Simplify ContrastAdjust().chromium/3102

Add a few constants in the process.

Change-Id: Id69b939e4ea6a3de879e0a1f29d1453e95c838db
Reviewed-on: https://pdfium-review.googlesource.com/5552
Commit-Queue: dsinclair <dsinclair@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>

1 files changed, 23 insertions, 19 deletions

diff --git a/core/fxge/ge/cfx_facecache.cpp b/core/fxge/ge/cfx_facecache.cpp
index 6d5e3d4355..9c79444dd3 100644
--- a/core/fxge/ge/cfx_facecache.cpp
+++ b/core/fxge/ge/cfx_facecache.cpp
@@ -35,44 +35,48 @@ namespace {
 
 constexpr uint32_t kInvalidGlyphIndex = static_cast<uint32_t>(-1);
 
+constexpr int kMinPixel = 0;
+constexpr int kMaxPixel = 255;
+
+constexpr int kMaxGlyphDimension = 2048;
+
 void ContrastAdjust(uint8_t* pDataIn,
                     uint8_t* pDataOut,
                     int nWidth,
                     int nHeight,
                     int nSrcRowBytes,
                     int nDstRowBytes) {
-  int col, row, temp;
-  int max = 0, min = 255;
-  float rate;
-  for (row = 0; row < nHeight; row++) {
+  int max = kMinPixel;
+  int min = kMaxPixel;
+  for (int row = 0; row < nHeight; row++) {
     uint8_t* pRow = pDataIn + row * nSrcRowBytes;
-    for (col = 0; col < nWidth; col++) {
-      temp = *pRow++;
-      max = std::max(temp, max);
-      min = std::min(temp, min);
+    for (int col = 0; col < nWidth; col++) {
+      int val = pRow[col];
+      max = std::max(val, max);
+      min = std::min(val, min);
     }
   }
-  temp = max - min;
-  if (temp == 0 || temp == 255) {
+  int diff = max - min;
+  if (diff == kMinPixel || diff == kMaxPixel) {
     int rowbytes = std::min(abs(nSrcRowBytes), nDstRowBytes);
-    for (row = 0; row < nHeight; row++) {
+    for (int row = 0; row < nHeight; row++) {
       memcpy(pDataOut + row * nDstRowBytes, pDataIn + row * nSrcRowBytes,
              rowbytes);
     }
     return;
   }
-  rate = 255.f / temp;
-  for (row = 0; row < nHeight; row++) {
+  float rate = 255.f / diff;
+  for (int row = 0; row < nHeight; row++) {
     uint8_t* pSrcRow = pDataIn + row * nSrcRowBytes;
     uint8_t* pDstRow = pDataOut + row * nDstRowBytes;
-    for (col = 0; col < nWidth; col++) {
-      temp = static_cast<int>((*(pSrcRow++) - min) * rate + 0.5);
-      temp = std::min(temp, 255);
-      temp = std::max(temp, 0);
-      *pDstRow++ = (uint8_t)temp;
+    for (int col = 0; col < nWidth; col++) {
+      int val = static_cast<int>((pSrcRow[col] - min) * rate + 0.5);
+      pDstRow[col] =
+          static_cast<uint8_t>(pdfium::clamp(val, kMinPixel, kMaxPixel));
     }
   }
 }
+
 }  // namespace
 
 CFX_FaceCache::CFX_FaceCache(FXFT_Face face)
@@ -179,7 +183,7 @@ std::unique_ptr<CFX_GlyphBitmap> CFX_FaceCache::RenderGlyph(
     return nullptr;
   int bmwidth = FXFT_Get_Bitmap_Width(FXFT_Get_Glyph_Bitmap(m_Face));
   int bmheight = FXFT_Get_Bitmap_Rows(FXFT_Get_Glyph_Bitmap(m_Face));
-  if (bmwidth > 2048 || bmheight > 2048)
+  if (bmwidth > kMaxGlyphDimension || bmheight > kMaxGlyphDimension)
     return nullptr;
   int dib_width = bmwidth;
   auto pGlyphBitmap = pdfium::MakeUnique<CFX_GlyphBitmap>();