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 25 typedef unsigned char etc1_byte; 26 typedef int etc1_bool; 27 typedef unsigned int etc1_uint32; 28 29 #ifdef __cplusplus 30 extern "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 44 void 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 54 void 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 58 etc1_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 67 int 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 78 int 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 88 void etc1_pkm_format_header(etc1_byte* pHeader, etc1_uint32 width, etc1_uint32 height); 89 90 // Check if a PKM header is correctly formatted. 91 92 etc1_bool etc1_pkm_is_valid(const etc1_byte* pHeader); 93 94 // Read the image width from a PKM header 95 96 etc1_uint32 etc1_pkm_get_width(const etc1_byte* pHeader); 97 98 // Read the image height from a PKM header 99 100 etc1_uint32 etc1_pkm_get_height(const etc1_byte* pHeader); 101 102 #ifdef __cplusplus 103 } 104 #endif 105 106 #endif 107