Make down-conversion explicit from CFX_Widetring to CFX_WideStringC.

xfa/fxfa/app/xfa_ffimageedit.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "xfa/fxfa/app/xfa_ffimageedit.h"
 
 #include "xfa/fwl/core/cfwl_message.h"
 #include "xfa/fwl/core/ifwl_app.h"
@@ skipping 90 matching lines @@
   FWLToClient(ms.m_fx, ms.m_fy);
   TranslateFWLMessage(&ms);
   IXFA_AppProvider* pAppProvider = GetAppProvider();
   if (!pAppProvider) {
     return TRUE;
   }
   CFX_WideString wsTitle;
   CFX_WideString wsFilter;
   pAppProvider->LoadString(XFA_IDS_ImageFilter, wsFilter);
   CFX_WideStringArray wsPathArray;
-  pAppProvider->ShowFileDialog(wsTitle, wsFilter, wsPathArray);
+  pAppProvider->ShowFileDialog(wsTitle.AsWideStringC(),
+                               wsFilter.AsWideStringC(), wsPathArray);
   int32_t iSize = wsPathArray.GetSize();
   if (iSize < 1) {
     return TRUE;
   }
   CFX_WideString wsFilePath = wsPathArray[0];
   FX_STRSIZE nLen = wsFilePath.GetLength();
   FX_STRSIZE nIndex = nLen - 1;
   while (nIndex > 0 && wsFilePath[nIndex] != '.') {
     nIndex--;
   }
   if (nIndex <= 0) {
     return TRUE;
   }
   CFX_WideString wsContentType(L"image/");
   wsContentType += wsFilePath.Right(nLen - nIndex - 1);
   wsContentType.MakeLower();
-  FXCODEC_IMAGE_TYPE eImageType = XFA_GetImageType(wsContentType);
+  FXCODEC_IMAGE_TYPE eImageType =
+      XFA_GetImageType(wsContentType.AsWideStringC());

[Lei Zhang, 2016/04/05 00:45:48]

XFA_GetImageType() takes the CFX_WideStringC and makes a CFX_WideString out of
it. Just pass in |wsContentType| by const ref instead? Ditto in
xfa/fxfa/app/xfa_ffwidget.cpp.

[Tom Sepez, 2016/04/05 16:34:22]

There are a bunch of these.  I was planning on a follow-up that looked at
routines that take strings, and asks, "does the string persist beyond the call?"
 If yes, the the routine should take a xxxString, if not, then a xxxStringC. In
the first case, the caller may already have one, and in the second case, we may
avoid making one.

[Tom Sepez, 2016/04/05 18:47:17]

Anyway, I did this here, but the first thing the XFA_ routine does is make a
copy of the string so it can lower-case it. 

   if (eImageType == FXCODEC_IMAGE_UNKNOWN) {
     return TRUE;
   }
   CFX_WideString wsImage;
   IFX_FileRead* pFileRead = FX_CreateFileRead(wsFilePath);
   if (pFileRead) {
     int32_t nDataSize = pFileRead->GetSize();
     if (nDataSize > 0) {
       CFX_ByteString bsBuf;
       FX_CHAR* pImageBuffer = bsBuf.GetBuffer(nDataSize);
       pFileRead->ReadBlock(pImageBuffer, 0, nDataSize);
       bsBuf.ReleaseBuffer();
       if (!bsBuf.IsEmpty()) {
         FX_CHAR* pData = XFA_Base64Encode(bsBuf, nDataSize);
         wsImage = CFX_WideString::FromLocal(pData);
         FX_Free(pData);
       }
     }
     m_pDataAcc->SetImageEditImage(NULL);
     pFileRead->Release();
   }
-  m_pDataAcc->SetImageEdit(wsContentType, CFX_WideStringC(), wsImage);
+  m_pDataAcc->SetImageEdit(wsContentType.AsWideStringC(), CFX_WideStringC(),
+                           wsImage.AsWideStringC());
   m_pDataAcc->LoadImageEditImage();
   AddInvalidateRect();
   m_pDocView->SetChangeMark();
   return TRUE;
 }
 void CXFA_FFImageEdit::SetFWLRect() {
   if (!m_pNormalWidget) {
     return;
   }
   CFX_RectF rtUIMargin;
@@ skipping 15 matching lines @@
   return m_pOldDelegate->OnProcessMessage(pMessage);
 }
 FWL_ERR CXFA_FFImageEdit::OnProcessEvent(CFWL_Event* pEvent) {
   CXFA_FFField::OnProcessEvent(pEvent);
   return m_pOldDelegate->OnProcessEvent(pEvent);
 }
 FWL_ERR CXFA_FFImageEdit::OnDrawWidget(CFX_Graphics* pGraphics,
                                        const CFX_Matrix* pMatrix) {
   return m_pOldDelegate->OnDrawWidget(pGraphics, pMatrix);
 }