Bug 458296. When a block doesn't carry out the bottom-margin of its children, add that bottom-margin to its overflow area. Also, add the bottom-padding of a scrolled block to its overflow area. r+sr=dbaron

layout/generic/nsBlockFrame.cpp

@@ -1107,9 +1107,9 @@ nsBlockFrame::Reflow(nsPresContext*           aPresContext,
   }
 
   // Compute our final size
-  ComputeFinalSize(aReflowState, state, aMetrics);
-
-  ComputeCombinedArea(aReflowState, aMetrics);
+  nscoord bottomEdgeOfChildren;
+  ComputeFinalSize(aReflowState, state, aMetrics, &bottomEdgeOfChildren);
+  ComputeCombinedArea(aReflowState, aMetrics, bottomEdgeOfChildren);
   // Factor overflow container child bounds into the overflow area
   aMetrics.mOverflowArea.UnionRect(aMetrics.mOverflowArea,
                                    overflowContainerBounds);
@@ -1272,7 +1272,8 @@ nsBlockFrame::CheckForCollapsedBottomMarginFromClearanceLine()
 void
 nsBlockFrame::ComputeFinalSize(const nsHTMLReflowState& aReflowState,
                                nsBlockReflowState&      aState,
-                               nsHTMLReflowMetrics&     aMetrics)
+                               nsHTMLReflowMetrics&     aMetrics,
+                               nscoord*                 aBottomEdgeOfChildren)
 {
   const nsMargin& borderPadding = aState.BorderPadding();
 #ifdef NOISY_FINAL_SIZE
@@ -1310,6 +1311,32 @@ nsBlockFrame::ComputeFinalSize(const nsHTMLReflowState& aReflowState,
     aMetrics.mCarriedOutBottomMargin.Zero();
   }
 
+  nscoord bottomEdgeOfChildren = aState.mY + nonCarriedOutVerticalMargin;
+  // Shrink wrap our height around our contents.
+  if (aState.GetFlag(BRS_ISBOTTOMMARGINROOT) ||
+      NS_UNCONSTRAINEDSIZE != aReflowState.ComputedHeight()) {
+    // When we are a bottom-margin root make sure that our last
+    // childs bottom margin is fully applied. We also do this when
+    // we have a computed height, since in that case the carried out
+    // margin is not going to be applied anywhere, so we should note it
+    // here to be included in the overflow area.
+    // Apply the margin only if there's space for it.
+    if (bottomEdgeOfChildren < aState.mReflowState.availableHeight)
+    {
+      // Truncate bottom margin if it doesn't fit to our available height.
+      bottomEdgeOfChildren =
+        PR_MIN(bottomEdgeOfChildren + aState.mPrevBottomMargin.get(),
+               aState.mReflowState.availableHeight);
+    }
+  }
+  if (aState.GetFlag(BRS_SPACE_MGR)) {
+    // Include the space manager's state to properly account for the
+    // bottom margin of any floated elements; e.g., inside a table cell.
+    nscoord floatHeight =
+      aState.ClearFloats(bottomEdgeOfChildren, NS_STYLE_CLEAR_LEFT_AND_RIGHT);
+    bottomEdgeOfChildren = PR_MAX(bottomEdgeOfChildren, floatHeight);
+  }
+
   // Compute final height
   if (NS_UNCONSTRAINEDSIZE != aReflowState.ComputedHeight()) {
     // Figure out how much of the computed height should be
@@ -1374,29 +1401,7 @@ nsBlockFrame::ComputeFinalSize(const nsHTMLReflowState& aReflowState,
     aMetrics.mCarriedOutBottomMargin.Zero();
   }
   else if (NS_FRAME_IS_COMPLETE(aState.mReflowStatus)) {
-    nscoord autoHeight = aState.mY + nonCarriedOutVerticalMargin;
-
-    // Shrink wrap our height around our contents.
-    if (aState.GetFlag(BRS_ISBOTTOMMARGINROOT)) {
-      // When we are a bottom-margin root make sure that our last
-      // childs bottom margin is fully applied.
-      // Apply the margin only if there's space for it.
-      if (autoHeight < aState.mReflowState.availableHeight)
-      {
-        // Truncate bottom margin if it doesn't fit to our available height.
-        autoHeight = PR_MIN(autoHeight + aState.mPrevBottomMargin.get(), aState.mReflowState.availableHeight);
-      }
-    }
-
-    if (aState.GetFlag(BRS_SPACE_MGR)) {
-      // Include the space manager's state to properly account for the
-      // bottom margin of any floated elements; e.g., inside a table cell.
-      nscoord floatHeight =
-        aState.ClearFloats(autoHeight, NS_STYLE_CLEAR_LEFT_AND_RIGHT);
-      autoHeight = PR_MAX(autoHeight, floatHeight);
-    }
-
-    // Apply min/max values
+    nscoord autoHeight = bottomEdgeOfChildren;
     autoHeight -= borderPadding.top;
     nscoord oldAutoHeight = autoHeight;
     aReflowState.ApplyMinMaxConstraints(nsnull, &autoHeight);
@@ -1427,6 +1432,7 @@ nsBlockFrame::ComputeFinalSize(const nsHTMLReflowState& aReflowState,
 
   // Screen out negative heights --- can happen due to integer overflows :-(
   aMetrics.height = PR_MAX(0, aMetrics.height);
+  *aBottomEdgeOfChildren = bottomEdgeOfChildren;
 
