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Fix System.ObjectDisposedException for TransparentTextBox #2619

Merged
merged 1 commit into from
Dec 30, 2018
Merged

Fix System.ObjectDisposedException for TransparentTextBox #2619

merged 1 commit into from
Dec 30, 2018
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DasSkelett
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@DasSkelett DasSkelett commented Dec 20, 2018 •
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With #2610 I created a new TransparentTextBox class derived from TextBox, which allows textboxes with transparent background.
For unknown reasons, they behave different to normal textboxes when you close the GUI.
The seem to get disposed too early, because DataGridView wants to clear the selection before getting disposed. This triggers multiple methods one after the other, including Main.ModList_SelectedIndexChanged(), which finally leads to hiding the mod info tab and its included controls.
But all transparent textboxes are already disposed, so it throws the

System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'CKAN.TransparentTextBox'.

error.

Workaround:

Now I break the chain in Main.ModList_SelectedIndexChanged() by testing if the ModInfoTabControl is already disposed, and if so, do nothing more, so don't try to hide every control in the end.

HebaruSan currently tries to find the cause of the bug.

Fixes #2618 , more or less.

@DasSkelett
Fix accessing TransparentTextBox after disposing
48dfd3a 
On form close, all controls are set to invisible, but TransparentTextBoxes are already disposed.
This commit blocks the method if the the tab control is already disposed.
@HebaruSan HebaruSan added Bug Something is not working as intended GUI Issues affecting the interactive GUI Pull request Linux Issues specific for Linux Mono Issues specific for Mono labels Dec 21, 2018
@HebaruSan
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Trying to figure out why your class is treated differently, TextBox has a couple of attributes on it:

	[ComVisible(true)]
	[ClassInterface (ClassInterfaceType.AutoDispatch)]

https://github.com/mono/mono/blob/0d6d334bcba28f2fb4c6cd5498b48e9c85c782d8/mcs/class/System.Windows.Forms/System.Windows.Forms/TextBox.cs#L39-L40

Can you check whether adding those to TransparentTextBox has any effect (without this PR's changes)? There must be some factor that tells the runtime to work around this exception for the built in controls, and ideally we ought to use the same thing.

If not, I kind of want to take it for a spin with a custom compiled Mono to investigate, but that would probably have to be after the 25th at this point.

@DasSkelett
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DasSkelett commented Dec 21, 2018 •
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Looks bad for your holidays...
Adding those lines without my previous changes throws the error again.

@politas
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politas commented Dec 26, 2018

Hmm, I'm getting this when I run this branch - I get the instance selector, then it throws the exception.

$ ckan gui
System.NullReferenceException: Object reference not set to an instance of an object
  at CKAN.Main._UpdateFilters () [0x00021] in <8879e6ea4bdf46bfb52dcc353054c973>:0 
  at CKAN.Util.Invoke[T] (T obj, System.Action action) [0x0002d] in <8879e6ea4bdf46bfb52dcc353054c973>:0 
  at CKAN.Main.UpdateFilters (CKAN.Main control) [0x00001] in <8879e6ea4bdf46bfb52dcc353054c973>:0 
  at CKAN.Main.<.ctor>b__37_0 (CKAN.MainModList source) [0x00000] in <8879e6ea4bdf46bfb52dcc353054c973>:0 
  at CKAN.MainModList.set_ModFilter (CKAN.GUIModFilter value) [0x00029] in <8879e6ea4bdf46bfb52dcc353054c973>:0 
  at CKAN.Main.Filter (CKAN.GUIModFilter filter) [0x00007] in <8879e6ea4bdf46bfb52dcc353054c973>:0 
  at CKAN.Main.CurrentInstanceUpdated () [0x00077] in <8879e6ea4bdf46bfb52dcc353054c973>:0 
  at CKAN.Main.OnLoad (System.EventArgs e) [0x00299] in <8879e6ea4bdf46bfb52dcc353054c973>:0 
  at System.Windows.Forms.Form.OnLoadInternal (System.EventArgs e) [0x00023] in <5bcdf2a3746f4353acffcd001a2c6899>:0

@DasSkelett
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Huh, I have no idea how my changes could affect _updateFilters() and what variable is null and not catched there, but I'm not at home until January 8th to properly investigate this error.

@HebaruSan
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I'm guessing that's #2624. I can't even launch current HEAD on Mono.

