src/codec/SkCodecPriv.h - platform/external/skqp - Gitiles

 /*
  * 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 "SkTypes.h"

 #ifdef SK_PRINT_CODEC_MESSAGES
     #define SkCodecPrintf SkDebugf
 #else
     #define SkCodecPrintf(...)
 #endif

 // 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) {
     if (kUnknown_SkAlphaType == dstAlpha) {
         return false;
     }

     if (srcAlpha != dstAlpha) {
         if (kOpaque_SkAlphaType == srcAlpha) {
             // If the source is opaque, we can support any.
             SkCodecPrintf("Warning: an opaque image should be decoded as opaque "
                           "- it is being decoded as non-opaque, which will draw slower\n");
             return true;
         }

         // 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 to any alpha type
  * - 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) {
     // FIXME: skbug.com/4895
     // Currently, we ignore the SkColorProfileType on the SkImageInfo.  We
     // will treat the encoded data as linear regardless of what the client
     // requests.

     // Ensure the alpha type is valid
     if (!valid_alpha(dst.alphaType(), src.alphaType())) {
         return false;
     }

     // Check for supported color types
     switch (dst.colorType()) {
         case kRGBA_8888_SkColorType:
         case kBGRA_8888_SkColorType:
             return true;
         case kRGB_565_SkColorType:
             return kOpaque_SkAlphaType == src.alphaType();
         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 kRGBA_8888_SkColorType:
         case kBGRA_8888_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
 }

 /*
  * @param data           Buffer to read bytes from
  * @param isLittleEndian Output parameter
  *                       Indicates if the data is little endian
  *                       Is unaffected on false returns
  */
 inline bool is_valid_endian_marker(const uint8_t* data, bool* isLittleEndian) {
     // II indicates Intel (little endian) and MM indicates motorola (big endian).
     if (('I' != data[0] || 'I' != data[1]) && ('M' != data[0] || 'M' != data[1])) {
         return false;
     }

     *isLittleEndian = ('I' == data[0]);
     return true;
 }

 inline uint16_t get_endian_short(const uint8_t* data, bool littleEndian) {
     if (littleEndian) {
         return (data[1] << 8) | (data[0]);
     }

     return (data[0] << 8) | (data[1]);
 }

 inline SkPMColor premultiply_argb_as_rgba(U8CPU a, U8CPU r, U8CPU g, U8CPU b) {
     if (a != 255) {
         r = SkMulDiv255Round(r, a);
         g = SkMulDiv255Round(g, a);
         b = SkMulDiv255Round(b, a);
     }

     return SkPackARGB_as_RGBA(a, r, g, b);
 }

 inline SkPMColor premultiply_argb_as_bgra(U8CPU a, U8CPU r, U8CPU g, U8CPU b) {
     if (a != 255) {
         r = SkMulDiv255Round(r, a);
         g = SkMulDiv255Round(g, a);
         b = SkMulDiv255Round(b, a);
     }

     return SkPackARGB_as_BGRA(a, r, g, b);
 }

 inline bool is_rgba(SkColorType colorType) {
 #ifdef SK_PMCOLOR_IS_RGBA
     return (kBGRA_8888_SkColorType != colorType);
 #else
     return (kRGBA_8888_SkColorType == colorType);
 #endif
 }

 // Method for coverting to a 32 bit pixel.
 typedef uint32_t (*PackColorProc)(U8CPU a, U8CPU r, U8CPU g, U8CPU b);

 inline PackColorProc choose_pack_color_proc(bool isPremul, SkColorType colorType) {
     bool isRGBA = is_rgba(colorType);
     if (isPremul) {
         if (isRGBA) {
             return &premultiply_argb_as_rgba;
         } else {
             return &premultiply_argb_as_bgra;
         }
     } else {
         if (isRGBA) {
             return &SkPackARGB_as_RGBA;
         } else {
             return &SkPackARGB_as_BGRA;
         }
     }
 }

