Type Alias freya_engine::prelude::Surface
pub type Surface = RCHandle<SkSurface>;
Expand description
Surface
is responsible for managing the pixels that a canvas draws into. The pixels can be
allocated either in CPU memory (a raster surface) or on the GPU (a RenderTarget
surface).
Surface
takes care of allocating a Canvas
that will draw into the surface. Call
surface_get_canvas()
to use that canvas (but don’t delete it, it is owned by the surface).
Surface
always has non-zero dimensions. If there is a request for a new surface, and either
of the requested dimensions are zero, then None
will be returned.
Aliased Type§
struct Surface(/* private fields */);
Implementations§
§impl RCHandle<SkSurface>
impl RCHandle<SkSurface>
pub fn new_raster_direct<'pixels>(
image_info: &Handle<SkImageInfo>,
pixels: &'pixels mut [u8],
row_bytes: impl Into<Option<usize>>,
surface_props: Option<&SurfaceProps>
) -> Option<Borrows<'pixels, RCHandle<SkSurface>>>
👎Deprecated since 0.64.0: use surfaces::wrap_pixels()
pub fn new_raster_direct<'pixels>( image_info: &Handle<SkImageInfo>, pixels: &'pixels mut [u8], row_bytes: impl Into<Option<usize>>, surface_props: Option<&SurfaceProps> ) -> Option<Borrows<'pixels, RCHandle<SkSurface>>>
Allocates raster Surface
. Canvas
returned by Surface
draws directly into pixels.
Surface
is returned if all parameters are valid.
Valid parameters include:
info dimensions are greater than zero;
info contains crate::ColorType
and [crate::AlphaType
] supported by raster surface;
pixels is not None
;
row_bytes
is large enough to contain info width pixels of crate::ColorType
.
Pixel buffer size should be info height times computed row_bytes
.
Pixels are not initialized.
To access pixels after drawing, [Self::peek_pixels()
] or [Self::read_pixels()
].
image_info
- width, height,crate::ColorType
, [crate::AlphaType
],crate::ColorSpace
, of raster surface; width and height must be greater than zeropixels
- pointer to destination pixels bufferrow_bytes
- interval from oneSurface
row to the nextsurface_props
- LCD striping orientation and setting for device independent fonts; may beNone
Returns:Surface
if all parameters are valid; otherwise,None
pub fn new_raster(
image_info: &Handle<SkImageInfo>,
row_bytes: impl Into<Option<usize>>,
surface_props: Option<&SurfaceProps>
) -> Option<RCHandle<SkSurface>>
👎Deprecated since 0.64.0: use surfaces::raster()
pub fn new_raster( image_info: &Handle<SkImageInfo>, row_bytes: impl Into<Option<usize>>, surface_props: Option<&SurfaceProps> ) -> Option<RCHandle<SkSurface>>
Allocates raster Surface
. Canvas
returned by Surface
draws directly into pixels.
Allocates and zeroes pixel memory. Pixel memory size is image_info.height()
times
row_bytes
, or times image_info.min_row_bytes()
if row_bytes
is zero.
Pixel memory is deleted when Surface
is deleted.
Surface
is returned if all parameters are valid.
Valid parameters include:
info dimensions are greater than zero;
info contains crate::ColorType
and [crate::AlphaType
] supported by raster surface;
row_bytes
is large enough to contain info width pixels of crate::ColorType
, or is zero.
If row_bytes
is zero, a suitable value will be chosen internally.
image_info
- width, height,crate::ColorType
, [crate::AlphaType
],crate::ColorSpace
, of raster surface; width and height must be greater than zerorow_bytes
- interval from oneSurface
row to the next; may be zerosurface_props
- LCD striping orientation and setting for device independent fonts; may beNone
Returns:Surface
if all parameters are valid; otherwise,None
pub fn new_raster_n32_premul(
size: impl Into<ISize>
) -> Option<RCHandle<SkSurface>>
👎Deprecated since 0.64.0: use surfaces::raster_n32_premul()
pub fn new_raster_n32_premul( size: impl Into<ISize> ) -> Option<RCHandle<SkSurface>>
Allocates raster Surface
. Canvas
returned by Surface
draws directly into pixels.
Allocates and zeroes pixel memory. Pixel memory size is height times width times
four. Pixel memory is deleted when Surface
is deleted.
