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  • Conseqences of assigning self

    - by Vegar
    Hi, Found a piece of code today, that I find a little smelly... TMyObject.LoadFromFile(const filename: String); begin if fileExists(filename) then self := TSomeObjectStreamer.ReadObjectFromFile(filename); end; If this code works, it will atleast leak some memory, but does it work? Is OK to assign to self in this manner? What if the streamed object is of a different subclass then the original self? What if the streamed object is of a different class with no common ancestore to the original self?

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  • Owner Vs PArent and Taction shortcuts on Frames

    - by Fred
    I have a form with a panel. I create frames at runtime and display them on the panel by setting frame's parent property to the panel. When creating panels I do not set the owner property because i manage myself the lifetime of the frame. Until now i got no problem. Next I put an TActionList on the frame with some shortcuts on the actions. I found that my actions did not execute until I set the owner property of the frame to the panel. Can someone can explain me that ? I thought that owner property was just about wich component is responsible to free the children components, and not responsible to forward key events.

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  • How to simulate a dial-up connection for testing purposes?

    - by mawg
    I have to code a server app where clients open a TCP/IP socket, send some data and close the connection. The data packets are small < 100 bytes, however there is talk of having them batch their transactions and send multiple packets. How can I best simulate a dial-up ut connection (using Delphy & Indy components, just FYI)? Is it as simple as open connection wait a while (what is the definition of "a while"?) close connection

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  • TStringGrid with BOTH editing AND range selection?

    - by Kevin Killion
    Question: Can anyone point to an article or code samples anywhere on how to provide BOTH editing AND range selection in a TStringGrid? Yes, I KNOW there are third-party grids that do this, but it's frustrating that the built-in grid lacks this basic capability. Background: It's pretty normal to expect to be able to both edit a cell in a grid, and also to select a range of cells such as for a Copy operation. As delivered, TStringGrid doesn't do that. It's either/or. In fact, the docs tell us about the grid Options, "When goEditing is included in Options, goRangeSelect has no effect". However, it looks like it may be possible to do editing and rangeselects in a TStringGrid anyway!!! Through careful use of the mousedown, mouseup, selectcell and exit events, you can get dang close by switching editing elements on and off at the right times. But I still don't have it perfect, and that only covers mouse use, not keyboard changes.

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  • Why do Pascal control structures appear to be inconsistent?

    - by 70Mike
    Most Pascal control structures make sense to me, like: for ... do {statement}; if (condition) then {statement}; while (condition) do {statement}; where the {statement} is either a single statement, or a begin ... end block. I have a problem with: repeat {statement-list} until (expression); try {statement-list} except {statement-list} end; Wouldn't it be better that repeat and try have the same general structure, accepting only a single statement or a begin ... end block, instead of having a statement-list that's not formally blocked with a begin and an end?

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  • How I can get information about the scrollbars of an Webbrowser control instance or the IE Webrowser?

    - by Salvador
    I need to get information about the scrollbars (position, size, visibility) of a Webbrowser control of an external application, I tried using the GetScrollBarInfo function from my previous question, but the function always return false, I checked this function with another applications and works fine , but not with the IE or the Webbrowser control. So how I can get information about the scrollbars of an Webbrowser control instance or the IE Webbrowser?

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  • Delphi7 - How can i copy a file that is being written to

    - by Simon
    I have an application that logs information to a daily text file every second on a master PC. A Slave PC on the network using the same application would like to copy this text file to its local drive. I can see there is going to be file access issues. These files should be no larger than 30-40MB each. the network will be 100MB ethernet. I can see there is potential for the copying process to take longer than 1 second meaning the logging PC will need to open the file for writing while it is being read. What is the best method for the file writing(logging) and file copying procedures? I know there is the standard Windows CopyFile() procedure, however this has given me file access problems. There is also TFileStream using the fmShareDenyNone flag, but this also very occasionally gives me an access problem too (like 1 per week). What is this the best way of accomplishing this task? My current File Logging: procedure FSWriteline(Filename,Header,s : String); var LogFile : TFileStream; line : String; begin if not FileExists(filename) then begin LogFile := TFileStream.Create(FileName, fmCreate or fmShareDenyNone); try LogFile.Seek(0,soFromEnd); line := Header + #13#10; LogFile.Write(line[1],Length(line)); line := s + #13#10; LogFile.Write(line[1],Length(line)); finally logfile.Free; end; end else begin line := s + #13#10; Logfile:=tfilestream.Create(Filename,fmOpenWrite or fmShareDenyNone); try logfile.Seek(0,soFromEnd); Logfile.Write(line[1], length(line)); finally Logfile.free; end; end; end; My file copy procedure: procedure DoCopy(infile, Outfile : String); begin ForceDirectories(ExtractFilePath(outfile)); //ensure folder exists if FileAge(inFile) = FileAge(OutFile) then Exit; //they are the same modified time try { Open existing destination } fo := TFileStream.Create(Outfile, fmOpenReadWrite or fmShareDenyNone); fo.Position := 0; except { otherwise Create destination } fo := TFileStream.Create(OutFile, fmCreate or fmShareDenyNone); end; try { open source } fi := TFileStream.Create(InFile, fmOpenRead or fmShareDenyNone); try cnt:= 0; fi.Position := cnt; max := fi.Size; {start copying } Repeat dod := BLOCKSIZE; // Block size if cnt+dod>max then dod := max-cnt; if dod>0 then did := fo.CopyFrom(fi, dod); cnt:=cnt+did; Percent := Round(Cnt/Max*100); until (dod=0) finally fi.free; end; finally fo.free; end; end;

