Enhance javafx Canvas API

[Bruce Johnson]

> On Feb 3, 2023, at 5:31 PM, Laurent Bourgès <bourges.laurent at gmail.com> wrote:
> 
> 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 <https://github.com/jfree/skijagraphics2d/blob/main/src/main/java/org/jfree/skija/SkijaGraphics2D.java>
> 
> Cheers,
> Laurent

I’d love to see this.  I find keeping track of the state of clipping and getting it restored to a specific state can be painful. Swing let you clear the clip with setClip(null) which was definitely useful and I was somewhat surprised to see that I couldn’t do that in JavaFX.

Bruce
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