ui/gfx/buffer_format_util.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.

#include "ui/gfx/buffer_format_util.h"

#include "base/logging.h"
#include "base/numerics/safe_math.h"

namespace gfx {

size_t NumberOfPlanesForBufferFormat(BufferFormat format) {
  switch (format) {
    case BufferFormat::ATC:
    case BufferFormat::ATCIA:
    case BufferFormat::DXT1:
    case BufferFormat::DXT5:
    case BufferFormat::ETC1:
    case BufferFormat::R_8:
    case BufferFormat::RGBA_4444:
    case BufferFormat::RGBA_8888:
    case BufferFormat::BGRX_8888:
    case BufferFormat::BGRA_8888:
    case BufferFormat::UYVY_422:
      return 1;
    case BufferFormat::YUV_420:
      return 3;
  }
  NOTREACHED();
  return 0;
}

size_t SubsamplingFactorForBufferFormat(BufferFormat format, int plane) {
  switch (format) {
    case BufferFormat::ATC:
    case BufferFormat::ATCIA:
    case BufferFormat::DXT1:
    case BufferFormat::DXT5:
    case BufferFormat::ETC1:
    case BufferFormat::R_8:
    case BufferFormat::RGBA_4444:
    case BufferFormat::RGBA_8888:
    case BufferFormat::BGRX_8888:
    case BufferFormat::BGRA_8888:
    case BufferFormat::UYVY_422:
      return 1;
    case BufferFormat::YUV_420: {
      static size_t factor[] = {1, 2, 2};
      DCHECK_LT(static_cast<size_t>(plane), arraysize(factor));
      return factor[plane];
    }
  }
  NOTREACHED();
  return 0;
}

size_t RowSizeForBufferFormat(size_t width, BufferFormat format, int plane) {
  size_t row_size = 0;
  bool valid = RowSizeForBufferFormatChecked(width, format, plane, &row_size);
  DCHECK(valid);
  return row_size;
}

bool RowSizeForBufferFormatChecked(
    size_t width, BufferFormat format, int plane, size_t* size_in_bytes) {
  base::CheckedNumeric<size_t> checked_size = width;
  switch (format) {
    case BufferFormat::ATCIA:
    case BufferFormat::DXT5:
      DCHECK_EQ(0, plane);
      *size_in_bytes = width;
      return true;
    case BufferFormat::ATC:
    case BufferFormat::DXT1:
    case BufferFormat::ETC1:
      DCHECK_EQ(0, plane);
      DCHECK_EQ(0u, width % 2);
      *size_in_bytes = width / 2;
      return true;
    case BufferFormat::R_8:
      checked_size += 3;
      if (!checked_size.IsValid())
        return false;
      *size_in_bytes = checked_size.ValueOrDie() & ~0x3;
      return true;
    case BufferFormat::RGBA_4444:
    case BufferFormat::UYVY_422:
      checked_size *= 2;
      if (!checked_size.IsValid())
        return false;
      *size_in_bytes = checked_size.ValueOrDie();
      return true;
    case BufferFormat::BGRX_8888:
    case BufferFormat::RGBA_8888:
    case BufferFormat::BGRA_8888:
      checked_size *= 4;
      if (!checked_size.IsValid())
        return false;
      *size_in_bytes = checked_size.ValueOrDie();
      return true;
    case BufferFormat::YUV_420:
      DCHECK_EQ(0u, width % 2);
      *size_in_bytes = width / SubsamplingFactorForBufferFormat(format, plane);
      return true;
  }
  NOTREACHED();
  return false;
}

size_t BufferSizeForBufferFormat(
    const Size& size, BufferFormat format) {
  size_t buffer_size = 0;
  bool valid = BufferSizeForBufferFormatChecked(size, format, &buffer_size);
  DCHECK(valid);
  return buffer_size;
}

bool BufferSizeForBufferFormatChecked(
    const Size& size, BufferFormat format, size_t* size_in_bytes) {
  base::CheckedNumeric<size_t> checked_size = 0;
  size_t num_planes = NumberOfPlanesForBufferFormat(format);
  for (size_t i = 0; i < num_planes; ++i) {
    size_t row_size = 0;
    if (!RowSizeForBufferFormatChecked(size.width(), format, i, &row_size))
      return false;
    base::CheckedNumeric<size_t> checked_plane_size = row_size;
    checked_plane_size *= size.height() /
                          SubsamplingFactorForBufferFormat(format, i);
    if (!checked_plane_size.IsValid())
      return false;
    checked_size += checked_plane_size.ValueOrDie();
    if (!checked_size.IsValid())
      return false;
  }
  *size_in_bytes = checked_size.ValueOrDie();
  return true;
}

}  // namespace gfx