APIs and tests for retrieving raw/decoded data from image objects

Added FPDFImageObj_GetImageDataDecoded() for retrieving the uncompressed
data of an image, and FPDFImageObj_GetImageDataRaw() for retrieving the
raw data of an image.
    * Refactored out DecodeStreamMaybeCopyAndReturnLength(), which is
      used to decode both attachment data and image data.
    * Within DecodeStreamMaybeCopyAndReturnLength(), used a different
      decoder function which takes care of multiple filters if exist. As
      a result, CPDF_StreamParser::DecodeInlineStream() which was made
      static previously is now moved back into namespace.

Bug=pdfium:677

Change-Id: I22a22c99acaca98ef8c15f88911f2646a2c854d5
Reviewed-on: https://pdfium-review.googlesource.com/9811
Commit-Queue: Jane Liu <janeliulwq@google.com>
Reviewed-by: Lei Zhang <thestig@chromium.org>
diff --git a/fpdfsdk/fpdfeditimg.cpp b/fpdfsdk/fpdfeditimg.cpp
index bfd12b2..0d0c546 100644
--- a/fpdfsdk/fpdfeditimg.cpp
+++ b/fpdfsdk/fpdfeditimg.cpp
@@ -137,3 +137,45 @@
 
   return pBitmap.Leak();
 }
+
+DLLEXPORT unsigned long STDCALL
+FPDFImageObj_GetImageDataDecoded(FPDF_PAGEOBJECT image_object,
+                                 void* buffer,
+                                 unsigned long buflen) {
+  CPDF_PageObject* pObj = CPDFPageObjectFromFPDFPageObject(image_object);
+  if (!pObj || !pObj->IsImage())
+    return 0;
+
+  CFX_RetainPtr<CPDF_Image> pImg = pObj->AsImage()->GetImage();
+  if (!pImg)
+    return 0;
+
+  CPDF_Stream* pImgStream = pImg->GetStream();
+  if (!pImgStream)
+    return 0;
+
+  return DecodeStreamMaybeCopyAndReturnLength(pImgStream, buffer, buflen);
+}
+
+DLLEXPORT unsigned long STDCALL
+FPDFImageObj_GetImageDataRaw(FPDF_PAGEOBJECT image_object,
+                             void* buffer,
+                             unsigned long buflen) {
+  CPDF_PageObject* pObj = CPDFPageObjectFromFPDFPageObject(image_object);
+  if (!pObj || !pObj->IsImage())
+    return 0;
+
+  CFX_RetainPtr<CPDF_Image> pImg = pObj->AsImage()->GetImage();
+  if (!pImg)
+    return 0;
+
+  CPDF_Stream* pImgStream = pImg->GetStream();
+  if (!pImgStream)
+    return 0;
+
+  uint32_t len = pImgStream->GetRawSize();
+  if (buffer && buflen >= len)
+    memcpy(buffer, pImgStream->GetRawData(), len);
+
+  return len;
+}