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 33 typedef unsigned char etc1_byte; 34 typedef int etc1_bool; 35 typedef unsigned int etc1_uint32; 36 37 #ifdef __cplusplus 38 extern "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 52 void 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 62 void 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 66 etc1_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 75 int 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 86 int 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 96 void etc1_pkm_format_header(etc1_byte* pHeader, etc1_uint32 width, etc1_uint32 height); 97 98 // Check if a PKM header is correctly formatted. 99 100 etc1_bool etc1_pkm_is_valid(const etc1_byte* pHeader); 101 102 // Read the image width from a PKM header 103 104 etc1_uint32 etc1_pkm_get_width(const etc1_byte* pHeader); 105 106 // Read the image height from a PKM header 107 108 etc1_uint32 etc1_pkm_get_height(const etc1_byte* pHeader); 109 110 #ifdef __cplusplus 111 } 112 #endif 113 114 #endif 115