// Copyright (c) 2016 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 "gpu/command_buffer/service/gl_utils.h"

#include <unordered_set>

#include "base/metrics/histogram.h"
#include "gpu/command_buffer/common/capabilities.h"
#include "gpu/command_buffer/service/error_state.h"
#include "gpu/command_buffer/service/feature_info.h"
#include "gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.h"
#include "gpu/command_buffer/service/logger.h"
#include "gpu/command_buffer/service/texture_manager.h"
#include "ui/gl/gl_version_info.h"

namespace gpu {
namespace gles2 {

namespace {

const int kASTCBlockSize = 16;
const int kS3TCBlockWidth = 4;
const int kS3TCBlockHeight = 4;
const int kS3TCDXT1BlockSize = 8;
const int kS3TCDXT3AndDXT5BlockSize = 16;
const int kEACAndETC2BlockSize = 4;

typedef struct {
  int blockWidth;
  int blockHeight;
} ASTCBlockArray;

const ASTCBlockArray kASTCBlockArray[] = {
    {4, 4}, /* GL_COMPRESSED_RGBA_ASTC_4x4_KHR */
    {5, 4}, /* and GL_COMPRESSED_SRGB8_ALPHA8_ASTC_4x4_KHR */
    {5, 5},  {6, 5},  {6, 6},  {8, 5},   {8, 6},   {8, 8},
    {10, 5}, {10, 6}, {10, 8}, {10, 10}, {12, 10}, {12, 12}};

const char* GetDebugSourceString(GLenum source) {
  switch (source) {
    case GL_DEBUG_SOURCE_API:
      return "OpenGL";
    case GL_DEBUG_SOURCE_WINDOW_SYSTEM:
      return "Window System";
    case GL_DEBUG_SOURCE_SHADER_COMPILER:
      return "Shader Compiler";
    case GL_DEBUG_SOURCE_THIRD_PARTY:
      return "Third Party";
    case GL_DEBUG_SOURCE_APPLICATION:
      return "Application";
    case GL_DEBUG_SOURCE_OTHER:
      return "Other";
    default:
      return "UNKNOWN";
  }
}

const char* GetDebugTypeString(GLenum type) {
  switch (type) {
    case GL_DEBUG_TYPE_ERROR:
      return "Error";
    case GL_DEBUG_TYPE_DEPRECATED_BEHAVIOR:
      return "Deprecated behavior";
    case GL_DEBUG_TYPE_UNDEFINED_BEHAVIOR:
      return "Undefined behavior";
    case GL_DEBUG_TYPE_PORTABILITY:
      return "Portability";
    case GL_DEBUG_TYPE_PERFORMANCE:
      return "Performance";
    case GL_DEBUG_TYPE_OTHER:
      return "Other";
    case GL_DEBUG_TYPE_MARKER:
      return "Marker";
    default:
      return "UNKNOWN";
  }
}

const char* GetDebugSeverityString(GLenum severity) {
  switch (severity) {
    case GL_DEBUG_SEVERITY_HIGH:
      return "High";
    case GL_DEBUG_SEVERITY_MEDIUM:
      return "Medium";
    case GL_DEBUG_SEVERITY_LOW:
      return "Low";
    case GL_DEBUG_SEVERITY_NOTIFICATION:
      return "Notification";
    default:
      return "UNKNOWN";
  }
}
}  // namespace

std::vector<int> GetAllGLErrors() {
  int gl_errors[] = {
      GL_NO_ERROR,
      GL_INVALID_ENUM,
      GL_INVALID_VALUE,
      GL_INVALID_OPERATION,
      GL_INVALID_FRAMEBUFFER_OPERATION,
      GL_OUT_OF_MEMORY,
  };
  return base::CustomHistogram::ArrayToCustomEnumRanges(gl_errors);
}

