Support margin-top for legend in fieldset.

third_party/WebKit/Source/core/paint/FieldsetPainter.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/FieldsetPainter.h"
 
 #include "core/layout/LayoutFieldset.h"
 #include "core/paint/BoxDecorationData.h"
 #include "core/paint/BoxPainter.h"
 #include "core/paint/LayoutObjectDrawingRecorder.h"
@@ skipping 13 matching lines @@
 
   if (LayoutObjectDrawingRecorder::useCachedDrawingIfPossible(
           paintInfo.context, m_layoutFieldset, paintInfo.phase))
     return;
 
   // FIXME: We need to work with "rl" and "bt" block flow directions.  In those
   // cases the legend is embedded in the right and bottom borders respectively.
   // https://bugs.webkit.org/show_bug.cgi?id=47236
   if (m_layoutFieldset.style()->isHorizontalWritingMode()) {
     LayoutUnit yOff =
-        (legend->location().y() > 0)
-            ? LayoutUnit()
-            : (legend->size().height() - m_layoutFieldset.borderTop()) / 2;
+        (legend->location().y() +
+         (legend->size().height() - m_layoutFieldset.borderTop()) / 2)
+            .clampNegativeToZero();
+
     paintRect.setHeight(paintRect.height() - yOff);
     paintRect.setY(paintRect.y() + yOff);
   } else {
     LayoutUnit xOff =
-        (legend->location().x() > 0)
-            ? LayoutUnit()
-            : (legend->size().width() - m_layoutFieldset.borderLeft()) / 2;
+        (legend->location().x() +
+         (legend->size().width() - m_layoutFieldset.borderLeft()) / 2)
+            .clampNegativeToZero();
+
     paintRect.setWidth(paintRect.width() - xOff);
     paintRect.setX(paintRect.x() + xOff);
   }
 
   LayoutObjectDrawingRecorder recorder(paintInfo.context, m_layoutFieldset,
                                        paintInfo.phase, paintRect);
   BoxDecorationData boxDecorationData(m_layoutFieldset);
 
   if (boxDecorationData.bleedAvoidance == BackgroundBleedNone)
     BoxPainter::paintBoxShadow(paintInfo, paintRect,
@@ skipping 50 matching lines @@
 
   if (LayoutObjectDrawingRecorder::useCachedDrawingIfPossible(
           paintInfo.context, m_layoutFieldset, paintInfo.phase))
     return;
 
   // FIXME: We need to work with "rl" and "bt" block flow directions.  In those
   // cases the legend is embedded in the right and bottom borders respectively.
   // https://bugs.webkit.org/show_bug.cgi?id=47236
   if (m_layoutFieldset.style()->isHorizontalWritingMode()) {
     LayoutUnit yOff =
-        (legend->location().y() > LayoutUnit())
-            ? LayoutUnit()
-            : (legend->size().height() - m_layoutFieldset.borderTop()) / 2;
+        (legend->location().y() +
+         (legend->size().height() - m_layoutFieldset.borderTop()) / 2)
+            .clampNegativeToZero();
+
     paintRect.expand(LayoutUnit(), -yOff);
     paintRect.move(LayoutUnit(), yOff);
   } else {
     LayoutUnit xOff =
-        (legend->location().x() > LayoutUnit())
-            ? LayoutUnit()
-            : (legend->size().width() - m_layoutFieldset.borderLeft()) / 2;
+        (legend->location().x() +
+         (legend->size().width() - m_layoutFieldset.borderLeft()) / 2)
+            .clampNegativeToZero();
+
     paintRect.expand(-xOff, LayoutUnit());
     paintRect.move(xOff, LayoutUnit());
   }
 
   LayoutObjectDrawingRecorder recorder(paintInfo.context, m_layoutFieldset,
                                        paintInfo.phase, paintRect);
   BoxPainter(m_layoutFieldset).paintMaskImages(paintInfo, paintRect);
 }
 
 }  // namespace blink