blob: 1b6723fd4afc15c55c928849af9c97508490a6b5 [file] [log] [blame]
/*
* 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);
// FIXME: Consider sharing with dm, nanbench, and tools.
inline float get_scale_from_sample_size(int sampleSize) {
return 1.0f / ((float) sampleSize);
}
inline bool is_valid_subset(const SkIRect& subset, const SkISize& imageDims) {
return SkIRect::MakeSize(imageDims).contains(subset);
}
/*
* 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
* FIXME: I think we should call this get_sampled_dimension().
*/
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.
*/
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.
*/
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.
*/
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;
}
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
*/
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
*/
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
*/
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
*/
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
*/
inline size_t compute_row_bytes_bpp(int width, uint32_t bytesPerPixel) {
return width * bytesPerPixel;
}
/*
* Compute row bytes for an image
*/
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);
}
}
/*
* Get a byte from a buffer
* This method is unsafe, the caller is responsible for performing a check
*/
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
*/
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
*/
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