third_party/WebKit/Source/platform/graphics/paint/GeometryMapperClipCache.cpp

// Copyright 2017 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/paint/GeometryMapperClipCache.h"

#include "platform/graphics/paint/FloatClipRect.h"

namespace blink {

// All clip caches invalidate themselves by tracking a local cache generation,
// and invalidating their cache if their cache generation disagrees with
// s_clipCacheGeneration.
static unsigned g_clip_cache_generation = 0;

GeometryMapperClipCache::GeometryMapperClipCache()
    : cache_generation_(g_clip_cache_generation) {}

void GeometryMapperClipCache::ClearCache() {
  g_clip_cache_generation++;
}

void GeometryMapperClipCache::InvalidateCacheIfNeeded() {
  if (cache_generation_ != g_clip_cache_generation) {
    clip_cache_.clear();
    cache_generation_ = g_clip_cache_generation;
  }
}

const FloatClipRect* GeometryMapperClipCache::GetCachedClip(
    const ClipAndTransform& clip_and_transform) {
  InvalidateCacheIfNeeded();
  for (const auto& entry : clip_cache_) {
    if (entry.clip_and_transform == clip_and_transform) {
      return &entry.clip_rect;
    }
  }
  return nullptr;
}

void GeometryMapperClipCache::SetCachedClip(
    const ClipAndTransform& clip_and_transform,
    const FloatClipRect& clip) {
  InvalidateCacheIfNeeded();
#if DCHECK_IS_ON()
  for (const auto& entry : clip_cache_) {
    if (entry.clip_and_transform == clip_and_transform)
      DCHECK(false);  // There should be no existing entry.
  }
#endif
  clip_cache_.push_back(ClipCacheEntry(clip_and_transform, clip));
}

}  // namespace blink