bool PrecisionMeetsSpecForHighpFloat(GLint rangeMin,
                                     GLint rangeMax,
                                     GLint precision) {
  return (rangeMin >= 62) && (rangeMax >= 62) && (precision >= 16);
}

void QueryShaderPrecisionFormat(const gl::GLVersionInfo& gl_version_info,
                                GLenum shader_type,
                                GLenum precision_type,
                                GLint* range,
                                GLint* precision) {
  switch (precision_type) {
    case GL_LOW_INT:
    case GL_MEDIUM_INT:
    case GL_HIGH_INT:
      // These values are for a 32-bit twos-complement integer format.
      range[0] = 31;
      range[1] = 30;
      *precision = 0;
      break;
    case GL_LOW_FLOAT:
    case GL_MEDIUM_FLOAT:
    case GL_HIGH_FLOAT:
      // These values are for an IEEE single-precision floating-point format.
      range[0] = 127;
      range[1] = 127;
      *precision = 23;
      break;
    default:
      NOTREACHED();
      break;
  }

  if (gl_version_info.is_es) {
    // This function is sometimes defined even though it's really just
    // a stub, so we need to set range and precision as if it weren't
    // defined before calling it.
    // On Mac OS with some GPUs, calling this generates a
    // GL_INVALID_OPERATION error. Avoid calling it on non-GLES2
    // platforms.
    glGetShaderPrecisionFormat(shader_type, precision_type, range, precision);

    // TODO(brianderson): Make the following official workarounds.

    // Some drivers have bugs where they report the ranges as a negative number.
    // Taking the absolute value here shouldn't hurt because negative numbers
    // aren't expected anyway.
    range[0] = abs(range[0]);
    range[1] = abs(range[1]);

    // If the driver reports a precision for highp float that isn't actually
    // highp, don't pretend like it's supported because shader compilation will
    // fail anyway.
    if (precision_type == GL_HIGH_FLOAT &&
        !PrecisionMeetsSpecForHighpFloat(range[0], range[1], *precision)) {
      range[0] = 0;
      range[1] = 0;
      *precision = 0;
    }
  }
}

void PopulateNumericCapabilities(Capabilities* caps,
                                 const FeatureInfo* feature_info) {
  DCHECK(caps != nullptr);

  const gl::GLVersionInfo& version_info = feature_info->gl_version_info();
  caps->VisitPrecisions([&version_info](
                            GLenum shader, GLenum type,
                            Capabilities::ShaderPrecision* shader_precision) {
    GLint range[2] = {0, 0};
    GLint precision = 0;
    QueryShaderPrecisionFormat(version_info, shader, type, range, &precision);
    shader_precision->min_range = range[0];
    shader_precision->max_range = range[1];
    shader_precision->precision = precision;
  });

  glGetIntegerv(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS,
                &caps->max_combined_texture_image_units);
  glGetIntegerv(GL_MAX_CUBE_MAP_TEXTURE_SIZE, &caps->max_cube_map_texture_size);
  glGetIntegerv(GL_MAX_FRAGMENT_UNIFORM_VECTORS,
                &caps->max_fragment_uniform_vectors);
  glGetIntegerv(GL_MAX_RENDERBUFFER_SIZE, &caps->max_renderbuffer_size);
  glGetIntegerv(GL_MAX_TEXTURE_IMAGE_UNITS, &caps->max_texture_image_units);
  glGetIntegerv(GL_MAX_TEXTURE_SIZE, &caps->max_texture_size);
  glGetIntegerv(GL_MAX_VARYING_VECTORS, &caps->max_varying_vectors);
  glGetIntegerv(GL_MAX_VERTEX_ATTRIBS, &caps->max_vertex_attribs);
  glGetIntegerv(GL_MAX_VERTEX_TEXTURE_IMAGE_UNITS,
                &caps->max_vertex_texture_image_units);
  glGetIntegerv(GL_MAX_VERTEX_UNIFORM_VECTORS,
                &caps->max_vertex_uniform_vectors);
  {
    GLint dims[2] = {0, 0};
    glGetIntegerv(GL_MAX_VIEWPORT_DIMS, dims);
    caps->max_viewport_width = dims[0];
    caps->max_viewport_height = dims[1];
  }
  glGetIntegerv(GL_NUM_COMPRESSED_TEXTURE_FORMATS,
                &caps->num_compressed_texture_formats);
  glGetIntegerv(GL_NUM_SHADER_BINARY_FORMATS, &caps->num_shader_binary_formats);