Internally, sets [ImageInfo
] to width, height, native color type, and
[crate::AlphaType::Premul
].
Surface
is returned if width and height are greater than zero.
Use to create Surface
that matches [crate::PMColor
], the native pixel arrangement on
the platform. Surface
drawn to output device skips converting its pixel format.
width
- pixel column count; must be greater than zeroheight
- pixel row count; must be greater than zerosurface_props
- LCD striping orientation and setting for device independent fonts; may beNone
Returns:Surface
if all parameters are valid; otherwise,None
§impl RCHandle<SkSurface>
impl RCHandle<SkSurface>
pub fn from_backend_texture(
context: &mut RCHandle<GrRecordingContext>,
backend_texture: &RefHandle<GrBackendTexture>,
origin: GrSurfaceOrigin,
sample_cnt: impl Into<Option<usize>>,
color_type: ColorType,
color_space: impl Into<Option<RCHandle<SkColorSpace>>>,
surface_props: Option<&SurfaceProps>
) -> Option<RCHandle<SkSurface>>
👎Deprecated since 0.64.0: use gpu::surfaces::wrap_backend_texture()
pub fn from_backend_texture( context: &mut RCHandle<GrRecordingContext>, backend_texture: &RefHandle<GrBackendTexture>, origin: GrSurfaceOrigin, sample_cnt: impl Into<Option<usize>>, color_type: ColorType, color_space: impl Into<Option<RCHandle<SkColorSpace>>>, surface_props: Option<&SurfaceProps> ) -> Option<RCHandle<SkSurface>>
Wraps a GPU-backed texture into Surface
. Caller must ensure the texture is
valid for the lifetime of returned Surface
. If sample_cnt
greater than zero,
creates an intermediate MSAA Surface
which is used for drawing backend_texture
.
Surface
is returned if all parameters are valid. backend_texture
is valid if
its pixel configuration agrees with color_space
and context; for instance, if
backend_texture
has an sRGB configuration, then context must support sRGB,
and color_space
must be present. Further, backend_texture
width and height must
not exceed context capabilities, and the context must be able to support
back-end textures.
context
- GPU contextbackend_texture
- texture residing on GPUsample_cnt
- samples per pixel, or 0 to disable full scene anti-aliasingcolor_space
- range of colors; may beNone
surface_props
- LCD striping orientation and setting for device independent fonts; may beNone
Returns:Surface
if all parameters are valid; otherwise,None
pub fn from_backend_render_target(
context: &mut RCHandle<GrRecordingContext>,
backend_render_target: &Handle<GrBackendRenderTarget>,
origin: GrSurfaceOrigin,
color_type: ColorType,
color_space: impl Into<Option<RCHandle<SkColorSpace>>>,
surface_props: Option<&SurfaceProps>
) -> Option<RCHandle<SkSurface>>
👎Deprecated since 0.64.0: use gpu::surfaces::wrap_backend_render_target()
pub fn from_backend_render_target( context: &mut RCHandle<GrRecordingContext>, backend_render_target: &Handle<GrBackendRenderTarget>, origin: GrSurfaceOrigin, color_type: ColorType, color_space: impl Into<Option<RCHandle<SkColorSpace>>>, surface_props: Option<&SurfaceProps> ) -> Option<RCHandle<SkSurface>>
Wraps a GPU-backed buffer into Surface
. Caller must ensure backend_render_target
is valid for the lifetime of returned Surface
.
Surface
is returned if all parameters are valid. backend_render_target
is valid if
its pixel configuration agrees with color_space
and context; for instance, if
backend_render_target
has an sRGB configuration, then context must support sRGB,
and color_space
must be present. Further, backend_render_target
width and height must
not exceed context capabilities, and the context must be able to support
back-end render targets.
