BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Fill an area in transparent mode          BorlandTalk.com Forum Index -> Delphi Graphics View previous topic :: View next topic   Author Message Keven Corazza Guest Posted: Fri Nov 17, 2006 8:29 pm    Post subject: Fill an area in transparent mode Hi to all, I would like to know if there is a way to fill an area, using standard Canvas.Polygon method, in a transparent mode. So I would like to fill the area, in red for example, but at the same time I would like to see the drawing below the area. Is there a way to reach this result ? Even if it is not possible with Canvas.Polygon method, could you suggest my a solution ? Thank you in advance for your help. Keven Corazza Back to top Peter Below (TeamB) Guest Posted: Sat Nov 18, 2006 12:50 am    Post subject: Re: Fill an area in transparent mode Keven Corazza wrote: Quote: Hi to all, I would like to know if there is a way to fill an area, using standard Canvas.Polygon method, in a transparent mode. So I would like to fill the area, in red for example, but at the same time I would like to see the drawing below the area. Is there a way to reach this result ? Even if it is not possible with Canvas.Polygon method, could you suggest my a solution ? The standard GDI API TCanvas is based on does not support brush colors with an alpha channel. GDI+, however, does. http://www.progdigy.com/modules.php?name=gdiplus (by Henri Gourvest) used to have Delphi units for interfacing with GDI+. It is a very different system then GDI in terms of usage, so may take some time to get used to. The Graphics32 library: http://sourceforge.net/projects/graphics32 has routines for a number of visual effects, you may find something useful there as well (never looked at it myself). It is possible to do this with plain GDI as well, but it requires considerable effort. The sequence would go like this: - create a region from the polygon (CreatePolygonRgn) - determine the regions bounding box (GetRgnBox) - copy the rectangle inside this box from your canvas to an off-screen bitmap that has been set up to the size of the bounding box. - alpha-blend the pixels in this bitmap with red in code. The algorithm for that has been published in this group several times in the past, you should be able to find it in the newsgroup archives (see my signature). - use SelectClipRgn to make the polygon the clipping region for your canvas. - copy the modified bitmap back to the canvas at its old position. - clear the clipping region - set the canvas brush style to bsClear and draw the polygon outline, if you need that. - delete the region created in step 1 -- Peter Below (TeamB) Don't be a vampire (http://slash7.com/pages/vampires), use the newsgroup archives : http://www.tamaracka.com/search.htm http://groups.google.com http://www.prolix.be Back to top Keven Corazza Guest Posted: Sat Nov 18, 2006 4:19 pm    Post subject: Re: Fill an area in transparent mode Dear Peter, I've to thank you for the very useful suggestion. GDIPLus library from Progdigy solve my problem and I've to say that they are very easy to use. Thank you again. Keven Corazza Italy "Peter Below (TeamB)" <none> ha scritto nel messaggio news:xn0etu2su1thlx001 (AT) newsgroups (DOT) borland.com... Quote: Keven Corazza wrote: Hi to all, I would like to know if there is a way to fill an area, using standard Canvas.Polygon method, in a transparent mode. So I would like to fill the area, in red for example, but at the same time I would like to see the drawing below the area. Is there a way to reach this result ? Even if it is not possible with Canvas.Polygon method, could you suggest my a solution ? The standard GDI API TCanvas is based on does not support brush colors with an alpha channel. GDI+, however, does. http://www.progdigy.com/modules.php?name=gdiplus (by Henri Gourvest) used to have Delphi units for interfacing with GDI+. It is a very different system then GDI in terms of usage, so may take some time to get used to. The Graphics32 library: http://sourceforge.net/projects/graphics32 has routines for a number of visual effects, you may find something useful there as well (never looked at it myself). It is possible to do this with plain GDI as well, but it requires considerable effort. The sequence would go like this: - create a region from the polygon (CreatePolygonRgn) - determine the regions bounding box (GetRgnBox) - copy the rectangle inside this box from your canvas to an off-screen bitmap that has been set up to the size of the bounding box. - alpha-blend the pixels in this bitmap with red in code. The algorithm for that has been published in this group several times in the past, you should be able to find it in the newsgroup archives (see my signature). - use SelectClipRgn to make the polygon the clipping region for your canvas. - copy the modified bitmap back to the canvas at its old position. - clear the clipping region - set the canvas brush style to bsClear and draw the polygon outline, if you need that. - delete the region created in step 1 -- Peter Below (TeamB) Don't be a vampire (http://slash7.com/pages/vampires), use the newsgroup archives : http://www.tamaracka.com/search.htm http://groups.google.com http://www.prolix.be Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> Delphi Graphics All times are GMT Page 1 of 1   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.