  if (feature_info->IsWebGL2OrES3Context()) {
    glGetIntegerv(GL_MAX_3D_TEXTURE_SIZE, &caps->max_3d_texture_size);
    glGetIntegerv(GL_MAX_ARRAY_TEXTURE_LAYERS, &caps->max_array_texture_layers);
    glGetIntegerv(GL_MAX_COLOR_ATTACHMENTS, &caps->max_color_attachments);
    glGetInteger64v(GL_MAX_COMBINED_FRAGMENT_UNIFORM_COMPONENTS,
                    &caps->max_combined_fragment_uniform_components);
    glGetIntegerv(GL_MAX_COMBINED_UNIFORM_BLOCKS,
                  &caps->max_combined_uniform_blocks);
    glGetInteger64v(GL_MAX_COMBINED_VERTEX_UNIFORM_COMPONENTS,
                    &caps->max_combined_vertex_uniform_components);
    glGetIntegerv(GL_MAX_DRAW_BUFFERS, &caps->max_draw_buffers);
    glGetInteger64v(GL_MAX_ELEMENT_INDEX, &caps->max_element_index);
    glGetIntegerv(GL_MAX_ELEMENTS_INDICES, &caps->max_elements_indices);
    glGetIntegerv(GL_MAX_ELEMENTS_VERTICES, &caps->max_elements_vertices);
    glGetIntegerv(GL_MAX_FRAGMENT_INPUT_COMPONENTS,
                  &caps->max_fragment_input_components);
    glGetIntegerv(GL_MAX_FRAGMENT_UNIFORM_BLOCKS,
                  &caps->max_fragment_uniform_blocks);
    glGetIntegerv(GL_MAX_FRAGMENT_UNIFORM_COMPONENTS,
                  &caps->max_fragment_uniform_components);
    glGetIntegerv(GL_MAX_PROGRAM_TEXEL_OFFSET, &caps->max_program_texel_offset);
    glGetInteger64v(GL_MAX_SERVER_WAIT_TIMEOUT, &caps->max_server_wait_timeout);
    glGetFloatv(GL_MAX_TEXTURE_LOD_BIAS, &caps->max_texture_lod_bias);
    glGetIntegerv(GL_MAX_TRANSFORM_FEEDBACK_INTERLEAVED_COMPONENTS,
                  &caps->max_transform_feedback_interleaved_components);
    glGetIntegerv(GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_ATTRIBS,
                  &caps->max_transform_feedback_separate_attribs);
    glGetIntegerv(GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_COMPONENTS,
                  &caps->max_transform_feedback_separate_components);
    glGetInteger64v(GL_MAX_UNIFORM_BLOCK_SIZE, &caps->max_uniform_block_size);
    glGetIntegerv(GL_MAX_UNIFORM_BUFFER_BINDINGS,
                  &caps->max_uniform_buffer_bindings);
    glGetIntegerv(GL_MAX_VARYING_COMPONENTS, &caps->max_varying_components);
    glGetIntegerv(GL_MAX_VERTEX_OUTPUT_COMPONENTS,
                  &caps->max_vertex_output_components);
    glGetIntegerv(GL_MAX_VERTEX_UNIFORM_BLOCKS,
                  &caps->max_vertex_uniform_blocks);
    glGetIntegerv(GL_MAX_VERTEX_UNIFORM_COMPONENTS,
                  &caps->max_vertex_uniform_components);
    glGetIntegerv(GL_MIN_PROGRAM_TEXEL_OFFSET, &caps->min_program_texel_offset);
    glGetIntegerv(GL_NUM_EXTENSIONS, &caps->num_extensions);
    glGetIntegerv(GL_NUM_PROGRAM_BINARY_FORMATS,
                  &caps->num_program_binary_formats);
    glGetIntegerv(GL_UNIFORM_BUFFER_OFFSET_ALIGNMENT,
                  &caps->uniform_buffer_offset_alignment);
    caps->major_version = 3;
    caps->minor_version = 0;
  }
  if (feature_info->feature_flags().multisampled_render_to_texture ||
      feature_info->feature_flags().chromium_framebuffer_multisample ||
      feature_info->IsWebGL2OrES3Context()) {
    glGetIntegerv(GL_MAX_SAMPLES, &caps->max_samples);
  }
}

