Scanline decoding for bmp

src/codec/SkCodecPriv.h

Index: src/codec/SkCodecPriv.h
diff --git a/src/codec/SkCodecPriv.h b/src/codec/SkCodecPriv.h
index 450457f630137c98b854be9f2ad8ad963f8c71d0..2c64bddc735388f1617f232bef6260604e1124e5 100644
--- a/src/codec/SkCodecPriv.h
+++ b/src/codec/SkCodecPriv.h
@@ -132,6 +132,23 @@ static inline size_t compute_row_bytes(int width, uint32_t bitsPerPixel) {
 }
 
 /*
+ * On incomplete images, get the color to fill with
+ */
+static inline SkPMColor get_fill_color_or_index(SkAlphaType alphaType) {
+    // This condition works properly for all supported output color types.
+    // kIndex8: The low 8-bits of both possible return values is 0, which is
+    //          our desired default index.
+    // kGray8:  The low 8-bits of both possible return values is 0, which is
+    //          black, our desired fill value.
+    // kRGB565: The low 16-bits of both possible return values is 0, which is
+    //          black, our desired fill value.
+    // kN32:    Return black for opaque images and transparent for non-opaque
+    //          images.
+    return kOpaque_SkAlphaType == alphaType ?
+            SK_ColorBLACK : SK_ColorTRANSPARENT;
+}
+
+/*
  * Get a byte from a buffer
  * This method is unsafe, the caller is responsible for performing a check
  */