1 files changed, 161 insertions, 0 deletions
diff --git a/dom/base/ImageTracker.cpp b/dom/base/ImageTracker.cpp
new file mode 100644
index 000000000..9fef059bc
--- /dev/null
+++ b/dom/base/ImageTracker.cpp
@@ -0,0 +1,161 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* table of images used in a document, for batch locking/unlocking and
+ * animating */
+
+#include "ImageTracker.h"
+
+namespace mozilla {
+namespace dom {
+
+ImageTracker::ImageTracker()
+  : mLocking(false)
+  , mAnimating(true)
+{
+}
+
+ImageTracker::~ImageTracker()
+{
+  SetLockingState(false);
+}
+
+nsresult
+ImageTracker::Add(imgIRequest* aImage)
+{
+  MOZ_ASSERT(aImage);
+
+  // See if the image is already in the hashtable. If it is, get the old count.
+  uint32_t oldCount = 0;
+  mImages.Get(aImage, &oldCount);
+
+  // Put the image in the hashtable, with the proper count.
+  mImages.Put(aImage, oldCount + 1);
+
+  nsresult rv = NS_OK;
+
+  // If this is the first insertion and we're locking images, lock this image
+  // too.
+  if (oldCount == 0 && mLocking) {
+    rv = aImage->LockImage();
+  }
+
+  // If this is the first insertion and we're animating images, request
+  // that this image be animated too.
+  if (oldCount == 0 && mAnimating) {
+    nsresult rv2 = aImage->IncrementAnimationConsumers();
+    rv = NS_SUCCEEDED(rv) ? rv2 : rv;
+  }
+
+  return rv;
+}
+
+nsresult
+ImageTracker::Remove(imgIRequest* aImage, uint32_t aFlags)
+{
+  NS_ENSURE_ARG_POINTER(aImage);
+
+  // Get the old count. It should exist and be > 0.
+  uint32_t count = 0;
+  DebugOnly<bool> found = mImages.Get(aImage, &count);
+  MOZ_ASSERT(found, "Removing image that wasn't in the tracker!");
+  MOZ_ASSERT(count > 0, "Entry in the cache tracker with count 0!");
+
+  // We're removing, so decrement the count.
+  count--;
+
+  // If the count is now zero, remove from the tracker.
+  // Otherwise, set the new value.
+  if (count != 0) {
+    mImages.Put(aImage, count);
+    return NS_OK;
+  }
+
+  mImages.Remove(aImage);
+
+  nsresult rv = NS_OK;
+
+  // Now that we're no longer tracking this image, unlock it if we'd
+  // previously locked it.
+  if (mLocking) {
+    rv = aImage->UnlockImage();
+  }
+
+  // If we're animating images, remove our request to animate this one.
+  if (mAnimating) {
+    nsresult rv2 = aImage->DecrementAnimationConsumers();
+    rv = NS_SUCCEEDED(rv) ? rv2 : rv;
+  }
+
+  if (aFlags & REQUEST_DISCARD) {
+    // Request that the image be discarded if nobody else holds a lock on it.
+    // Do this even if !mLocking, because even if we didn't just unlock
+    // this image, it might still be a candidate for discarding.
+    aImage->RequestDiscard();
+  }
+
+  return rv;
+}
+
+nsresult
+ImageTracker::SetLockingState(bool aLocked)
+{
+  if (XRE_IsContentProcess() &&
+      !Preferences::GetBool("image.mem.allow_locking_in_content_processes", true)) {
+    return NS_OK;
+  }
+
+  // If there's no change, there's nothing to do.
+  if (mLocking == aLocked)
+    return NS_OK;
+
+  // Otherwise, iterate over our images and perform the appropriate action.
+  for (auto iter = mImages.Iter(); !iter.Done(); iter.Next()) {
+    imgIRequest* image = iter.Key();
+    if (aLocked) {
+      image->LockImage();
+    } else {
+      image->UnlockImage();
+    }
+  }
+
+  // Update state.
+  mLocking = aLocked;
+
+  return NS_OK;
+}
+
+void
+ImageTracker::SetAnimatingState(bool aAnimating)
+{
+  // If there's no change, there's nothing to do.
+  if (mAnimating == aAnimating)
+    return;
+
+  // Otherwise, iterate over our images and perform the appropriate action.
+  for (auto iter = mImages.Iter(); !iter.Done(); iter.Next()) {
+    imgIRequest* image = iter.Key();
+    if (aAnimating) {
+      image->IncrementAnimationConsumers();
+    } else {
+      image->DecrementAnimationConsumers();
+    }
+  }
+
+  // Update state.
+  mAnimating = aAnimating;
+}
+
+void
+ImageTracker::RequestDiscardAll()
+{
+  for (auto iter = mImages.Iter(); !iter.Done(); iter.Next()) {
+    iter.Key()->RequestDiscard();
+  }
+}
+
+} // namespace dom
+} // namespace mozilla