cc: Move files out of cc/resources/.

cc/resources/texture_compressor_etc1.cc

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// See the following specification for details on the ETC1 format:
-// https://www.khronos.org/registry/gles/extensions/OES/OES_compressed_ETC1_RGB8_texture.txt
-
-#include "cc/resources/texture_compressor_etc1.h"
-
-#include <string.h>
-#include <limits>
-
-#include "base/logging.h"
-
-// Defining the following macro will cause the error metric function to weigh
-// each color channel differently depending on how the human eye can perceive
-// them. This can give a slight improvement in image quality at the cost of a
-// performance hit.
-// #define USE_PERCEIVED_ERROR_METRIC
-
-namespace cc {
-
-namespace {
-
-// Constructs a color from a given base color and luminance value.
-inline Color MakeColor(const Color& base, int16_t lum) {
-  int b = static_cast<int>(base.channels.b) + lum;
-  int g = static_cast<int>(base.channels.g) + lum;
-  int r = static_cast<int>(base.channels.r) + lum;
-  Color color;
-  color.channels.b = static_cast<uint8_t>(clamp(b, 0, 255));
-  color.channels.g = static_cast<uint8_t>(clamp(g, 0, 255));
-  color.channels.r = static_cast<uint8_t>(clamp(r, 0, 255));
-  return color;
-}
-
-// Calculates the error metric for two colors. A small error signals that the
-// colors are similar to each other, a large error the signals the opposite.
-inline uint32_t GetColorError(const Color& u, const Color& v) {
-#ifdef USE_PERCEIVED_ERROR_METRIC
-  float delta_b = static_cast<float>(u.channels.b) - v.channels.b;
-  float delta_g = static_cast<float>(u.channels.g) - v.channels.g;
-  float delta_r = static_cast<float>(u.channels.r) - v.channels.r;
-  return static_cast<uint32_t>(0.299f * delta_b * delta_b +
-                               0.587f * delta_g * delta_g +
-                               0.114f * delta_r * delta_r);
-#else
-  int delta_b = static_cast<int>(u.channels.b) - v.channels.b;
-  int delta_g = static_cast<int>(u.channels.g) - v.channels.g;
-  int delta_r = static_cast<int>(u.channels.r) - v.channels.r;
-  return delta_b * delta_b + delta_g * delta_g + delta_r * delta_r;
-#endif
-}
-
-void GetAverageColor(const Color* src, float* avg_color) {
-  uint32_t sum_b = 0, sum_g = 0, sum_r = 0;
-
-  for (unsigned int i = 0; i < 8; ++i) {
-    sum_b += src[i].channels.b;
-    sum_g += src[i].channels.g;
-    sum_r += src[i].channels.r;
-  }
-
-  const float kInv8 = 1.0f / 8.0f;
-  avg_color[0] = static_cast<float>(sum_b) * kInv8;
-  avg_color[1] = static_cast<float>(sum_g) * kInv8;
-  avg_color[2] = static_cast<float>(sum_r) * kInv8;
-}
-
-void ComputeLuminance(uint8_t* block,
-                      const Color* src,
-                      const Color& base,
-                      int sub_block_id,
-                      const uint8_t* idx_to_num_tab) {
-  uint32_t best_tbl_err = std::numeric_limits<uint32_t>::max();
-  uint8_t best_tbl_idx = 0;
-  uint8_t best_mod_idx[8][8];  // [table][texel]
-
-  // Try all codeword tables to find the one giving the best results for this
-  // block.
-  for (unsigned int tbl_idx = 0; tbl_idx < 8; ++tbl_idx) {
-    // Pre-compute all the candidate colors; combinations of the base color and
-    // all available luminance values.
-    Color candidate_color[4];  // [modifier]
-    for (unsigned int mod_idx = 0; mod_idx < 4; ++mod_idx) {
-      int16_t lum = g_codeword_tables[tbl_idx][mod_idx];
-      candidate_color[mod_idx] = MakeColor(base, lum);
-    }
-
-    uint32_t tbl_err = 0;
-
-    for (unsigned int i = 0; i < 8; ++i) {
-      // Try all modifiers in the current table to find which one gives the
-      // smallest error.
-      uint32_t best_mod_err = std::numeric_limits<uint32_t>::max();
-      for (unsigned int mod_idx = 0; mod_idx < 4; ++mod_idx) {
-        const Color& color = candidate_color[mod_idx];
-
-        uint32_t mod_err = GetColorError(src[i], color);
-        if (mod_err < best_mod_err) {
-          best_mod_idx[tbl_idx][i] = mod_idx;
-          best_mod_err = mod_err;
-
-          if (mod_err == 0)
-            break;  // We cannot do any better than this.
