Fix bugs in SkBmpCodec

src/codec/SkMaskSwizzler.cpp

 /*
  * 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 "SkCodecPriv.h"
 #include "SkColorPriv.h"
 #include "SkMaskSwizzler.h"
@@ skipping 217 matching lines @@
 SkMaskSwizzler* SkMaskSwizzler::CreateMaskSwizzler(const SkImageInfo& dstInfo,
         const SkImageInfo& srcInfo, SkMasks* masks, uint32_t bitsPerPixel,
         const SkCodec::Options& options) {
 
     // Choose the appropriate row procedure
     RowProc proc = nullptr;
     switch (bitsPerPixel) {
         case 16:
             switch (dstInfo.colorType()) {
                 case kN32_SkColorType:
-                    switch (dstInfo.alphaType()) {
-                        case kUnpremul_SkAlphaType:
-                            proc = &swizzle_mask16_to_n32_unpremul;
-                            break;
-                        case kPremul_SkAlphaType:
-                            proc = &swizzle_mask16_to_n32_premul;
-                            break;
-                        case kOpaque_SkAlphaType:
-                            proc = &swizzle_mask16_to_n32_opaque;
-                            break;
-                        default:
-                            break;
+                    if (kOpaque_SkAlphaType == srcInfo.alphaType()) {
+                        proc = &swizzle_mask16_to_n32_opaque;
+                    } else {
+                        switch (dstInfo.alphaType()) {
+                            case kUnpremul_SkAlphaType:
+                                proc = &swizzle_mask16_to_n32_unpremul;
+                                break;
+                            case kPremul_SkAlphaType:
+                                proc = &swizzle_mask16_to_n32_premul;
+                                break;
+                            default:
+                                break;
+                        }
                     }
                     break;
                 case kRGB_565_SkColorType:
                     proc = &swizzle_mask16_to_565;
                     break;
                 default:
                     break;
             }
             break;
         case 24:
             switch (dstInfo.colorType()) {
                 case kN32_SkColorType:
-                    switch (dstInfo.alphaType()) {
-                        case kUnpremul_SkAlphaType:
-                            proc = &swizzle_mask24_to_n32_unpremul;
-                            break;
-                        case kPremul_SkAlphaType:
-                            proc = &swizzle_mask24_to_n32_premul;
-                            break;
-                        case kOpaque_SkAlphaType:
-                            proc = &swizzle_mask24_to_n32_opaque;
-                            break;
-                        default:
-                            break;
+                    if (kOpaque_SkAlphaType == srcInfo.alphaType()) {
+                        proc = &swizzle_mask24_to_n32_opaque;
+                    } else {
+                        switch (dstInfo.alphaType()) {
+                            case kUnpremul_SkAlphaType:
+                                proc = &swizzle_mask24_to_n32_unpremul;
+                                break;
+                            case kPremul_SkAlphaType:
+                                proc = &swizzle_mask24_to_n32_premul;
+                                break;
+                            default:
+                                break;
+                        }
                     }
                     break;
                 case kRGB_565_SkColorType:
                     proc = &swizzle_mask24_to_565;
                     break;
                 default:
                     break;
             }
             break;
         case 32:
             switch (dstInfo.colorType()) {
                 case kN32_SkColorType:
-                    switch (dstInfo.alphaType()) {
-                        case kUnpremul_SkAlphaType:
-                            proc = &swizzle_mask32_to_n32_unpremul;
-                            break;
-                        case kPremul_SkAlphaType:
-                            proc = &swizzle_mask32_to_n32_premul;
-                            break;
-                        case kOpaque_SkAlphaType:
-                            proc = &swizzle_mask32_to_n32_opaque;
-                            break;
-                        default:
-                            break;
+                    if (kOpaque_SkAlphaType == srcInfo.alphaType()) {
+                        proc = &swizzle_mask32_to_n32_opaque;
+                    } else {
+                        switch (dstInfo.alphaType()) {
+                            case kUnpremul_SkAlphaType:
+                                proc = &swizzle_mask32_to_n32_unpremul;
+                                break;
+                            case kPremul_SkAlphaType:
+                                proc = &swizzle_mask32_to_n32_premul;
+                                break;
+                            default:
+                                break;
+                        }
                     }
                     break;
                 case kRGB_565_SkColorType:
                     proc = &swizzle_mask32_to_565;
                     break;
                 default:
                     break;
             }
             break;
         default:
@@ skipping 41 matching lines @@
 
 /*
  *
  * Swizzle the specified row
  *
  */
 void SkMaskSwizzler::swizzle(void* dst, const uint8_t* SK_RESTRICT src) {
     SkASSERT(nullptr != dst && nullptr != src);
     fRowProc(dst, src, fDstWidth, fMasks, fX0, fSampleX);
 }