BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Prevent refreshing of a TImage? Goto page 1, 2  Next          BorlandTalk.com Forum Index -> C++ Builder (VCL Components Usage) View previous topic :: View next topic   Author Message Analian Guest Posted: Sun May 22, 2005 8:27 am    Post subject: Prevent refreshing of a TImage? I've got a TImage component on which I draw lines. I'm performing lots of calculations which take for about 2 minutes. At certain states of these 2 minutes I draw I single line on the Image and call Application->ProcessMessages() to make sure that the line is drawn immediately or else all the lines would be drawn at the end when the calcs finish. But I want to preserve this dynamic displaying of the lines and the problem is that everytime a single line is drawn and then Application->ProcessMessages() i called the Image seems to repaint _all_ of its surface and thus drawing 2000 single lines in 2 minutes results in a lot of flicker. Well I don't want the Image to refresh at all until all the calculations are done so I would avoid the flicker. How can I accomplish this? Thank you. Back to top JD Guest Posted: Sun May 22, 2005 9:42 am    Post subject: Re: Prevent refreshing of a TImage? "Analian" <analian (AT) mail (DOT) bg> wrote: Quote: [...] I don't want the Image to refresh at all until all the calculations are done [...] Use the win32 API SendMesssage to disable and reenable an objects refresh. When finished, manually refresh to show your work: ::SendMessage( Image1->Handle, WM_SETREDRAW, FALSE, 0 ); // your drawing code ::SendMessage( Image1->Handle, WM_SETREDRAW, TRUE, 0 ); Image1->Refresh(); ~ JD Back to top Analian Guest Posted: Sun May 22, 2005 10:30 am    Post subject: Re: Prevent refreshing of a TImage? Quote: ::SendMessage( Image1->Handle, WM_SETREDRAW, FALSE, 0 ); // your drawing code ::SendMessage( Image1->Handle, WM_SETREDRAW, TRUE, 0 ); Image1->Refresh(); Umm.. Handle is not a member of the TImage component. Then how do I get the handle needed? Back to top JD Guest Posted: Sun May 22, 2005 10:55 am    Post subject: Re: Prevent refreshing of a TImage? "Analian" <analian (AT) mail (DOT) bg> wrote: Quote: ::SendMessage( Image1->Handle, WM_SETREDRAW, FALSE, 0 ); // your drawing code ::SendMessage( Image1->Handle, WM_SETREDRAW, TRUE, 0 ); Image1->Refresh(); Umm.. Handle is not a member of the TImage component. Then how do I get the handle needed? Sorry about that. You can use the Image->Canvas->Handle but that will throw if the underlying image is not a TBitmap. ~ JD Back to top Analian Guest Posted: Sun May 22, 2005 11:32 am    Post subject: Re: Prevent refreshing of a TImage? "JD" <nospam (AT) nospam (DOT) com> wrote Quote: "Analian" <analian (AT) mail (DOT) bg> wrote: ::SendMessage( Image1->Handle, WM_SETREDRAW, FALSE, 0 ); // your drawing code ::SendMessage( Image1->Handle, WM_SETREDRAW, TRUE, 0 ); Image1->Refresh(); Umm.. Handle is not a member of the TImage component. Then how do I get the handle needed? Sorry about that. You can use the Image->Canvas->Handle but that will throw if the underlying image is not a TBitmap. ~ JD ::SendMessage(Form1->Image1->Canvas->Handle, WM_SETREDRAW, FALSE, 0); Application->ProcessMessages(); // do calcs and single line drawals ::SendMessage(Form1->Image1->Canvas->Handle, WM_SETREDRAW, TRUE, 0); Form1->MyImage1->Refresh(); Application->ProcessMessages(); and yet no effect.. The image continues to refresh after every line is drawn. Any other suggestions? Back to top JD Guest Posted: Sun May 22, 2005 1:11 pm    Post subject: Re: Prevent refreshing of a TImage? "Analian" <analian (AT) mail (DOT) bg> wrote: Quote: ::SendMessage(Form1->Image1->Canvas->Handle, WM_SETREDRAW, FALSE, 0); Application->ProcessMessages(); You don't need to process message here. SendMessage waits for it to be executed. Quote: Any other suggestions? I