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

Rob Wilkens robwilkens at gmail.com
Mon Jun 18 20:54:27 UTC 2012

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)

I don't think it'll be a problem though and can probably stand as-is.


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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