And if you want to think of even further advances (which I’d avoid at this point because I’d like this to get done in a useful time frame), I’ve often thought that all JavaFX scene drawing should use the Canvas GraphicsContext. So with the changes I’m suggesting that would allow export of the complete scene graph to another device (vector graphics files etc.)
Bruce > On Nov 2, 2020, at 9:17 AM, Michael Paus <m...@jugs.org> wrote: > > Hi, > I very much like the idea in general but I think it falls too short. > Such an interface should not be tied to any existing graphics > framework. Instead it should be just pure Java. This would allow > to write complex graphics rendering code for a lot of different > platforms and not only platforms where JavaFX already exists > and can be used. Just think of the Android canvas or, via cross- > compilation, even the HTML 5 canvas. > Just my two €ent. > Michael > > Am 02.11.20 um 14:18 schrieb Bruce Johnson: >> A variety of packages (for example, VectorGraphics or JFreeSVG) exist that >> allow redirecting Java2D drawing to output other than the Java2D canvas. >> >> These work by extending java.awt.Graphics2D. By passing the extended >> Graphics2D object into a paint method, output can be redirected to a file >> (.svg, .pdf, etc.). >> >> The GraphicsContext class of JavaFX serves a similar function to Graphics2D >> of java.awt, but because it is a final class it cannot be extended to create >> similar functionality as found in VectorgGraphics or JFreeSVG. >> >> This is a serious limitation (at least as far as I can tell) to JavaFX >> applications. It would be highly desirable to be able to redirect drawing >> on a Canvas to other output formats such as vector graphics files (.svg, >> .pdf etc.). >> >> I currently work around this by using composition. I have a Java interface >> that has most methods of GraphicsContext. Then a GraphicsContextProxy class >> implements the interface and contains an instance of GraphicsContext. This >> class is used for drawing to the Canvas. I’ve then created a >> SVGGraphicsContext and PDFGraphicsContext that implement the interface and >> these can be used to draw to .svg or .pdf files. >> >> This works, but means that all code that draws on the canvas has to be >> rewritten to take the GraphicsContextInterface rather than the normal >> GraphicsContext. >> >> It would be much simpler if >> 1) GraphicsContext was not final and could be extended. >> or >> 2) A GraphicsContextInterface existed that GraphicsContext implemented. >> Developers could then have alternative GraphicsContext implementations that >> implemented that interface. This would require canvas drawing code to be >> written to use the interface, but would still be very useful. >> >> Either solution could (I think) be easily implemented in JavaFX without >> breaking existing code and add a significant advance to the toolkit. >> >> If there are alternative solutions to the problem, that would allow >> exporting canvas drawing to vector graphics files without requiring a change >> to the code that draws to the canvas, I’d appreciate hearing them. >> >> — Bruce >> >
