From 57a0ff75ad7318299d70d79842ebce5005381983 Mon Sep 17 00:00:00 2001
From: Timothy Nikkel <tnikkel@gmail.com>
Date: Mon, 6 Dec 2021 01:08:55 +0000
Subject: [PATCH] Bug 1743533. Handle the visible rect of oop iframes that span
 multiple pages in print documents. r=botond

Differential Revision: https://phabricator.services.mozilla.com/D132789
---
 layout/painting/nsDisplayList.cpp | 22 ++++++++++++++++++++++
 layout/painting/nsDisplayList.h   |  5 ++---
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/layout/painting/nsDisplayList.cpp b/layout/painting/nsDisplayList.cpp
index 498c81e22f88..5d485dde9e6e 100644
--- a/layout/painting/nsDisplayList.cpp
+++ b/layout/painting/nsDisplayList.cpp
@@ -742,6 +742,28 @@ void nsDisplayListBuilder::BeginFrame() {
   }
 }
 
+void nsDisplayListBuilder::AddEffectUpdate(dom::RemoteBrowser* aBrowser,
+                                           const dom::EffectsInfo& aUpdate) {
+  dom::EffectsInfo update = aUpdate;
+  // For printing we create one display item for each page that an iframe
+  // appears on, the proper visible rect is the union of all the visible rects
+  // we get from each display item.
+  nsPresContext* pc =
+      mReferenceFrame ? mReferenceFrame->PresContext() : nullptr;
+  if (pc && (pc->Type() != nsPresContext::eContext_Galley)) {
+    Maybe<dom::EffectsInfo> existing = mEffectsUpdates.MaybeGet(aBrowser);
+    if (existing.isSome()) {
+      // Only the visible rect should differ, the scales should match.
+      MOZ_ASSERT(existing->mScaleX == aUpdate.mScaleX &&
+                 existing->mScaleY == aUpdate.mScaleY &&
+                 existing->mTransformToAncestorScale ==
+                     aUpdate.mTransformToAncestorScale);
+      update.mVisibleRect = update.mVisibleRect.Union(existing->mVisibleRect);
+    }
+  }
+  mEffectsUpdates.InsertOrUpdate(aBrowser, update);
+}
+
 void nsDisplayListBuilder::EndFrame() {
   NS_ASSERTION(!mInInvalidSubtree,
                "Someone forgot to cleanup mInInvalidSubtree!");
diff --git a/layout/painting/nsDisplayList.h b/layout/painting/nsDisplayList.h
index 03949363b05e..a9a31664903d 100644
--- a/layout/painting/nsDisplayList.h
+++ b/layout/painting/nsDisplayList.h
@@ -875,9 +875,8 @@ class nsDisplayListBuilder {
     return mEffectsUpdates;
   }
 
-  void AddEffectUpdate(dom::RemoteBrowser* aBrowser, dom::EffectsInfo aUpdate) {
-    mEffectsUpdates.InsertOrUpdate(aBrowser, aUpdate);
-  }
+  void AddEffectUpdate(dom::RemoteBrowser* aBrowser,
+                       const dom::EffectsInfo& aUpdate);
 
   /**
    * Allocate memory in our arena. It will only be freed when this display list