context
- GPU contextbackend_render_target
- GPU intermediate memory buffercolor_space
- range of colorssurface_props
- LCD striping orientation and setting for device independent fonts; may beNone
Returns:Surface
if all parameters are valid; otherwise,None
pub fn new_render_target(
context: &mut RCHandle<GrRecordingContext>,
budgeted: Budgeted,
image_info: &Handle<SkImageInfo>,
sample_count: impl Into<Option<usize>>,
surface_origin: impl Into<Option<GrSurfaceOrigin>>,
surface_props: Option<&SurfaceProps>,
should_create_with_mips: impl Into<Option<bool>>
) -> Option<RCHandle<SkSurface>>
👎Deprecated since 0.64.0: use gpu::surfaces::render_target()
pub fn new_render_target( context: &mut RCHandle<GrRecordingContext>, budgeted: Budgeted, image_info: &Handle<SkImageInfo>, sample_count: impl Into<Option<usize>>, surface_origin: impl Into<Option<GrSurfaceOrigin>>, surface_props: Option<&SurfaceProps>, should_create_with_mips: impl Into<Option<bool>> ) -> Option<RCHandle<SkSurface>>
Returns Surface
on GPU indicated by context. Allocates memory for
pixels, based on the width, height, and crate::ColorType
in [ImageInfo
]. budgeted
selects whether allocation for pixels is tracked by context. image_info
describes the pixel format in crate::ColorType
, and transparency in
[crate::AlphaType
], and color matching in crate::ColorSpace
.
sample_count
requests the number of samples per pixel.
Pass zero to disable multi-sample anti-aliasing. The request is rounded
up to the next supported count, or rounded down if it is larger than the
maximum supported count.
surface_origin
pins either the top-left or the bottom-left corner to the origin.
should_create_with_mips
hints that Image
returned by [Image::image_snapshot
] is mip map.
context
- GPU contextimage_info
- width, height,crate::ColorType
, [crate::AlphaType
],crate::ColorSpace
; width, or height, or both, may be zerosample_count
- samples per pixel, or 0 to disable full scene anti-aliasingsurface_props
- LCD striping orientation and setting for device independent fonts; may beNone
should_create_with_mips
- hint thatSurface
will host mip map images Returns:Surface
if all parameters are valid; otherwise,None
§impl RCHandle<SkSurface>
impl RCHandle<SkSurface>
pub fn new_null(size: impl Into<ISize>) -> Option<RCHandle<SkSurface>>
👎Deprecated since 0.64.0: use surfaces::null()
pub fn new_null(size: impl Into<ISize>) -> Option<RCHandle<SkSurface>>
pub fn width(&self) -> i32
pub fn width(&self) -> i32
Returns pixel count in each row; may be zero or greater.
Returns: number of pixel columns
pub fn height(&self) -> i32
pub fn height(&self) -> i32
Returns pixel row count; may be zero or greater.
Returns: number of pixel rows
pub fn image_info(&mut self) -> Handle<SkImageInfo>
pub fn image_info(&mut self) -> Handle<SkImageInfo>
Returns an [ImageInfo
] describing the surface.
pub fn generation_id(&mut self) -> u32
pub fn generation_id(&mut self) -> u32
Returns unique value identifying the content of Surface
. Returned value changes
each time the content changes. Content is changed by drawing, or by calling
[Self::notify_content_will_change()
].
Returns: unique content identifier
example: https://fiddle.skia.org/c/@Surface_notifyContentWillChange
pub fn notify_content_will_change(
&mut self,
mode: SkSurface_ContentChangeMode
) -> &mut RCHandle<SkSurface>
pub fn notify_content_will_change( &mut self, mode: SkSurface_ContentChangeMode ) -> &mut RCHandle<SkSurface>
Notifies that Surface
contents will be changed by code outside of Skia.
Subsequent calls to [Self::generation_id()
] return a different value.
example: https://fiddle.skia.org/c/@Surface_notifyContentWillChange
§impl RCHandle<SkSurface>
impl RCHandle<SkSurface>
pub fn recording_context(&self) -> Option<RCHandle<GrRecordingContext>>
pub fn recording_context(&self) -> Option<RCHandle<GrRecordingContext>>
Returns the recording context being used by the Surface
.
Returns: the recording context, if available; None
otherwise
pub fn direct_context(&self) -> Option<RCHandle<GrDirectContext>>
pub fn direct_context(&self) -> Option<RCHandle<GrDirectContext>>
rust-skia helper, not in Skia
pub fn get_backend_texture(
&mut self,
handle_access: SkSurface_BackendHandleAccess
) -> Option<RefHandle<GrBackendTexture>>
👎Deprecated since 0.64.0: use gpu::surfaces::get_backend_texture()
pub fn get_backend_texture( &mut self, handle_access: SkSurface_BackendHandleAccess ) -> Option<RefHandle<GrBackendTexture>>
pub fn get_backend_render_target(
&mut self,
handle_access: SkSurface_BackendHandleAccess
) -> Option<Handle<GrBackendRenderTarget>>
👎Deprecated since 0.64.0: use gpu::surfaces::get_backend_render_target()
pub fn get_backend_render_target( &mut self, handle_access: SkSurface_BackendHandleAccess ) -> Option<Handle<GrBackendRenderTarget>>
Retrieves the back-end render target. If Surface
has no back-end render target, None
is returned.
