Bmp Image Decoding

src/codec/SkMaskSwizzler.h

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkSwizzler.h"
+#include "SkTemplates.h"
+
+/*
+ *
+ * Used to swizzle images whose pixel components are extracted by bit masks
+ * Currently only used by bmp
+ *
+ */
+class SkMaskSwizzler {
+public:
+
+    /*
+     *
+     * Input bit masks format
+     *
+     */
+    struct InputMasks {
+        uint32_t red;
+        uint32_t green;
+        uint32_t blue;
+        uint32_t alpha;
+    };
+
+    /*
+     *
+     * Contains all of the information for a single mask
+     *
+     */
+     struct MaskInfo {
+        uint32_t mask;
+        uint32_t shift;
+        uint32_t size;
+     };
+
+     /*
+      *
+      * The bit masks used in the decode
+      *
+      */
+    struct Masks {
+        const MaskInfo red;
+        const MaskInfo green;
+        const MaskInfo blue;
+        const MaskInfo alpha;
+    };
+
+    /*
+     *
+     * Process an input mask to obtain the necessary information
+     *
+     */
+    static const MaskInfo& ProcessMask(uint32_t mask, uint32_t bpp);
+
+    /*
+     *
+     * Create a new swizzler
+     *
+     */
+    static SkMaskSwizzler* CreateMaskSwizzler(const SkImageInfo& imageInfo,
+                                              InputMasks masks,
+                                              uint32_t bitsPerPixel);
+
+    /*
+     *
+     * Swizzle the next row
+     *
+     */
+    SkSwizzler::ResultAlpha next(void* dst, const uint8_t* src);
+
+private:
+
+    /*
+     *
+     * Row procedure used for swizzle
+     *
+     */
+    typedef SkSwizzler::ResultAlpha (*RowProc)(
+            void* dstRow, const uint8_t* srcRow, int width, const Masks& masks);
+
+    /*
+     *
+     * Constructor for mask swizzler
+     *
+     */
+    SkMaskSwizzler(const SkImageInfo& info, const Masks& masks, RowProc proc);
+
+    // Fields
+    const SkImageInfo& fImageInfo;
+    const Masks        fMasks;
+    const RowProc      fRowProc;
+};