etc1.h 3.8 KB

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