Canvas API maintenance

[Kevin Rushforth]

I like it.

-- Kevin


Jim Graham wrote:
> As was already mentioned, the existing (deprecated) methods on 
> GraphicsContext for dealing with ImageData and writing pixels were 
> preliminary and intended to be replaced by a mechanism that would be 
> compatible with the FX Image Ops which were just reviewed and 
> integrated.  To that end, I am proposing the following modification of 
> the GraphicsContext API:
>
> Remove deprecated methods, fields, and inner classes:
>
> Remove Canvas.ImageData class
> Remove createImageData(...) factory methods // all variants
> Remove putImageData(...) // all variants
>
> Add the following method:
>
>     /**
>      * Returns a {@link PixelWriter} object that can be used to modify
>      * the pixels of the {@link Canvas} associated with this
>      * {@code GraphicsContext}.
>      * All coordinates in the {@code PixelWriter} methods on the returned
>      * object will be in device space since they refer directly to 
> pixels.
>      *
>      * @return the {@code PixelWriter} for modifying the pixels of this
>      *         {@code Canvas}
>      */
>     public PixelWriter getPixelWriter();
>
> Note that, just as it was in the draft of the Canvas API, there are no 
> methods to get a PixelReader for the Canvas in this release.  Due to 
> the asynchronous nature of our rendering threads it would require a 
> bit of effort and documentation about blocking conditions to create 
> such a mechanism.  We will try to implement that in an upcoming 
> release, but in order to reduce the risk and simplify the 
> implementation of this feature for this release, we are only providing 
> similar pixel writing methods as were in the earlier API drafts...
>
>             ...jim