BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  TPageControl - Freeing a page ---> Awful flickering Goto page 1, 2  Next          BorlandTalk.com Forum Index -> Delphi VCL Components Using View previous topic :: View next topic   Author Message Alan Garny Guest Posted: Mon Jul 28, 2003 10:36 pm    Post subject: TPageControl - Freeing a page ---> Awful flickering Hi, I have a TPageControl component (used as part of an editor) in which I create different tab sheets (one for each file I open/create). Within each tab sheet, I have my editor. All works fine, except when I want to close... Basically, I have something like that: .... (PageControl.ActivePage.Controls[0] As TSyntaxEdit).Free; PageControl.ActivePage.Free; PageControl.ActivePageIndex := <whatever>; .... My problem is with the freeing of the active page... this indeed reset the active page index to zero... which means that if the new active page index ois not zero, then we end up with some awful flickering... Any idea as how to avoid that very annoying behaviour? Cheers, Alan. Back to top Ignacio Vazquez Guest Posted: Tue Jul 29, 2003 2:39 am    Post subject: Re: TPageControl - Freeing a page ---> Awful flickering "Alan Garny" <agml (AT) hellix (DOT) com> wrote Quote: Any idea as how to avoid that very annoying behaviour? Try changing to the new page, then freeing the old one. Cheers, Ignacio Back to top Alan Garny Guest Posted: Tue Jul 29, 2003 7:57 am    Post subject: Re: TPageControl - Freeing a page ---> Awful flickering "Ignacio Vazquez" <ivazquezATorioncommunications.com> wrote Quote: "Alan Garny" <agml (AT) hellix (DOT) com> wrote in message news:3f25a57e$1 (AT) newsgroups (DOT) borland.com... Any idea as how to avoid that very annoying behaviour? Try changing to the new page, then freeing the old one. I have tried that, but it doesn't do it. The freeing of the page itself automatically resets the ActivePageIndex to zero, so I will end up with the first page activated, which is not necessarily the one I want to be in the end. I would hate having to change the VCL just to avoid this... Cheers, Alan. Back to top Deck Guest Posted: Wed Jul 30, 2003 6:18 am    Post subject: Re: TPageControl - Freeing a page ---> Awful flickering i've had that flickering problem before. in my case i'm just hiding some pages based on certain conditions. i suspect it redraws itself everytime you add/delete/hide/show pages. so what i did was set pagecontorl.visible:=false try ...do your thingy finally pagecontorl.visible:=true ; end; solves my problem. i guess redraw doesn't need to be fired as it knows its not visible. try it and let us know. cheers "Alan Garny" <agml (AT) hellix (DOT) com> wrote Quote: "Ignacio Vazquez" <ivazquezATorioncommunications.com> wrote in message news:3f25df5d$1 (AT) newsgroups (DOT) borland.com... "Alan Garny" <agml (AT) hellix (DOT) com> wrote in message news:3f25a57e$1 (AT) newsgroups (DOT) borland.com... Any idea as how to avoid that very annoying behaviour? Try changing to the new page, then freeing the old one. I have tried that, but it doesn't do it. The freeing of the page itself automatically resets the ActivePageIndex to zero, so I will end up with the first page activated, which is not necessarily the one I want to be in the end. I would hate having to change the VCL just to avoid this... Cheers, Alan. Back to top Chris Luck Guest Posted: Wed Jul 30, 2003 6:55 pm    Post subject: Re: TPageControl - Freeing a page ---> Awful flickering "Alan Garny" <agml (AT) hellix (DOT) com> wrote Quote: I have a TPageControl component (used as part of an editor) in which I create different tab sheets (one for each file I open/create). Within each tab sheet, I have my editor. All works fine, except when I want to close... Basically, I have something like that: <snip> Quote: My problem is with the freeing of the active page... this indeed reset the active page index to zero... which means that if the new active page index ois not zero, then we end up with some awful flickering... Any idea as how to avoid that very annoying behaviour? In form create - PageControl1.DoubleBuffered := true; In your TabFree proc - PageControl1.Perform(WM_SETREDRAW, 0, 0); try // let's go freeing... finally PageControl1.Perform(WM_SETREDRAW,1, 0); end; Use either or both, whatever works best for you. -- Regards, Chris Luck. Back to top Deck Guest