Bmp Image Decoding

include/codec/SkCodec.h

Index: include/codec/SkCodec.h
diff --git a/include/codec/SkCodec.h b/include/codec/SkCodec.h
index beb9cb97b32bdb51bed7cc4d76d24b968fe0858d..590827059c16d17bebaf89e3b238431456c246d1 100644
--- a/include/codec/SkCodec.h
+++ b/include/codec/SkCodec.h
@@ -8,6 +8,7 @@
 #ifndef SkCodec_DEFINED
 #define SkCodec_DEFINED
 
+#include "SkEndian.h"
 #include "SkImageGenerator.h"
 #include "SkImageInfo.h"
 #include "SkSize.h"
@@ -48,6 +49,15 @@ public:
      */
     SkISize getScaledDimensions(float desiredScale) const;
 
+    /*
+     *
+     * Checks if alpha types are premul and unpremul
+     *
+     */
+    static bool premul_and_unpremul(SkAlphaType dst, SkAlphaType src) {

[scroggo, 2015/03/12 15:19:57]

I think it'd be better if we moved all these static helper functions to a new
file, in src/codec, perhaps named SkCodecPriv.h. They're not really a part of
the API so much as part of the implementation.

[msarett, 2015/03/12 18:37:46]

Agreed.  I didn't really think they belonged here, but wasn't sure where to put
them.  That makes sense.

+        return kPremul_SkAlphaType == dst && kUnpremul_SkAlphaType == src;
+    }
+
 protected:
     SkCodec(const SkImageInfo&, SkStream*);
 
@@ -83,6 +93,59 @@ protected:
      *  kCouldNotRewind.
      */
     bool SK_WARN_UNUSED_RESULT rewindIfNeeded();
+ 
+    // Additional helper methods for subclasses
+
+     /*
+      *
+      * Get method for the input stream
+      *
+      */
+     SkStream* stream() {
+         return fStream.get();
+     }
+
+    /*
+     *
+     * Get a byte from a buffer
+     * This method is unsafe, the caller is responsible for performing a check
+     *
+     */
+    static uint8_t get_byte(uint8_t* buffer, uint32_t i) {
+        return buffer[i];
+    }
+
+    /*
+     *
+     * Get a short from a buffer
+     * This method is unsafe, the caller is responsible for performing a check
+     *
+     */
+    static uint16_t get_short(uint8_t* buffer, uint32_t i) {
+        uint16_t result;
+        memcpy(&result, &(buffer[i]), 2);
+#ifdef SK_CPU_BENDIAN
+        return SkEndianSwap16(result);
+#else
+        return result;
+#endif
+    }
+
+    /*
+     *
+     * Get an int from a buffer
+     * This method is unsafe, the caller is responsible for performing a check
+     *
+     */
+    static uint32_t get_int(uint8_t* buffer, uint32_t i) {
+        uint32_t result;
+        memcpy(&result, &(buffer[i]), 4);
+#ifdef SK_CPU_BENDIAN
+        return SkEndianSwap32(result);
+#else
+        return result;
+#endif
+    }
 
 private:
     const SkImageInfo fInfo;