MarkShark

Summary: Using a Parallel.BackgroundWorker if I check for WorkItem.CancellationToken.IsSignalled within the .OnExecute anonymous procedure I see that it is terminated immediately if I call FWorker.CancelAll from the main thread. HOWEVER if I use a function called from the OnExecute handler it seems that the token is only signaled once the function completes. I've included some code below, but if anyone could explain what I'm seeing it would be much appreciated! Using a Paralel.BackgroundWorker created like: FWorker := Parallel.BackgroundWorker.Execute(nil); I then schedule a work item like: FWorker.Schedule( FWorker.CreateWorkItem(TOmniValue.Null), FWorker.Config .OnExecute( procedure(const WorkItem: IOmniWorkItem) begin var LElapsed: Integer := 1; repeat Sleep(100); Inc(LElapsed, 100); until WorkItem.CancellationToken.IsSignalled or (LElapsed > 5000); end) .OnRequestDone( procedure (const Sender: IOmniBackgroundWorker; const WorkItem: IOmniWorkItem) begin if WorkItem.CancellationToken.IsSignalled then Memo1.Lines.Add('Task ' + WorkItem.UniqueID.ToString + ' onRequestDone and was cancelled.') else Memo1.Lines.Add('Task ' + WorkItem.UniqueID.ToString + ' onRequestDone'); end ) ); Calling FWorker.CancelAll; from the main thread cancels this workitem immediately. However if instead of the "repeat until" above I call the following function, the token is never signaled "during the call", though it is signaled after the call returns. function NiceWaitEx(const ACancelToken: IOmniCancellationToken; AWaitMs: Integer): Integer; begin const LagMs = 100; var LElapsed: Integer := 1; repeat Sleep(LagMs); Inc(LElapsed, LagMs); until ACancelToken.IsSignalled or (LElapsed > AWaitMs); Result := LElapsed; end; FWorker.Schedule( FWorker.CreateWorkItem(TOmniValue.Null), FWorker.Config .OnExecute( procedure(const WorkItem: IOmniWorkItem) begin NiceWaitEx(WorkItem.CancellationToken, 5000); end) .OnRequestDone( procedure (const Sender: IOmniBackgroundWorker; const WorkItem: IOmniWorkItem) begin if WorkItem.CancellationToken.IsSignalled then Memo1.Lines.Add('Task ' + WorkItem.UniqueID.ToString + ' onRequestDone and was cancelled.') else Memo1.Lines.Add('Task ' + WorkItem.UniqueID.ToString + ' onRequestDone'); end ) ); When I use the second version (with the call) the workitem always goes the full 5 seconds although shows that it was cancelled at the end. I hope that's enough to explain the issue (and my confusion lol.) Any thoughts appreciated! -Mark

Ha! Sorry about that. I didn't notice this question was in FMX! -Mark

I can confirm it. The only solutions are to use a different control (such as the Virtual String Tree) or to use the following library. RRuz VCL Style Utils -Mark

I can confirm the change as well. I've also noticed that the Ctrl-Alt-Up and Ctrl-Alt-Down keys don't seem to navigate between methods anymore (although Ctrl-Alt-Mousewheel still seems to do it.) I was going to suggest it to jump to the first line after begin, but it's gone. So if you want the old behavior you can do Ctrl-Shift-Up, Ctrl-Shift-Down, and then Ctrl-Alt-Mousewheel up! Simple, right? (Wink) Method Hopping: http://docwiki.embarcadero.com/RADStudio/Sydney/en/Code_Navigation_(IDE_Tutorial)

Thanks! I notice you're calling it like ACanvas.SaveDC so I thought maybe you were encapsulating the API functions (my TCanvas doesn't seem to have those as methods.) I do use the api calls directly, but obviously your code is cleaner.

@Anders Melander Are your SaveDC and RestoreDC calls from a class helper for TCanvas? I don't do a lot of canvas drawing and only recently need to use the API functions for this and I don't fully understand when calling Canvas.Refresh is needed... and I'm wondering if your calls handle that. Thanks!