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  • how important to register(license) your own components?

    - by XBasic3000
    i am new to component building, and i had notice to other components has a a comment on top of there units like agreement, terms and condition etc. wither its free or commercial. How important is to register(license) your own component and how/where? and when do you need to register it? how about the freeware? must have a licese too?

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  • Visibility of reintroduced constructor

    - by avenmore
    I have reintroduced the form constructor in a base form, but if I override the original constructor in a descendant form, the reintroduced constructor is no longer visible. type TfrmA = class(TForm) private FWndParent: HWnd; public constructor Create(AOwner: TComponent; const AWndParent: Hwnd); reintroduce; overload; virtual; end; constructor TfrmA.Create(AOwner: TComponent; const AWndParent: Hwnd); begin FWndParent := AWndParent; inherited Create(AOwner); end; type TfrmB = class(TfrmA) private public end; type TfrmC = class(TfrmB) private public constructor Create(AOwner: TComponent); override; end; constructor TfrmC.Create(AOwner: TComponent); begin inherited Create(AOwner); end; When creating: frmA := TfrmA.Create(nil, 0); frmB := TfrmB.Create(nil, 0); frmC := TfrmC.Create(nil, 0); // Compiler error My work-around is to override the reintroduced constructor or to declare the original constructor overloaded, but I'd like to understand the reason for this behavior. type TfrmA = class(TForm) private FWndParent: HWnd; public constructor Create(AOwner: TComponent); overload; override; constructor Create(AOwner: TComponent; const AWndParent: Hwnd); reintroduce; overload; virtual; end; type TfrmC = class(TfrmB) private public constructor Create(AOwner: TComponent; const AWndParent: Hwnd); override; end;

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  • Active X Development: VC++ or VB or Other technologies

    - by Gopalakrishnan Subramani
    We are in the process of creating active-x controls used within our application. Since Microsoft stopped supporting classic Visual Basic, is it wise to use Visual Basic to develop the Active X control or the latest VC++/ATL/MFC libraries provide more feature where we can create controls faster by leaving Visual Basic flexibility? We will not be able to use .NET/VB.NET/C# since the application is supposed to work inside containers and containers may not support latest .NET runtime. Any other language is best fit for Active X control development other than VB and VC++?

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  • How to modify TList<record> value?

    - by Astronavigator
    How to modify TList < record value ? type TTest = record a,b,c:Integer end; var List:TList<TTest>; A:TTest; P:Pointer; .... .... List[10] := A; <- OK List[10].a:=1; <- Here compiler error : Left side cannot be assined to P:=@List[10]; <- Error: Variable requied

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  • List local printers

    - by vladimir
    hi all, i am using this routine to list the local printers installed on on a machine... var p: pointer; hpi: _PRINTER_INFO_2A; hGlobal: cardinal; dwNeeded, dwReturned: DWORD; bFlag: boolean; i: dword; begin p := nil; EnumPrinters(PRINTER_ENUM_LOCAL, nil, 2, p, 0, dwNeeded, dwReturned); if (dwNeeded = 0) then exit; GetMem(p,dwNeeded); if (p = nil) then exit; bFlag := EnumPrinters(PRINTER_ENUM_LOCAL, nil, 2, p, dwneeded, dwNeeded, dwReturned); if (not bFlag) then exit; CbLblPrinterPath.Properties.Items.Clear; for i := 0 to dwReturned - 1 do begin CbLblPrinterPath.Properties.Items.Add(TPrinterInfos(p^)[i].pPrinterName); end; FreeMem(p); TPrinterInfos(p^)[i].pPrinterName returns a 'P' for printer name. i have a PdfCreator installed as a printer. TPrinterInfos is an array of _PRINTER_INFO_2A. how can i fix this?

