[PATCH v3 2/2] winex11: Clear only non-empty existing Composition String.

[Byeongsik Jeon]

Signed-off-by: Byeongsik Jeon 
---
v2: rework. minimize change from e4d94e48138f
v3: no changes

preedit start::
preedit draw:: caret 1 chg_first  0 chg_length  0 string 'ㄱ'
preedit draw:: caret 1 chg_first  0 chg_length  1 string '가'
preedit draw:: caret 1 chg_first  0 chg_length  1 string '간'
preedit draw:: caret 0 chg_first  0 chg_length  1 NULL      <== HERE
preedit done::
lookup chars::  keycode    0 string  3 '가'  <== IME_SetResultString
preedit start::
preedit draw:: caret 1 chg_first  0 chg_length  0 string '나'

Some xim server generate the "events" that erase the "preedit draw" string
before "lookup chars". These translates to WM_IME_ messages.
In this case, the corresponding action of IME_SetResultString() is not
required.
I tried to reduce the side effects because I can't test the issue of
e4d94e48138f .

dlls/winex11.drv/ime.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/dlls/winex11.drv/ime.c b/dlls/winex11.drv/ime.c
index c1584930861..1e50d187f19 100644
--- a/dlls/winex11.drv/ime.c
+++ b/dlls/winex11.drv/ime.c
@@ -1022,15 +1022,21 @@ void IME_SetResultString(LPWSTR lpResult, DWORD dwResultLen)
     HIMCC newCompStr;
     LPIMEPRIVATE myPrivate;
     BOOL inComp;
+    LPBYTE compdata;
+    DWORD compstr_len;

imc = RealIMC(FROM_X11);
     lpIMC = ImmLockIMC(imc);
     if (lpIMC == NULL)
         return;

-    newCompStr = updateCompStr(lpIMC->hCompStr, NULL, 0);
-    ImmDestroyIMCC(lpIMC->hCompStr);
-    lpIMC->hCompStr = newCompStr;
+    if (lpIMC->hCompStr && (compdata = ImmLockIMCC( lpIMC->hCompStr )) &&
+        (compstr_len = ((LPCOMPOSITIONSTRING)compdata)->dwCompStrLen))
+    {
+        newCompStr = updateCompStr( lpIMC->hCompStr, NULL, 0 );
+        ImmDestroyIMCC( lpIMC->hCompStr );
+        lpIMC->hCompStr = newCompStr;
+    }

newCompStr = updateResultStr(lpIMC->hCompStr, lpResult, dwResultLen);
     ImmDestroyIMCC(lpIMC->hCompStr);
@@ -1040,7 +1046,7 @@ void IME_SetResultString(LPWSTR lpResult, DWORD dwResultLen)
     inComp = myPrivate->bInComposition;
     ImmUnlockIMCC(lpIMC->hPrivate);

-    if (!inComp)
+    if (!inComp && compstr_len)
     {
         ImmSetOpenStatus(imc, TRUE);
         GenerateIMEMessage(imc, WM_IME_STARTCOMPOSITION, 0, 0);
@@ -1050,7 +1056,7 @@ void IME_SetResultString(LPWSTR lpResult, DWORD dwResultLen)
     GenerateIMEMessage(imc, WM_IME_COMPOSITION, lpResult[0], GCS_RESULTSTR|GCS_RESULTCLAUSE);
     GenerateIMEMessage(imc, WM_IME_ENDCOMPOSITION, 0, 0);

-    if (!inComp)
+    if (!inComp && compstr_len)
         ImmSetOpenStatus(imc, FALSE);

ImmUnlockIMC(imc);