The returned gpu::BackendRenderTarget
should be discarded if the Surface
is drawn to
or deleted.
Returns: GPU render target reference; None
on failure
pub fn replace_backend_texture(
&mut self,
backend_texture: &RefHandle<GrBackendTexture>,
origin: GrSurfaceOrigin
) -> bool
pub fn replace_backend_texture( &mut self, backend_texture: &RefHandle<GrBackendTexture>, origin: GrSurfaceOrigin ) -> bool
If the surface was made via [Self::from_backend_texture
] then it’s backing texture may be
substituted with a different texture. The contents of the previous backing texture are
copied into the new texture. Canvas
state is preserved. The original sample count is
used. The [gpu::BackendFormat
] and dimensions of replacement texture must match that of
the original.
backend_texture
- the new backing texture for the surface
pub fn replace_backend_texture_with_mode(
&mut self,
backend_texture: &RefHandle<GrBackendTexture>,
origin: GrSurfaceOrigin,
mode: impl Into<Option<SkSurface_ContentChangeMode>>
) -> bool
pub fn replace_backend_texture_with_mode( &mut self, backend_texture: &RefHandle<GrBackendTexture>, origin: GrSurfaceOrigin, mode: impl Into<Option<SkSurface_ContentChangeMode>> ) -> bool
If the surface was made via [Self::from_backend_texture()
] then it’s backing texture may be
substituted with a different texture. The contents of the previous backing texture are
copied into the new texture. Canvas
state is preserved. The original sample count is
used. The [gpu::BackendFormat
] and dimensions of replacement texture must match that of
the original.
backend_texture
- the new backing texture for the surfacemode
- Retain or discard current Content
§impl RCHandle<SkSurface>
impl RCHandle<SkSurface>
pub fn new_surface(
&mut self,
image_info: &Handle<SkImageInfo>
) -> Option<RCHandle<SkSurface>>
pub fn new_surface( &mut self, image_info: &Handle<SkImageInfo> ) -> Option<RCHandle<SkSurface>>
Returns a compatible Surface
, or None
. Returned Surface
contains
the same raster, GPU, or null properties as the original. Returned Surface
does not share the same pixels.
Returns None
if image_info
width or height are zero, or if image_info
is incompatible with Surface
.
image_info
- width, height,crate::ColorType
, [crate::AlphaType
],crate::ColorSpace
, ofSurface
; width and height must be greater than zero Returns: compatibleSurface
orNone
pub fn new_surface_with_dimensions(
&mut self,
dim: impl Into<ISize>
) -> Option<RCHandle<SkSurface>>
pub fn new_surface_with_dimensions( &mut self, dim: impl Into<ISize> ) -> Option<RCHandle<SkSurface>>
Calls [Self::new_surface()
] with the same [ImageInfo
] as this surface, but with the
specified width and height.
pub fn image_snapshot(&mut self) -> RCHandle<SkImage>
pub fn image_snapshot(&mut self) -> RCHandle<SkImage>
pub fn image_snapshot_with_bounds(
&mut self,
bounds: impl AsRef<IRect>
) -> Option<RCHandle<SkImage>>
pub fn image_snapshot_with_bounds( &mut self, bounds: impl AsRef<IRect> ) -> Option<RCHandle<SkImage>>
Like the no-parameter version, this returns an image of the current surface contents. This variant takes a rectangle specifying the subset of the surface that is of interest. These bounds will be sanitized before being used.
- If bounds extends beyond the surface, it will be trimmed to just the intersection of it and the surface.
- If bounds does not intersect the surface, then this returns
None
. - If bounds == the surface, then this is the same as calling the no-parameter variant.
example: https://fiddle.skia.org/c/@Surface_makeImageSnapshot_2
pub fn draw(
&mut self,
canvas: &Canvas,
offset: impl Into<Point>,
sampling: impl Into<SamplingOptions>,
paint: Option<&Handle<SkPaint>>
)
pub fn draw( &mut self, canvas: &Canvas, offset: impl Into<Point>, sampling: impl Into<SamplingOptions>, paint: Option<&Handle<SkPaint>> )
Draws Surface
contents to canvas, with its top-left corner at (offset.x, offset.y)
.