I have a background worker that I create with: FWorker := Parallel.BackgroundWorker .NumTasks(1) .Execute(HandleQueryWorkItem); I queue jobs to this worker and everything works great . I have a situation where I want to check if the worker is idle with a timeout, so I'm trying to use: FWorker.WaitFor(MyMilliseconds); This seems to work in my test cases, however calling WaitFor calls "CompleteAdding" (which seems to make sense.) However it never gets turned back on and future queueing of jobs raises "Adding to completed collection". So is there a way to turn queueing back on, or am I doing something fundamentally wrong? Thanks for any insight or tips! -Mark

Windows file explorer in detail view shows combobox-like headers (on hover over) that allow filtering the data based on the column type (for example to only show files changed today, or to only show Excel documents.) Does anyone know if this is something that the standard TListView control is capable of directly, or is this more an owner draw header type thing? Alternately, is there a similar control that can do this? The TVirtualStringTree in column mode perhaps? My searches on this haven't panned out so I'm wondering if anyone has any suggestions or thoughts. Thanks! -Mark

Thank you François! I ended up creating my own TEmbeddedComboBox and used the handling suggested in Remy's answer to your linked SO question.. and SCORE! procedure TEmbeddedComboBox.WndProc(var Msg: TMessage); begin inherited; if Msg.Msg = WM_GETDLGCODE then Msg.Result := Msg.Result or DLGC_WANTTAB; end;

Lars, thanks. This is code I'm writing for a VirtualStringTree that allows editing. I'm sure you're correct that the actions could be handled at the form level, but obviously I'd prefer to keep the handling internal to the control if possible. I was hoping this was just something I'm thinking incorrectly about, maybe there's another way to handle it. Although the fact that the VST demo app shows the same behavior makes me think it's not an easy fix. I did some code searching and it looks like Delphi's TInplaceEditList (part of the Grids Unit) is what they use instead of just using a TComboBox, I assume that's to give more control and to handle this issue. It's a bit complex for a transplant, so I'm hoping someone can suggest an alternative. It's one of those things where it seems like I'm so close to getting it to work the way I want.

The specific case is that I'm using a TComboBox as an editor in a VirtualStringTree. Unfortunately I can't seem to capture VK_TAB on the KeyDown event of the control. I've used code very similar to the "Properties" tree demo included in the Advanced Demo. Running that demo I get the same affect, pressing Tab while a combobox is active goes to the next focus control. I'd like to handle it much like the enter key and move to the next cell after accepting the edit. Apparently the tab handling is happening at the form level and the TCombobox never seems to get it. Any suggestions on how to handle this? Thanks!

I've attached ProjTest.dproj. I took the following steps: Created a new Vcl project. Added Target Platform Win64 Used the Project Options Dialog to add version info to "All Configurations - All Platforms" setting version 1.2.3.4 (and also editing the key/values) Used the Project Options Dialog to add version info to "All Configurations - Windows 32-bit Platform" setting version 5.6.7.8 (and also editing the key/values) Used the Project Options Dialog to add version info to "All Configurations - Windows 64-bit Platform" setting version 9.10.11.12 (and also editing the key/values) Also added some debug and release version info for each target. Save on Project Options Save Project Result: The debug and release verinfo sections were correctly removed. The Base, Base-Win32 and Base-Win64 sections remain intact (I'm still unsure if that's "as intended" or not.) ProjTest.dproj [added: I'm using Delphi 10.4.1 and the latest Project Magician.]

Yes, though I'll make a new test case and retest my findings just in case it's project specific (this particular project is one that's been around for years.) Thanks for clarifying about when Project Magician does its work!

My projects platforms are Win32 and Win64. Am I correct that the Magician actions take place on Project Save? Basically I'm just switching Targets, changing the version info, then saving the project and then looking at the dproj file to see the results. [added] In my testing with a project that has Win32 and Win64 target platforms only, that Base_Win32 and Base_Win64 retain <verinfo_*> changes when saving the project.

I've been doing some testing of the current version and I might be misunderstanding things. I have a dproj file with a Base config with verinfo information (including <VerInfo_Keys> info.) I added a new one under Base-Win32 and both seem to stay around. I was expecting the win32 one to be removed in favor of Base. Am I misunderstanding how it works? It did correctly remove the verinfo stuff from a debug section. Is this so that you can have different version info for different target platforms? Project Magician is awesome btw!