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// Copyright (c) 2006-2008 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 "chrome/browser/renderer_host/backing_store_manager.h"
#include "base/sys_info.h"
#include "chrome/browser/renderer_host/backing_store.h"
#include "chrome/browser/renderer_host/render_widget_host.h"
#include "chrome/common/chrome_constants.h"
namespace {
typedef OwningMRUCache<RenderWidgetHost*, BackingStore*> BackingStoreCache;
static BackingStoreCache* cache = NULL;
// Returns the size of the backing store cache.
static int GetBackingStoreCacheSize() {
// This uses a similar approach to GetMaxRendererProcessCount. The goal
// is to reduce memory pressure and swapping on low-resource machines.
static const int kMaxDibCountByRamTier[] = {
2, // less than 256MB
3, // 256MB
4, // 512MB
5 // 768MB and above
};
static int max_size = kMaxDibCountByRamTier[
std::min(base::SysInfo::AmountOfPhysicalMemoryMB() / 256,
static_cast<int>(arraysize(kMaxDibCountByRamTier)) - 1)];
return max_size;
}
// Creates the backing store for the host based on the dimensions passed in.
// Removes the existing backing store if there is one.
BackingStore* CreateBackingStore(RenderWidgetHost* host,
const gfx::Size& backing_store_size) {
BackingStoreManager::RemoveBackingStore(host);
BackingStore* backing_store = host->AllocBackingStore(backing_store_size);
int backing_store_cache_size = GetBackingStoreCacheSize();
if (backing_store_cache_size > 0) {
if (!cache)
cache = new BackingStoreCache(backing_store_cache_size);
cache->Put(host, backing_store);
}
return backing_store;
}
} // namespace
// Assume that somewhere along the line, someone will do width * height * 4
// with signed numbers. If the maximum value is 2**31, then 2**31 / 4 =
// 2**29 and floor(sqrt(2**29)) = 23170.
int BackingStore::kMaxBitmapLengthAllowed = 23170;
// BackingStoreManager ---------------------------------------------------------
// static
BackingStore* BackingStoreManager::GetBackingStore(
RenderWidgetHost* host,
const gfx::Size& desired_size) {
BackingStore* backing_store = Lookup(host);
if (backing_store) {
// If we already have a backing store, then make sure it is the correct
// size.
if (backing_store->size() == desired_size)
return backing_store;
backing_store = NULL;
}
return backing_store;
}
// static
BackingStore* BackingStoreManager::PrepareBackingStore(
RenderWidgetHost* host,
const gfx::Size& backing_store_size,
base::ProcessHandle process_handle,
TransportDIB* bitmap,
const gfx::Rect& bitmap_rect,
const gfx::Rect& paint_rect,
bool* needs_full_paint) {
BackingStore* backing_store = GetBackingStore(host, backing_store_size);
if (!backing_store) {
// We need to get Webkit to generate a new paint here, as we
// don't have a previous snapshot.
if (paint_rect.size() != backing_store_size ||
paint_rect.x() != 0 || paint_rect.y() != 0) {
DCHECK(needs_full_paint != NULL);
*needs_full_paint = true;
}
backing_store = CreateBackingStore(host, backing_store_size);
}
DCHECK(backing_store != NULL);
backing_store->PaintRect(process_handle, bitmap, bitmap_rect, paint_rect);
return backing_store;
}
// static
BackingStore* BackingStoreManager::Lookup(RenderWidgetHost* host) {
if (cache) {
BackingStoreCache::iterator it = cache->Peek(host);
if (it != cache->end())
return it->second;
}
return NULL;
}
// static
void BackingStoreManager::RemoveBackingStore(RenderWidgetHost* host) {
if (!cache)
return;
BackingStoreCache::iterator it = cache->Peek(host);
if (it == cache->end())
return;
cache->Erase(it);
if (cache->empty()) {
delete cache;
cache = NULL;
}
}
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