 #endif // SkCodecPriv_DEFINED
	/*
	* 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 "SkTypes.h"

	#ifdef SK_PRINT_CODEC_MESSAGES
	#define SkCodecPrintf SkDebugf
	#else
	#define SkCodecPrintf(...)
	#endif

	// 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) {
	if (kUnknown_SkAlphaType == dstAlpha) {
	return false;
	}

	if (srcAlpha != dstAlpha) {
	if (kOpaque_SkAlphaType == srcAlpha) {
	// If the source is opaque, we can support any.
	SkCodecPrintf("Warning: an opaque image should be decoded as opaque "
	"- it is being decoded as non-opaque, which will draw slower\n");
	return true;
	}

	// 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 to any alpha type
	* - 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) {
	// FIXME: skbug.com/4895
	// Currently, we ignore the SkColorProfileType on the SkImageInfo. We
	// will treat the encoded data as linear regardless of what the client
	// requests.

	// Ensure the alpha type is valid
	if (!valid_alpha(dst.alphaType(), src.alphaType())) {
	return false;
	}

	// Check for supported color types
	switch (dst.colorType()) {
	case kRGBA_8888_SkColorType:
	case kBGRA_8888_SkColorType:
	return true;
	case kRGB_565_SkColorType:
	return kOpaque_SkAlphaType == src.alphaType();
	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 kRGBA_8888_SkColorType:
	case kBGRA_8888_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
	}

	/*
	* @param data Buffer to read bytes from
	* @param isLittleEndian Output parameter
	* Indicates if the data is little endian
	* Is unaffected on false returns
	*/
	inline bool is_valid_endian_marker(const uint8_t* data, bool* isLittleEndian) {
	// II indicates Intel (little endian) and MM indicates motorola (big endian).
	if (('I' != data[0] \|\| 'I' != data[1]) && ('M' != data[0] \|\| 'M' != data[1])) {
	return false;
	}

	*isLittleEndian = ('I' == data[0]);
	return true;
	}

	inline uint16_t get_endian_short(const uint8_t* data, bool littleEndian) {
	if (littleEndian) {
	return (data[1] << 8) \| (data[0]);
	}

	return (data[0] << 8) \| (data[1]);
	}

	inline SkPMColor premultiply_argb_as_rgba(U8CPU a, U8CPU r, U8CPU g, U8CPU b) {
	if (a != 255) {
	r = SkMulDiv255Round(r, a);
	g = SkMulDiv255Round(g, a);
	b = SkMulDiv255Round(b, a);
	}

	return SkPackARGB_as_RGBA(a, r, g, b);
	}

	inline SkPMColor premultiply_argb_as_bgra(U8CPU a, U8CPU r, U8CPU g, U8CPU b) {
	if (a != 255) {
	r = SkMulDiv255Round(r, a);
	g = SkMulDiv255Round(g, a);
	b = SkMulDiv255Round(b, a);
	}

	return SkPackARGB_as_BGRA(a, r, g, b);
	}

	inline bool is_rgba(SkColorType colorType) {
	#ifdef SK_PMCOLOR_IS_RGBA
	return (kBGRA_8888_SkColorType != colorType);
	#else
	return (kRGBA_8888_SkColorType == colorType);
	#endif
	}

	// Method for coverting to a 32 bit pixel.
	typedef uint32_t (*PackColorProc)(U8CPU a, U8CPU r, U8CPU g, U8CPU b);

	inline PackColorProc choose_pack_color_proc(bool isPremul, SkColorType colorType) {
	bool isRGBA = is_rgba(colorType);
	if (isPremul) {
	if (isRGBA) {
	return &premultiply_argb_as_rgba;
	} else {
	return &premultiply_argb_as_bgra;
	}
	} else {
	if (isRGBA) {
	return &SkPackARGB_as_RGBA;
	} else {
	return &SkPackARGB_as_BGRA;
	}
	}
	}

	#endif // SkCodecPriv_DEFINED