If Paint
paint is not None
, apply [crate::ColorFilter
], alpha, [crate::ImageFilter
], and [crate::BlendMode
].
pub fn peek_pixels(&mut self) -> Option<Pixmap<'_>>
pub fn read_pixels_to_pixmap(
&mut self,
dst: &Pixmap<'_>,
src: impl Into<IPoint>
) -> bool
pub fn read_pixels_to_pixmap( &mut self, dst: &Pixmap<'_>, src: impl Into<IPoint> ) -> bool
Copies crate::Rect
of pixels to dst.
Source crate::Rect
corners are (src.x
, src.y
) and Surface
(width(), height())
.
Destination crate::Rect
corners are (0, 0)
and (dst.width(), dst.height())
.
Copies each readable pixel intersecting both rectangles, without scaling,
converting to dst_color_type()
and dst_alpha_type()
if required.
Pixels are readable when Surface
is raster, or backed by a GPU.
The destination pixel storage must be allocated by the caller.
Pixel values are converted only if crate::ColorType
and [crate::AlphaType
]
do not match. Only pixels within both source and destination rectangles
are copied. dst contents outside crate::Rect
intersection are unchanged.
Pass negative values for src.x
or src.y
to offset pixels across or down destination.
Does not copy, and returns false
if:
- Source and destination rectangles do not intersect.
- [
Pixmap
] pixels could not be allocated. dst.row_bytes()
is too small to contain one row of pixels.
dst
- storage for pixels copied fromSurface
src_x
- offset into readable pixels on x-axis; may be negativesrc_y
- offset into readable pixels on y-axis; may be negative Returns:true
if pixels were copied
pub fn read_pixels(
&mut self,
dst_info: &Handle<SkImageInfo>,
dst_pixels: &mut [u8],
dst_row_bytes: usize,
src: impl Into<IPoint>
) -> bool
pub fn read_pixels( &mut self, dst_info: &Handle<SkImageInfo>, dst_pixels: &mut [u8], dst_row_bytes: usize, src: impl Into<IPoint> ) -> bool
Copies crate::Rect
of pixels from Canvas
into dst_pixels
.
Source crate::Rect
corners are (src.x
, src.y
) and Surface
(width(), height()).
Destination crate::Rect
corners are (0, 0) and (dst_info
.width(), dst_info
.height()).
Copies each readable pixel intersecting both rectangles, without scaling,
converting to dst_info_color_type()
and dst_info_alpha_type()
if required.
Pixels are readable when Surface
is raster, or backed by a GPU.
The destination pixel storage must be allocated by the caller.
Pixel values are converted only if crate::ColorType
and [crate::AlphaType
]
do not match. Only pixels within both source and destination rectangles
are copied. dst_pixels
contents outside crate::Rect
intersection are unchanged.
Pass negative values for src.x
or src.y
to offset pixels across or down destination.
Does not copy, and returns false
if:
- Source and destination rectangles do not intersect.
Surface
pixels could not be converted todst_info.color_type()
ordst_info.alpha_type()
.dst_row_bytes
is too small to contain one row of pixels.
dst_info
- width, height,crate::ColorType
, and [crate::AlphaType
] ofdst_pixels
dst_pixels
- storage for pixels;dst_info.height()
timesdst_row_bytes
, or largerdst_row_bytes
- size of one destination row;dst_info.width()
times pixel size, or largersrc.x
- offset into readable pixels on x-axis; may be negativesrc.y
- offset into readable pixels on y-axis; may be negative Returns:true
if pixels were copied
pub fn read_pixels_to_bitmap(
&mut self,
bitmap: &Handle<SkBitmap>,
src: impl Into<IPoint>
) -> bool
pub fn read_pixels_to_bitmap( &mut self, bitmap: &Handle<SkBitmap>, src: impl Into<IPoint> ) -> bool
Copies crate::Rect
of pixels from Surface
into bitmap.
Source crate::Rect
corners are (src.x
, src.y
) and Surface
(width(), height()).
Destination crate::Rect
corners are (0, 0)
and (bitmap.width(), bitmap.height())
.
