Fill incomplete images in SkCodec parent class

Rather than implementing some sort of "fill" in every
SkCodec subclass for incomplete images, let's make the
parent class handle this situation.

This includes an API change to SkCodec.h

SkCodec::getScanlines() now returns the number of lines it
read successfully, rather than an SkCodec::Result enum.
getScanlines() most often fails on an incomplete input, in
which case it is useful to know how many lines were
successfully decoded - this provides more information than
kIncomplete vs kSuccess.  We do lose information when the
API is used improperly, as we are no longer able to return
kInvalidParameter or kScanlineNotStarted.

Known Issues:
Does not work for incomplete fFrameIsSubset gifs.
Does not work for incomplete icos.

BUG=skia:

Review URL: https://codereview.chromium.org/1332053002

1 files changed, 34 insertions, 31 deletions

diff --git a/src/codec/SkCodecPriv.h b/src/codec/SkCodecPriv.h
index 2769cec1cd..0442625dd2 100644
--- a/src/codec/SkCodecPriv.h
+++ b/src/codec/SkCodecPriv.h
@@ -8,6 +8,7 @@
 #ifndef SkCodecPriv_DEFINED
 #define SkCodecPriv_DEFINED
 
+#include "SkColorPriv.h"
 #include "SkColorTable.h"
 #include "SkImageInfo.h"
 #include "SkSwizzler.h"
@@ -34,7 +35,7 @@
  * 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;
     }
@@ -47,7 +48,7 @@ static int get_scaled_dimension(int srcDimension, int sampleSize) {
  *
  * 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
@@ -57,7 +58,7 @@ static int get_start_coord(int sampleFactor) { return sampleFactor / 2; };
  *
  * 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
@@ -67,7 +68,7 @@ static int get_dst_coord(int srcCoord, int sampleFactor) { return srcCoord / sam
  *
  * 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);
 
@@ -80,7 +81,7 @@ static bool is_coord_necessary(int srcCoord, int sampleFactor, int scaledDim) {
     return ((srcCoord - startCoord) % sampleFactor) == 0;
 }
 
-static inline bool valid_alpha(SkAlphaType dstAlpha, SkAlphaType srcAlpha) {
+inline bool valid_alpha(SkAlphaType dstAlpha, SkAlphaType srcAlpha) {
     // Check for supported alpha types
     if (srcAlpha != dstAlpha) {
         if (kOpaque_SkAlphaType == srcAlpha) {
@@ -110,7 +111,7 @@ static inline bool valid_alpha(SkAlphaType dstAlpha, SkAlphaType srcAlpha) {
  * - 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;
     }
@@ -134,15 +135,34 @@ static bool conversion_possible(const SkImageInfo& dst, const SkImageInfo& src)
 /*
  * 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);
@@ -155,21 +175,21 @@ static inline void copy_color_table(const SkImageInfo& dstInfo, SkColorTable* co
 /*
  * 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;
@@ -182,27 +202,10 @@ 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
  */
-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];
 }
 
@@ -210,7 +213,7 @@ static inline uint8_t get_byte(uint8_t* buffer, uint32_t 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
@@ -224,7 +227,7 @@ static inline uint16_t get_short(uint8_t* buffer, uint32_t i) {
  * 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