Bmp Image Decoding

src/codec/SkMasks.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 "SkTypes.h"
+
+/*
+ *
+ * Contains useful mask routines for SkMaskSwizzler
+ *
+ */
+class SkMasks {
+public:
+
+    /*
+     *
+     * Input bit masks format
+     *
+     */
+    struct InputMasks {
+        uint32_t red;
+        uint32_t green;
+        uint32_t blue;
+        uint32_t alpha;
+    };
+
+    /*
+     *
+     * Create the masks object
+     *
+     */
+    static SkMasks* CreateMasks(InputMasks masks, uint32_t bpp);
+
+    /*
+     *
+     * Get a color component
+     *
+     */
+    uint8_t getRed(uint32_t pixel);
+    uint8_t getGreen(uint32_t pixel);
+    uint8_t getBlue(uint32_t pixel);
+    uint8_t getAlpha(uint32_t pixel);
+
+    /*
+     *
+     * Getter for the alpha mask
+     * The alpha mask may be used in other decoding modes
+     *
+     */
+     uint32_t getAlphaMask() {
+        return fAlpha.mask;
+     }
+
+private:
+
+    /*
+     *
+     * Contains all of the information for a single mask
+     *
+     */
+     struct MaskInfo {
+        uint32_t mask;
+        uint32_t shift;
+        uint32_t size;
+     };
+
+    /*
+     *
+     * Process an input mask
+     *
+     */
+    static const MaskInfo ProcessMask(uint32_t mask, uint32_t bpp);
+
+    /*
+     *
+     * Constrcutor
+     *
+     */
+    SkMasks(const MaskInfo red, const MaskInfo green, const MaskInfo blue,
+            const MaskInfo alpha);
+
+    const MaskInfo fRed;
+    const MaskInfo fGreen;
+    const MaskInfo fBlue;
+    const MaskInfo fAlpha;
+};