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| 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/l
ibs/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 whethe
r |
| 48 // the corresponding (x,y) pixel is valid. Invalid pixel color values are ignore
d 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_by
te* 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 heade
r). |
| 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_BYT
E 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 heigh
t, |
| 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_BYT
E 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 h
eight); |
| 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 |
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