Fill incomplete images in SkCodec parent class

src/codec/SkCodecPriv.h

 /*
  * Copyright 2015 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkCodecPriv_DEFINED
 #define SkCodecPriv_DEFINED
 
+#include "SkColorPriv.h"
 #include "SkColorTable.h"
 #include "SkImageInfo.h"
 #include "SkSwizzler.h"
 #include "SkTypes.h"
 #include "SkUtils.h"
 
 /*
  *
  * Helper routine for alpha result codes
  *
  */
 #define INIT_RESULT_ALPHA                       \
     uint8_t zeroAlpha = 0;                      \
     uint8_t maxAlpha = 0xFF;
 
 #define UPDATE_RESULT_ALPHA(alpha)              \
     zeroAlpha |= (alpha);                       \
     maxAlpha  &= (alpha);
 
 #define COMPUTE_RESULT_ALPHA                    \
     SkSwizzler::GetResult(zeroAlpha, maxAlpha);
 
 /*
  * returns a scaled dimension based on the original dimension and the sampleSize
  * NOTE: we round down here for scaled dimension to match the behavior of SkImageDecoder
  */
-static int get_scaled_dimension(int srcDimension, int sampleSize) {
+inline int get_scaled_dimension(int srcDimension, int sampleSize) {
     if (sampleSize > srcDimension) {
         return 1;
     }
     return srcDimension / sampleSize;
 }
 
 /*
  * Returns the first coordinate that we will keep during a scaled decode.
  * The output can be interpreted as an x-coordinate or a y-coordinate.
  *
  * This does not need to be called and is not called when sampleFactor == 1.
  */
-static int get_start_coord(int sampleFactor) { return sampleFactor / 2; };
+inline int get_start_coord(int sampleFactor) { return sampleFactor / 2; };
 
 /*
  * Given a coordinate in the original image, this returns the corresponding
  * coordinate in the scaled image.  This function is meaningless if
  * IsCoordNecessary returns false.
  * The output can be interpreted as an x-coordinate or a y-coordinate.
  *
  * This does not need to be called and is not called when sampleFactor == 1.
  */
-static int get_dst_coord(int srcCoord, int sampleFactor) { return srcCoord / sampleFactor; };
+inline int get_dst_coord(int srcCoord, int sampleFactor) { return srcCoord / sampleFactor; };
 
 /*
  * When scaling, we will discard certain y-coordinates (rows) and
  * x-coordinates (columns).  This function returns true if we should keep the
  * coordinate and false otherwise.
  * The inputs may be x-coordinates or y-coordinates.
  *
  * This does not need to be called and is not called when sampleFactor == 1.
  */
-static bool is_coord_necessary(int srcCoord, int sampleFactor, int scaledDim) {
+inline bool is_coord_necessary(int srcCoord, int sampleFactor, int scaledDim) {
     // Get the first coordinate that we want to keep
     int startCoord = get_start_coord(sampleFactor);
 
     // Return false on edge cases
     if (srcCoord < startCoord || get_dst_coord(srcCoord, sampleFactor) >= scaledDim) {
         return false;
     }
 
     // Every sampleFactor rows are necessary
     return ((srcCoord - startCoord) % sampleFactor) == 0;
 }
 
-static inline bool valid_alpha(SkAlphaType dstAlpha, SkAlphaType srcAlpha) {
+inline uint32_t ceil_div(uint32_t a, uint32_t b) {
+    return (a + b - 1) / b;
+}
+
+/*
+ * Gets the output row corresponding to the encoded row for interlaced gifs
+ */
+inline uint32_t get_output_row_interlaced(uint32_t encodedRow, uint32_t height) {
+    SkASSERT(encodedRow < height);
+    // First pass
+    if (encodedRow * 8 < height) {
+        return encodedRow * 8;
+    }
+    // Second pass
+    if (encodedRow * 4 < height) {
+        return 4 + 8 * (encodedRow - ceil_div(height, 8));
+    }
+    // Third pass
+    if (encodedRow * 2 < height) {
+        return 2 + 4 * (encodedRow - ceil_div(height, 4));
+    }
+    // Fourth pass
+    return 1 + 2 * (encodedRow - ceil_div(height, 2));
+}
+
+inline bool valid_alpha(SkAlphaType dstAlpha, SkAlphaType srcAlpha) {
     // Check for supported alpha types
     if (srcAlpha != dstAlpha) {
         if (kOpaque_SkAlphaType == srcAlpha) {
             // If the source is opaque, we must decode to opaque
             return false;
         }
 
         // The source is not opaque
         switch (dstAlpha) {
             case kPremul_SkAlphaType:
             case kUnpremul_SkAlphaType:
                 // The source is not opaque, so either of these is okay
                 break;
             default:
                 // We cannot decode a non-opaque image to opaque (or unknown)
                 return false;
         }
     }
     return true;
 }
 