bool CheckUniqueAndNonNullIds(GLsizei n, const GLuint* client_ids) {
  if (n <= 0)
    return true;
  std::unordered_set<uint32_t> unique_ids(client_ids, client_ids + n);
  return (unique_ids.size() == static_cast<size_t>(n)) &&
         (unique_ids.find(0) == unique_ids.end());
}

const char* GetServiceVersionString(const FeatureInfo* feature_info) {
  if (feature_info->IsWebGL2OrES3Context())
    return "OpenGL ES 3.0 Chromium";
  else
    return "OpenGL ES 2.0 Chromium";
}

const char* GetServiceShadingLanguageVersionString(
    const FeatureInfo* feature_info) {
  if (feature_info->IsWebGL2OrES3Context())
    return "OpenGL ES GLSL ES 3.0 Chromium";
  else
    return "OpenGL ES GLSL ES 1.0 Chromium";
}

void LogGLDebugMessage(GLenum source,
                       GLenum type,
                       GLuint id,
                       GLenum severity,
                       GLsizei length,
                       const GLchar* message,
                       Logger* error_logger) {
  std::string id_string = GLES2Util::GetStringEnum(id);
  if (type == GL_DEBUG_TYPE_ERROR && source == GL_DEBUG_SOURCE_API) {
    error_logger->LogMessage(__FILE__, __LINE__,
                             " " + id_string + ": " + message);
  } else {
    error_logger->LogMessage(
        __FILE__, __LINE__,
        std::string("GL Driver Message (") + GetDebugSourceString(source) +
            ", " + GetDebugTypeString(type) + ", " + id_string + ", " +
            GetDebugSeverityString(severity) + "): " + message);
  }
}

void InitializeGLDebugLogging(bool log_non_errors,
                              GLDEBUGPROC callback,
                              const void* user_param) {
  glEnable(GL_DEBUG_OUTPUT);
  glEnable(GL_DEBUG_OUTPUT_SYNCHRONOUS);

  glDebugMessageControl(GL_DEBUG_SOURCE_API, GL_DEBUG_TYPE_ERROR, GL_DONT_CARE,
                        0, nullptr, GL_TRUE);

  if (log_non_errors) {
    // Enable logging of medium and high severity messages
    glDebugMessageControl(GL_DONT_CARE, GL_DONT_CARE, GL_DEBUG_SEVERITY_HIGH, 0,
                          nullptr, GL_TRUE);
    glDebugMessageControl(GL_DONT_CARE, GL_DONT_CARE, GL_DEBUG_SEVERITY_MEDIUM,
                          0, nullptr, GL_TRUE);
    glDebugMessageControl(GL_DONT_CARE, GL_DONT_CARE, GL_DEBUG_SEVERITY_LOW, 0,
                          nullptr, GL_FALSE);
    glDebugMessageControl(GL_DONT_CARE, GL_DONT_CARE,
                          GL_DEBUG_SEVERITY_NOTIFICATION, 0, nullptr, GL_FALSE);
  }