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  • Display field from another table in SQL

    - by Roland Bengtsson
    I'm a newbie with SQL... Now I want to do display some instances of AddrDistances from DevExpress CxGrid with SQL. Select Cast((DistanceAsMeters * 0.001) as Decimal(8,1)) DistanceAsKm, bold_id, created, fromAddress, toAddress From AddrDistance Where DistanceAsMeters = 0 and PseudoDistanceAsCostKm = 0 and not AddrDistance.bold_id in (select bold_id from DistanceQueryTask) Order By Created Desc This SQL is working and the result is: DistanceAsKM Bold_ID Created FromAddress ToAddress 0 134808 16.02.2010 121795 134570 0 121701 10.03.2010 120850 122991 The result I want is this: DistanceAsKM Bold_ID Created FromAddress ToAddress 0 134808 16.02.2010 Kalmar Stockholm 0 121701 10.03.2010 Falkenberg Oslo So the amount of rows is right but I want to replace the numbers in FromAddress and ToAddress with strings from another table. The numbers shows here is just the boldid. Every object in the database have an unique boldid. The addresses above is stored in table Address and it have a City field with the column and a boldid as a key. What should I write in SQL to get this right ? Is there something in the CxGrid that could help here ? Regards

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  • Converting an AnsiString to a Unicode String

    - by jrodenhi
    I'm converting a D2006 program to D2010. I have a value stored in a single byte per character string in my database and I need to load it into a control that has a LoadFromStream, so my plan was to write the string to a stream and use that with LoadFromStream. But it did not work. In studying the problem, I see an issue that tells me that I don't really understand how conversion from AnsiString to Unicode string works. Here is some code I am puzzling over: oStringStream := TStringStream.Create(sBuffer); sUnicodeStream := oPayGrid.sStream; //explicit conversion to unicode string iSize1 := StringElementSize(oPaygrid.sStream); iSize2 := StringElementSize(sUnicodeStream); oStringStream.WriteString(sUnicodeStream); When I get to the last line, iSize1 does equal 1 and iSize2 does equal 2, so that part is what I understood from my reading. But, on the last line, after I write the string to the stream, and look at the Bytes Property of the string, it shows this (the string starts as '16,159'): (49 {$31}, 54 {$36}, 44 {$2C}, 49 {$31}, 53 {$35}, 57 {$39} ... I was expecting that it might look something like (49 {$31}, 00 {$00}, 54 {$36}, 00 {$00}, 44 {$2C}, 00 {$00}, 49 {$31}, 00 {$00}, 53 {$35}, 00 {$00}, 57 {$39}, 00 {$00} ... I'm not getting the right results out of the LoadFromStream because it is reading from the stream two bytes at a time, but the data it is receiving is not arranged that way. What is it that I should do to give the LoadFromStream a well formed stream of data based on a unicode string? Thank you for your help.

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  • Resize PNG image

    - by serhiyiv
    HI! Could you please tell me how to resize a .png image. Or better give an example. I've been searching for the answer for a long time and it seems that nobody knows how to resize a .png image and keep its transparency. :(

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  • Manually Writing the HTML in TWebBrowser

    - by nomad311
    I am using the strategy suggested here: http://cc.embarcadero.com/Item/23992 to get my HTML in the TWebBrowser, but I get a bunch of JavaScript errors when the page loads. If I click yes enough times I can see a page with no formatting and I'm guessing the page does nothing. My theory is that because the links in the HTML are relative, the browser can't load any of it. I have switch from passing the URL, 'about:blank' to the navigate function, to passing the servers home page - in the hopes that some internal mechanism will be able to generate full paths, but no luck. Any one successfully been able to manually write HTML to the TWebBrowser.

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  • How do I mock a method with an open array parameter in PascalMock?

