Bug 960899 - Add debug function and lldb command to print frame state symbolically. r=dbaron

layout/generic/moz.build

@@ -63,6 +63,7 @@ UNIFIED_SOURCES += [
     'nsFrame.cpp',
     'nsFrameList.cpp',
     'nsFrameSetFrame.cpp',
+    'nsFrameState.cpp',
     'nsFrameUtil.cpp',
     'nsGfxScrollFrame.cpp',
     'nsHTMLCanvasFrame.cpp',

layout/generic/nsBulletFrame.cpp

@@ -35,6 +35,12 @@ NS_DECLARE_FRAME_PROPERTY(FontSizeInflationProperty, nullptr)
 
 NS_IMPL_FRAMEARENA_HELPERS(nsBulletFrame)
 
+#ifdef DEBUG
+NS_QUERYFRAME_HEAD(nsBulletFrame)
+  NS_QUERYFRAME_ENTRY(nsBulletFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsFrame)
+#endif
+
 nsBulletFrame::~nsBulletFrame()
 {
 }

layout/generic/nsBulletFrame.h

@@ -40,6 +40,10 @@ private:
 class nsBulletFrame : public nsFrame {
 public:
   NS_DECL_FRAMEARENA_HELPERS
+#ifdef DEBUG
+  NS_DECL_QUERYFRAME_TARGET(nsBulletFrame)
+  NS_DECL_QUERYFRAME
+#endif
 
   nsBulletFrame(nsStyleContext* aContext)
     : nsFrame(aContext)

layout/generic/nsFrameState.cpp

@@ -0,0 +1,74 @@
+/* -*- 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/. */
+
+/* constants for frame state bits and a type to store them in a uint64_t */
+
+#include "nsFrameState.h"
+
+#include "nsBlockFrame.h"
+#include "nsBoxFrame.h"
+#include "nsBulletFrame.h"
+#include "nsGfxScrollFrame.h"
+#include "nsIFrame.h"
+#include "nsISVGChildFrame.h"
+#include "nsImageFrame.h"
+#include "nsInlineFrame.h"
+#include "nsPlaceholderFrame.h"
+#include "nsSVGContainerFrame.h"
+#include "nsTableCellFrame.h"
+#include "nsTableRowFrame.h"
+#include "nsTableRowGroupFrame.h"
+#include "nsTextFrame.h"
+
+namespace mozilla {
+
+#ifdef DEBUG
+nsCString
+GetFrameState(nsIFrame* aFrame)
+{
+  nsCString result;
+  nsAutoTArray<const char*,3> groups;
+
+  nsFrameState state = aFrame->GetStateBits();
+
+  if (state == nsFrameState(0)) {
+    result.AssignLiteral("0");
+    return result;
+  }
+
+#define FRAME_STATE_GROUP(name_, class_)                                      \
+  {                                                                           \
+    class_* frame = do_QueryFrame(aFrame);                                    \
+    if (frame && (groups.IsEmpty() || strcmp(groups.LastElement(), #name_))) {\
+      groups.AppendElement(#name_);                                           \
+    }                                                                         \
+  }
+#define FRAME_STATE_BIT(group_, value_, name_)                                \
+  if ((state & NS_FRAME_STATE_BIT(value_)) && groups.Contains(#group_)) {     \
+    if (!result.IsEmpty()) {                                                  \
+      result.Insert(" | ", 0);                                                \
+    }                                                                         \
+    result.Insert(#name_, 0);                                                 \
+    state = state & ~NS_FRAME_STATE_BIT(value_);                              \
+  }
+#include "nsFrameStateBits.h"
+#undef FRAME_STATE_GROUP
+#undef FRAME_STATE_BIT
+
+  if (state) {
+    result.AppendPrintf(" | 0x%0llx", state);
+  }
+
+  return result;
+}
+
+void
+PrintFrameState(nsIFrame* aFrame)
+{
+  printf("%s\n", GetFrameState(aFrame).get());
+}
+#endif
+
+} // namespace mozilla

layout/generic/nsFrameState.h

@@ -63,4 +63,11 @@ inline nsFrameState& operator^=(nsFrameState& aLeft, nsFrameState aRight)
 #define NS_FRAME_IMPL_RESERVED                      nsFrameState(0xF0000000FFF00000)
 #define NS_FRAME_RESERVED                           ~NS_FRAME_IMPL_RESERVED
 
+namespace mozilla {
+#ifdef DEBUG
+nsCString GetFrameState(nsIFrame* aFrame);
+void PrintFrameState(nsIFrame* aFrame);
+#endif
+}
+
 #endif /* nsFrameState_h_ */ 

layout/generic/nsFrameStateBits.h

@@ -30,6 +30,11 @@
     which group the bit belongs to, value_ is the bit number (0..63),
     and name_ is the name of the frame state bit constant.
 