Posted: Wed Jul 30, 2003 9:18 pm    Post subject: Re: TPageControl - Freeing a page ---> Awful flickering Quote: Maybe I have missed something here, but how can making the page control invisible and then visible avoid the flickering issue? If anything, this is going to make the flickering even worse... Am puzzled... Cheers, Alan. did you try it? Back to top Alan Garny Guest Posted: Wed Jul 30, 2003 11:22 pm    Post subject: Re: TPageControl - Freeing a page ---> Awful flickering "Chris Luck" <chris (AT) bvhg (DOT) freeXYZserve.co.uk> wrote Quote: "Alan Garny" <agml (AT) hellix (DOT) com> wrote in message news:3f25a57e$1 (AT) newsgroups (DOT) borland.com... I have a TPageControl component (used as part of an editor) in which I create different tab sheets (one for each file I open/create). Within each tab sheet, I have my editor. All works fine, except when I want to close... Basically, I have something like that: snip My problem is with the freeing of the active page... this indeed reset the active page index to zero... which means that if the new active page index ois not zero, then we end up with some awful flickering... Any idea as how to avoid that very annoying behaviour? In form create - PageControl1.DoubleBuffered := true; In your TabFree proc - PageControl1.Perform(WM_SETREDRAW, 0, 0); try // let's go freeing... finally PageControl1.Perform(WM_SETREDRAW,1, 0); end; Use either or both, whatever works best for you. I was very hopeful when I saw your suggestions, but: 1) I had already set DoubleBuffered to true. I guess I must have had some other flickering issues in the past, which kind of forced me to set DoubleBuffered to true. 2) Using WM_SETREDRAW on the page control doesn't make any difference whatsoever. To use on the form that holds the control, however, it does... but only to some extent. In other words, I don't get the flickering anymore, but I don't see the contents of any page either. I am not sure I am happy with this trade off... <g> This said, I have the feeling that WM_SETREDRAW is the way forward. I guess I just have to try to understand what's exactly going here... Maybe I should have a look at the source code for TPageControl... Cheers, Alan. Back to top Chris Luck Guest Posted: Wed Jul 30, 2003 11:30 pm    Post subject: Re: TPageControl - Freeing a page ---> Awful flickering "Alan Garny" <agml (AT) hellix (DOT) com> wrote Quote: 2) Using WM_SETREDRAW on the page control doesn't make any difference whatsoever. Curious. Quote: To use on the form that holds the control, however, it does... but only to some extent. In other words, I don't get the flickering anymore, but I don't see the contents of any page either. I am not sure I am happy with this trade off... finally PageControl1.Perform(WM_SETREDRAW,1, 0); Invalidate. end; -- Regards, Chris Luck. Back to top Alan Garny Guest Posted: Thu Jul 31, 2003 6:45 am    Post subject: Re: TPageControl - Freeing a page ---> Awful flickering "Chris Luck" <chris (AT) bvhg (DOT) freeXYZserve.co.uk> wrote Quote: "Alan Garny" <agml (AT) hellix (DOT) com> wrote in message news:3f285352$1 (AT) newsgroups (DOT) borland.com... 2) Using WM_SETREDRAW on the page control doesn't make any difference whatsoever. Curious. To use on the form that holds the control, however, it does... but only to some extent. In other words, I don't get the flickering anymore, but I don't see the contents of any page either. I am not sure I am happy with this trade off... finally PageControl1.Perform(WM_SETREDRAW,1, 0); Invalidate. end; I had tried something similar (Repaint and Refresh instead of Invalidate), but didn't work either. Basically, at the moment, I have something like: MainForm.Perform(WM_SETREDRAW, 0, 0); PageControl.ActivePage.Free; PageControl.ActivePageIndex := NewPageIndex; MainForm.Perform(WM_SETREDRAW, 1, 0); PageControl.Invalidate; I must confess that this is driving me nuts... :( Cheers, Alan. Back to top Chris Luck Guest Posted: Thu Jul 31, 2003 10:53 am    Post subject: Re: TPageControl - Freeing a page ---> Awful flickering "Alan Garny" <agml (AT) hellix (DOT) com> wrote Quote: I had tried something similar (Repaint and Refresh instead of Invalidate), but didn't work either. Basically, at the moment, I have something like: MainForm.Perform(WM_SETREDRAW, 0, 0); PageControl.ActivePage.Free; PageControl.ActivePageIndex := NewPageIndex; MainForm.Perform(WM_SETREDRAW, 