AppletTalk.com Java discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Pre-draw part of JComponent          AppletTalk.com Forum Index -> Java GUI Toolkits View previous topic :: View next topic   Author Message Lars Guest Posted: Mon Jun 28, 2004 10:08 am    Post subject: Pre-draw part of JComponent Hello all, I have a class Graph that inherits JComponent. It is used for displaying graphs and consists of a grid and the actual graph "line". Now, it seems unneccesary to calculate all the coordinates for all the lines each time the graph is cleared and redrawn (when new values need to be added to the graph) especially since I have a large number of graphs that all have exactly the same background grid. So I would like to draw the grid once and for all and store it so that it could be shared by all the graphs, and then "copy" it to the graphics object when I redraw the component. I'd appreciate any pointers on how to achieve this! Thanks for your time and help, /Lars Back to top VisionSet Guest Posted: Mon Jun 28, 2004 10:23 am    Post subject: Re: Pre-draw part of JComponent "Lars" <larsgj (AT) hotmail (DOT) com> wrote Quote: Hello all, I have a class Graph that inherits JComponent. It is used for displaying graphs and consists of a grid and the actual graph "line". Now, it seems unneccesary to calculate all the coordinates for all the lines each time the graph is cleared and redrawn (when new values need to be added to the graph) especially since I have a large number of graphs that all have exactly the same background grid. So I would like to draw the grid once and for all and store it so that it could be shared by all the graphs, and then "copy" it to the graphics object when I redraw the component. I'd appreciate any pointers on how to achieve this! All drawing must be done from paintComponent. You cannot separate the grid from the graphs since that drawing code is used to replace a window that has popped up over the top of it. The performance comes from only repainting what is required through use of the overloaded repaint method that only repaints a specific rectangle. repaint(int x, int y, int width, int height) This is used at a lower level to replace that popped up window. All you have to do is do the same for each graph that is drawn. The calculation will be negligible next to the painting, I'd make sure the painting is optimised first, then see if you still have a problem. -- Mike W Back to top Andrew Thompson Guest Posted: Mon Jun 28, 2004 11:52 am    Post subject: Re: Pre-draw part of JComponent On 28 Jun 2004 03:08:52 -0700, Lars wrote: Quote: So I would like to draw the grid once and for all and store it so that it could be shared by all the graphs, 'BufferdImage'.. <http://groups.google.com/groups?q=g:thl2641509862d&dq=&selm=1dk3u9o29fhkr%24.1ewtjet4iz3ls.dlg%4040tude.net> HTH -- Andrew Thompson http://www.PhySci.org/ Open-source software suite http://www.PhySci.org/codes/ Web & IT Help http://www.1point1C.org/ Science & Technology Back to top Nigel Wade Guest Posted: Tue Jun 29, 2004 9:32 am    Post subject: Re: Pre-draw part of JComponent On Mon, 28 Jun 2004 03:08:52 -0700, Lars wrote: Quote: Hello all, I have a class Graph that inherits JComponent. It is used for displaying graphs and consists of a grid and the actual graph "line". Now, it seems unneccesary to calculate all the coordinates for all the lines each time the graph is cleared and redrawn (when new values need to be added to the graph) especially since I have a large number of graphs that all have exactly the same background grid. So I would like to draw the grid once and for all and store it so that it could be shared by all the graphs, and then "copy" it to the graphics object when I redraw the component. I'd appreciate any pointers on how to achieve this! Thanks for your time and help, /Lars Draw the grid into a BufferedImage. Then, in paintComponent draw the image into the Graphics of the Graph. This is a potted version of what I do to draw grid lines on a world map. I use 4BYTE_AGBR to get a transparent image gridImage = new BufferedImage(w,h,BufferedImage.TYPE_4BYTE_ABGR ); then either: Graphics gridGraphics = gridImage.getGraphics(); or Graphics2D gridGraphics = gridImage.createGraphics(); draw the grid into gridGraphics. I use Graphics2D because I want the AffineTransforms it allows, but I think you can use Graphics. If you use Graphics2D dispose() of the gridGraphics if you don't need it any more. in the paintComponent of Graph you would, at some point, do: g.drawImage( gridImage, 0, 0, this ); -- Nigel Wade, System Administrator, Space Plasma Physics Group, University of Leicester, Leicester, LE1 7RH, UK E-mail : [email]nmw (AT) ion (DOT) le.ac.uk[/email] Phone : +44 (0)116 2523548, Fax : +44 (0)116 2523555 Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         AppletTalk.com Forum Index -> Java GUI Toolkits All times are GMT Page 1 of 1   Jump to: Select a forum Java Newsgroups----------------Java DiscussionsWeb-based java games comp.lang.java 3D Graphics API's for Java Java: Support and criticism Java System Announcements comp.lang.java.api JavaBeans Java and CORBA Java and Databases comp.lang.java.developer Java GUI Toolkits Java Help comp.lang.java.javascript JVM, native methods and hardware comp.lang.java.misc Java Language Programming Security and Java comp.lang.java.setup Java Software Tools comp.lang.java.tech ibm.software.java.linux  Non-English Java Newsgroups----------------Java Language (German)Language Java (Français)Java (Italian)  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.