Enhance javafx Canvas API

[Kevin Rushforth]

This seems like a good enhancement to me. I might suggest the following 
naming for the restore method:

     void restore(int index)

Would it be useful to other app developers?

-- Kevin


On 2/12/2023 1:21 AM, Laurent Bourgès wrote:
> Hi,
>
> For jfree.FXGraphics2D, I implemented the proposed approach in the new 
> GCHandler:
> https://github.com/jfree/fxgraphics2d/blob/1994b9cb3a9bff93bf95100d398756d7f9f626c2/src/main/java/org/jfree/fx/GCStateHandler.java
>
> It boosts fxG2D performance & correctness.
>
> Ideally, such methods getSavePoint(), restoreToCount() should be added 
> to GraphicsContext API...
>
> Cheers,
> Laurent
>
> Le ven. 3 févr. 2023, 23:31, Laurent Bourgès 
> <bourges.laurent at gmail.com> a écrit :
>
>     Hi,
>
>     While working with skia & jfree's skijaGraphics2D wrapper, I
>     observed skia offers nice methods in SkCanvas missing in javafx
>     Canvas/GraphicsContext to deal with save/restore state:
>
>     - int getSaveCount ()
>       Returns the number of saved states, each containing: SkMatrix
>     and clip.
>     - void restoreToCount (int saveCount)
>       Restores state to SkMatrix and clip values when save(), returned
>     saveCount.
>
>     As javafx canvas also maintains s stack of saved states, such
>     methods are trivial to implement to allow resetting completely the
>     canvas state by restoreToCount(0).
>
>     Moreover, clip(shape) + save/restore are really tricky to allows
>     ensure clip is reset to previous state ...
>
>     Would you agree to add such methods to have more predictive
>     behaviour than counting all save() calls to ensure to call
>     restore() the same number of times to reset the canvas to its
>     initial state ?
>
>     See SkijaGraphics2d implementation that saves / restore skCanvas
>     clip using such index property:
>     https://github.com/jfree/skijagraphics2d/blob/main/src/main/java/org/jfree/skija/SkijaGraphics2D.java
>
>     Cheers,
>     Laurent
>
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