+  Note that if you add a new frame state group, you'll need to #include
+  the header for its frame classes in nsFrameState.cpp and, if they don't
+  already, add nsQueryFrame implementations (which can be DEBUG-only) to
+  the frame classes.
+
  ******/
 
 #ifndef FRAME_STATE_GROUP

layout/generic/nsPlaceholderFrame.cpp

@@ -26,6 +26,12 @@ NS_NewPlaceholderFrame(nsIPresShell* aPresShell, nsStyleContext* aContext,
 
 NS_IMPL_FRAMEARENA_HELPERS(nsPlaceholderFrame)
 
+#ifdef DEBUG
+NS_QUERYFRAME_HEAD(nsPlaceholderFrame)
+  NS_QUERYFRAME_ENTRY(nsPlaceholderFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsFrame)
+#endif
+
 /* virtual */ nsSize
 nsPlaceholderFrame::GetMinSize(nsBoxLayoutState& aBoxLayoutState)
 {

layout/generic/nsPlaceholderFrame.h

@@ -54,6 +54,10 @@ nsIFrame* NS_NewPlaceholderFrame(nsIPresShell* aPresShell,
 class nsPlaceholderFrame MOZ_FINAL : public nsFrame {
 public:
   NS_DECL_FRAMEARENA_HELPERS
+#ifdef DEBUG
+  NS_DECL_QUERYFRAME_TARGET(nsPlaceholderFrame)
+  NS_DECL_QUERYFRAME
+#endif
 
   /**
    * Create a new placeholder frame.  aTypeBit must be one of the

layout/xul/nsBoxFrame.cpp

@@ -104,6 +104,12 @@ NS_NewBoxFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
 
 NS_IMPL_FRAMEARENA_HELPERS(nsBoxFrame)
 
+#ifdef DEBUG
+NS_QUERYFRAME_HEAD(nsBoxFrame)
+  NS_QUERYFRAME_ENTRY(nsBoxFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsContainerFrame)
+#endif
+
 nsBoxFrame::nsBoxFrame(nsIPresShell* aPresShell,
                        nsStyleContext* aContext,
                        bool aIsRoot,

layout/xul/nsBoxFrame.h

@@ -32,6 +32,10 @@ class nsBoxFrame : public nsContainerFrame
 {
 public:
   NS_DECL_FRAMEARENA_HELPERS
+#ifdef DEBUG
+  NS_DECL_QUERYFRAME_TARGET(nsBoxFrame)
+  NS_DECL_QUERYFRAME
+#endif
 
   friend nsIFrame* NS_NewBoxFrame(nsIPresShell* aPresShell, 
                                   nsStyleContext* aContext,

python/lldbutils/README.txt

@@ -84,6 +84,19 @@ called with a smart pointer like nsRefPtr or nsCOMPtr.
   11
 
 
+* pstate EXPR
+
+  Shows the frame state bits (using their symbolic names) of a given frame.
+  EXPR is an expression that is evaluated, and must be an nsIFrame*.
+
+  (lldb) p this
+  (nsTextFrame *) $1 = 0x000000011f470b10
+  (lldb) p/x mState
+  (nsFrameState) $2 = 0x0000004080604000
+  (lldb) pstate this
+  TEXT_HAS_NONCOLLAPSED_CHARACTERS | TEXT_END_OF_LINE | TEXT_START_OF_LINE | NS_FRAME_PAINTED_THEBES | NS_FRAME_INDEPENDENT_SELECTION
+
+
 * ptag EXPR
 
   Shows the DOM tag name of a node.  EXPR is an expression that is

python/lldbutils/lldbutils/layout.py

@@ -8,8 +8,13 @@ def frametreelimited(debugger, command, result, dict):
     """Dumps the subtree of a frame tree rooted at the given nsIFrame*."""
     debugger.HandleCommand('expr (' + command + ')->DumpFrameTreeLimited()')
 
+def pstate(debugger, command, result, dict):
+    """Displays a frame's state bits symbolically."""
+    debugger.HandleCommand('expr mozilla::PrintFrameState(' + command + ')')
+
 def init(debugger):
     debugger.HandleCommand('command script add -f lldbutils.layout.frametree frametree')
     debugger.HandleCommand('command script add -f lldbutils.layout.frametreelimited frametreelimited')
     debugger.HandleCommand('command alias ft frametree')
     debugger.HandleCommand('command alias ftl frametreelimited')
+    debugger.HandleCommand('command script add -f lldbutils.layout.pstate pstate');