From aa7b258a8a037c8bc1cb6587f3252cda909780ec Mon Sep 17 00:00:00 2001
From: fanlumaster <1730976608@qq.com>
Date: Sat, 22 Mar 2025 11:55:44 +0800
Subject: [PATCH] do not repeat WM_COPYDATA if not necessary

---
 src/Global/Globals.h           |  1 +
 src/Window/CandidateWindow.cpp | 28 ++++++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/src/Global/Globals.h b/src/Global/Globals.h
index 06550dcd..e8afd56f 100644
--- a/src/Global/Globals.h
+++ b/src/Global/Globals.h
@@ -175,4 +175,5 @@ inline std::vector<std::wstring> WStringCandidateList;
 inline std::wstring FindKeyCode;
 
 inline POINT PointDTO = {0, 0};
+inline std::wstring CandidateWString = L"";
 } // namespace Global
diff --git a/src/Window/CandidateWindow.cpp b/src/Window/CandidateWindow.cpp
index a5f26261..19506af1 100644
--- a/src/Window/CandidateWindow.cpp
+++ b/src/Window/CandidateWindow.cpp
@@ -2,7 +2,9 @@
 #include "Globals.h"
 #include "BaseWindow.h"
 #include "Globals.h"
+#include <corecrt_wstring.h>
 #include <string>
+#include <winnt.h>
 #include <winuser.h>
 #include <dwmapi.h>
 #include "CandidateWindow.h"
@@ -545,6 +547,8 @@ void CCandidateWindow::_DrawListWithWebview2(_In_ UINT iIndex)
 
     std::wstring preeditString(preeditStringRange.Get(), preeditStringRange.GetLength());
 
+    std::wstring candWString = preeditString;
+
     //
     // Draw candidate list
     //
@@ -553,6 +557,30 @@ void CCandidateWindow::_DrawListWithWebview2(_In_ UINT iIndex)
         std::wstring pageCountString = std::to_wstring(*_pIndexRange->GetAt(pageCount));
         CCandidateListItem *pItemList = _candidateList.GetAt(iIndex);
         std::wstring itemString(pItemList->_ItemString.Get(), pItemList->_ItemString.GetLength());
+        candWString = candWString + L"," + pageCountString + L". " + itemString;
+    }
+
+    if (Global::CandidateWString != candWString)
+    {
+        Global::CandidateWString = candWString;
+
+        HWND UIHwnd = FindWindow(L"global_candidate_window", NULL);
+        if (UIHwnd == NULL)
+        {
+            DWORD error = GetLastError();
+            std::wstring errorString = L"FindWindow failed with error: " + std::to_wstring(error);
+            Global::LogMessageW(errorString.c_str());
+        }
+        COPYDATASTRUCT cds;
+        cds.dwData = 1;
+        cds.cbData = (candWString.size() + 1) * sizeof(WCHAR);
+        cds.lpData = (PVOID)candWString.c_str();
+        if (!SendMessage(UIHwnd, WM_COPYDATA, (WPARAM)UIHwnd, (LPARAM)&cds))
+        {
+            DWORD error = GetLastError();
+            std::wstring errorString = L"PostMessage failed with error: " + std::to_wstring(error);
+            Global::LogMessageW(errorString.c_str());
+        }
     }
 }