Implement IME reconversion on windows.

Windows IME supports reconversion of text. e.g. On a Japanese layout,
up on pressing the HENKAN key a list of choices for the current word are
shown in a popup. This patch adds that support to Qt. We will select the
current word in the widget and the choices are shown as in the editing
mode.

Task-number:225588
Reviewed-by: axis

3 files changed, 74 insertions, 1 deletions

diff --git a/src/gui/inputmethod/qwininputcontext_p.h b/src/gui/inputmethod/qwininputcontext_p.h
index eff223b..767fc33 100644
--- a/src/gui/inputmethod/qwininputcontext_p.h
+++ b/src/gui/inputmethod/qwininputcontext_p.h
@@ -79,6 +79,7 @@ public:
     bool startComposition();
     bool endComposition();
     bool composition(LPARAM lparam);
+    int reconvertString(RECONVERTSTRING *reconv);
 
     static void TranslateMessage(const MSG *msg);
     static LRESULT DefWindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam);
diff --git a/src/gui/inputmethod/qwininputcontext_win.cpp b/src/gui/inputmethod/qwininputcontext_win.cpp
index 684f325..d917cb3 100644
--- a/src/gui/inputmethod/qwininputcontext_win.cpp
+++ b/src/gui/inputmethod/qwininputcontext_win.cpp
@@ -47,6 +47,7 @@
 #include "qapplication.h"
 #include "qevent.h"
 #include "qtextformat.h"
+#include "qtextboundaryfinder.h"
 
 //#define Q_IME_DEBUG
 
@@ -810,4 +811,52 @@ QString QWinInputContext::language()
     return QString();
 }
 
+int QWinInputContext::reconvertString(RECONVERTSTRING *reconv)
+{
+    QWidget *w = focusWidget();
+    if(!w)
+        return -1;
+
+    Q_ASSERT(w->testAttribute(Qt::WA_WState_Created));
+    QString surroundingText = qvariant_cast<QString>(w->inputMethodQuery(Qt::ImSurroundingText));
+    int memSize = sizeof(RECONVERTSTRING)+(surroundingText.length()+1)*sizeof(ushort);
+    // If memory is not allocated, return the required size.
+    if (!reconv) {
+        if (surroundingText.isEmpty())
+            return -1;
+        else
+            return memSize;
+    }
+    int pos = qvariant_cast<int>(w->inputMethodQuery(Qt::ImCursorPosition));
+    // find the word in the surrounding text.
+    QTextBoundaryFinder bounds(QTextBoundaryFinder::Word, surroundingText);
+    bounds.setPosition(pos);
+    if (bounds.isAtBoundary()) {
+        if (QTextBoundaryFinder::EndWord == bounds.boundaryReasons())
+            bounds.toPreviousBoundary();
+    } else {
+        bounds.toPreviousBoundary();
+    }
+    int startPos = bounds.position();
+    bounds.toNextBoundary();
+    int endPos = bounds.position();
+    // select the text, this will be overwritten by following ime events.
+    QList<QInputMethodEvent::Attribute> attrs;
+    attrs << QInputMethodEvent::Attribute(QInputMethodEvent::Selection, startPos, endPos-startPos, QVariant());
+    QInputMethodEvent e(QString(), attrs);
+    qt_sendSpontaneousEvent(w, &e);
+
+    reconv->dwSize = memSize;
+    reconv->dwVersion = 0;
+
+    reconv->dwStrLen = surroundingText.length();
+    reconv->dwStrOffset = sizeof(RECONVERTSTRING);
+    reconv->dwCompStrLen = endPos-startPos;
+    reconv->dwCompStrOffset = startPos*sizeof(ushort);
+    reconv->dwTargetStrLen = reconv->dwCompStrLen;
+    reconv->dwTargetStrOffset = reconv->dwCompStrOffset;
+    memcpy((char*)(reconv+1), surroundingText.utf16(), surroundingText.length()*sizeof(ushort));
+    return memSize;
+}
+
 QT_END_NAMESPACE
diff --git a/src/gui/kernel/qapplication_win.cpp b/src/gui/kernel/qapplication_win.cpp
index 76a3b1e..b92bf03 100644
--- a/src/gui/kernel/qapplication_win.cpp
+++ b/src/gui/kernel/qapplication_win.cpp
@@ -171,6 +171,10 @@ typedef struct tagTOUCHINPUT
 #include <mywinsock.h>
 #endif
 
+#ifndef IMR_CONFIRMRECONVERTSTRING
+#define IMR_CONFIRMRECONVERTSTRING 0x0005
+#endif
+
 QT_BEGIN_NAMESPACE
 
 #ifdef Q_WS_WINCE
@@ -2263,7 +2267,26 @@ LRESULT CALLBACK QtWndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam
             }
             break;
         }
-
+        case WM_IME_REQUEST: {
+            QWidget *fw = QApplication::focusWidget();
+            QWinInputContext *im = fw ? qobject_cast<QWinInputContext *>(fw->inputContext()) : 0;
+            if (fw && im) {
+                if(wParam == IMR_RECONVERTSTRING) {
+                    int ret = im->reconvertString((RECONVERTSTRING *)lParam);
+                    if (ret == -1) {
+                        result = false;
+                    } else {
+                        return ret;
+                    }
+                } else if (wParam == IMR_CONFIRMRECONVERTSTRING) {
+                    RETURN(TRUE);
+                } else {
+                    // in all other cases, call DefWindowProc()
+                    result = false;
+                }
+            }
+            break;
+        }
 #ifndef Q_WS_WINCE
         case WM_CHANGECBCHAIN:
         case WM_DRAWCLIPBOARD: