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#ifndef __etc1_h__ 16#define __etc1_h__ 17 18#define ETC1_ENCODED_BLOCK_SIZE 8 19#define ETC1_DECODED_BLOCK_SIZE 48 20 21#ifndef ETC1_RGB8_OES 22#define ETC1_RGB8_OES 0x8D64 23#endif 24 25typedef unsigned char etc1_byte; 26typedef int etc1_bool; 27typedef unsigned int etc1_uint32; 28 29#ifdef __cplusplus 30extern "C" { 31#endif 32 33// Encode a block of pixels. 34// 35// pIn is a pointer to a ETC_DECODED_BLOCK_SIZE array of bytes that represent a 36// 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R 37// value of pixel (x, y). 38// 39// validPixelMask is a 16-bit mask where bit (1 << (x + y * 4)) indicates whether 40// the corresponding (x,y) pixel is valid. Invalid pixel color values are ignored when compressing. 41// 42// pOut is an ETC1 compressed version of the data. 43 44void etc1_encode_block(const etc1_byte* pIn, etc1_uint32 validPixelMask, etc1_byte* pOut); 45 46// Decode a block of pixels. 47// 48// pIn is an ETC1 compressed version of the data. 49// 50// pOut is a pointer to a ETC_DECODED_BLOCK_SIZE array of bytes that represent a 51// 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R 52// value of pixel (x, y). 53 54void etc1_decode_block(const etc1_byte* pIn, etc1_byte* pOut); 55 56// Return the size of the encoded image data (does not include size of PKM header). 57 58etc1_uint32 etc1_get_encoded_data_size(etc1_uint32 width, etc1_uint32 height); 59 60// Encode an entire image. 61// pIn - pointer to the image data. Formatted such that 62// pixel (x,y) is at pIn + pixelSize * x + stride * y; 63// pOut - pointer to encoded data. Must be large enough to store entire encoded image. 64// pixelSize can be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image, 3 is a GL_BYTE RGB image. 65// returns non-zero if there is an error. 66 67int etc1_encode_image(const etc1_byte* pIn, etc1_uint32 width, etc1_uint32 height, 68 etc1_uint32 pixelSize, etc1_uint32 stride, etc1_byte* pOut); 69 70// Decode an entire image. 71// pIn - pointer to encoded data. 72// pOut - pointer to the image data. Will be written such that 73// pixel (x,y) is at pIn + pixelSize * x + stride * y. Must be 74// large enough to store entire image. 75// pixelSize can be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image, 3 is a GL_BYTE RGB image. 76// returns non-zero if there is an error. 77 78int etc1_decode_image(const etc1_byte* pIn, etc1_byte* pOut, 79 etc1_uint32 width, etc1_uint32 height, 80 etc1_uint32 pixelSize, etc1_uint32 stride); 81 82// Size of a PKM header, in bytes. 83 84#define ETC_PKM_HEADER_SIZE 16 85 86// Format a PKM header 87 88void etc1_pkm_format_header(etc1_byte* pHeader, etc1_uint32 width, etc1_uint32 height); 89 90// Check if a PKM header is correctly formatted. 91 92etc1_bool etc1_pkm_is_valid(const etc1_byte* pHeader); 93 94// Read the image width from a PKM header 95 96etc1_uint32 etc1_pkm_get_width(const etc1_byte* pHeader); 97 98// Read the image height from a PKM header 99 100etc1_uint32 etc1_pkm_get_height(const etc1_byte* pHeader); 101 102#ifdef __cplusplus 103} 104#endif 105 106#endif 107