BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  TListBox - Controling Selection Color Goto page 1, 2, 3  Next          BorlandTalk.com Forum Index -> C++ Builder (VCL Components Usage) View previous topic :: View next topic   Author Message Db Guest Posted: Sun Feb 19, 2006 7:03 pm    Post subject: TListBox - Controling Selection Color When A list box item is selected and focused I want it to be in a different color than when it is just selected. I used the owner draw style to accomplish this and it worked great at 800x600 screen size. When my resizing object came into play though it didn't work properly. The wrong Rect size was passed to the OnDrawItem method. I was able to partially deal with that but then when you clicked on an item the wrong one would be highlighted and focus rects are being drawn in the wrong place and in the wrong size. Is there a way to easily control the colors that a list box selection is draw in? Db Back to top Db Guest Posted: Sun Feb 19, 2006 7:03 pm    Post subject: Re: TListBox - Controling Selection Color Thanks but never mind. Altering my sizing object to set the ItemHeight property to the scaled height did the trick. Db "Db" <drbsname_at_aol.com> wrote in message news:43f8b644$1 (AT) newsgroups (DOT) borland.com... Quote: When A list box item is selected and focused I want it to be in a different color than when it is just selected. I used the owner draw style to accomplish this and it worked great at 800x600 screen size. When my resizing object came into play though it didn't work properly. The wrong Rect size was passed to the OnDrawItem method. I was able to partially deal with that but then when you clicked on an item the wrong one would be highlighted and focus rects are being drawn in the wrong place and in the wrong size. Is there a way to easily control the colors that a list box selection is draw in? Db Back to top HF Guest Posted: Sun Feb 19, 2006 8:03 pm    Post subject: Re: TListBox - Controling Selection Color Set the Style of ListBox to Owner-draw the following example may help you //--------------------------------------------------------------------------- void __fastcall TForm1::ListBox1DrawItem(TWinControl *Control, int Index, TRect &Rect, TOwnerDrawState State) { TListBox* lb = reinterpret_cast<TListBox*>(Control); TBrush* bb = lb->Canvas->Brush; TFont* tmpFont = lb->Canvas->Font; if (State.Contains(odSelected)){ lb->Canvas->Brush->Color = clYellow; lb->Canvas->FillRect(Rect); lb->Canvas->Font->Color =clBlue; lb->Canvas->TextOut(Rect.Left,Rect.Top,lb->Items->Strings[Index]); } else{ lb->Canvas->Brush = bb; lb->Canvas->FillRect(Rect); lb->Canvas->Font = tmpFont; lb->Canvas->TextOut(Rect.Left,Rect.Top,lb->Items->Strings[Index]); } } //--------------------------------------------------------------------------- -minas Ï "Db" <drbsname_at_aol.com> Ýãñáøå óôï ìÞíõìá news:43f8b644$1 (AT) newsgroups (DOT) borland.com... Quote: When A list box item is selected and focused I want it to be in a different color than when it is just selected. I used the owner draw style to accomplish this and it worked great at 800x600 screen size. When my resizing object came into play though it didn't work properly. The wrong Rect size was passed to the OnDrawItem method. I was able to partially deal with that but then when you clicked on an item the wrong one would be highlighted and focus rects are being drawn in the wrong place and in the wrong size. Is there a way to easily control the colors that a list box selection is draw in? Db Back to top HF Guest Posted: Sun Feb 19, 2006 8:03 pm    Post subject: Re: TListBox - Controling Selection Color Ah,sorry dynamic_cast<TListBox*>(Control). -minas Back to top JD Guest Posted: Mon Feb 20, 2006 2:12 am    Post subject: Re: TListBox - Controling Selection Color "HF" <(min_charATyahooPUTADOTgr)(HellenicFire)> wrote: Quote: Ah,sorry dynamic_cast<TListBox*>(Control). That is incorrect as well. While both reinterpret_cast and dynamic_cast will work as long as the event is always assigned to a TListBox, it is also true that static_cast will work as well and static_cast is the correct cast to use in this case. The reason