From 28208f1d3efe0b0cf8e00f06fcbd8c3c5981f2f8 Mon Sep 17 00:00:00 2001
From: wolfbeast <mcwerewolf@wolfbeast.com>
Date: Sun, 2 Feb 2020 02:16:41 +0100
Subject: Issue #1378 - Align the drawing of table cell backgrounds with the
 spec.

---
 layout/tables/nsTableCellFrame.cpp | 37 +++++++++++++++++++++++++++++--------
 1 file changed, 29 insertions(+), 8 deletions(-)

(limited to 'layout/tables/nsTableCellFrame.cpp')

diff --git a/layout/tables/nsTableCellFrame.cpp b/layout/tables/nsTableCellFrame.cpp
index 043509fc4..2862bb201 100644
--- a/layout/tables/nsTableCellFrame.cpp
+++ b/layout/tables/nsTableCellFrame.cpp
@@ -450,19 +450,40 @@ PaintTableCellSelection(nsIFrame* aFrame, DrawTarget* aDrawTarget,
                                                                aPt);
 }
 
+bool
+nsTableCellFrame::ShouldPaintBordersAndBackgrounds() const
+{
+  // If we're not visible, we don't paint.
+  if (!StyleVisibility()->IsVisible()) {
+    return false;
+  }
+
+  // Consider 'empty-cells', but only in separated borders mode.
+  if (!GetContentEmpty()) {
+    return true;
+  }
+
+  nsTableFrame* tableFrame = GetTableFrame();
+  if (tableFrame->IsBorderCollapse()) {
+    return true;
+  }
+
+  return StyleTableBorder()->mEmptyCells == NS_STYLE_TABLE_EMPTY_CELLS_SHOW;
+}
+
+bool
+nsTableCellFrame::ShouldPaintBackground(nsDisplayListBuilder* aBuilder)
+{
+  return ShouldPaintBordersAndBackgrounds() && IsVisibleInSelection(aBuilder);
+}
+
 void
 nsTableCellFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
                                    const nsRect&           aDirtyRect,
                                    const nsDisplayListSet& aLists)
 {
   DO_GLOBAL_REFLOW_COUNT_DSP("nsTableCellFrame");
-  nsTableFrame* tableFrame = GetTableFrame();
-  int32_t emptyCellStyle = GetContentEmpty() && !tableFrame->IsBorderCollapse() ?
-                              StyleTableBorder()->mEmptyCells
-                              : NS_STYLE_TABLE_EMPTY_CELLS_SHOW;
-  // take account of 'empty-cells'
-  if (StyleVisibility()->IsVisible() &&
-      (NS_STYLE_TABLE_EMPTY_CELLS_HIDE != emptyCellStyle)) {
+  if (ShouldPaintBordersAndBackgrounds()) {
     // display outset box-shadows if we need to.
     bool hasBoxShadow = !!StyleEffects()->mBoxShadow;
     if (hasBoxShadow) {
@@ -487,7 +508,7 @@ nsTableCellFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
     }
 
     // display borders if we need to
-    ProcessBorders(tableFrame, aBuilder, aLists);
+    ProcessBorders(GetTableFrame(), aBuilder, aLists);
 
     // and display the selection border if we need to
     if (IsSelected()) {
-- 
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