Copies each readable pixel intersecting both rectangles, without scaling,
converting to bitmap.color_type()
and bitmap.alpha_type()
if required.
Pixels are readable when Surface
is raster, or backed by a GPU.
The destination pixel storage must be allocated by the caller.
Pixel values are converted only if crate::ColorType
and [crate::AlphaType
]
do not match. Only pixels within both source and destination rectangles
are copied. dst contents outside crate::Rect
intersection are unchanged.
Pass negative values for src.x
or src.y
to offset pixels across or down destination.
Does not copy, and returns false
if:
- Source and destination rectangles do not intersect.
Surface
pixels could not be converted todst.color_type()
ordst.alpha_type()
.- dst pixels could not be allocated.
dst.row_bytes()
is too small to contain one row of pixels.
dst
- storage for pixels copied fromSurface
src.x
- offset into readable pixels on x-axis; may be negativesrc.y
- offset into readable pixels on y-axis; may be negative Returns:true
if pixels were copied
pub fn write_pixels_from_pixmap(
&mut self,
src: &Pixmap<'_>,
dst: impl Into<IPoint>
)
pub fn write_pixels_from_pixmap( &mut self, src: &Pixmap<'_>, dst: impl Into<IPoint> )
Copies crate::Rect
of pixels from the src [Pixmap
] to the Surface
.
Source crate::Rect
corners are (0, 0)
and (src.width(), src.height())
.
Destination crate::Rect
corners are (
dst.x,
dst.y)
and
(dst.x
+ Surface width(), dst.y
+ Surface height()).
Copies each readable pixel intersecting both rectangles, without scaling,
converting to Surface
color_type()
and Surface
alpha_type()
if required.
pub fn write_pixels_from_bitmap(
&mut self,
bitmap: &Handle<SkBitmap>,
dst: impl Into<IPoint>
)
pub fn write_pixels_from_bitmap( &mut self, bitmap: &Handle<SkBitmap>, dst: impl Into<IPoint> )
Copies crate::Rect
of pixels from the src [Bitmap
] to the Surface
.
Source crate::Rect
corners are (0, 0)
and (src.width(), src.height())
.
Destination crate::Rect
corners are (
dst.x,
dst.y)
and
(
dst.x+ Surface width(),
dst.y + Surface height())
.
Copies each readable pixel intersecting both rectangles, without scaling,
converting to Surface
color_type()
and Surface
alpha_type()
if required.
pub fn props(&self) -> &SurfaceProps
pub fn props(&self) -> &SurfaceProps
Returns [SurfaceProps
] for surface.
Returns: LCD striping orientation and setting for device independent fonts
§impl RCHandle<SkSurface>
impl RCHandle<SkSurface>
pub fn resolve_msaa(&mut self)
👎Deprecated since 0.65.0: Use gpu::surfaces::resolve_msaa
pub fn resolve_msaa(&mut self)
If a surface is GPU texture backed, is being drawn with MSAA, and there is a resolve
texture, this call will insert a resolve command into the stream of gpu commands. In order
for the resolve to actually have an effect, the work still needs to be flushed and submitted
to the GPU after recording the resolve command. If a resolve is not supported or the
Surface
has no dirty work to resolve, then this call is a no-op.
This call is most useful when the Surface
is created by wrapping a single sampled gpu
texture, but asking Skia to render with MSAA. If the client wants to use the wrapped texture
outside of Skia, the only way to trigger a resolve is either to call this command or use
[Self::flush()
].
Trait Implementations§
§impl<H> ConditionallySend for RCHandle<H>where
H: NativeRefCountedBase,
impl<H> ConditionallySend for RCHandle<H>where H: NativeRefCountedBase,
RCHandle<H>
is conditionally Send and can be sent to
another thread when its reference count is 1.
§impl<N> Flattenable for RCHandle<N>where
N: NativeFlattenable + NativeRefCountedBase,
impl<N> Flattenable for RCHandle<N>where N: NativeFlattenable + NativeRefCountedBase,
§impl<N> From<&RCHandle<N>> for RCHandle<N>where
N: NativeRefCounted,
impl<N> From<&RCHandle<N>> for RCHandle<N>where N: NativeRefCounted,
A reference counted handle is cheap to clone, so we do support a conversion from a reference to a ref counter to an owned handle.