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 MAX_ETC_SUPPORTED 1 19 20 #define ETC1_ENCODED_BLOCK_SIZE 8 21 #define ETC1_DECODED_BLOCK_SIZE 48 22 23 #ifndef ETC1_RGB8_OES 24 #define ETC1_RGB8_OES 0x8D64 25 #endif 26 27 typedef unsigned char etc1_byte; 28 typedef int etc1_bool; 29 typedef unsigned int etc1_uint32; 30 31 #ifdef __cplusplus 32 extern "C" { 33 #endif 34 35 // Encode a block of pixels. 36 // 37 // pIn is a pointer to a ETC_DECODED_BLOCK_SIZE array of bytes that represent a 38 // 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R 39 // value of pixel (x, y). 40 // 41 // validPixelMask is a 16-bit mask where bit (1 << (x + y * 4)) indicates whether 42 // the corresponding (x,y) pixel is valid. Invalid pixel color values are ignored when compressing. 43 // 44 // pOut is an ETC1 compressed version of the data. 45 46 void etc1_encode_block(const etc1_byte* pIn, etc1_uint32 validPixelMask, etc1_byte* pOut); 47 48 // Decode a block of pixels. 49 // 50 // pIn is an ETC1 compressed version of the data. 51 // 52 // pOut is a pointer to a ETC_DECODED_BLOCK_SIZE array of bytes that represent a 53 // 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R 54 // value of pixel (x, y). 55 56 void etc1_decode_block(const etc1_byte* pIn, etc1_byte* pOut); 57 58 // Return the size of the encoded image data (does not include size of PKM header). 59 60 etc1_uint32 etc1_get_encoded_data_size(etc1_uint32 width, etc1_uint32 height); 61 62 // Encode an entire image. 63 // pIn - pointer to the image data. Formatted such that 64 // pixel (x,y) is at pIn + pixelSize * x + stride * y; 65 // pOut - pointer to encoded data. Must be large enough to store entire encoded image. 66 // pixelSize can be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image, 3 is a GL_BYTE RGB image. 67 // returns non-zero if there is an error. 68 69 int etc1_encode_image(const etc1_byte* pIn, etc1_uint32 width, etc1_uint32 height, 70 etc1_uint32 pixelSize, etc1_uint32 stride, etc1_byte* pOut); 71 72 // Decode an entire image. 73 // pIn - pointer to encoded data. 74 // pOut - pointer to the image data. Will be written such that 75 // pixel (x,y) is at pIn + pixelSize * x + stride * y. Must be 76 // large enough to store entire image. 77 // pixelSize can be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image, 3 is a GL_BYTE RGB image. 78 // returns non-zero if there is an error. 79 80 int etc1_decode_image(const etc1_byte* pIn, etc1_byte* pOut, 81 etc1_uint32 width, etc1_uint32 height, 82 etc1_uint32 pixelSize, etc1_uint32 stride); 83 84 // Size of a PKM header, in bytes. 85 86 #define ETC_PKM_HEADER_SIZE 16 87 88 // Format a PKM header 89 90 void etc1_pkm_format_header(etc1_byte* pHeader, etc1_uint32 width, etc1_uint32 height); 91 92 // Check if a PKM header is correctly formatted. 93 94 etc1_bool etc1_pkm_is_valid(const etc1_byte* pHeader); 95 96 // Read the image width from a PKM header 97 98 etc1_uint32 etc1_pkm_get_width(const etc1_byte* pHeader); 99 100 // Read the image height from a PKM header 101 102 etc1_uint32 etc1_pkm_get_height(const etc1_byte* pHeader); 103 104 #ifdef __cplusplus 105 } 106 #endif 107 108 #endif 109