 /*
  * Most of our codecs support the same conversions:
  * - profileType must be the same
  * - opaque only to opaque (and 565 only if opaque)
  * - premul to unpremul and vice versa
  * - always support N32
  * - otherwise match the src color type
  */
-static bool conversion_possible(const SkImageInfo& dst, const SkImageInfo& src) {
+inline bool conversion_possible(const SkImageInfo& dst, const SkImageInfo& src) {
     if (dst.profileType() != src.profileType()) {
         return false;
     }
 
     // Ensure the alpha type is valid
     if (!valid_alpha(dst.alphaType(), src.alphaType())) {
         return false;
     }
 
     // Check for supported color types
     switch (dst.colorType()) {
         case kN32_SkColorType:
             return true;
         case kRGB_565_SkColorType:
             return src.alphaType() == kOpaque_SkAlphaType;
         default:
             return dst.colorType() == src.colorType();
     }
 }
 
 /*
  * If there is a color table, get a pointer to the colors, otherwise return nullptr
  */
-static const SkPMColor* get_color_ptr(SkColorTable* colorTable) {
+inline const SkPMColor* get_color_ptr(SkColorTable* colorTable) {
      return nullptr != colorTable ? colorTable->readColors() : nullptr;
 }
 
 /*
+ * Given that the encoded image uses a color table, return the fill value
+ */
+inline uint32_t get_color_table_fill_value(SkColorType colorType, const SkPMColor* colorPtr,
+        uint8_t fillIndex) {
+    SkASSERT(nullptr != colorPtr);
+    switch (colorType) {
+        case kN32_SkColorType:
+            return colorPtr[fillIndex];
+        case kRGB_565_SkColorType:
+            return SkPixel32ToPixel16(colorPtr[fillIndex]);
+        case kIndex_8_SkColorType:
+            return fillIndex;
+        default:
+            SkASSERT(false);
+            return 0;
+    }
+}
+
+/*
  *
  * Copy the codec color table back to the client when kIndex8 color type is requested
  */
-static inline void copy_color_table(const SkImageInfo& dstInfo, SkColorTable* colorTable,
+inline void copy_color_table(const SkImageInfo& dstInfo, SkColorTable* colorTable,
         SkPMColor* inputColorPtr, int* inputColorCount) {
     if (kIndex_8_SkColorType == dstInfo.colorType()) {
         SkASSERT(nullptr != inputColorPtr);
         SkASSERT(nullptr != inputColorCount);
         SkASSERT(nullptr != colorTable);
         memcpy(inputColorPtr, colorTable->readColors(), *inputColorCount * sizeof(SkPMColor));
     }
 }
 
 /*
  * Compute row bytes for an image using pixels per byte
  */
-static inline size_t compute_row_bytes_ppb(int width, uint32_t pixelsPerByte) {
+inline size_t compute_row_bytes_ppb(int width, uint32_t pixelsPerByte) {
     return (width + pixelsPerByte - 1) / pixelsPerByte;
 }
 
 /*
  * Compute row bytes for an image using bytes per pixel
  */
-static inline size_t compute_row_bytes_bpp(int width, uint32_t bytesPerPixel) {
+inline size_t compute_row_bytes_bpp(int width, uint32_t bytesPerPixel) {
     return width * bytesPerPixel;
 }
 
 /*
  * Compute row bytes for an image
  */
-static inline size_t compute_row_bytes(int width, uint32_t bitsPerPixel) {
+inline size_t compute_row_bytes(int width, uint32_t bitsPerPixel) {
     if (bitsPerPixel < 16) {
         SkASSERT(0 == 8 % bitsPerPixel);
         const uint32_t pixelsPerByte = 8 / bitsPerPixel;
         return compute_row_bytes_ppb(width, pixelsPerByte);
     } else {
         SkASSERT(0 == bitsPerPixel % 8);
         const uint32_t bytesPerPixel = bitsPerPixel / 8;
         return compute_row_bytes_bpp(width, bytesPerPixel);
     }
 }
 
 /*
- * 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
  */
-static inline uint8_t get_byte(uint8_t* buffer, uint32_t i) {
+inline 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 inline uint16_t get_short(uint8_t* buffer, uint32_t i) {
+inline 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 inline uint32_t get_int(uint8_t* buffer, uint32_t i) {
+inline 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
 }
 
 #ifdef SK_PRINT_CODEC_MESSAGES
     #define SkCodecPrintf SkDebugf
 #else
     #define SkCodecPrintf(...)
 #endif
 
 #endif // SkCodecPriv_DEFINED