@DasSkelett
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DasSkelett commented Dec 26, 2018 •
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I would be happy if this is the case. I can't find any way in which my change leave something Null which is later somehow accessed (even over detours) by _updateFilters(), especially as ModList_SelectedIndexChanged() only is used to handle the mod info panel.
Also my addition should only affect closing, not opening CKAN.

Sorry, something went wrong.

@HebaruSan
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Wait, if this branch hasn't been rebased or merged, then that wouldn't make sense since #2617's change wouldn't be here. Never mind...

@DasSkelett
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That's not what I was hoping for...

@DasSkelett
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@politas On which OS do you get the error? I don't encounter it on Kubuntu nor Windows...

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politas commented Dec 29, 2018

@DasSkelett ignore my report. I'm getting the same error on master Head.

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That's an emotional rollercoaster with you guys...

@HebaruSan
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Good news, @DasSkelett, it's not your fault! Changing the controls back to ordinary TextBoxes...

System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'System.Windows.Forms.TextBox'.
  at System.Windows.Forms.Control.CreateHandle () [0x00013] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.TextBoxBase.CreateHandle () [0x00006] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.CreateGraphics () [0x00008] in <a78030b9a9a543b381a52822d20656d0>:0 
  at (wrapper remoting-invoke-with-check) System.Windows.Forms.Control.CreateGraphics()
  at System.Windows.Forms.Document.owner_VisibleChanged (System.Object sender, System.EventArgs e) [0x0000d] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.OnVisibleChanged (System.EventArgs e) [0x0002f] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.OnParentVisibleChanged (System.EventArgs e) [0x00008] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.OnVisibleChanged (System.EventArgs e) [0x00053] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.ScrollableControl.OnVisibleChanged (System.EventArgs e) [0x0001a] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.OnParentVisibleChanged (System.EventArgs e) [0x00008] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.OnVisibleChanged (System.EventArgs e) [0x00053] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.ScrollableControl.OnVisibleChanged (System.EventArgs e) [0x0001a] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.OnParentVisibleChanged (System.EventArgs e) [0x00008] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.OnVisibleChanged (System.EventArgs e) [0x00053] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.OnParentVisibleChanged (System.EventArgs e) [0x00008] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.OnVisibleChanged (System.EventArgs e) [0x00053] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.ScrollableControl.OnVisibleChanged (System.EventArgs e) [0x0001a] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.OnParentVisibleChanged (System.EventArgs e) [0x00008] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.OnVisibleChanged (System.EventArgs e) [0x00053] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.ScrollableControl.OnVisibleChanged (System.EventArgs e) [0x0001a] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.OnParentVisibleChanged (System.EventArgs e) [0x00008] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.OnVisibleChanged (System.EventArgs e) [0x00053] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.ScrollableControl.OnVisibleChanged (System.EventArgs e) [0x0001a] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.OnParentVisibleChanged (System.EventArgs e) [0x00008] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.OnVisibleChanged (System.EventArgs e) [0x00053] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.ScrollableControl.OnVisibleChanged (System.EventArgs e) [0x0001a] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.SetVisibleCore (System.Boolean value) [0x00176] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.Control.set_Visible (System.Boolean value) [0x00009] in <a78030b9a9a543b381a52822d20656d0>:0 
  at System.Windows.Forms.SplitterPanel.set_Visible (System.Boolean value) [0x00000] in <a78030b9a9a543b381a52822d20656d0>:0 
  at (wrapper remoting-invoke-with-check) System.Windows.Forms.SplitterPanel.set_Visible(bool)

(etc., etc.) So this is probably caused purely by #2556. With that in mind, I think the current fix makes sense.

@DasSkelett
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Christmas is 5 days late, but I won't complain.

@DasSkelett DasSkelett mentioned this pull request Dec 30, 2018
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@politas politas merged commit 48dfd3a into KSP-CKAN:master Dec 30, 2018
politas added a commit that referenced this pull request Dec 30, 2018
@politas
Merge #2619 Fix System.ObjectDisposedException for TransparentTextBox
f98b9f0
@DasSkelett DasSkelett deleted the fix/disposedTextBox branch December 31, 2018 01:21
@DasSkelett DasSkelett mentioned this pull request Jan 10, 2019
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"System.ObjectDisposedException: Cannot access a disposed object." error on closing form
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