On 2016-02-08 10:44-0000 Phil Rosenberg wrote: > The wxWidgets drivers certainly does as you say - it's response to > plclear is to simply draw a rectangle of the appropriate colour. If > that colour was transparent then I think we end up drawing over some > default window background which I think is black, but I'm not sure - > perhaps it depends on the window type, and it may even be unassigned > memory. > > I can go with the idea of transparent windows - I have just checked > and wxWidgets does have the capability to do transparent windows - we > will see how well tested that code is I guess. > > Would you be interested in writing an example (prefereably multipaged) > Alan? Perhaps this could just be one of the existing examples with a > transparent background or a flag for transparent backgrounds. I will > then try and get the wxWidgets driver to do as it should for that > example.
I suggest example 9 because I know that that already works (see below). All you have to do is use the command line -bg option which is documented (using the -h command-line option) as -bg color Background color (FF0000=opaque red, 0000FF_0.1=blue with alpha of 0.1) So I tried examples/c/x08c -dev pdfqt -bg FF0000_0.0 -fam -o test.pdf I got the expected result (transparent background as indicated by a checkerboard pattern for the ImageMagick display programme) for all 5 pages of that example, i.e., test.pdf.[1-5]. In other words, transparent backgrounds are working properly for the qt file devices. On the other hand, if I run examples/c/x09c -dev qtwidget -bg FF0000_0.0 I do not get the expected result; each page had an opaque red background inserted rather than the specified transparent one. So I expect something special is being done to ignore background transparency in that particular qt device that is not done for the corresponding qt file devices. I am tied up with something else at the moment, but I will attempt to fix that in the next week or so if you don't beat me to it. Once you implement the alpha channel properly for wxwidgets backgrounds, then examples/c/x09c -dev wxwidgets -bg FF0000_0.0 should show all the pages stacked on top of each other for our current "stack of pages" interactive model (which you have advocated changing to an individual page model which I think is a good idea). But for the present interactive model if you specify some intermediate alpha like examples/c/x09c -dev wxwidgets -bg FF0000_0.2 then if the alpha channel is implemented properly for wxwidgets backgrounds, there should be "interesting" successive fading caused by each additional semitransparent layer as you look down through the stack of pages that will be displayed. Alan __________________________ Alan W. Irwin Astronomical research affiliation with Department of Physics and Astronomy, University of Victoria (astrowww.phys.uvic.ca). Programming affiliations with the FreeEOS equation-of-state implementation for stellar interiors (freeeos.sf.net); the Time Ephemerides project (timeephem.sf.net); PLplot scientific plotting software package (plplot.sf.net); the libLASi project (unifont.org/lasi); the Loads of Linux Links project (loll.sf.net); and the Linux Brochure Project (lbproject.sf.net). __________________________ Linux-powered Science __________________________ ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 _______________________________________________ Plplot-devel mailing list Plplot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/plplot-devel