don't have a compiler on this machine so I can't test it for you. Try using the Bitmap's handle. ~ JD Back to top Analian Guest Posted: Sun May 22, 2005 2:38 pm    Post subject: Re: Prevent refreshing of a TImage? Quote: You don't need to process message here. SendMessage waits for it to be executed. Nice. I'll have that in mind in the future. Quote: I don't have a compiler on this machine so I can't test it for you. Try using the Bitmap's handle. The Bitmap handle doesn't work also. The Image->Picture property doesn't have a handle and so again I'm stuck. Back to top JD Guest Posted: Sun May 22, 2005 7:27 pm    Post subject: Re: Prevent refreshing of a TImage? "Analian" <analian (AT) mail (DOT) bg> wrote: Quote: [...] so again I'm stuck. Then you have 2 choices: Try putting the Image on a Panel and use the SendMessage with the Panel's Handle. The other is to use a second in-memory bitmap. When you begin your drawing, first Assign the TImage::Bitmap to the TBitmap. When finished drawing, Assign the TBitmap to the TImage::Bitmap. ~ JD Back to top Remy Lebeau (TeamB) Guest Posted: Sun May 22, 2005 7:30 pm    Post subject: Re: Prevent refreshing of a TImage? "JD" <nospam (AT) nospam (DOT) com> wrote Quote: ::SendMessage( Image1->Handle, WM_SETREDRAW, FALSE, 0 ); // your drawing code ::SendMessage( Image1->Handle, WM_SETREDRAW, TRUE, 0 ); That won't work. TImage is a TGraphicControl descendant. It doesn't have a window handle at all. Gambit Back to top Remy Lebeau (TeamB) Guest Posted: Sun May 22, 2005 7:31 pm    Post subject: Re: Prevent refreshing of a TImage? "JD" <nospam (AT) nospam (DOT) com> wrote Quote: Sorry about that. You can use the Image->Canvas->Handle A Canvas Handle is not a Window Handle. You cannot send messages to a Canvas Handle. Gambit Back to top Analian Guest Posted: Sun May 22, 2005 9:38 pm    Post subject: Re: Prevent refreshing of a TImage? I put the Image into a ScrollBox and used the ScrollBox handle to prevent redrawal but now even the single lines aren't displayed when needed but all at the end. Hm. What to do now? Back to top JD Guest Posted: Mon May 23, 2005 5:04 am    Post subject: Re: Prevent refreshing of a TImage? "Analian" <analian (AT) mail (DOT) bg> wrote: Quote: [...] What to do now? I would suggest using a TPaintBox instead of a TScrollBox ... unless the image is larger than the screen height and/or width. Then I would suggest putting the TPaintBox inside the TScrollBox which is what I've done for a print preview. Dynamically allocate a TBitmap that you do all of the drawing on (all of you drawing code will be the same - just remove the 'Image1->' part). Add a definition for a TBitmap and a destructor to the header: private: // User declarations Graphics::TBitmap *pBitmap; public: // User declarations __fastcall ~TForm1(); Allocate the TBitmap in the constructor: __fastcall TForm1::TForm1(TComponent* Owner) : TForm(Owner) { pBitmap = NULL; pBitmap = new Graphics::TBitmap(); pBitmap->PixelFormat = pf24bit; // Make sure that bitmap is usable when the // TPaintBox tries to use it pBitmap->Width = SomeWidth; pBitmap->Height = SomeHeight; // set the bitmap background pBitmap->Canvas->Brush->Color = clFuchsia; pBitmap->Canvas->FillRect( Rect(0, 0, SomeWidth, SomeHeight) ); // This can be done in the IDE PaintBox1->SetBounds( PaintBox1->Left, PaintBox1->Top, PaintBox1->Left + SomeWidth, PaintBox1->Top + SomeHeight ); } Delete the TBitmap in the destructor: __fastcall TForm1::~TForm1() { delete pBitmap; } Add an OnPaint event to the TPaintBox. That's where the TBitmap gets rendered to the screen: void __fastcall TForm1::PaintBox1Paint(TObject *Sender) { PaintBox1->Canvas->CopyRect( R, pBitmap->Canvas, R ); } The above assumes that the TRect R is the same dimensions for the source and target TRect's. If you want to make it appear larger or smaller, use 2 differently sized