[jira] [Comment Edited] (BATIK-985) allow "opacity" attribute on group of paths

    [ https://issues.apache.org/jira/browse/BATIK-985?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16285645#comment-16285645 ] 

Patrick Valsecchi edited comment on BATIK-985 at 12/11/17 8:36 AM:
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Hummm, I had a quick look, and I'm afraid Graphics2D doesn't allow that. There is Graphics2D.setComposite(), but it doesn't quite does the job. If I have a group with opacity 0.5 that contains a big opaque red square with a small opaque white square within, I don't want the white square to appear pink, since the element within the group should be drawn fully opaque. Graphics2D.setComposite() would just draw a semi transparent white square on top of the semi-transparent red square,  making it an incorrect light-pink.

A solution could be to create an image with the content of the group and then draw this image semi-transparent, but this is not going to play well with my use-case. I use IText's Graphics2D implementation. So this trick would pixelize the vectors I'm rendering.

OK, maybe there is no solution to that :-(


was (Author: pvalsecc):
Hummm, I had a quick look, and I'm afraid Graphics2D doesn't allow that. There is Graphics2D.setComposite(), but it doesn't quite does the job. If I have a group with opacity 0.5 that contains a big opaque red square with a small opaque white square within, I don't want the white square to appear pink, since the element within the group should be drawn fully opaque and the white square . Graphics2D.setComposite() would just draw a semi transparent white square on top of the semi-transparent red square,  making it an incorrect light-pink.

A solution could be to create an image with the content of the group and then draw this image semi-transparent, but this is not going to play well with my use-case. I use IText's Graphics2D implementation. So this trick would pixelize the vectors I'm rendering.

OK, maybe there is no solution to that :-(

> allow "opacity" attribute on group of paths
> -------------------------------------------
>
>                 Key: BATIK-985
>                 URL: https://issues.apache.org/jira/browse/BATIK-985
>             Project: Batik
>          Issue Type: Bug
>          Components: SVG DOM
>    Affects Versions: 1.7
>         Environment: Operating System: All
> Platform: All
>            Reporter: couk
>            Assignee: Batik Developer's Mailing list
>
> I have a bit of code that uses batik at a low level, and sending SVG with the following elements seems to result in the GraphicsNode not painting anything.
> <g opacity="0.1">
>   <path d="M101.5,325.5c0-37.396,19.75-70.263,49.364-88.731h-5.481C117.096,256.154,98.5,288.693,98.5,325.5
>       c0,36.062,17.85,68.032,45.178,87.543h5.324C120.425,394.373,101.5,362.107,101.5,325.5z"/>
>   <path d="M310.5,325.5c0,36.607-18.925,68.873-47.501,87.543h5.324c27.327-19.511,45.177-51.48,45.177-87.543
>       c0-36.807-18.596-69.346-46.883-88.731h-5.481C290.75,255.237,310.5,288.104,310.5,325.5z"/>
> </g>
> changing "opacity" to "fill-opacity" results in the desired behavior when painting. But according to the SVG spec, opacity should be allowed on groups?
> Here's now the GraphicsNode is created.
> // Parse the SVG document.
> SVGDocument doc = new SAXSVGDocumentFactory(XMLResourceDescriptor.getXMLParserClassName()).createSVGDocument(null, data.inputStream());
> UserAgent userAgent = new UserAgentAdapter();
> BridgeContext ctx = new BridgeContext(userAgent, new DocumentLoader(userAgent));
> ctx.setDynamicState(BridgeContext.STATIC);
> GraphicsNode node = new GVTBuilder().build(ctx, doc);
> Sorry this isn't more detailed - let me know if this isn't enough information.



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