  glDebugMessageCallback(callback, user_param);
}

bool ValidContextLostReason(GLenum reason) {
  switch (reason) {
    case GL_NO_ERROR:
    case GL_GUILTY_CONTEXT_RESET_ARB:
    case GL_INNOCENT_CONTEXT_RESET_ARB:
    case GL_UNKNOWN_CONTEXT_RESET_ARB:
      return true;
    default:
      return false;
  }
}

error::ContextLostReason GetContextLostReasonFromResetStatus(
    GLenum reset_status) {
  switch (reset_status) {
    case GL_NO_ERROR:
      // TODO(kbr): improve the precision of the error code in this case.
      // Consider delegating to context for error code if MakeCurrent fails.
      return error::kUnknown;
    case GL_GUILTY_CONTEXT_RESET_ARB:
      return error::kGuilty;
    case GL_INNOCENT_CONTEXT_RESET_ARB:
      return error::kInnocent;
    case GL_UNKNOWN_CONTEXT_RESET_ARB:
      return error::kUnknown;
  }

  NOTREACHED();
  return error::kUnknown;
}

bool GetCompressedTexSizeInBytes(const char* function_name,
                                 GLsizei width,
                                 GLsizei height,
                                 GLsizei depth,
                                 GLenum format,
                                 GLsizei* size_in_bytes,
                                 ErrorState* error_state) {
  base::CheckedNumeric<GLsizei> bytes_required(0);

  switch (format) {
    case GL_ATC_RGB_AMD:
    case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
    case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
    case GL_COMPRESSED_SRGB_S3TC_DXT1_EXT:
    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT:
    case GL_ETC1_RGB8_OES:
      bytes_required = (width + kS3TCBlockWidth - 1) / kS3TCBlockWidth;
      bytes_required *= (height + kS3TCBlockHeight - 1) / kS3TCBlockHeight;
      bytes_required *= kS3TCDXT1BlockSize;
      break;
    case GL_COMPRESSED_RGBA_ASTC_4x4_KHR:
    case GL_COMPRESSED_RGBA_ASTC_5x4_KHR:
    case GL_COMPRESSED_RGBA_ASTC_5x5_KHR:
    case GL_COMPRESSED_RGBA_ASTC_6x5_KHR:
    case GL_COMPRESSED_RGBA_ASTC_6x6_KHR:
    case GL_COMPRESSED_RGBA_ASTC_8x5_KHR:
    case GL_COMPRESSED_RGBA_ASTC_8x6_KHR:
    case GL_COMPRESSED_RGBA_ASTC_8x8_KHR:
    case GL_COMPRESSED_RGBA_ASTC_10x5_KHR:
    case GL_COMPRESSED_RGBA_ASTC_10x6_KHR:
    case GL_COMPRESSED_RGBA_ASTC_10x8_KHR:
    case GL_COMPRESSED_RGBA_ASTC_10x10_KHR:
    case GL_COMPRESSED_RGBA_ASTC_12x10_KHR:
    case GL_COMPRESSED_RGBA_ASTC_12x12_KHR:
    case GL_COMPRESSED_SRGB8_ALPHA8_ASTC_4x4_KHR:
    case GL_COMPRESSED_SRGB8_ALPHA8_ASTC_5x4_KHR:
    case GL_COMPRESSED_SRGB8_ALPHA8_ASTC_5x5_KHR:
    case GL_COMPRESSED_SRGB8_ALPHA8_ASTC_6x5_KHR:
    case GL_COMPRESSED_SRGB8_ALPHA8_ASTC_6x6_KHR:
    case GL_COMPRESSED_SRGB8_ALPHA8_ASTC_8x5_KHR:
    case GL_COMPRESSED_SRGB8_ALPHA8_ASTC_8x6_KHR:
    case GL_COMPRESSED_SRGB8_ALPHA8_ASTC_8x8_KHR:
    case GL_COMPRESSED_SRGB8_ALPHA8_ASTC_10x5_KHR:
    case GL_COMPRESSED_SRGB8_ALPHA8_ASTC_10x6_KHR:
    case GL_COMPRESSED_SRGB8_ALPHA8_ASTC_10x8_KHR:
    case GL_COMPRESSED_SRGB8_ALPHA8_ASTC_10x10_KHR:
    case GL_COMPRESSED_SRGB8_ALPHA8_ASTC_12x10_KHR:
    case GL_COMPRESSED_SRGB8_ALPHA8_ASTC_12x12_KHR: {
      const int index =
          (format < GL_COMPRESSED_SRGB8_ALPHA8_ASTC_4x4_KHR)
              ? static_cast<int>(format - GL_COMPRESSED_RGBA_ASTC_4x4_KHR)
              : static_cast<int>(format -
                                 GL_COMPRESSED_SRGB8_ALPHA8_ASTC_4x4_KHR);

