Tidy JBig2_Image.cppchromium/3511

Add checked/unchecked GetLine(y) methods and use them.
Introduce BIT_INDEX_TO_ALIGNED_BYTE() to de-mystify some shifting.
Move local declarations to spot of use.
Remove spurious Fill(), as we initialize to 0s.
Initialize members in header where possible.
Add unit tests.

Change-Id: I41ccb91b57320dbc790fd0f680f6d98571280343
Reviewed-on: https://pdfium-review.googlesource.com/39370
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>

1 files changed, 6 insertions, 3 deletions

diff --git a/core/fxcodec/jbig2/JBig2_Image.h b/core/fxcodec/jbig2/JBig2_Image.h
index 3cf28b0643..b1b1489506 100644
--- a/core/fxcodec/jbig2/JBig2_Image.h
+++ b/core/fxcodec/jbig2/JBig2_Image.h
@@ -34,11 +34,14 @@ class CJBig2_Image {
   int32_t width() const { return m_nWidth; }
   int32_t height() const { return m_nHeight; }
   int32_t stride() const { return m_nStride; }
+
   uint8_t* data() const { return m_pData.Get(); }
 
   int GetPixel(int32_t x, int32_t y) const;
   void SetPixel(int32_t x, int32_t y, int bVal);
 
+  uint8_t* GetLine(int32_t y) const;
+  uint8_t* GetLineUnsafe(int32_t y) const { return data() + y * m_nStride; }
   void CopyLine(int32_t hTo, int32_t hFrom);
   void Fill(bool v);
 
@@ -74,9 +77,9 @@ class CJBig2_Image {
                              const FX_RECT& rtSrc);
 
   MaybeOwned<uint8_t, FxFreeDeleter> m_pData;
-  int32_t m_nWidth;   // 1-bit pixels
-  int32_t m_nHeight;  // lines
-  int32_t m_nStride;  // bytes
+  int32_t m_nWidth = 0;   // 1-bit pixels
+  int32_t m_nHeight = 0;  // lines
+  int32_t m_nStride = 0;  // bytes, must be multiple of 4.
 };
 
 #endif  // CORE_FXCODEC_JBIG2_JBIG2_IMAGE_H_