context.cc

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// Copyright 2013 The Flutter 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 "impeller/toolkit/egl/context.h"
 
#include "impeller/toolkit/egl/surface.h"
 
namespace impeller {
namespace egl {
 
Context::Context(EGLDisplay display, EGLContext context)
    : display_(display), context_(context) {}
 
Context::~Context() {
  if (context_ != EGL_NO_CONTEXT) {
    if (::eglDestroyContext(display_, context_) != EGL_TRUE) {
      IMPELLER_LOG_EGL_ERROR;
    }
  }
}
 
bool Context::IsValid() const {
  return context_ != EGL_NO_CONTEXT;
}
 
const EGLContext& Context::GetHandle() const {
  return context_;
}
 
static EGLBoolean EGLMakeCurrentIfNecessary(EGLDisplay display,
                                            EGLSurface draw,
                                            EGLSurface read,
                                            EGLContext context) {
  if (display != ::eglGetCurrentDisplay() ||
      draw != ::eglGetCurrentSurface(EGL_DRAW) ||
      read != ::eglGetCurrentSurface(EGL_READ) ||
      context != ::eglGetCurrentContext()) {
    return ::eglMakeCurrent(display, draw, read, context);
  }
  // The specified context configuration is already current.
  return EGL_TRUE;
}
 
bool Context::MakeCurrent(const Surface& surface) const {
  if (context_ == EGL_NO_CONTEXT) {
    return false;
  }
  const auto result = EGLMakeCurrentIfNecessary(display_,             //
                                                surface.GetHandle(),  //
                                                surface.GetHandle(),  //
                                                context_              //
                                                ) == EGL_TRUE;
  if (!result) {
    IMPELLER_LOG_EGL_ERROR;
  }
  DispatchLifecyleEvent(LifecycleEvent::kDidMakeCurrent);
  return result;
}
 
bool Context::ClearCurrent() const {
  DispatchLifecyleEvent(LifecycleEvent::kWillClearCurrent);
  const auto result = EGLMakeCurrentIfNecessary(display_,        //
                                                EGL_NO_SURFACE,  //
                                                EGL_NO_SURFACE,  //
                                                EGL_NO_CONTEXT   //
                                                ) == EGL_TRUE;
  if (!result) {
    IMPELLER_LOG_EGL_ERROR;
  }
  return result;
}
 
std::optional<UniqueID> Context::AddLifecycleListener(
    const LifecycleListener& listener) {
  if (!listener) {
    return std::nullopt;
  }
  WriterLock lock(listeners_mutex_);
  UniqueID id;
  listeners_[id] = listener;
  return id;
}
 
bool Context::RemoveLifecycleListener(UniqueID id) {
  WriterLock lock(listeners_mutex_);
  auto found = listeners_.find(id);
  if (found == listeners_.end()) {
    return false;
  }
  listeners_.erase(found);
  return true;
}
 
void Context::DispatchLifecyleEvent(LifecycleEvent event) const {
  ReaderLock lock(listeners_mutex_);
  for (const auto& listener : listeners_) {
    listener.second(event);
  }
}
 
bool Context::IsCurrent() const {
  return ::eglGetCurrentContext() == context_;
}
 
}  // namespace egl
}  // namespace impeller