      const int kBlockWidth = kASTCBlockArray[index].blockWidth;
      const int kBlockHeight = kASTCBlockArray[index].blockHeight;

      bytes_required = (width + kBlockWidth - 1) / kBlockWidth;
      bytes_required *= (height + kBlockHeight - 1) / kBlockHeight;

      bytes_required *= kASTCBlockSize;
      break;
    }
    case GL_ATC_RGBA_EXPLICIT_ALPHA_AMD:
    case GL_ATC_RGBA_INTERPOLATED_ALPHA_AMD:
    case GL_COMPRESSED_RGBA_S3TC_DXT3_EXT:
    case GL_COMPRESSED_RGBA_S3TC_DXT5_EXT:
    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT:
    case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT:
      bytes_required = (width + kS3TCBlockWidth - 1) / kS3TCBlockWidth;
      bytes_required *= (height + kS3TCBlockHeight - 1) / kS3TCBlockHeight;
      bytes_required *= kS3TCDXT3AndDXT5BlockSize;
      break;
    case GL_COMPRESSED_RGB_PVRTC_4BPPV1_IMG:
    case GL_COMPRESSED_RGBA_PVRTC_4BPPV1_IMG:
      bytes_required = std::max(width, 8);
      bytes_required *= std::max(height, 8);
      bytes_required *= 4;
      bytes_required += 7;
      bytes_required /= 8;
      break;
    case GL_COMPRESSED_RGB_PVRTC_2BPPV1_IMG:
    case GL_COMPRESSED_RGBA_PVRTC_2BPPV1_IMG:
      bytes_required = std::max(width, 16);
      bytes_required *= std::max(height, 8);
      bytes_required *= 2;
      bytes_required += 7;
      bytes_required /= 8;
      break;

    // ES3 formats.
    case GL_COMPRESSED_R11_EAC:
    case GL_COMPRESSED_SIGNED_R11_EAC:
    case GL_COMPRESSED_RGB8_ETC2:
    case GL_COMPRESSED_SRGB8_ETC2:
    case GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2:
    case GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2:
      bytes_required =
          (width + kEACAndETC2BlockSize - 1) / kEACAndETC2BlockSize;
      bytes_required *=
          (height + kEACAndETC2BlockSize - 1) / kEACAndETC2BlockSize;
      bytes_required *= 8;
      bytes_required *= depth;
      break;
    case GL_COMPRESSED_RG11_EAC:
    case GL_COMPRESSED_SIGNED_RG11_EAC:
    case GL_COMPRESSED_RGBA8_ETC2_EAC:
    case GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC:
      bytes_required =
          (width + kEACAndETC2BlockSize - 1) / kEACAndETC2BlockSize;
      bytes_required *=
          (height + kEACAndETC2BlockSize - 1) / kEACAndETC2BlockSize;
      bytes_required *= 16;
      bytes_required *= depth;
      break;
    default:
      ERRORSTATE_SET_GL_ERROR_INVALID_ENUM(error_state, function_name, format,
                                           "format");
      return false;
  }

  if (!bytes_required.IsValid()) {
    ERRORSTATE_SET_GL_ERROR(error_state, GL_INVALID_VALUE, function_name,
                            "invalid size");
    return false;
  }

