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diff --git a/layout/base/nsDisplayListInvalidation.h b/layout/base/nsDisplayListInvalidation.h
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+/*-*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * 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/. */
+
+#ifndef NSDISPLAYLISTINVALIDATION_H_
+#define NSDISPLAYLISTINVALIDATION_H_
+
+#include "mozilla/Attributes.h"
+#include "FrameLayerBuilder.h"
+#include "imgIContainer.h"
+#include "nsRect.h"
+#include "nsColor.h"
+#include "gfxRect.h"
+
+class nsDisplayBackgroundImage;
+class nsCharClipDisplayItem;
+class nsDisplayItem;
+class nsDisplayListBuilder;
+class nsDisplayTableItem;
+class nsDisplayThemedBackground;
+class nsDisplaySVGEffects;
+class nsDisplayMask;
+class nsDisplayFilter;
+
+namespace mozilla {
+namespace gfx {
+struct Color;
+}
+}
+
+/**
+ * This stores the geometry of an nsDisplayItem, and the area
+ * that will be affected when painting the item.
+ *
+ * It is used to retain information about display items so they
+ * can be compared against new display items in the next paint.
+ */
+class nsDisplayItemGeometry
+{
+public:
+  nsDisplayItemGeometry(nsDisplayItem* aItem, nsDisplayListBuilder* aBuilder);
+  virtual ~nsDisplayItemGeometry();
+
+  /**
+   * Compute the area required to be invalidated if this
+   * display item is removed.
+   */
+  const nsRect& ComputeInvalidationRegion() { return mBounds; }
+
+  /**
+   * Shifts all retained areas of the nsDisplayItemGeometry by the given offset.
+   *
+   * This is used to compensate for scrolling, since the destination buffer
+   * can scroll without requiring a full repaint.
+   *
+   * @param aOffset Offset to shift by.
+   */
+  virtual void MoveBy(const nsPoint& aOffset)
+  {
+    mBounds.MoveBy(aOffset);
+  }
+
+  /**
+   * Bounds of the display item
+   */
+  nsRect mBounds;
+};
+
+/**
+ * A default geometry implementation, used by nsDisplayItem. Retains
+ * and compares the bounds, and border rect.
+ *
+ * This should be sufficient for the majority of display items.
+ */
+class nsDisplayItemGenericGeometry : public nsDisplayItemGeometry
+{
+public:
+  nsDisplayItemGenericGeometry(nsDisplayItem* aItem, nsDisplayListBuilder* aBuilder);
+
+  virtual void MoveBy(const nsPoint& aOffset) override;
+
+  nsRect mBorderRect;
+};
+
+bool ShouldSyncDecodeImages(nsDisplayListBuilder* aBuilder);
+
+/**
+ * nsImageGeometryMixin is a mixin for geometry items that draw images.
+ * Geometry items that include this mixin can track drawing results and use
+ * that information to inform invalidation decisions.
+ *
+ * This mixin uses CRTP; its template parameter should be the type of the class
+ * that is inheriting from it. See nsDisplayItemGenericImageGeometry for an
+ * example.
+ */
+template <typename T>
+class nsImageGeometryMixin
+{
+public:
+  nsImageGeometryMixin(nsDisplayItem* aItem, nsDisplayListBuilder* aBuilder)
+    : mLastDrawResult(mozilla::image::DrawResult::NOT_READY)
+    , mWaitingForPaint(false)
+  {
+    // Transfer state from the previous version of this geometry item.
+    auto lastGeometry =
+      static_cast<T*>(mozilla::FrameLayerBuilder::GetMostRecentGeometry(aItem));
+    if (lastGeometry) {
+      mLastDrawResult = lastGeometry->mLastDrawResult;
+      mWaitingForPaint = lastGeometry->mWaitingForPaint;
+    }
+
+    // If our display item is going to invalidate to trigger sync decoding of
+    // images, mark ourselves as waiting for a paint. If we actually get
+    // painted, UpdateDrawResult will get called, and we'll clear the flag.
