Scanline decoding for bmp

src/codec/SkCodecPriv.h

 /*
  * Copyright 2015 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkCodecPriv_DEFINED
 #define SkCodecPriv_DEFINED
 
@@ skipping 113 matching lines @@
         SkASSERT(0 == 8 % bitsPerPixel);
         const uint32_t pixelsPerByte = 8 / bitsPerPixel;
         return compute_row_bytes_ppb(width, pixelsPerByte);
     } else {
         SkASSERT(0 == bitsPerPixel % 8);
         const uint32_t bytesPerPixel = bitsPerPixel / 8;
         return compute_row_bytes_bpp(width, bytesPerPixel);
     }
 }
 
+static bool is_coord_necessary(int srcCoord, int start, int sampleSize, int scaledDim) {
+    // Check for edge cases on the first few rows or the last few rows
+    if (srcCoord < start || srcCoord / sampleSize >= scaledDim) {
+        return false;
+    }
+
+    // Every sampleY rows are necessary
+    return ((srcCoord - start) % sampleSize) == 0;
+}
+
 /*
  * Get a byte from a buffer
  * This method is unsafe, the caller is responsible for performing a check
  */
 static inline uint8_t get_byte(uint8_t* buffer, uint32_t i) {
     return buffer[i];
 }
 
 /*
  * Get a short from a buffer
@@ skipping 23 matching lines @@
 #endif
 }
 
 #ifdef SK_PRINT_CODEC_MESSAGES
     #define SkCodecPrintf SkDebugf
 #else
     #define SkCodecPrintf(...)
 #endif
 
 #endif // SkCodecPriv_DEFINED