ static VOID WINAPI winEventProc(HWINEVENTHOOK hWinEventHook, DWORD event,
   }
 }
 
+static DWORD WINAPI updateThreadProc(LPVOID lParam)
+{
+  HANDLE events[2] = {
+    mouseHook.event,
+    mouseHook.updateEvent
+  };
+
+  while(true)
+  {
+    switch(WaitForMultipleObjects(2, events, FALSE, INFINITE))
+    {
+      case WAIT_OBJECT_0:
+        DEBUG_INFO("Mouse hook update thread received quit request");
+        return 0;
+
+      case WAIT_OBJECT_0 + 1:
+        mouseHook.callback(mouseHook.x, mouseHook.y);
+
+        // limit this to 1000Hz, who has a mouse that updates faster anyway?
+        delayExecution(1.0f);
+        break;
+    }
+  }
+}
+
 static DWORD WINAPI threadProc(LPVOID lParam) {
   if (mouseHook.installed)
   {
@@ -143,11 +169,28 @@ void mouseHook_install(MouseHookFn callback)
     mouseHook.event = CreateEventA(NULL, FALSE, FALSE, NULL);
     if (!mouseHook.event)
     {
-      DEBUG_WINERROR("Failed to create mouse hook uninstall event", GetLastError());
+      DEBUG_WINERROR("Failed to create mouse hook uninstall event",
+          GetLastError());
       return;
     }
   }
-  mouseHook.thread = CreateThread(NULL, 0, threadProc, callback, 0, NULL);
+
+  if (!mouseHook.updateEvent)
+  {
+    mouseHook.updateEvent = CreateEventA(NULL, FALSE, FALSE, NULL);
+    if (!mouseHook.event)
+    {
+      DEBUG_WINERROR("Failed to create mouse hook update event",
+          GetLastError());
+      return;
+    }
+  }
+
+  mouseHook.thread =
+    CreateThread(NULL, 0, threadProc, callback, 0, NULL);
+
+  mouseHook.updateThread =
+    CreateThread(NULL, 0, updateThreadProc, 0, 0, NULL);
 }
 
 void mouseHook_remove(void)
@@ -157,7 +200,9 @@ void mouseHook_remove(void)
 
   SetEvent(mouseHook.event);
   WaitForSingleObject(mouseHook.thread      , INFINITE);
+  WaitForSingleObject(mouseHook.updateThread, INFINITE);
   CloseHandle(mouseHook.thread);
+  CloseHandle(mouseHook.updateThread);
 }
 
 static LRESULT WINAPI mouseHook_hook(int nCode, WPARAM wParam, LPARAM lParam)
@@ -169,7 +214,7 @@ static LRESULT WINAPI mouseHook_hook(int nCode, WPARAM wParam, LPARAM lParam)
     {
       mouseHook.x = msg->pt.x;
       mouseHook.y = msg->pt.y;
-      mouseHook.callback(msg->pt.x, msg->pt.y);
+      SetEvent(mouseHook.updateEvent);
     }
   }
   return CallNextHookEx(mouseHook.hook, nCode, wParam, lParam);

host/platform/Windows/src/platform.c

@@ -20,6 +20,7 @@
 
 #include "platform.h"
 #include "service.h"
+#include "windows/delay.h"
 #include "windows/mousehook.h"
 
 #include <windows.h>
@@ -61,10 +62,6 @@ struct AppState
 static struct AppState app = {0};
 HWND MessageHWND;
 
-// undocumented API to adjust the system timer resolution (yes, its a nasty hack)
-typedef NTSTATUS (__stdcall *ZwSetTimerResolution_t)(ULONG RequestedResolution, BOOLEAN Set, PULONG ActualResolution);
-static ZwSetTimerResolution_t ZwSetTimerResolution = NULL;
-
 // linux mingw64 is missing this
 #ifndef MSGFLT_RESET
   #define MSGFLT_RESET (0)
@@ -513,14 +510,7 @@ bool app_init(void)
   // always flush stderr
   setbuf(stderr, NULL);
 
-  // Increase the timer resolution
+  delayInit();
-  ZwSetTimerResolution = (ZwSetTimerResolution_t)GetProcAddress(GetModuleHandle("ntdll.dll"), "ZwSetTimerResolution");
-  if (ZwSetTimerResolution)
-  {
-    ULONG actualResolution;
-    ZwSetTimerResolution(1, true, &actualResolution);
-    DEBUG_INFO("System timer resolution: %.2f ns", (float)actualResolution / 100.0f);
-  }
 
   // get the performance frequency for spinlocks
   QueryPerformanceFrequency(&app.perfFreq);

obs/main.c

@@ -22,6 +22,8 @@
 #include <common/version.h>
 #include <stdio.h>
 
+#include "common/debug.h"
+
 #ifdef _WIN32
 #undef EXPORT
 #define EXPORT __declspec(dllexport)
@@ -38,6 +40,7 @@ extern struct obs_source_info lg_source;
 
 MODULE_EXPORT bool obs_module_load(void)
 {
+  debug_init();
   printf("Looking Glass OBS Client (%s)\n", BUILD_VERSION);
   obs_register_source(&lg_source);
   return true;