chromium/third_party/skia/src/gpu/ganesh/GrDeferredProxyUploader.h

/*
 * Copyright 2017 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef GrDeferredProxyUploader_DEFINED
#define GrDeferredProxyUploader_DEFINED

#include "include/core/SkRefCnt.h"
#include "include/private/base/SkSemaphore.h"
#include "src/core/SkAutoPixmapStorage.h"

#include "src/gpu/ganesh/GrOpFlushState.h"
#include "src/gpu/ganesh/GrTextureProxyPriv.h"

/**
 * GrDeferredProxyUploader assists with threaded generation of textures. Currently used by both
 * software clip masks, and the software path renderer. The calling code typically needs to store
 * some additional data (T) for use on the worker thread. GrTDeferredProxyUploader allows storing
 * such data. The common flow is:
 *
 * 1) A GrTDeferredProxyUploader is created, with some payload (eg an SkPath to draw).
 *    The uploader is owned by the proxy that it's going to populate.
 * 2) A task is created with a pointer to the uploader. A worker thread executes that task, using
 *    the payload data to allocate and fill in the fPixels pixmap.
 * 3) The worker thread calls signalAndFreeData(), which notifies the main thread that the pixmap
 *    is ready, and then deletes the payload data (which is no longer needed).
 * 4) In parallel to 2-3, on the main thread... Some op is created that refers to the proxy. When
 *    that op is added to an op list, the op list retains a pointer to the "deferred" proxies.
 * 5) At flush time, the op list ensures that the deferred proxies are instantiated, then calls
 *    scheduleUpload on those proxies, which calls scheduleUpload on the uploader (below).
 * 6) scheduleUpload defers the upload even further, by adding an ASAPUpload to the flush.
 * 7) When the ASAP upload happens, we wait to make sure that the pixels are marked ready
 *    (from step #3 on the worker thread). Then we perform the actual upload to the texture.
 *    Finally, we call resetDeferredUploader, which deletes the uploader object, causing fPixels
 *    to be freed.
 */
class GrDeferredProxyUploader : public SkNoncopyable { … };

template <typename T>
class GrTDeferredProxyUploader : public GrDeferredProxyUploader { … };

#endif