is that reinterpret_cast has not type checking at all and dynamic_cast performs run-time checking while static_cast performs compile-time checking. The only reason to use dynamic_cast would be if the event was assigned to multiple type objects and in that case, one should be checking the result of dynamic_cast because it can fail and return NULL. ~ JD Back to top Michel Leunen Guest Posted: Mon Feb 20, 2006 9:03 pm    Post subject: Re: TListBox - Controling Selection Color JD wrote: Quote: Ah,sorry dynamic_cast<TListBox*>(Control). That is incorrect as well. If a static_cast is the prefered way to go, using dynamic_cast is certainly *NOT* incorrect. As you stated, it is used when you are not sure that it will be always a TListBox. Michel -- ---------------------------------------- Michel Leunen mailto: see my homepage. C++Builder, BCC5.5.1 Web site: http://www.leunen.com/ ---------------------------------------- Back to top Rudy Velthuis [TeamB] Guest Posted: Mon Feb 20, 2006 11:03 pm    Post subject: Re: TListBox - Controling Selection Color At 01:54:57, 20.02.2006, JD wrote: Quote: The reason is that reinterpret_cast has not type checking at all and dynamic_cast performs run-time checking while static_cast performs compile-time checking. Don't you think this would be more maintainable and reusable if dynamic_cast is used? If one day, this handler is assigned (perhaps inadvertently) to something that is not a TListBox, the error should at least be caught at runtime, instead of producing erroneous results. Note that at compile time of the handler, there is no way to ensure that only a TListBox* is passed. I think that in such cases, static_cast is simply wrong. IOW, IMO, if there is the slightest possibility that (someday) something else than a TListBox* is passed (and that posibility exists, since the formal argument is after all a TControl*), one should use dynamic_cast. -- Rudy Velthuis [TeamB] http://rvelthuis.de/ "Defining and analyzing humor is a pastime of humorless people." -- Robert Benchley (1889 - 1945) Back to top JD Guest Posted: Tue Feb 21, 2006 2:03 am    Post subject: Re: TListBox - Controling Selection Color "Rudy Velthuis [TeamB]" <velthuis (AT) gmail (DOT) com> wrote: Quote: IOW, IMO, [...] one should use dynamic_cast. Tell that to Gambit: http://groups.google.com/group/borland.public.cppbuilder.vcl.components.using/msg/229e161151b87a0a?hl=en& ~ JD Back to top JD Guest Posted: Tue Feb 21, 2006 2:03 am    Post subject: Re: TListBox - Controling Selection Color Michel Leunen <nospam (AT) noreply (DOT) please> wrote: Quote: JD wrote: Ah,sorry dynamic_cast<TListBox*>(Control). That is incorrect as well. If a static_cast is the prefered way to go, using dynamic_cast is certainly *NOT* incorrect. As you stated, it is used when you are not sure that it will be always a TListBox. C'mon. That's a poor argument because events don't get assigned on their own. One knows when one assigns events so one is always 'sure' of what it's been assigned to. Besides, even if dynamic_cast is purposefully used, it's still incorrect. Using your argument, that the programmer is not 'sure', as I also stated, dynamic_cast can fail and the result of the cast *must* be checked which the OP did not do. ~ JD Back to top Rudy Velthuis [TeamB] Guest Posted: Tue Feb 21, 2006 11:03 am    Post subject: Re: TListBox - Controling Selection Color At 01:02:39, 21.02.2006, JD wrote: Quote: "Rudy Velthuis [TeamB]" <velthuis (AT) gmail (DOT) com> wrote: IOW, IMO, [...] one should use dynamic_cast. Tell that to Gambit: http://groups.google.com/group/borland.public.cppbuilder.vcl.components. using/msg/229e161151b87a0a?hl=en& "He does it too"? <g> -- Rudy Velthuis [TeamB] http://rvelthuis.de/ "Deliver yesterday, code today, think tomorrow." -- unknown Back to top JD Guest Posted: Tue Feb 21, 2006 8:03 pm    Post subject: Re: TListBox - Controling Selection Color "Rudy Velthuis [TeamB]" <velthuis (AT) gmail (DOT) com> wrote: Quote: "He does it too"? <g Yes, and I strongly agree with him on this point. If we consider your reasoning for using it, then one can use the same argument against using it. If, at some future date the