[Mono-dev] Win Patches for Datagrid (first here) then idle

Rob Wilkens robwilkens at gmail.com
Mon Jun 18 21:06:19 UTC 2012

I couldn't see it before you pushed it, and may have done it wrong
myself (I don't recall now)..  :-)

I'm sure in the case where this version you wrote would result in a zero
result, the zero result is probably OK.

The version below is probably good if you're ok with it.


On 06/18/2012 04:58 PM, Stifu wrote:
> Hah, that thought did cross my mind.
> Did you just wait for me to push it before saying that? :p
> We could go for:
> 			int next_pixel_offset = pixel_offset;
> 			if (CurrentColumn < CurrentTableStyle.GridColumnStyles.Count)	
> 			{
> 				next_pixel_offset +=
> CurrentTableStyle.GridColumnStyles[CurrentColumn].Width;
> 			}
> Rob Wilkens wrote
>> Slight issue which probably will never be a problem:
>> I'd replace the "0" with "pixel_offset" since the normal condition for
>> that is pixel_offset PLUS the current column (which may be invalid)
>> width.. 
>> I don't think it'll be a problem though and can probably stand as-is.
>> -Rob
>> On 06/18/2012 04:39 PM, Stifu wrote:
>>> Alright, the first patch is in
>>> (https://github.com/mono/mono/commit/42ebb31fc143a171a6a5930bc647627c557842ee).
>>> I took the liberty to change the coding style.
>>> Thanks.
>>> Rob Wilkens wrote
>>>> This is for Stifu:
>>>> Please follow this sequence when applying or testing the patches listed
>>>> below.  Doing in other order may break things.  If you want me to create
>>>> a unit test for something you don't see a unit test for, let me know,
>>>> but in some cases, clicks are required with a mouse and i'm not
>>>> necessarily sure how to create a patch to do that.
>>>> Ok, I've attached the patches i had queued as separate individual
>>>> patches, i hope i did this right..  These are from ranges of git
>>>> diffs..  Please let me know if there are issues, my feelings won't be
>>>> hurt, i'd rather do this right than do it fast.
>>>> The order to apply them in (then i'll get into what it fixes after):
>>>> I'd suggest the DataGrid patches first because they are in the middle of
>>>> everything and get in the way -- except don't apply the
>>>> IdleAndDataGrid.Whitespace.Jun10.patch until you've applied ALL the
>>>> patches prior to Jun 10 (including idle patches), those patches in the
>>>> Whitespace patch don't fix anything other the prettying up the code, but
>>>> they depend on both set of patches in sequence..
>>>> So the sequence i'm suggesting they must be applied in if they are
>>>> applied at all are:
>>>> (1) DataGrid1.Jun3.patch first
>>>> (2) DataGrid2.Jun4.patch second
>>>> (3) DataGrid3.Novell322563.jun4.patch third
>>>> (4) DataGrid4.Novell322154.jun6.patch
>>>> -- but don't do the other one i said not to do at this point --
>>>> now to the idle fixes, these next ones (5-9) are meant to all be applied
>>>> as part of essentially one patch for it to work, but is broken up so you
>>>> can see progression.
>>>> (5) Idle1-3.Jun2 (sorry for forgetting patch extension), This contains 3
>>>> commits in one but they were all related, and makes life easier by being
>>>> summarized into one like this.
>>>> (6) Now you should do IdleAndDataGrid.Whitespace.Jun10.patch
>>>> (7) Next, do Idle-Win32IdleEnable.jun11.patch
>>>> (8) Idle-RaceConditionFix-Jun12.patch is next
>>>> (9) Idle-TestFixForIdle.jun12.patch is last
>>>> There, I have 9 attachments, and above is the sequence to apply them in.
>>>> The below numbering system matches the above patch order
>>>> #1: from the commit message:
>>>> The sample code in
>>>> https://bugzilla.novell.com/show_bug.cgi?id=MONO79788 was crashing on me
>>>> if I clicked on a row header (where the + was). I investigated and found
>>>> that it was because, when the table had no data to display yet, and if
>>>> you clicked on a row header (that's the area to the left of what would
>>>> be the data), as part of assigning the current cell, it would call
>>>> ensure cell visibility function, which would call ScrollToColumnInPixels
>>>> which would try to get the next pixel offset by looking at
>>>> CurrentTableStyle.GridColumnStyles[CurrentColumn].Width, but when no
>>>> data was being displayed there were no columns. So while current column
>>>> had a value of zero, there were no items in the GridColumnStyles
>>>> Array/List, even at zero index. The fix for this was before indexing
>>>> into GridColumnStyles to Check The Length to make sure we're not going
>>>> beyond its bounds. It is probably perfectly acceptable if we're beyond
>>>> the bounds to just leave this value at zero for the offset.
>>>> #2 From the commit message:
>>>> Xamaring bug 5511: This fixes this and some side issues..