  *size_in_bytes = bytes_required.ValueOrDefault(0);
  return true;
}

bool ValidateCopyTexFormatHelper(const FeatureInfo* feature_info,
                                 GLenum internal_format,
                                 GLenum read_format,
                                 GLenum read_type,
                                 std::string* output_error_msg) {
  DCHECK(output_error_msg);
  if (read_format == 0) {
    *output_error_msg = std::string("no valid color image");
    return false;
  }
  // Check we have compatible formats.
  uint32_t channels_exist = GLES2Util::GetChannelsForFormat(read_format);
  uint32_t channels_needed = GLES2Util::GetChannelsForFormat(internal_format);
  if (!channels_needed ||
      (channels_needed & channels_exist) != channels_needed) {
    *output_error_msg = std::string("incompatible format");
    return false;
  }
  if (feature_info->IsWebGL2OrES3Context()) {
    GLint color_encoding =
        GLES2Util::GetColorEncodingFromInternalFormat(read_format);
    bool float_mismatch = feature_info->ext_color_buffer_float_available()
                              ? (GLES2Util::IsIntegerFormat(internal_format) !=
                                 GLES2Util::IsIntegerFormat(read_format))
                              : GLES2Util::IsFloatFormat(internal_format);
    if (color_encoding !=
            GLES2Util::GetColorEncodingFromInternalFormat(internal_format) ||
        float_mismatch ||
        (GLES2Util::IsSignedIntegerFormat(internal_format) !=
         GLES2Util::IsSignedIntegerFormat(read_format)) ||
        (GLES2Util::IsUnsignedIntegerFormat(internal_format) !=
         GLES2Util::IsUnsignedIntegerFormat(read_format))) {
      *output_error_msg = std::string("incompatible format");
      return false;
    }
  }
  if ((channels_needed & (GLES2Util::kDepth | GLES2Util::kStencil)) != 0) {
    *output_error_msg =
        std::string("can not be used with depth or stencil textures");
    return false;
  }
  if (feature_info->IsWebGL2OrES3Context() ||
      (feature_info->feature_flags().chromium_color_buffer_float_rgb &&
       internal_format == GL_RGB32F) ||
      (feature_info->feature_flags().chromium_color_buffer_float_rgba &&
       internal_format == GL_RGBA32F)) {
    if (GLES2Util::IsSizedColorFormat(internal_format)) {
      int sr, sg, sb, sa;
      GLES2Util::GetColorFormatComponentSizes(read_format, read_type, &sr, &sg,
                                              &sb, &sa);
      DCHECK(sr > 0 || sg > 0 || sb > 0 || sa > 0);
      int dr, dg, db, da;
      GLES2Util::GetColorFormatComponentSizes(internal_format, 0, &dr, &dg, &db,
                                              &da);
      DCHECK(dr > 0 || dg > 0 || db > 0 || da > 0);
      if ((dr > 0 && sr != dr) || (dg > 0 && sg != dg) ||
          (db > 0 && sb != db) || (da > 0 && sa != da)) {
        *output_error_msg = std::string("incompatible color component sizes");
        return false;
      }
    }
  }
  return true;
}

