[FancyZones] Implement File Watcher (#8603)

* Implement File Watcher in FancyZones

* Simplify code, address PR comments

* Add check to result of CreateEventW

* Rebase fix

Removed unneeded newline. If we keep it now, VS will just remove it some other time.

src/modules/fancyzones/lib/FancyZones.cpp

@@ -10,6 +10,7 @@
 #include "lib/ZoneWindow.h"
 #include "lib/FancyZonesData.h"
 #include "lib/ZoneSet.h"
+#include "lib/FileWatcher.h"
 #include "lib/WindowMoveHandler.h"
 #include "lib/FancyZonesWinHookEventIDs.h"
 #include "lib/util.h"
@@ -50,6 +51,9 @@ public:
         m_settings(settings),
         m_windowMoveHandler(settings, [this]() {
             PostMessageW(m_window, WM_PRIV_LOCATIONCHANGE, NULL, NULL);
+        }),
+        m_fileWatcher(FancyZonesDataInstance().GetZonesSettingsFileName(), [this]() {
+            PostMessageW(m_window, WM_PRIV_FILE_UPDATE, NULL, NULL);
         })
     {
         m_settings->SetCallback(this);
@@ -221,6 +225,7 @@ private:
     void MoveWindowIntoZone(HWND window, winrt::com_ptr<IZoneWindow> zoneWindow, const std::vector<size_t>& zoneIndexSet) noexcept;
 
     void OnEditorExitEvent() noexcept;
+    void UpdateZoneSets() noexcept;
     bool ShouldProcessSnapHotkey(DWORD vkCode) noexcept;
 
     std::vector<std::pair<HMONITOR, RECT>> GetRawMonitorData() noexcept;
@@ -232,6 +237,7 @@ private:
     HWND m_window{};
     WindowMoveHandler m_windowMoveHandler;
     MonitorWorkAreaHandler m_workAreaHandler;
+    FileWatcher m_fileWatcher;
 
     winrt::com_ptr<IFancyZonesSettings> m_settings{};
     GUID m_previousDesktopId{}; // UUID of previously active virtual desktop.
@@ -249,6 +255,7 @@ private:
     static UINT WM_PRIV_VD_SWITCH; // Scheduled when virtual desktop switch occurs
     static UINT WM_PRIV_VD_UPDATE; // Scheduled on virtual desktops update (creation/deletion)
     static UINT WM_PRIV_EDITOR; // Scheduled when the editor exits
+    static UINT WM_PRIV_FILE_UPDATE; // Scheduled when the a watched file is updated
 
     static UINT WM_PRIV_LOWLEVELKB; // Scheduled when we receive a key down press
 
@@ -266,6 +273,7 @@ UINT FancyZones::WM_PRIV_VD_INIT = RegisterWindowMessage(L"{469818a8-00fa-4069-b
 UINT FancyZones::WM_PRIV_VD_SWITCH = RegisterWindowMessage(L"{128c2cb0-6bdf-493e-abbe-f8705e04aa95}");
 UINT FancyZones::WM_PRIV_VD_UPDATE = RegisterWindowMessage(L"{b8b72b46-f42f-4c26-9e20-29336cf2f22e}");
 UINT FancyZones::WM_PRIV_EDITOR = RegisterWindowMessage(L"{87543824-7080-4e91-9d9c-0404642fc7b6}");
+UINT FancyZones::WM_PRIV_FILE_UPDATE = RegisterWindowMessage(L"{632f17a9-55a7-45f1-a4db-162e39271d92}");
 UINT FancyZones::WM_PRIV_LOWLEVELKB = RegisterWindowMessage(L"{763c03a3-03d9-4cde-8d71-f0358b0b4b52}");
 
 // IFancyZones
@@ -856,6 +864,11 @@ LRESULT FancyZones::WndProc(HWND window, UINT message, WPARAM wparam, LPARAM lpa
             auto hwnd = reinterpret_cast<HWND>(wparam);
             WindowCreated(hwnd);
         }
+        else if (message == WM_PRIV_FILE_UPDATE)
+        {
+            FancyZonesDataInstance().LoadFancyZonesData();
+            UpdateZoneSets();
+        }
         else
         {
             return DefWindowProc(window, message, wparam, lparam);
@@ -1296,7 +1309,11 @@ void FancyZones::OnEditorExitEvent() noexcept
 {
     // Collect information about changes in zone layout after editor exited.
     FancyZonesDataInstance().ParseDataFromTmpFiles();
+    UpdateZoneSets();
+}
 