1, 0); PageControl.Invalidate; I must confess that this is driving me nuts... What I had meant with my last post was MainForm.Invalidate or just Invalidate as it is the Form that you are locking. If that doesn't do it then there must be something else going on here - but at this distance it's difficult to see. The initial fact of the pages flickering so much that it is intrusive seems a bit odd in itself. It may be that the contents of the Tabsheets are themselves taking a long time to draw and causing an exaggerated flicker, can you set the contents (of Tabsheet[0] for instance) visible := false before freeing? Do you get the same effect in a simple test app. with minimal Tabsheet contents? -- Regards, Chris Luck. Back to top Alan Garny Guest Posted: Thu Jul 31, 2003 2:24 pm    Post subject: Re: TPageControl - Freeing a page ---> Awful flickering "Chris Luck" <chris (AT) bvhg (DOT) freeXYZserve.co.uk> wrote Quote: "Alan Garny" <agml (AT) hellix (DOT) com> wrote in message news:3f28baf7$1 (AT) newsgroups (DOT) borland.com... I had tried something similar (Repaint and Refresh instead of Invalidate), but didn't work either. Basically, at the moment, I have something like: MainForm.Perform(WM_SETREDRAW, 0, 0); PageControl.ActivePage.Free; PageControl.ActivePageIndex := NewPageIndex; MainForm.Perform(WM_SETREDRAW, 1, 0); PageControl.Invalidate; I must confess that this is driving me nuts... :( What I had meant with my last post was MainForm.Invalidate or just Invalidate as it is the Form that you are locking. If that doesn't do it then there must be something else going on here - but at this distance it's difficult to see. The initial fact of the pages flickering so much that it is intrusive seems a bit odd in itself. It may be that the contents of the Tabsheets are themselves taking a long time to draw and causing an exaggerated flicker, can you set the contents (of Tabsheet[0] for instance) visible := false before freeing? Do you get the same effect in a simple test app. with minimal Tabsheet contents? Ok, I have just created a very simple application that shows the problem I am experiencing... See b.p.attachments. Note that I have double buffered everything, just in case... yet not difference... If you have any idea, please let me know... Cheers, Alan. Back to top Chris Luck Guest Posted: Fri Aug 01, 2003 10:50 am    Post subject: Re: TPageControl - Freeing a page ---> Awful flickering "Alan Garny" <agml (AT) hellix (DOT) com> wrote Quote: I'll give it a closer look (when the world stops intruding) and come back. Right, having chased the world away long enough to explore, I have come to the same conclusion as Ignacio had done earlier: switch to the next tab first then free the unwanted page. But looking at your response to Ignacio leaves me wondering if there are version issues showing here. Anyway, I'm a bit puzzled by your statement - "The freeing of the page itself automatically resets the ActivePageIndex to zero". I'm using BCB4 (and D2 btw) which don't have ActivePageIndex. If the ActivePageIndex doesn't work for you do you have the option of using the old codeing style using ActivePage.PageIndex? I dispensed with explicitly freeing the Memo as you gave the Tabsheet as the Memo's owner. procedure TForm1.Button2Click(Sender: TObject); var I: Integer; begin if (PageControl1.PageCount > 0) then begin I := PageControl1.ActivePage.PageIndex; if I > 0 then begin PageControl1.ActivePage := PageControl1.Pages[I - 1]; PageControl1.Pages[I].Free; end else begin if (PageControl1.PageCount > 1) then PageControl1.ActivePage := PageControl1.Pages[I + 1]; PageControl1.Pages[I].Free; if (PageControl1.PageCount > 0) then PageControl1.ActivePage := PageControl1.Pages[I]; end; end; end; Tested here without DoubleBuffering gives an expected level of flicker over that part of the Memo that contains text, but none of the screen-wide flashing. I haven't come to any useful conclusion as to why it flickers so much when you do free the active page . -- Regards, Chris Luck. Back to top Alan Garny Guest Posted: Fri Aug 01, 2003 1:08 pm    Post subject: Re: TPageControl - Freeing a page ---> Awful flickering "Chris Luck" <chris (AT) bvhg (DOT) freeXYZserve.co.uk> wrote Quote: "Alan Garny" <agml (AT) hellix (DOT) com> wrote in message news:3f293ac0$1 (AT) newsgroups (DOT) borland.com... I'll give it