1// Copyright 2009 Google Inc. 2// 3// Licensed under the Apache License, Version 2.0 (the "License"); 4// you may not use this file except in compliance with the License. 5// You may obtain a copy of the License at 6// 7// http://www.apache.org/licenses/LICENSE-2.0 8// 9// Unless required by applicable law or agreed to in writing, software 10// distributed under the License is distributed on an "AS IS" BASIS, 11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12// See the License for the specific language governing permissions and 13// limitations under the License. 14 15////////////////////////////////////////////////////////////////////////////////////////// 16 17// This is a fork of the AOSP project ETC1 codec. The original code can be found 18// at the following web site: 19// https://android.googlesource.com/platform/frameworks/native/+/master/opengl/libs/ETC1/ 20 21////////////////////////////////////////////////////////////////////////////////////////// 22 23#ifndef __etc1_h__ 24#define __etc1_h__ 25 26#define ETC1_ENCODED_BLOCK_SIZE 8 27#define ETC1_DECODED_BLOCK_SIZE 48 28 29#ifndef ETC1_RGB8_OES 30#define ETC1_RGB8_OES 0x8D64 31#endif 32 33typedef unsigned char etc1_byte; 34typedef int etc1_bool; 35typedef unsigned int etc1_uint32; 36 37#ifdef __cplusplus 38extern "C" { 39#endif 40 41// Encode a block of pixels. 42// 43// pIn is a pointer to a ETC_DECODED_BLOCK_SIZE array of bytes that represent a 44// 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R 45// value of pixel (x, y). 46// 47// validPixelMask is a 16-bit mask where bit (1 << (x + y * 4)) indicates whether 48// the corresponding (x,y) pixel is valid. Invalid pixel color values are ignored when compressing. 49// 50// pOut is an ETC1 compressed version of the data. 51 52void etc1_encode_block(const etc1_byte* pIn, etc1_uint32 validPixelMask, etc1_byte* pOut); 53 54// Decode a block of pixels. 55// 56// pIn is an ETC1 compressed version of the data. 57// 58// pOut is a pointer to a ETC_DECODED_BLOCK_SIZE array of bytes that represent a 59// 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R 60// value of pixel (x, y). 61 62void etc1_decode_block(const etc1_byte* pIn, etc1_byte* pOut); 63 64// Return the size of the encoded image data (does not include size of PKM header). 65 66etc1_uint32 etc1_get_encoded_data_size(etc1_uint32 width, etc1_uint32 height); 67 68// Encode an entire image. 69// pIn - pointer to the image data. Formatted such that 70// pixel (x,y) is at pIn + pixelSize * x + stride * y; 71// pOut - pointer to encoded data. Must be large enough to store entire encoded image. 72// pixelSize can be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image, 3 is a GL_BYTE RGB image. 73// returns non-zero if there is an error. 74 75int etc1_encode_image(const etc1_byte* pIn, etc1_uint32 width, etc1_uint32 height, 76 etc1_uint32 pixelSize, etc1_uint32 stride, etc1_byte* pOut); 77 78// Decode an entire image. 79// pIn - pointer to encoded data. 80// pOut - pointer to the image data. Will be written such that 81// pixel (x,y) is at pIn + pixelSize * x + stride * y. Must be 82// large enough to store entire image. 83// pixelSize can be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image, 3 is a GL_BYTE RGB image. 84// returns non-zero if there is an error. 85 86int etc1_decode_image(const etc1_byte* pIn, etc1_byte* pOut, 87 etc1_uint32 width, etc1_uint32 height, 88 etc1_uint32 pixelSize, etc1_uint32 stride); 89 90// Size of a PKM header, in bytes. 91 92#define ETC_PKM_HEADER_SIZE 16 93 94// Format a PKM header 95 96void etc1_pkm_format_header(etc1_byte* pHeader, etc1_uint32 width, etc1_uint32 height); 97 98// Check if a PKM header is correctly formatted. 99 100etc1_bool etc1_pkm_is_valid(const etc1_byte* pHeader); 101 102// Read the image width from a PKM header 103 104etc1_uint32 etc1_pkm_get_width(const etc1_byte* pHeader); 105 106// Read the image height from a PKM header 107 108etc1_uint32 etc1_pkm_get_height(const etc1_byte* pHeader); 109 110#ifdef __cplusplus 111} 112#endif 113 114#endif 115