>>>> First, fixed the crash by creating two additional stacks for when
>>>> navigating to and from other sub tables... Both were 'style' stacks
>>>> which tracked per column styles. Those needed to be updated and reset on
>>>> a per table basis. Second, When navigating forward or back, EndEdit
>>>> needed to be called so that we don't leave an editing cell open when we
>>>> navigate, otherwise there was the possibility and reality that the
>>>> edited cell would still be visible and editing on the next table either
>>>> forward or back. To recreate this on the sample code, presuming you can
>>>> get past the initial crash which was fixed here, this could be
>>>> illustrated without the endedits that were added as follows : Run: 1.
>>>> click + 2. click pb 3. click + 4. click pb 3. click + 5. click pd 6.
>>>> click back 6. click pc 7. See 0 highlighted in column header from
>>>> previous table Finally, I modified some previous submissions on a
>>>> related problem so that they had more "Love for Spaces" (whitespace)
>>>> without changing the actual code other than that.
>>>> The above may have fixed, i think it was 5510 too.
>>>> #3: From the commit
>>>> This solves PART of Novell Bugzilla Issue #322563
>>>> https://bugzilla.novell.com/show_bug.cgi?id=322563 What this
>>>> accomplishes is that it hides the non browsable columns (columns that
>>>> were not part of the original dataset, in the test case) from view in
>>>> the DataGrid. Unfortunately, i can't see an obvious way to hide
>>>> the'parent rows' display of those non browsable columns value. That is
>>>> if You viewed a subtable off hidden field pb_Id=0 it would show that
>>>> value (pb_Id=0) on the top of the datagrid where it shows the previous
>>>> rows. The remaining issue seems to be a non major issue since it is a
>>>> non functional issue.
>>>> #4: From the commit
>>>> Novell #323154
>>>> Decided to include this in same branch (same pull request) as earlier
>>>> changes due to it affecting the same DataGrid.cs -- i didn't want any
>>>> conflicts. Here's a copy of what i wrote up earlier about this: the
>>>> problem report is here:
>>>> https://bugzilla.novell.com/show_bug.cgi?id=323154 I found by deduction
>>>> that the repaint wasn't cancelling the active edit box after the row was
>>>> deleted .. So while the table updated, the edit box with the old value
>>>> didn't go away... The repaint was initiated from an Invalidate call
>>>> which stack trace looked something like this:
>>>> System.Windows.Forms.DataGrid.CalcAreasAndInvalidate() at
>>>> System.Windows.Forms.DataGrid.RecreateDataGridRows(Boolean recalc) at
>>>> System.Windows.Forms.DataGrid.OnListManagerItemChanged(System.Object
>>>> sender, System.Windows.Forms.ItemChangedEventArgs e) at
>>>> System.Windows.Forms.CurrencyManager.OnItemChanged(System.Windows.Forms.ItemChangedEventArgs
>>>> e) at System.Windows.Forms.CurrencyManager.UpdateIsBinding() at
>>>> System.Windows.Forms.CurrencyManager.ListChangedHandler(System.Object
>>>> sender, System.ComponentModel.ListChangedEventArgs e) at
>>>> System.Data.DataView.OnListChanged(System.ComponentModel.ListChangedEventArgs
>>>> e) at System.Data.DataView.OnRowDeleted(System.Object sender,
>>>> System.Data.DataRowChangeEventArgs args) at
>>>> System.Data.DataTable.OnRowDeleted(System.Data.DataRowChangeEventArgs e)
>>>> at System.Data.DataTable.DeletedDataRow(System.Data.DataRow dr,
>>>> DataRowAction action) at System.Data.DataRow.Delete() at
>>>> System.Data.DataView.Delete(Int32 index) at
>>>> System.Data.DataRowView.Delete() at grid.ProcessCmdKey(Message ByRef
>>>> msg, Keys keyData) (etc) ProcessCmdKey is from user code in sample in
>>>> bug report... After the delete (as seen above), the first thing the
>>>> DataGrid gets back is an OnListManagerItemChanged... Before that would
>>>> call RecreateDataGridRows(), if it was going to do that, i inserted a
>>>> check to see if we're editing, and if so, i cancel the edit (because
>>>> we're reloading dataset), here is a summary of what my patch will look
>>>> like in ONListManagerItemChanged in DataGrid.cs in System.Windows.Forms
>>>> directory: if (rows == null || RowsCount != rows.Length - (ShowEditRow ?
>>>> 1 : 0)) + { + if (is_editing) + CancelEditing (); RecreateDataGridRows
>>>> (true); + } This solved the problem reported. It is now identical to
>>>> windows .net behavior from what i can see, as far as this problem report
>>>> goes anyway. MS .NET Crashes as well as mono in the sample code if you
>>>> press a key twice to delete two rows when there was only one row to
>>>> delete (index out of range). This is not necessarily a good thing, but