    - by Oliver Giesen
    I'm currently in the process of getting started with unit testing and mocking for good and I stumbled over the following method that I can't seem to fabricate a working mock implementation for: function GetInstance(const AIID: TGUID; out AInstance; const AArgs: array of const; const AContextID: TImplContextID = CID_DEFAULT): Boolean; (TImplContextID is just an alias for Integer) I thought it would have to look something like this: function TImplementationProviderMock.GetInstance( const AIID: TGUID; out AInstance; const AArgs: array of const; const AContextID: TImplContextID): Boolean; begin Result := AddCall('GetInstance') .WithParams([@AIID, AContextID]) .ReturnsOutParams([AInstance]) .ReturnValue; end; But the compiler complains about the .ReturnsOutParams([AInstance]) saying "Bad argument type in variable type array constructor.". Also I haven't found a way to specify the open array parameter AArgs at all. Also, is using the @-notation for the TGUID-typed parameter the right way to go? Is it possible to mock this method with the current version of PascalMock at all? Update: I now realize I got the purpose of ReturnsOutParams completely wrong: It's intended to be used for populating the values to be returned when defining the expectations rather than for mocking the call itself. I now think the correct syntax for mocking the out parameter would probably have to look more like this: function TImplementationProviderMock.GetInstance( const AIID: TGUID; out AInstance; const AArgs: array of const; const AContextID: TImplContextID): Boolean; var lCall: TMockMethod; begin lCall := AddCall('GetInstance').WithParams([@AIID, AContextID]); Pointer(AInstance) := lCall.OutParams[0]; Result := lCall.ReturnValue; end; The questions that remain are how to mock the open array parameter AArgs and whether passing the TGUID argument (i.e. a value type) by address will work out...

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  • Why do conditional breakpoints slow my program down so much?

    - by Bob
    When I'm debugging something that goes wrong inside a loop, say on the 600th iteration, it can be a pain to have to break for every one. So I tried setting a conditional breakpoint, to only break if I = 600. That works, but now it takes almost a full minute to reach that point, where before it was almost instantaneous. What's going on, and is there any way to fix it?

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  • How do I make my program run with different privileges at Windows 7 startup?

    - by iira
    Hi, I am trying to add my program run in Windows 7 startup, but it doesn't work. My program has an embedded UAC manifest. My current way is by adding a string value at HKCU..\Run. I found a manual solution for Vista from http://social.technet.microsoft.com/Forums/en/w7itprosecurity/thread/81c3c1f2-0169-493a-8f87-d300ea708ecf Click Start, right click on Computer and choose “Manage”. Click “Task Scheduler” on the left panel. Click “Create Task” on the right panel. Type a name for the task. Check “Run with highest privileges”. Click Actions tab. Click “New…”. Browse to the program in the “Program/script” box. Click OK. On desktop, right click, choose New and click “Shortcut”. In the box type: schtasks.exe /run /tn TaskName where TaskName is the name of task you put in on the basics tab and click next. Type a name for the shortcut and click Finish. Additionally, you need to run the saved scheduled task shortcut to run the program instead of running the application shortcut to ignore the IAC prompt. When startup the system will run the program via the original shortcut. Therefore you need to change the location to run the saved task. Please: Open Regedit. Find the entry of the startup item in Registry. It will be stored in one of the following branches. HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run HKEY_USERS.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Run HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run Double-click on the correct key, change the path to the saved scheduled task you created. Is there any free code to add item with privileges option in scheduled task? I haven't found the free one in torry.net. Thanks a lot.

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  • Detecting a stale Mutex

    - by sum1stolemyname
    Is there any technique or tool available to detect this kind of a deadlock during runtime? picture this in a worker thread (one of several, normally 4-6) try WaitForSingleObject(myMutex); DoSTuffThatMightCauseAnException; Except ReleaseMutex(myMutex); end; or more generally is there a design-pattern to avoid these kind of bugs? I coded the above code in the little hous after a longer hacking run

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  • Looking for solution to persist rows sequence in a database table that allow efficient reordering at

    - by Chau Chee Yang
    I have a database table. There is a field name "Sequence" that indicate sequence when user presents the rows in report or grid visually. When the rows are retrieved and presented in a grid, there are few UI gadget that allow user to reorder the rows arbitrary. The new sequence will be persist in database table when user commit the changes. Here are some UI operations: Move to first Move to last Move up 1 row Move down 1 row multi-select rows and move up or down multi-select rows and drag to new position For operation like "Move to first" or "Move to Last", it usually involve many rows and the sequence those rows would need to be updated accordingly. This may not be efficient enough at runtime. It is a common practice to use INTEGER as sequence's data type. Other solution is using "DOUBLE" or "FLOAT" that could overcome the mass update of row sequence but we will face problem if we reach the limit of precision.

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  • How to prevent form from being activated when the users clicks on it?

    - by riot_starter
    I have a main form and non-modal autocomplete form. How can I prevent the autocomplete form from being activated by the user, when the user clicks on the list in the autocomplete form? So, basically I want the autocomplete form the receive the mouse click message when the users clicks, but to never become active, because it causes problems with a third-party component in the main form over which I have no control.

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