+    if (ShouldSyncDecodeImages(aBuilder) &&
+        ShouldInvalidateToSyncDecodeImages()) {
+      mWaitingForPaint = true;
+    }
+  }
+
+  static void UpdateDrawResult(nsDisplayItem* aItem,
+                               mozilla::image::DrawResult aResult)
+  {
+    auto lastGeometry =
+      static_cast<T*>(mozilla::FrameLayerBuilder::GetMostRecentGeometry(aItem));
+    if (lastGeometry) {
+      lastGeometry->mLastDrawResult = aResult;
+      lastGeometry->mWaitingForPaint = false;
+    }
+  }
+
+  bool ShouldInvalidateToSyncDecodeImages() const
+  {
+    if (mWaitingForPaint) {
+      // We previously invalidated for sync decoding and haven't gotten painted
+      // since them. This suggests that our display item is completely occluded
+      // and there's no point in invalidating again - and because the reftest
+      // harness takes a new snapshot every time we invalidate, doing so might
+      // lead to an invalidation loop if we're in a reftest.
+      return false;
+    }
+
+    if (mLastDrawResult == mozilla::image::DrawResult::SUCCESS ||
+        mLastDrawResult == mozilla::image::DrawResult::BAD_IMAGE) {
+      return false;
+    }
+
+    return true;
+  }
+
+private:
+  mozilla::image::DrawResult mLastDrawResult;
+  bool mWaitingForPaint;
+};
+
+/**
+ * nsDisplayItemGenericImageGeometry is a generic geometry item class that
+ * includes nsImageGeometryMixin.
+ *
+ * This should be sufficient for most display items that draw images.
+ */
+class nsDisplayItemGenericImageGeometry
+  : public nsDisplayItemGenericGeometry
+  , public nsImageGeometryMixin<nsDisplayItemGenericImageGeometry>
+{
+public:
+  nsDisplayItemGenericImageGeometry(nsDisplayItem* aItem,
+                                    nsDisplayListBuilder* aBuilder)
+    : nsDisplayItemGenericGeometry(aItem, aBuilder)
+    , nsImageGeometryMixin(aItem, aBuilder)
+  { }
+};
+
+class nsDisplayItemBoundsGeometry : public nsDisplayItemGeometry
+{
+public:
+  nsDisplayItemBoundsGeometry(nsDisplayItem* aItem, nsDisplayListBuilder* aBuilder);
+
+  bool mHasRoundedCorners;
+};
+
+class nsDisplayBorderGeometry
+  : public nsDisplayItemGeometry
+  , public nsImageGeometryMixin<nsDisplayBorderGeometry>
+{
+public:
+  nsDisplayBorderGeometry(nsDisplayItem* aItem, nsDisplayListBuilder* aBuilder);
+
+  virtual void MoveBy(const nsPoint& aOffset) override;
+
+  nsRect mContentRect;
+};
+
+class nsDisplayBackgroundGeometry
+  : public nsDisplayItemGeometry
+  , public nsImageGeometryMixin<nsDisplayBackgroundGeometry>
+{
+public:
+  nsDisplayBackgroundGeometry(nsDisplayBackgroundImage* aItem, nsDisplayListBuilder* aBuilder);
+
+  virtual void MoveBy(const nsPoint& aOffset) override;
+
+  nsRect mPositioningArea;
+  nsRect mDestRect;
+};
+
+class nsDisplayThemedBackgroundGeometry : public nsDisplayItemGeometry
+{
+public:
+  nsDisplayThemedBackgroundGeometry(nsDisplayThemedBackground* aItem, nsDisplayListBuilder* aBuilder);
+
+  virtual void MoveBy(const nsPoint& aOffset) override;
+
+  nsRect mPositioningArea;
