third_party/WebKit/Source/platform/graphics/gpu/Extensions3DUtil.cpp

// Copyright 2014 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 "platform/graphics/gpu/Extensions3DUtil.h"

#include "gpu/command_buffer/client/gles2_interface.h"
#include "wtf/PtrUtil.h"
#include "wtf/text/CString.h"
#include "wtf/text/StringHash.h"
#include <memory>

namespace blink {

namespace {

void splitStringHelper(const String& str, HashSet<String>& set) {
  Vector<String> substrings;
  str.split(' ', substrings);
  for (size_t i = 0; i < substrings.size(); ++i)
    set.add(substrings[i]);
}

}  // anonymous namespace

std::unique_ptr<Extensions3DUtil> Extensions3DUtil::create(
    gpu::gles2::GLES2Interface* gl) {
  std::unique_ptr<Extensions3DUtil> out = wrapUnique(new Extensions3DUtil(gl));
  out->initializeExtensions();
  return out;
}

Extensions3DUtil::Extensions3DUtil(gpu::gles2::GLES2Interface* gl)
    : m_gl(gl), m_isValid(true) {}

Extensions3DUtil::~Extensions3DUtil() {}

void Extensions3DUtil::initializeExtensions() {
  if (m_gl->GetGraphicsResetStatusKHR() != GL_NO_ERROR) {
    // If the context is lost don't initialize the extension strings.
    // This will cause supportsExtension, ensureExtensionEnabled, and
    // isExtensionEnabled to always return false.
    m_isValid = false;
    return;
  }

  String extensionsString(m_gl->GetString(GL_EXTENSIONS));
  splitStringHelper(extensionsString, m_enabledExtensions);

  String requestableExtensionsString(m_gl->GetRequestableExtensionsCHROMIUM());
  splitStringHelper(requestableExtensionsString, m_requestableExtensions);
}

bool Extensions3DUtil::supportsExtension(const String& name) {
  return m_enabledExtensions.contains(name) ||
         m_requestableExtensions.contains(name);
}

bool Extensions3DUtil::ensureExtensionEnabled(const String& name) {
  if (m_enabledExtensions.contains(name))
    return true;

  if (m_requestableExtensions.contains(name)) {
    m_gl->RequestExtensionCHROMIUM(name.ascii().data());
    m_enabledExtensions.clear();
    m_requestableExtensions.clear();
    initializeExtensions();
  }
  return m_enabledExtensions.contains(name);
}

bool Extensions3DUtil::isExtensionEnabled(const String& name) {
  return m_enabledExtensions.contains(name);
}

bool Extensions3DUtil::canUseCopyTextureCHROMIUM(GLenum destTarget,
                                                 GLenum destFormat,
                                                 GLenum destType,
                                                 GLint level) {
  // TODO(zmo): restriction of (RGB || RGBA)/UNSIGNED_BYTE/(Level 0) should be
  // lifted when GLES2Interface::CopyTextureCHROMIUM(...) are fully functional.
  if (destTarget == GL_TEXTURE_2D &&
      (destFormat == GL_RGB || destFormat == GL_RGBA) &&
      destType == GL_UNSIGNED_BYTE && !level)
    return true;
  return false;
}

}  // namespace blink