-        }
-      }
-
-      tbl_err += best_mod_err;
-      if (tbl_err > best_tbl_err)
-        break;  // We're already doing worse than the best table so skip.
-    }
-
-    if (tbl_err < best_tbl_err) {
-      best_tbl_err = tbl_err;
-      best_tbl_idx = tbl_idx;
-
-      if (tbl_err == 0)
-        break;  // We cannot do any better than this.
-    }
-  }
-
-  WriteCodewordTable(block, sub_block_id, best_tbl_idx);
-
-  uint32_t pix_data = 0;
-
-  for (unsigned int i = 0; i < 8; ++i) {
-    uint8_t mod_idx = best_mod_idx[best_tbl_idx][i];
-    uint8_t pix_idx = g_mod_to_pix[mod_idx];
-
-    uint32_t lsb = pix_idx & 0x1;
-    uint32_t msb = pix_idx >> 1;
-
-    // Obtain the texel number as specified in the standard.
-    int texel_num = idx_to_num_tab[i];
-    pix_data |= msb << (texel_num + 16);
-    pix_data |= lsb << (texel_num);
-  }
-
-  WritePixelData(block, pix_data);
-}
-
-/**
- * Tries to compress the block under the assumption that it's a single color
- * block. If it's not the function will bail out without writing anything to
- * the destination buffer.
- */
-bool TryCompressSolidBlock(uint8_t* dst, const Color* src) {
-  for (unsigned int i = 1; i < 16; ++i) {
-    if (src[i].bits != src[0].bits)
-      return false;
-  }
-
-  // Clear destination buffer so that we can "or" in the results.
-  memset(dst, 0, 8);
-
-  float src_color_float[3] = {static_cast<float>(src->channels.b),
-                              static_cast<float>(src->channels.g),
-                              static_cast<float>(src->channels.r)};
-  Color base = MakeColor555(src_color_float);
-
-  WriteDiff(dst, true);
-  WriteFlip(dst, false);
-  WriteColors555(dst, base, base);
-
-  uint8_t best_tbl_idx = 0;
-  uint8_t best_mod_idx = 0;
-  uint32_t best_mod_err = std::numeric_limits<uint32_t>::max();
-
-  // Try all codeword tables to find the one giving the best results for this
-  // block.
-  for (unsigned int tbl_idx = 0; tbl_idx < 8; ++tbl_idx) {
-    // Try all modifiers in the current table to find which one gives the
-    // smallest error.
-    for (unsigned int mod_idx = 0; mod_idx < 4; ++mod_idx) {
-      int16_t lum = g_codeword_tables[tbl_idx][mod_idx];
-      const Color& color = MakeColor(base, lum);
-
-      uint32_t mod_err = GetColorError(*src, color);
-      if (mod_err < best_mod_err) {
-        best_tbl_idx = tbl_idx;
-        best_mod_idx = mod_idx;
-        best_mod_err = mod_err;
-
-        if (mod_err == 0)
-          break;  // We cannot do any better than this.
-      }
-    }
-
-    if (best_mod_err == 0)
-      break;
-  }
-
-  WriteCodewordTable(dst, 0, best_tbl_idx);
-  WriteCodewordTable(dst, 1, best_tbl_idx);
-
-  uint8_t pix_idx = g_mod_to_pix[best_mod_idx];
-  uint32_t lsb = pix_idx & 0x1;
-  uint32_t msb = pix_idx >> 1;
-
-  uint32_t pix_data = 0;
-  for (unsigned int i = 0; i < 2; ++i) {
-    for (unsigned int j = 0; j < 8; ++j) {
-      // Obtain the texel number as specified in the standard.
-      int texel_num = g_idx_to_num[i][j];
-      pix_data |= msb << (texel_num + 16);
-      pix_data |= lsb << (texel_num);
-    }
-  }
-
-  WritePixelData(dst, pix_data);
-  return true;
-}
-
-void CompressBlock(uint8_t* dst, const Color* ver_src, const Color* hor_src) {
-  if (TryCompressSolidBlock(dst, ver_src))
-    return;
-
-  const Color* sub_block_src[4] = {ver_src, ver_src + 8, hor_src, hor_src + 8};
-
-  Color sub_block_avg[4];
-  bool use_differential[2] = {true, true};
-
-  // Compute the average color for each sub block and determine if differential
-  // coding can be used.