 #ifdef DEBUG_blocks
   if (CRAZY_WIDTH(aMetrics.width) || CRAZY_HEIGHT(aMetrics.height)) {
@@ -1438,7 +1444,8 @@ nsBlockFrame::ComputeFinalSize(const nsHTMLReflowState& aReflowState,
 
 void
 nsBlockFrame::ComputeCombinedArea(const nsHTMLReflowState& aReflowState,
-                                  nsHTMLReflowMetrics& aMetrics)
+                                  nsHTMLReflowMetrics&     aMetrics,
+                                  nscoord                  aBottomEdgeOfChildren)
 {
   // Compute the combined area of our children
   // XXX_perf: This can be done incrementally.  It is currently one of
@@ -1469,6 +1476,20 @@ nsBlockFrame::ComputeCombinedArea(const nsHTMLReflowState& aReflowState,
     if (mBullet) {
       area.UnionRect(area, mBullet->GetRect());
     }
+
+    // Factor in the bottom edge of the children. Child frames
+    // will be added to the overflow area as we iterate through the lines,
+    // but their margins won't, so we need to account for bottom margins
+    // here. If we're a scrolled block then we also need to account
+    // for the scrollframe's padding, which is logically below the
+    // bottom margins of the children.
+    nscoord bottomEdgeOfContents = aBottomEdgeOfChildren;
+    if (GetStyleContext()->GetPseudoType() == nsCSSAnonBoxes::scrolledContent) {
+      // We're a scrolled frame; the scrollframe's padding should be added
+      // to the bottom edge of the children
+      bottomEdgeOfContents += aReflowState.mComputedPadding.bottom;
+    }
+    area.height = PR_MAX(area.YMost(), bottomEdgeOfContents) - area.y;
   }
 #ifdef NOISY_COMBINED_AREA
   ListTag(stdout);

layout/generic/nsBlockFrame.h

@@ -379,10 +379,12 @@ protected:
 
   virtual void ComputeFinalSize(const nsHTMLReflowState& aReflowState,
                                 nsBlockReflowState&      aState,
-                                nsHTMLReflowMetrics&     aMetrics);
+                                nsHTMLReflowMetrics&     aMetrics,
+                                nscoord*                 aBottomEdgeOfChildren);
 
   void ComputeCombinedArea(const nsHTMLReflowState& aReflowState,
-                           nsHTMLReflowMetrics& aMetrics);
+                           nsHTMLReflowMetrics&     aMetrics,
+                           nscoord                  aBottomEdgeOfChildren);
 
   /** add the frames in aFrameList to this block after aPrevSibling
     * this block thinks in terms of lines, but the frame construction code

layout/reftests/bugs/458296-1-ref.html

@@ -0,0 +1,10 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+<div style="overflow:auto; width:300px; height:300px; background:green;">
+  <div style="height:100px;"></div>
+  <div style="height:200px; margin-left:100px; width:100px; background:yellow;"></div>
+  <div style="height:100px;"></div>
+</div>
+</body>
+</html>

layout/reftests/bugs/458296-1a.html

@@ -0,0 +1,8 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+<div style="overflow:auto; width:100px; height:100px; padding:100px; background:green;">
+  <div style="height:200px; width:100px; background:yellow;"></div>
+</div>
+</body>
+</html>

layout/reftests/bugs/458296-1b.html

@@ -0,0 +1,8 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+<div style="overflow:auto; width:300px; height:300px; background:green;">
+  <div style="height:200px; width:100px; margin:100px; background:yellow;"></div>
+</div>
+</body>
+</html>

layout/reftests/bugs/458296-1c.html

@@ -0,0 +1,10 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+<div style="overflow:auto; width:300px; height:300px; background:green;">
+  <div style="height:100px; margin-top:100px;">
+    <div style="height:200px; margin-left:100px; width:100px; margin-bottom:100px; background:yellow;"></div>
+  </div>
+</div>
+</body>
+</html>

layout/reftests/bugs/458296-1d.html

@@ -0,0 +1,8 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+<div style="overflow:auto; width:300px; height:300px; background:green;">
+  <div style="height:200px; margin-left:100px; width:100px; margin-top:100px; float:left; margin-bottom:100px; background:yellow;"></div>
+</div>
+</body>
+</html>

layout/reftests/bugs/reftest.list

@@ -798,7 +798,7 @@ fails == 411585-3.html 411585-3-ref.html # bug 426909
 == 412607-1b.html 412607-1-ref.html
 == 412679-1.html 412679-1-ref.html
 == 412679-2.html 412679-2-ref.html
-fails == 413027-1.html 413027-1-ref.html
+== 413027-1.html 413027-1-ref.html
 fails == 413027-2.html 413027-2-ref.html
 fails == 413027-3.html 413027-3-ref.html
 == 413027-4.html 413027-4-ref.html
@@ -964,6 +964,10 @@ fails-if(MOZ_WIDGET_TOOLKIT=="cocoa") == 456147.xul 456147-ref.html # bug 456147
 == 456484-1.html 456484-1-ref.html
 == 457398-1.html 457398-1-ref.html
 == 457398-2.html 457398-2-ref.html
+== 458296-1a.html 458926-1-ref.html
+== 458296-1b.html 458926-1-ref.html
+== 458296-1c.html 458926-1-ref.html
+== 458296-1d.html 458926-1-ref.html
 == 458487-1a.html 458487-1-ref.html
 == 458487-1b.html 458487-1-ref.html
 == 458487-1c.html 458487-1-ref.html