Gecko:Debugging Tools: Difference between revisions

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Revision as of 20:11, 15 March 2019

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→‎Frame Tree Dump: add link to a page with documentation on layout debugger

Dholbert

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 == Frame Tree Dump ==
-<bz> for a frame dump, you can use the layout debugger, or... if you're in a debugger and want to examine the tree, you can do
+<bz> for a frame dump, you can use the [https://developer.mozilla.org/en-US/docs/Mozilla/Debugging/Layout_Debugger layout debugger], or... if you're in a debugger and want to examine the tree, you can do
   def frametree
@@ Line 79: / Line 79: @@
 == Printing nsIAtoms ==
-<bz> To print an nsIAtom, you see what concrete type it is using "set print object on", then cast it to that type, etc
+ def pa
+   set $atom = $arg0
+   if (sizeof(*((&*$atom)->mString)) == 2)
+     pu (&*$atom)->mString
+   end
+ end
-<bz> if it's an nsStaticAtom:
+== Reflow Logs ==
-  def satom
+See [[http://www.mozilla.org/newlayout/doc/frame_reflow_debug.html Debugging Frame Reflow]]
-    p *((class nsStaticAtomWrapper*)$arg0)->mStaticAtom
-  end
-<bz> to be used as: ''satom content->Tag()'' or ''satom frame->GetType()''
+== Printing strings ==
-<bz> for nsGkAtoms it'll work great
+ # Define a "ps" command to display subclasses of nsAC?String.  Note that
+ # this assumes strings as of Gecko 1.9 (well, and probably a few
+ # releases before that as well); going back far enough will get you
+ # to string classes that this function doesn't work for.
+ def ps
+   set $str = $arg0
+   if (sizeof(*$str.mData) == 1 && ($str.mFlags & 1) != 0)
+     print $str.mData
+   else
+     pu $str.mData $str.mLength
+   end
+ end
-== Reflow Logs ==
+ # Define a "pu" command to display PRUnichar * strings (100 chars max)
+ # Also allows an optional argument for how many chars to print as long as
+ # it's less than 100.
+ def pu
+  set $uni = $arg0
+  if $argc == 2
+    set $limit = $arg1
+    if $limit > 100
+      set $limit = 100
+    end
+  else
+    set $limit = 100
+  end
+  # scratch array with space for 100 chars plus null terminator.  Make
+  # sure to not use ' ' as the char so this copy/pastes well.
+  set $scratch = "____________________________________________________________________________________________________"
+  set $i = 0
+  set $scratch_idx = 0
+  while (*$uni && $i++ < $limit)
+    if (*$uni < 0x80)
+      set $scratch[$scratch_idx++] = *(char*)$uni++
+    else
+      if ($scratch_idx > 0)
+	set $scratch[$scratch_idx] = '\0'
+	print $scratch
+	set $scratch_idx = 0
+      end
+      print /x *(short*)$uni++
+    end
+  end
+  if ($scratch_idx > 0)
+    set $scratch[$scratch_idx] = '\0'
+    print $scratch
+  end
+ end
+== Dumping the JS Stack ==
-See [[http://www.mozilla.org/newlayout/doc/frame_reflow_debug.html Debugging Frame Reflow]]
+ def js
+   call DumpJSStack()
+ end