-  for (unsigned int i = 0, j = 1; i < 4; i += 2, j += 2) {
-    float avg_color_0[3];
-    GetAverageColor(sub_block_src[i], avg_color_0);
-    Color avg_color_555_0 = MakeColor555(avg_color_0);
-
-    float avg_color_1[3];
-    GetAverageColor(sub_block_src[j], avg_color_1);
-    Color avg_color_555_1 = MakeColor555(avg_color_1);
-
-    for (unsigned int light_idx = 0; light_idx < 3; ++light_idx) {
-      int u = avg_color_555_0.components[light_idx] >> 3;
-      int v = avg_color_555_1.components[light_idx] >> 3;
-
-      int component_diff = v - u;
-      if (component_diff < -4 || component_diff > 3) {
-        use_differential[i / 2] = false;
-        sub_block_avg[i] = MakeColor444(avg_color_0);
-        sub_block_avg[j] = MakeColor444(avg_color_1);
-      } else {
-        sub_block_avg[i] = avg_color_555_0;
-        sub_block_avg[j] = avg_color_555_1;
-      }
-    }
-  }
-
-  // Compute the error of each sub block before adjusting for luminance. These
-  // error values are later used for determining if we should flip the sub
-  // block or not.
-  uint32_t sub_block_err[4] = {0};
-  for (unsigned int i = 0; i < 4; ++i) {
-    for (unsigned int j = 0; j < 8; ++j) {
-      sub_block_err[i] += GetColorError(sub_block_avg[i], sub_block_src[i][j]);
-    }
-  }
-
-  bool flip =
-      sub_block_err[2] + sub_block_err[3] < sub_block_err[0] + sub_block_err[1];
-
-  // Clear destination buffer so that we can "or" in the results.
-  memset(dst, 0, 8);
-
-  WriteDiff(dst, use_differential[!!flip]);
-  WriteFlip(dst, flip);
-
-  uint8_t sub_block_off_0 = flip ? 2 : 0;
-  uint8_t sub_block_off_1 = sub_block_off_0 + 1;
-
-  if (use_differential[!!flip]) {
-    WriteColors555(dst, sub_block_avg[sub_block_off_0],
-                   sub_block_avg[sub_block_off_1]);
-  } else {
-    WriteColors444(dst, sub_block_avg[sub_block_off_0],
-                   sub_block_avg[sub_block_off_1]);
-  }
-
-  // Compute luminance for the first sub block.
-  ComputeLuminance(dst, sub_block_src[sub_block_off_0],
-                   sub_block_avg[sub_block_off_0], 0,
-                   g_idx_to_num[sub_block_off_0]);
-  // Compute luminance for the second sub block.
-  ComputeLuminance(dst, sub_block_src[sub_block_off_1],
-                   sub_block_avg[sub_block_off_1], 1,
-                   g_idx_to_num[sub_block_off_1]);
-}
-
-}  // namespace
-
-void TextureCompressorETC1::Compress(const uint8_t* src,
-                                     uint8_t* dst,
-                                     int width,
-                                     int height,
-                                     Quality quality) {
-  DCHECK_GE(width, 4);
-  DCHECK_EQ((width & 3), 0);
-  DCHECK_GE(height, 4);
-  DCHECK_EQ((height & 3), 0);
-
-  Color ver_blocks[16];
-  Color hor_blocks[16];
-
-  for (int y = 0; y < height; y += 4, src += width * 4 * 4) {
-    for (int x = 0; x < width; x += 4, dst += 8) {
-      const Color* row0 = reinterpret_cast<const Color*>(src + x * 4);
-      const Color* row1 = row0 + width;
-      const Color* row2 = row1 + width;
-      const Color* row3 = row2 + width;
-
-      memcpy(ver_blocks, row0, 8);
-      memcpy(ver_blocks + 2, row1, 8);
-      memcpy(ver_blocks + 4, row2, 8);
-      memcpy(ver_blocks + 6, row3, 8);
-      memcpy(ver_blocks + 8, row0 + 2, 8);
-      memcpy(ver_blocks + 10, row1 + 2, 8);
-      memcpy(ver_blocks + 12, row2 + 2, 8);
-      memcpy(ver_blocks + 14, row3 + 2, 8);
-
-      memcpy(hor_blocks, row0, 16);
-      memcpy(hor_blocks + 4, row1, 16);
-      memcpy(hor_blocks + 8, row2, 16);
-      memcpy(hor_blocks + 12, row3, 16);
-
-      CompressBlock(dst, ver_blocks, hor_blocks);
-    }
-  }
-}
-
-}  // namespace cc