event is assigned to a different type object and the use of dynamic_cast was correctly coded as such: TListBox *pBox = dynamic_cast<TListBox*>( Sender ); if( pBox ) { // } the net result is that the programmer is left with no clues at all as to why the event isn't doing anything. To fix this, one would need to add an else block that displayed some kind of message or threw something and IMO, this is excessive because of all of the events that one encounters in a normal VCL application. OTOH, if one sticks with static_cast, you're gonna get an exception thrown your way which should alert you immediately that there is a problem and point you to it as well. ~ JD Back to top Rudy Velthuis [TeamB] Guest Posted: Tue Feb 21, 2006 9:03 pm    Post subject: Re: TListBox - Controling Selection Color At 19:11:10, 21.02.2006, JD wrote: Quote: "Rudy Velthuis [TeamB]" <velthuis (AT) gmail (DOT) com> wrote: "He does it too"? <g Yes, and I strongly agree with him on this point. I don't. IMO, this is unsafe design. -- Rudy Velthuis [TeamB] http://rvelthuis.de/ "Shoot, you should've told me about your humorectomy; I'd've sent flowers." -- Ignacio Vazquez in borland.public-off-topic Back to top Michel Leunen Guest Posted: Tue Feb 21, 2006 9:03 pm    Post subject: Re: TListBox - Controling Selection Color JD wrote: Quote: C'mon. That's a poor argument because events don't get assigned on their own. One knows when one assigns events so one is always 'sure' of what it's been assigned to. That's not defensive programming. The writer and the user are not always the same person. But you're right in a sense and that's not my point. I just said that using dynamic_cast is not incorrect. If you want to avoid the overhead of using dynamic_cast then use static_cast. Ok. But in this case dynamic_cast is not wrong. But... Quote: Besides, even if dynamic_cast is purposefully used, it's still incorrect. Using your argument, that the programmer is not 'sure', as I also stated, dynamic_cast can fail and the result of the cast *must* be checked which the OP did not do. ....yes, the result of the cast must be checked. Of course. Michel -- ---------------------------------------- Michel Leunen mailto: see my homepage. C++Builder, BCC5.5.1 Web site: http://www.leunen.com/ ---------------------------------------- Back to top Rudy Velthuis [TeamB] Guest Posted: Tue Feb 21, 2006 10:03 pm    Post subject: Re: TListBox - Controling Selection Color At 19:11:10, 21.02.2006, JD wrote: Quote: OTOH, if one sticks with static_cast, you're gonna get an exception thrown your way which should alert you immediately that there is a problem and point you to it as well. You get an exception? I didn't know static_cast did runtime checks? Or did you mean a compiler error? At the time of compilation, the event handler can not know what kind of class will be passed. static_cast can not diagnose anything at compile time (since a TListBox is a TControl). -- Rudy Velthuis [TeamB] http://rvelthuis.de/ "I just bought a Mac to help me design the next Cray." -- Seymoure Cray (1925-1996) when was informed that Apple Inc. had recently bought a Cray supercomputer to help them design the next Mac. Back to top Rudy Velthuis [TeamB] Guest Posted: Tue Feb 21, 2006 11:03 pm    Post subject: Re: TListBox - Controling Selection Color At 22:08:34, 21.02.2006, JD wrote: Quote: No. What I was refering to was your example of assigning the event to a different type object. The moment that the resulting pointer is used (when Control is static_cast to the wrong type), it's going to throw. Control is a TWinControl. And TComboBox and TOutline have the same event, of the same type TDrawItemEvent, so the same handler could be legally assigned to a TComboBox or a TOutline. No static cast could ever catch this. A dynamic cast would, however, at runtime. -- Rudy Velthuis [TeamB] http://rvelthuis.de/ "Diplomacy is the art of saying 'Nice doggie!'... 'til you can find a rock." -- bumper sticker Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> C++ Builder (VCL Components Usage) All times are GMT Goto page 1, 2, 3  Next Page 1 of 3   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.