Change FPDFImageObj_GetImageFilter() to return byte strings.

Since the returned data is a key, it should be a byte string and not a
wide string.

Change-Id: I9243d88586ea5b13c4b6556479d17316bf07e32e
Reviewed-on: https://pdfium-review.googlesource.com/12710
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>

3 files changed, 20 insertions, 17 deletions

diff --git a/fpdfsdk/fpdfedit_embeddertest.cpp b/fpdfsdk/fpdfedit_embeddertest.cpp
index 6dc177e2b5..71933fea43 100644
--- a/fpdfsdk/fpdfedit_embeddertest.cpp
+++ b/fpdfsdk/fpdfedit_embeddertest.cpp
@@ -1056,10 +1056,10 @@ TEST_F(FPDFEditEmbeddertest, GetImageFilters) {
   ASSERT_EQ(1, FPDFImageObj_GetImageFilterCount(obj));
   unsigned long len = FPDFImageObj_GetImageFilter(obj, 0, nullptr, 0);
   std::vector<char> buf(len);
-  EXPECT_EQ(24u, FPDFImageObj_GetImageFilter(obj, 0, buf.data(), len));
-  EXPECT_STREQ(L"FlateDecode",
-               GetPlatformWString(reinterpret_cast<unsigned short*>(buf.data()))
-                   .c_str());
+  static constexpr char kFlateDecode[] = "FlateDecode";
+  EXPECT_EQ(sizeof(kFlateDecode),
+            FPDFImageObj_GetImageFilter(obj, 0, buf.data(), len));
+  EXPECT_STREQ(kFlateDecode, buf.data());
   EXPECT_EQ(0u, FPDFImageObj_GetImageFilter(obj, 1, nullptr, 0));
 
   // Verify all the filters for an image object with a list of filters.
@@ -1069,18 +1069,18 @@ TEST_F(FPDFEditEmbeddertest, GetImageFilters) {
   len = FPDFImageObj_GetImageFilter(obj, 0, nullptr, 0);
   buf.clear();
   buf.resize(len);
-  EXPECT_EQ(30u, FPDFImageObj_GetImageFilter(obj, 0, buf.data(), len));
-  EXPECT_STREQ(L"ASCIIHexDecode",
-               GetPlatformWString(reinterpret_cast<unsigned short*>(buf.data()))
-                   .c_str());
+  static constexpr char kASCIIHexDecode[] = "ASCIIHexDecode";
+  EXPECT_EQ(sizeof(kASCIIHexDecode),
+            FPDFImageObj_GetImageFilter(obj, 0, buf.data(), len));
+  EXPECT_STREQ(kASCIIHexDecode, buf.data());
 
   len = FPDFImageObj_GetImageFilter(obj, 1, nullptr, 0);
   buf.clear();
   buf.resize(len);
-  EXPECT_EQ(20u, FPDFImageObj_GetImageFilter(obj, 1, buf.data(), len));
-  EXPECT_STREQ(L"DCTDecode",
-               GetPlatformWString(reinterpret_cast<unsigned short*>(buf.data()))
-                   .c_str());
+  static constexpr char kDCTDecode[] = "DCTDecode";
+  EXPECT_EQ(sizeof(kDCTDecode),
+            FPDFImageObj_GetImageFilter(obj, 1, buf.data(), len));
+  EXPECT_STREQ(kDCTDecode, buf.data());
 
   UnloadPage(page);
 }
diff --git a/fpdfsdk/fpdfeditimg.cpp b/fpdfsdk/fpdfeditimg.cpp
index 662ad23d76..5e3191635e 100644
--- a/fpdfsdk/fpdfeditimg.cpp
+++ b/fpdfsdk/fpdfeditimg.cpp
@@ -244,13 +244,16 @@ FPDFImageObj_GetImageFilter(FPDF_PAGEOBJECT image_object,
   CPDF_PageObject* pObj = CPDFPageObjectFromFPDFPageObject(image_object);
   CPDF_Object* pFilter =
       pObj->AsImage()->GetImage()->GetDict()->GetDirectObjectFor("Filter");
-  CFX_WideString wsFilters;
+  CFX_ByteString bsFilter;
   if (pFilter->IsName())
-    wsFilters = pFilter->AsName()->GetUnicodeText();
+    bsFilter = pFilter->AsName()->GetString();
   else
-    wsFilters = pFilter->AsArray()->GetUnicodeTextAt(index);
+    bsFilter = pFilter->AsArray()->GetStringAt(index);
 
-  return Utf16EncodeMaybeCopyAndReturnLength(wsFilters, buffer, buflen);
+  unsigned long len = bsFilter.GetLength() + 1;
+  if (buffer && len <= buflen)
+    memcpy(buffer, bsFilter.c_str(), len);
+  return len;
 }
 
 FPDF_EXPORT FPDF_BOOL FPDF_CALLCONV
diff --git a/public/fpdf_edit.h b/public/fpdf_edit.h
index c547f07890..22582674ea 100644
--- a/public/fpdf_edit.h
+++ b/public/fpdf_edit.h
@@ -385,7 +385,7 @@ FPDFImageObj_GetImageFilterCount(FPDF_PAGEOBJECT image_object);
 //
 //   image_object - handle to an image object.
 //   index        - the index of the filter requested.
-//   buffer       - buffer for holding filter string, encoded in UTF16-LE.
+//   buffer       - buffer for holding filter string, encoded in UTF-8.
 //   buflen       - length of the buffer.
 //
 // Returns the length of the filter string.