+  bool mWindowIsActive;
+};
+
+class nsDisplayBoxShadowInnerGeometry : public nsDisplayItemGeometry
+{
+public:
+  nsDisplayBoxShadowInnerGeometry(nsDisplayItem* aItem, nsDisplayListBuilder* aBuilder);
+
+  virtual void MoveBy(const nsPoint& aOffset) override;
+
+  nsRect mPaddingRect;
+};
+
+class nsDisplayBoxShadowOuterGeometry : public nsDisplayItemGenericGeometry
+{
+public:
+  nsDisplayBoxShadowOuterGeometry(nsDisplayItem* aItem,
+                                  nsDisplayListBuilder* aBuilder,
+                                  float aOpacity);
+
+  float mOpacity;
+};
+
+class nsDisplaySolidColorGeometry : public nsDisplayItemBoundsGeometry
+{
+public:
+  nsDisplaySolidColorGeometry(nsDisplayItem* aItem,
+                              nsDisplayListBuilder* aBuilder,
+                              nscolor aColor)
+    : nsDisplayItemBoundsGeometry(aItem, aBuilder)
+    , mColor(aColor)
+  { }
+
+  nscolor mColor;
+};
+
+class nsDisplaySolidColorRegionGeometry : public nsDisplayItemBoundsGeometry
+{
+public:
+  nsDisplaySolidColorRegionGeometry(nsDisplayItem* aItem,
+                                    nsDisplayListBuilder* aBuilder,
+                                    const nsRegion& aRegion,
+                                    mozilla::gfx::Color aColor)
+    : nsDisplayItemBoundsGeometry(aItem, aBuilder)
+    , mRegion(aRegion)
+    , mColor(aColor)
+  { }
+
+  virtual void MoveBy(const nsPoint& aOffset) override;
+
+  nsRegion mRegion;
+  mozilla::gfx::Color mColor;
+};
+
+class nsDisplaySVGEffectGeometry : public nsDisplayItemGeometry
+{
+public:
+  nsDisplaySVGEffectGeometry(nsDisplaySVGEffects* aItem,
+                             nsDisplayListBuilder* aBuilder);
+
+  virtual void MoveBy(const nsPoint& aOffset) override;
+
+  gfxRect mBBox;
+  gfxPoint mUserSpaceOffset;
+  nsPoint mFrameOffsetToReferenceFrame;
+};
+
+class nsDisplayMaskGeometry : public nsDisplaySVGEffectGeometry
+  , public nsImageGeometryMixin<nsDisplayMaskGeometry>
+{
+public:
+  nsDisplayMaskGeometry(nsDisplayMask* aItem, nsDisplayListBuilder* aBuilder);
+
+  nsTArray<nsRect> mDestRects;
+};
+
+class nsDisplayFilterGeometry : public nsDisplaySVGEffectGeometry
+  , public nsImageGeometryMixin<nsDisplayFilterGeometry>
+{
+public:
+  nsDisplayFilterGeometry(nsDisplayFilter* aItem,
+                          nsDisplayListBuilder* aBuilder);
+};
+
+class nsCharClipGeometry : public nsDisplayItemGenericGeometry
+{
+public:
+  nsCharClipGeometry(nsCharClipDisplayItem* aItem,
+                     nsDisplayListBuilder* aBuilder);
+
+  nscoord mVisIStartEdge;
+  nscoord mVisIEndEdge;
+};
+
+class nsDisplayTableItemGeometry
+  : public nsDisplayItemGenericGeometry
+  , public nsImageGeometryMixin<nsDisplayTableItemGeometry>
+{
+public:
+  nsDisplayTableItemGeometry(nsDisplayTableItem* aItem,
+                             nsDisplayListBuilder* aBuilder,
+                             const nsPoint& aFrameOffsetToViewport);
+
+  nsPoint mFrameOffsetToViewport;
+};
+
+#endif /*NSDISPLAYLISTINVALIDATION_H_*/