a closer look (when the world stops intruding) and come back. Right, having chased the world away long enough to explore, I have come to the same conclusion as Ignacio had done earlier: switch to the next tab first then free the unwanted page. But looking at your response to Ignacio leaves me wondering if there are version issues showing here. Anyway, I'm a bit puzzled by your statement - "The freeing of the page itself automatically resets the ActivePageIndex to zero". I'm using BCB4 (and D2 btw) which don't have ActivePageIndex. If the ActivePageIndex doesn't work for you do you have the option of using the old codeing style using ActivePage.PageIndex? I dispensed with explicitly freeing the Memo as you gave the Tabsheet as the Memo's owner. procedure TForm1.Button2Click(Sender: TObject); var I: Integer; begin if (PageControl1.PageCount > 0) then begin I := PageControl1.ActivePage.PageIndex; if I > 0 then begin PageControl1.ActivePage := PageControl1.Pages[I - 1]; PageControl1.Pages[I].Free; end else begin if (PageControl1.PageCount > 1) then PageControl1.ActivePage := PageControl1.Pages[I + 1]; PageControl1.Pages[I].Free; if (PageControl1.PageCount > 0) then PageControl1.ActivePage := PageControl1.Pages[I]; end; end; end; Tested here without DoubleBuffering gives an expected level of flicker over that part of the Memo that contains text, but none of the screen-wide flashing. I haven't come to any useful conclusion as to why it flickers so much when you do free the active page . Ok, I just had a look at the VCL source code and... maybe that's what I should have done before even posting my original message... Basically the issue is that the freeing of a page is done via a procedure called RemovePage. The first thing that procedure does is to find out which is the next page to activate and rather than looking for the PREVIOUS page or the NEXT page if we are freeing the first page (as does the Delphi IDE, for instance), it ALWAYS looks for the NEXT page... This means that when I said that freeing a page resets ActivePageIndex to zero (i.e. the first page), I was partially wrong. It's just that I had always done my tests by freeing the last page... but if one frees a "middle" page, then the new active page will be the next one, as expected from the source code... Anyway, the problem remains... For some reasons I really don't understand, TPageControl decides to select the NEXT page when one removes a page, while IMHO it should select the PREVIOUS one... and if we remove the first page, then just select the new first page. At least, that's how the Delphi IDE behaves and that's also the behaviour that I find "normal" and that I would like to have in my application... So, in the end, I decided to make a local copy of ComCtrls.pas in my project's directory and modified the RemovePage procedure so that it does what I think it should be doing... Originally, we had: NextSheet := FindNextPage(Page, True, not (csDesigning in ComponentState)); and now, I have: NextSheet := FindNextPage(Page, Page.PageIndex = 0, not (csDesigning in ComponentState)); Now, the issue that I am facing is the distribution of my program... indeed, I also intend to distribute the source code... and I wonder whether I am allowed to distribute "my" version of ComCtrls.pas... I would think not, but in that case, what could be done? Cheers, Alan. Back to top Alan Garny Guest Posted: Sun Aug 03, 2003 1:33 am    Post subject: Re: TPageControl - Freeing a page ---> Awful flickering "Chris Luck" <chris (AT) bvhg (DOT) freeXYZserve.co.uk> wrote Quote: "Alan Garny" <agml (AT) hellix (DOT) com> wrote in message news:3f2a6666$1 (AT) newsgroups (DOT) borland.com... Now, the issue that I am facing is the distribution of my program... indeed, I also intend to distribute the source code... and I wonder whether I am allowed to distribute "my" version of ComCtrls.pas... I would think not, but in that case, what could be done? No, changing a line or two of Borlands code won't allow you to pass it off as your code! If Buffering the Tabsheet contents doesn't do it them I'm stumped too. I have no intention to claim Borland's code to be mine. No, I have actually left everything as it is. I have just commented out the line that I personally believe to be wrong and replaced it with mine and put a comment about what I have done and why I have done it. Nothing