TRects and use StretchDraw instead. If you're going to use StretchDraw, I would suggest using an additional TBitmap that you StretchDraw onto once and use only CopyRect to get the image to the screen because it's much much faster. If you put the TPainBox in a TScrollBox: ::SendMessage( ScrollBox1->Handle, WM_SETREDRAW, FALSE, 0 ); // drawing code goes here ::SendMessage( ScrollBox1->Handle, WM_SETREDRAW, TRUE, 0 ); ScrollBox1->Refresh(); other wise just add a bool flag that is set to true when drawing and check that flag in the OnPaint event before you render to the screen. When done drawing, you'll need to explicitly cause the TPaintBox to be repainted: PaintBox1Paint( PaintBox1 ); or PaintBox1Paint( this ); or PaintBox1Paint( NULL ); it really doesn't matter what parameter you pass (as long as the compiler doesn't complain) because the OnPaint event is not using the Sender. ~ JD Back to top JD Guest Posted: Mon May 23, 2005 5:12 am    Post subject: Re: Prevent refreshing of a TImage? "Remy Lebeau (TeamB)" <no.spam (AT) no (DOT) spam.com> wrote: Quote: [...] TImage is a TGraphicControl descendant. It doesn't have a window handle at all. I learned the hard way that TGraphicControl descendants don't have window handles but for the hierarchy, I still depend heavily on the docs and they simply weren't available for me. ~ JD Back to top Analian Guest Posted: Thu May 26, 2005 5:37 pm    Post subject: Re: Prevent refreshing of a TImage? Isn't there a more direct way to prevent refreshing than using an other component's (the paintbox) properties? I guess this is a solution but I'd like to know why the other proposition doesn't work? Also: when a line is drawn to an image's canvas, can it be displayed without explicitly repainting all the surface of the image? I mean when a line draw is requested, is the line simply drawn on the drawing area and then independently a repaint is requested by something or the line is put in some sort of a buffer and when the repaint is requested, then the actual drawing is performed? Back to top JD Guest Posted: Thu May 26, 2005 10:11 pm    Post subject: Re: Prevent refreshing of a TImage? "Analian" <analian (AT) mail (DOT) bg> wrote: Quote: Isn't there a more direct way to prevent refreshing than using an other component's (the paintbox) properties? Yes. However, they all involve *not* using a TImage. Quote: I guess this is a solution but I'd like to know why the other proposition doesn't work? Read Gambit's post for an explaination as to why you can't manipulate a TImage that way. Quote: Also: when a line is drawn to an image's canvas, can it be displayed without explicitly repainting all the surface of the image? Not using a TImage. If you were to subclass a TPanel so that you could gain access to it's Canvas property so that you could draw on it, you could use the WM_SETREDRAW message as previousely shown *and* you could use the win32 API InvalidateRect to cause only the specified RECT to be repainted. Quote: [...] or the line is put in some sort of a buffer and when the repaint is requested, then the actual drawing is performed? There is no buffering unless you explicitly cause it to happen. You can't use DoubleBuffered (well you can but it won't help) because TImage is not a TWinControl decendent. Besides, it's a memory hog. Implementing it manually requires an in-memory TBitmap that you would do your drawing on and then Assign the TBitmap to the TImage ... or (more efficiently) use CopyRect to copy only the changed portion of the bitmap to the TImage. You can accomplish what you want equally as well (in terms of speed) using a TPaintBox, TPanel or a TImage/TBitmap combo but of the 3, a TPaintBox is easiest to implement because that's what it's designed to do. ~ JD 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  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.