>>>> it's user code from the bug report which causes that, not anything
>>>> inherently different in mono.
>>>> #5-#9 are all about fixing bug From Novell #321541 which if i have the
>>>> right number is adding the ability to have the idle event handler only
>>>> send idle events to the thread the idle handler was assigned in.  So if
>>>> you have 2 threads, and they each assigned an idle event handler, they
>>>> would each get their own idle event handler called when that thread went
>>>> idle.  Or if only one thread had an idle event handler assigned that
>>>> same idle handler wouldn't be called for EVERY thread, it would only be
>>>> called on the thread it was assigned on.  This is so it more closely
>>>> matches the windows .net behavior.
>>>> I'll include each of the individual commit messages though they were all
>>>> towards the same goal
>>>> #5 had three commits:
>>>> This addresses a 6-year old Novell bugzilla issue: 321541...
>>>> Created a hashtable of per-thread event handlers for idle.. Assigned in
>>>> to that hashtable when the regular Idle eventhandler was assigned by
>>>> mapping it by ManagedThreadId. The hashtable had to use a separate
>>>> object (different class) rather than an EventHandler directly, because
>>>> an eventhandler apparently cannot be assigned to another object, it can
>>>> only be a part of a class. It also couldn't be checked for null or
>>>> called from outside the class so i handled that as appropriate (by
>>>> secondary callers). This has been checked against the code in 321541 and
>>>> the code appears to work fine now. I have also confirmed no new unit
>>>> test failures have been introduced by this change. There were 3 failures
>>>> before, and are three failures now. Also, This includes a unit test,
>>>> which will fail without this patch. Here's a shortcut to the Novell bug:
>>>> https://bugzilla.novell.com/show_bug.cgi?id=321541
>>>> Per suggestion, Changed a Hashtable to a generic dictionary.
>>>> This change is to properly use the GenericDictionary to use
>>>> the EventHandler type directly rather than the temporary class that was
>>>> being used in my first attempt at this.
>>>> (so some of the changes from the first commit you don't see here because
>>>> they were thrown away by the second and third in a rewrite)
>>>> #6 is a bunch of whitespace fixes for Datagrid and idle which has to be
>>>> applied at this point in sequence.
>>>> #7 Enables the idle message to work on Win32.  When i tested on Win32 i
>>>> realized the Idle event handler was never called, so i fixed that so
>>>> when it went idle it would call it.
>>>> Here's the commit from #7:
>>>> This patch will enable the idle event to be called when the applicati...
>>>> ...on is idle on Win32. This was necessary to make an earlier unit test
>>>> from the same set of patches work on win32. Plus, it's a good idea.
>>>> #8 This is important, essentially this had a lock set to stop a race
>>>> condition that was happening with the test. There was an 'if something
>>>> == null assign something to something new... And two threads were
>>>> hitting this code at the same time and this was causing one thread to
>>>> assign it, and before it would start working with it, thread 2 would
>>>> reassign it, and this resulted in a stack dump (exception) in add_Idle,
>>>> this fix seemed to stop that.
>>>> Here's the commit message
>>>> This code fixes a possible race condition which during my testing seemed
>>>> to be hit about once every twenty runs or so. Sometimes if two threads
>>>> were assigning the idle handler at the same time, and it's the first
>>>> assignment, they will both try to assign a new dictionary. This resulted
>>>> in funny behavior, such as immediately after an add, the item wouldn't
>>>> be found. After applying this fix, a lock around that particular
>>>> check/assignment, I reran the tests about 50-75 times and never ran into
>>>> this race condition again.
>>>> #9 the last one is just some test changes after what i was told about
>>>> mono requiring that all threads create the forms in the same thread.
>>>> This only seemed to be a problem on windows, from what i recall, and
>>>> only occasionally.
>>>> The commit message reads:
>>>> Due to a WinForms requriement (which only seems to occasionally be a
>>>> problem on Windows), where all Controls (including Forms) must be
>>>> created on One Thread, and then to do work on them from other threads
>>>> only by use of invoke ( According to :
>>>> http://www.mono-project.com/FAQ:_Winforms ), I modified my unit test
>>>> accordingly to be in compliance.
>>>> _______________________________________________
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