CopyTextureMethod GetCopyTextureCHROMIUMMethod(const FeatureInfo* feature_info,
                                               GLenum source_target,
                                               GLint source_level,
                                               GLenum source_internal_format,
                                               GLenum source_type,
                                               GLenum dest_target,
                                               GLint dest_level,
                                               GLenum dest_internal_format,
                                               bool flip_y,
                                               bool premultiply_alpha,
                                               bool unpremultiply_alpha,
                                               bool dither) {
  bool premultiply_alpha_change = premultiply_alpha ^ unpremultiply_alpha;
  bool source_format_color_renderable =
      Texture::ColorRenderable(feature_info, source_internal_format, false);
  bool dest_format_color_renderable =
      Texture::ColorRenderable(feature_info, dest_internal_format, false);
  std::string output_error_msg;

  switch (dest_internal_format) {
#if defined(OS_MACOSX)
    // RGB5_A1 is not color-renderable on NVIDIA Mac, see
    // https://crbug.com/676209.
    case GL_RGB5_A1:
      return CopyTextureMethod::DRAW_AND_READBACK;
#endif
    // RGB9_E5 isn't accepted by glCopyTexImage2D if underlying context is ES.
    case GL_RGB9_E5:
      if (feature_info->gl_version_info().is_es)
        return CopyTextureMethod::DRAW_AND_READBACK;
      break;
    // SRGB format has color-space conversion issue. WebGL spec doesn't define
    // clearly if linear-to-srgb color space conversion is required or not when
    // uploading DOM elements to SRGB textures. WebGL conformance test expects
    // no linear-to-srgb conversion, while current GPU path for
    // CopyTextureCHROMIUM does the conversion. Do a fallback path before the
    // issue is resolved. see https://github.com/KhronosGroup/WebGL/issues/2165.
    // TODO(qiankun.miao@intel.com): revisit this once the above issue is
    // resolved.
    case GL_SRGB_EXT:
    case GL_SRGB_ALPHA_EXT:
    case GL_SRGB8:
    case GL_SRGB8_ALPHA8:
      if (feature_info->IsWebGLContext())
        return CopyTextureMethod::DRAW_AND_READBACK;
      break;
    default:
      break;
  }

  // CopyTexImage* should not allow internalformat of GL_BGRA_EXT and
  // GL_BGRA8_EXT. https://crbug.com/663086.
  bool copy_tex_image_format_valid =
      source_internal_format != GL_BGRA_EXT &&
      dest_internal_format != GL_BGRA_EXT &&
      source_internal_format != GL_BGRA8_EXT &&
      dest_internal_format != GL_BGRA8_EXT &&
      ValidateCopyTexFormatHelper(feature_info, dest_internal_format,
                                  source_internal_format, source_type,
                                  &output_error_msg);

  // TODO(qiankun.miao@intel.com): for WebGL 2.0 or OpenGL ES 3.0, both
  // DIRECT_DRAW path for dest_level > 0 and DIRECT_COPY path for source_level >
  // 0 are not available due to a framebuffer completeness bug:
  // https://crbug.com/678526. Once the bug is fixed, the limitation for WebGL
  // 2.0 and OpenGL ES 3.0 can be lifted. For WebGL 1.0 or OpenGL ES 2.0,
  // DIRECT_DRAW path isn't available for dest_level > 0 due to level > 0 isn't
  // supported by glFramebufferTexture2D in ES2 context. DIRECT_DRAW path isn't
  // available for cube map dest texture either due to it may be cube map
  // incomplete. Go to DRAW_AND_COPY path in these cases.
  if (source_target == GL_TEXTURE_2D &&
      (dest_target == GL_TEXTURE_2D || dest_target == GL_TEXTURE_CUBE_MAP) &&
      source_format_color_renderable && copy_tex_image_format_valid &&
      source_level == 0 && !flip_y && !premultiply_alpha_change && !dither)
    return CopyTextureMethod::DIRECT_COPY;
  if (dest_format_color_renderable && dest_level == 0 &&
      dest_target != GL_TEXTURE_CUBE_MAP)
    return CopyTextureMethod::DIRECT_DRAW;

  // Draw to a fbo attaching level 0 of an intermediate texture,
  // then copy from the fbo to dest texture level with glCopyTexImage2D.
  return CopyTextureMethod::DRAW_AND_COPY;
}

}  // namespace gles2
}  // namespace gpu