APIs and tests for extracting bitmaps from image objects

Added FPDFImageObj_GetBitmap() that returns the bitmap of an image
object, and a FPDFBitmap_GetFormat() that returns the format of a
bitmap.
    * Fixed a small bitmap conversion bug in cfx_dibsource.cpp.
    * Enabled EmbedderTest::CompareBitmap() to support different formats
      of bitmaps.
    * Added an embedder test and a test PDF file with images of many
      different formats.

Bug=pdfium:677

Change-Id: I6a72f9d969cf5f3577db9400ca33197c213622ed
Reviewed-on: https://pdfium-review.googlesource.com/9690
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Jane Liu <janeliulwq@google.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/fpdfsdk/fpdfeditimg.cpp b/fpdfsdk/fpdfeditimg.cpp
index fdc98e06e9..bfd12b2441 100644
--- a/fpdfsdk/fpdfeditimg.cpp
+++ b/fpdfsdk/fpdfeditimg.cpp
@@ -110,3 +110,30 @@ DLLEXPORT FPDF_BOOL STDCALL FPDFImageObj_SetBitmap(FPDF_PAGE* pages,
   pImgObj->SetDirty(true);
   return true;
 }
+
+DLLEXPORT FPDF_BITMAP STDCALL
+FPDFImageObj_GetBitmap(FPDF_PAGEOBJECT image_object) {
+  CPDF_PageObject* pObj = CPDFPageObjectFromFPDFPageObject(image_object);
+  if (!pObj || !pObj->IsImage())
+    return nullptr;
+
+  CFX_RetainPtr<CPDF_Image> pImg = pObj->AsImage()->GetImage();
+  if (!pImg)
+    return nullptr;
+
+  CFX_RetainPtr<CFX_DIBSource> pSource = pImg->LoadDIBSource();
+  if (!pSource)
+    return nullptr;
+
+  CFX_RetainPtr<CFX_DIBitmap> pBitmap;
+  // If the source image has a representation of 1 bit per pixel, then convert
+  // it to a grayscale bitmap having 1 byte per pixel, since bitmaps have no
+  // concept of bits. Otherwise, convert the source image to a bitmap directly,
+  // retaining its color representation.
+  if (pSource->GetBPP() == 1)
+    pBitmap = pSource->CloneConvert(FXDIB_8bppRgb);
+  else
+    pBitmap = pSource->Clone(nullptr);
+
+  return pBitmap.Leak();
+}