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// Copyright 2009 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#pragma once
#define MAX_ETC_SUPPORTED 12
#define ETC1_ENCODED_BLOCK_SIZE 8
#define ETC1_DECODED_BLOCK_SIZE 48
#define ETC2_DECODED_RGB8A1_BLOCK_SIZE 64
#define EAC_ENCODE_ALPHA_BLOCK_SIZE 8
#define EAC_DECODED_ALPHA_BLOCK_SIZE 16
#define EAC_ENCODE_R11_BLOCK_SIZE 8
#define EAC_DECODED_R11_BLOCK_SIZE 64
#define EAC_DECODED_RG11_BLOCK_SIZE (EAC_DECODED_R11_BLOCK_SIZE*2)
#ifndef ETC1_RGB8_OES
#define ETC1_RGB8_OES 0x8D64
#endif
typedef unsigned char etc1_byte;
typedef int etc1_bool;
typedef unsigned int etc1_uint32;
enum ETC2ImageFormat {
EtcRGB8, EtcRGBA8, EtcR11, EtcSignedR11, EtcRG11, EtcSignedRG11, EtcRGB8A1
};
#ifdef __cplusplus
extern "C" {
#endif
// Encode a block of pixels.
//
// pIn is a pointer to a ETC_DECODED_BLOCK_SIZE array of bytes that represent a
// 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R
// value of pixel (x, y).
//
// validPixelMask is a 16-bit mask where bit (1 << (x + y * 4)) indicates whether
// the corresponding (x,y) pixel is valid. Invalid pixel color values are ignored when compressing.
//
// pOut is an ETC1 compressed version of the data.
void etc1_encode_block(const etc1_byte* pIn, etc1_uint32 validPixelMask, etc1_byte* pOut);
// Decode a block of rgb pixels.
//
// pIn is an ETC2 compressed version of the data.
//
// pOut is a pointer to a ETC_DECODED_BLOCK_SIZE array of bytes that represent a
// 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R
// value of pixel (x, y).
void etc2_decode_rgb_block(const etc1_byte* pIn, bool isPunchthroughAlpha, etc1_byte* pOut);
// Decode a block of single channel pixels
// This is used when decoding the alpha channel of RGBA8_ETC2_EAC format, or
// when decoding R11_EAC format
// decodedElementBytes: number of bits per element after decoding.
// For RGBA8_ETC2_EAC it must be 1, for R11_EAC it must be 2
void eac_decode_single_channel_block(const etc1_byte* pIn,
int decodedElementBytes, bool isSigned,
etc1_byte* pOut);
// Return the size of the encoded image data (does not include size of PKM header).
etc1_uint32 etc1_get_encoded_data_size(etc1_uint32 width, etc1_uint32 height);
etc1_uint32 etc_get_encoded_data_size(ETC2ImageFormat format, etc1_uint32 width,
etc1_uint32 height);
etc1_uint32 etc_get_decoded_pixel_size(ETC2ImageFormat format);
// Encode an entire image.
// pIn - pointer to the image data. Formatted such that
// pixel (x,y) is at pIn + pixelSize * x + stride * y;
// pOut - pointer to encoded data. Must be large enough to store entire encoded image.
// pixelSize can be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image, 3 is a GL_BYTE RGB image.
// returns non-zero if there is an error.
int etc1_encode_image(const etc1_byte* pIn, etc1_uint32 width, etc1_uint32 height,
etc1_uint32 pixelSize, etc1_uint32 stride, etc1_byte* pOut);
// Decode an entire image.
// pIn - pointer to encoded data.
// pOut - pointer to the image data. Will be written such that
// pixel (x,y) is at pIn + pixelSize * x + stride * y. Must be
// large enough to store entire image.
// (pixelSize=3 for rgb images, pixelSize=4 for images with alpha channel)
// returns non-zero if there is an error.
int etc2_decode_image(const etc1_byte* pIn, ETC2ImageFormat format,
etc1_byte* pOut,
etc1_uint32 width, etc1_uint32 height,
etc1_uint32 stride);
// Size of a PKM header, in bytes.
#define ETC_PKM_HEADER_SIZE 16
// Format a PKM header
void etc1_pkm_format_header(etc1_byte* pHeader, etc1_uint32 width, etc1_uint32 height);
// Check if a PKM header is correctly formatted.
etc1_bool etc1_pkm_is_valid(const etc1_byte* pHeader);
// Read the image width from a PKM header
etc1_uint32 etc1_pkm_get_width(const etc1_byte* pHeader);
// Read the image height from a PKM header
etc1_uint32 etc1_pkm_get_height(const etc1_byte* pHeader);
#ifdef __cplusplus
}
#endif