+void FancyZones::UpdateZoneSets() noexcept
+{
     for (auto workArea : m_workAreaHandler.GetAllWorkAreas())
     {
         workArea->UpdateActiveZoneSet();

src/modules/fancyzones/lib/FancyZonesData.h

@@ -59,6 +59,11 @@ public:
         return appZoneHistoryMap;
     }
 
+    inline const std::wstring& GetZonesSettingsFileName() const 
+    {
+        return zonesSettingsFileName;
+    }
+
     bool AddDevice(const std::wstring& deviceId);
     void CloneDeviceInfo(const std::wstring& source, const std::wstring& destination);
     void UpdatePrimaryDesktopData(const std::wstring& desktopId);

src/modules/fancyzones/lib/FancyZonesLib.vcxproj

@@ -40,6 +40,7 @@
     <ClInclude Include="FancyZones.h" />
     <ClInclude Include="FancyZonesDataTypes.h" />
     <ClInclude Include="FancyZonesWinHookEventIDs.h" />
+    <ClInclude Include="FileWatcher.h" />
     <ClInclude Include="GenericKeyHook.h" />
     <ClInclude Include="FancyZonesData.h" />
     <ClInclude Include="JsonHelpers.h" />
@@ -64,6 +65,7 @@
     <ClCompile Include="FancyZonesDataTypes.cpp" />
     <ClCompile Include="FancyZonesWinHookEventIDs.cpp" />
     <ClCompile Include="FancyZonesData.cpp" />
+    <ClCompile Include="FileWatcher.cpp" />
     <ClCompile Include="JsonHelpers.cpp" />
     <ClCompile Include="MonitorWorkAreaHandler.cpp" />
     <ClCompile Include="OnThreadExecutor.cpp" />

src/modules/fancyzones/lib/FancyZonesLib.vcxproj.filters

@@ -78,6 +78,9 @@
     <ClInclude Include="ZoneWindowDrawing.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="FileWatcher.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="pch.cpp">
@@ -134,6 +137,9 @@
     <ClCompile Include="OnThreadExecutor.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="FileWatcher.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <None Include="packages.config" />

src/modules/fancyzones/lib/FileWatcher.cpp

@@ -0,0 +1,68 @@
+#include "pch.h"
+#include "FileWatcher.h"
+
+std::optional<FILETIME> FileWatcher::MyFileTime()
+{
+    HANDLE hFile = CreateFileW(m_path.c_str(), FILE_READ_ATTRIBUTES, FILE_SHARE_DELETE | FILE_SHARE_READ | FILE_SHARE_WRITE, nullptr, OPEN_EXISTING, 0, nullptr);
+    std::optional<FILETIME> result;
+    if (hFile != INVALID_HANDLE_VALUE)
+    {
+        FILETIME lastWrite;
+        if (GetFileTime(hFile, nullptr, nullptr, &lastWrite))
+        {
+            result = lastWrite;
+        }
+
+        CloseHandle(hFile);
+    }
+
+    return result;
+}
+
+void FileWatcher::Run()
+{
+    while (1)
+    {
+        auto lastWrite = MyFileTime();
+        if (!m_lastWrite.has_value())
+        {
+            m_lastWrite = lastWrite;
+        }
+        else if (lastWrite.has_value())
+        {
+            if (m_lastWrite->dwHighDateTime != lastWrite->dwHighDateTime ||
+                m_lastWrite->dwLowDateTime != lastWrite->dwLowDateTime)
+            {
+                m_lastWrite = lastWrite;
+                m_callback();
+            }
+        }
+
+        if (WaitForSingleObject(m_abortEvent, m_refreshPeriod) == WAIT_OBJECT_0)
+        {
+            return;
+        }
+    }
+}
+
+FileWatcher::FileWatcher(const std::wstring& path, std::function<void()> callback, DWORD refreshPeriod) :
+    m_refreshPeriod(refreshPeriod),
+    m_path(path),
+    m_callback(callback)
+{
+    m_abortEvent = CreateEventW(nullptr, TRUE, FALSE, nullptr);
+    if (m_abortEvent)
+    {
+        m_thread = std::thread([this]() { Run(); });
+    }
+}
+
+FileWatcher::~FileWatcher()
+{
+    if (m_abortEvent)
+    {
+        SetEvent(m_abortEvent);
+        m_thread.join();
+        CloseHandle(m_abortEvent);
+    }
+}

src/modules/fancyzones/lib/FileWatcher.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include "pch.h"
+
+class FileWatcher
+{
+    DWORD m_refreshPeriod;
+    std::wstring m_path;
+    std::optional<FILETIME> m_lastWrite;
+    std::function<void()> m_callback;
+    HANDLE m_abortEvent;
+    std::thread m_thread;
+    
+    std::optional<FILETIME> MyFileTime();
+    void Run();
+public:
+    FileWatcher(const std::wstring& path, std::function<void()> callback, DWORD refreshPeriod = 1000);
+    ~FileWatcher();
+};

src/modules/fancyzones/lib/pch.h

@@ -21,6 +21,7 @@
 #include <functional>
 #include <unordered_set>
 #include <ShObjIdl.h>
+#include <optional>
 
 #pragma comment(lib, "windowsapp")