more nothing less. No, my concern is to know whether I can distribute that source code from Borland, keeping in mind that my project is open source and as such will be released with source code. So, I wouldn't want to have to tell any interested user to modify Borland's source code themselves, when I have done it... Anyway, I have the feeling that it might not be legal... So I will have a look at your other suggestion, since it looks interesting and may avoid me having to modify Borland's source code... Cheers, Alan. Back to top Ignacio Vazquez Guest Posted: Sun Aug 03, 2003 1:38 am    Post subject: Re: TPageControl - Freeing a page ---> Awful flickering "Alan Garny" <agml (AT) hellix (DOT) com> wrote Quote: ...and I wonder whether I am allowed to distribute "my" version of ComCtrls.pas... I would think not, but in that case, what could be done? One thing you can/should do is post your problem as well as the solution you've discovered to Quality Central as a Design Problem. http://qc.borland.com/ Cheers, Ignacio Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> Delphi VCL Components Using All times are GMT Goto page 1, 2  Next Page 1 of 2   Jump to: Select a forum C++ Builder Newsgroups----------------C++ BuilderC++ Builder (ActiveX)C++ Builder (Announcements)C++ Builder (Command Line Tools)C++ Builder DatabasesC++ Builder Databases (ADO)C++ Builder Databases (Desktop)C++ Builder Databases (InterBase Express)C++ Builder Databases (Multi-Tier)C++ Builder Databases (SQL Servers)C++ Builder (Graphics)C++ Builder (IDE)C++ Builder (Internet)C++ Builder (Internet Socket)C++ Builder (Internet Web)C++ Builder (Jobs)C++ Builder (Language)C++ Builder (Language C++)C++ Builder (Compatibility with MFC)C++ Builder (Native API)C++ Builder (Non-Technical)C++ Builder (Students)C++ Builder (Third Party Tools)C++ Builder (Upgrade)C++ Builder (VCL)C++ Builder (VCL Components Usage)C++ Builder (VCL Components Development)C++ Builder (VCL Usage)C++ Builder (WinAPI)C++ Builder Installation Delphi Newsgroups----------------Delphi (General)Delphi ActiveX Controls UsageDelphi ActiveX Controls DevelopmentDelphi As400Delphi DatabasesDelphi Databases (ADO)Delphi Databases (dbExpress)Delphi Databases (Desktop)Delphi Databases (InterBase Express)Delphi Databases (Multi-Tier)Delphi Databases (SQL Servers)Delphi DeploymentDelphi GraphicsDelphi IDEDelphi InternationalizationDelphi InternetDelphi Internet Isapi-WebBrokerDelphi Internet WebSnapDelphi Internet WinsockDelphi JobsDelphi Language BASMDelphi Language ObjectPascalDelphi Model Driven Architecture (General)Delphi Model Driven Architecture (Third Party)Delphi MultimediaDelphi Native APIDelphi Non-TechnicalDelphi ObjectPascalDelphi OLE AutomationDelphi OO designDelphi OpenToolsAPIDelphi Reporting-ChartingDelphi RTLDelphi StudentsDelphi TeamSourceDelphi Thirdparty ToolsDelphi Thirdparty Tools (General)Delphi Thirdparty Tools (IntraWeb)Delphi Thirdparty Tools (RaveReports)Delphi UpgradeDelphi VCLDelphi VCL ComponentsDelphi VCL Components UsingDelphi VCL Components WritingDelphi WebServices SOAPDelphi WinAPIDelphi XMLDelphi Installationcomp.lang.pascal.delphi.components.misccomp.lang.pascal.delphi.components.usagecomp.lang.pascal.delphi.components.writingcomp.lang.pascal.delphi.databasescomp.lang.pascal.delphi.misccomp.sources.delphi JBuilder Newsgroups----------------JBuilderJBuilder AnnouncementsJBuilder Applet IssuesJBuilder As400JBuilder CompilerJBuilder CORBA/RMIJBuilder DatabasesJBuilder DB SwingJBuilder DebuggerJBuilder DeploymentJBuilder DocumentationJBuilder EnterpriseJBuilder HandheldJBuilder IDEJBuilder JavaJBuilder JavaAPIJBuilder Java LanguageJBuilder Java SwingJBuilder Java BeansJBuilder Java Beans UsageJBuilder Java Beans DevelopmentJBuilder JBCLJBuilder JDataStoreJBuilder JobsJBuilder LinuxJBuilder MacintoshJBuilder & MobileSetJBuilder MultiLingual AppsJBuilder Non-TechnicalJBuilder OpenToolsJBuilder Servlets (JSP)JBuilder StudentsJBuilder Team DevelopmentJBuilder Thirdparty ToolsJBuilder UpgradeJBuilder Installation InterBase Newsgroups----------------InterBaseInterBase Bug DiscussionInterBase GeneralInterBase IBConsoleInterBase OpenSourceInterBase ReplicationInterBase SQLInterBase ThirdpartyInterBase Installation Miscellaneous Borland Newsgroups----------------AppCenterAppServerEnteraVisiBroker  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.