Struct image::flat::View

pub struct View<Buffer, P: Pixel>where
    Buffer: AsRef<[P::Subpixel]>,{ /* private fields */ }

A flat buffer that can be used as an image view.

This is a nearly trivial wrapper around a buffer but at least sanitizes by checking the buffer length first and constraining the pixel type.

Note that this does not eliminate panics as the AsRef<[T]> implementation of Buffer may be unreliable, i.e. return different buffers at different times. This of course is a non-issue for all common collections where the bounds check once must be enough.

Inner invariants

• For all indices inside bounds, the corresponding index is valid in the buffer
• P::channel_count() agrees with self.inner.layout.channels

Implementations

impl<Buffer, P: Pixel> View<Buffer, P>where
    Buffer: AsRef<[P::Subpixel]>,

pub fn into_inner(self) -> FlatSamples<Buffer>

Take out the sample buffer.

Gives up the normalization invariants on the buffer format.

pub fn flat(&self) -> &FlatSamples<Buffer>

Get a reference on the inner sample descriptor.

There is no mutable counterpart as modifying the buffer format, including strides and lengths, could invalidate the accessibility invariants of the View. It is not specified if the inner buffer is the same as the buffer of the image from which this view was created. It might have been truncated as an optimization.

pub fn samples(&self) -> &Buffer

Get a reference on the inner buffer.

There is no mutable counter part since it is not intended to allow you to reassign the buffer or otherwise change its size or properties.

pub fn get_sample(&self, channel: u8, x: u32, y: u32) -> Option<&P::Subpixel>

Get a reference to a selected subpixel if it is in-bounds.

This method will return None when the sample is out-of-bounds. All errors that could occur due to overflow have been eliminated while construction the View.

pub fn get_mut_sample(
    &mut self,
    channel: u8,
    x: u32,
    y: u32
) -> Option<&mut P::Subpixel>where
    Buffer: AsMut<[P::Subpixel]>,

Get a mutable reference to a selected subpixel if it is in-bounds.

This is relevant only when constructed with FlatSamples::as_view_with_mut_samples. This method will return None when the sample is out-of-bounds. All errors that could occur due to overflow have been eliminated while construction the View.

WARNING: Note that of course samples may alias, so that the mutable reference returned here can in fact modify more than the coordinate in the argument.

pub fn min_length(&self) -> usize

Get the minimum length of a buffer such that all in-bounds samples have valid indices.

See FlatSamples::min_length. This method will always succeed.

pub fn image_slice(&self) -> &[P::Subpixel]

Return the portion of the buffer that holds sample values.

While this can not fail–the validity of all coordinates has been validated during the conversion from FlatSamples–the resulting slice may still contain holes.

pub fn image_mut_slice(&mut self) -> &mut [P::Subpixel]where
    Buffer: AsMut<[P::Subpixel]>,

Return the mutable portion of the buffer that holds sample values.

This is relevant only when constructed with FlatSamples::as_view_with_mut_samples. While this can not fail–the validity of all coordinates has been validated during the conversion from FlatSamples–the resulting slice may still contain holes.

pub fn shrink_to(&mut self, width: u32, height: u32)

Shrink the inner image.

The new dimensions will be the minimum of the previous dimensions. Since the set of in-bounds pixels afterwards is a subset of the current ones, this is allowed on a View. Note that you can not change the number of channels as an intrinsic property of P.

pub fn try_upgrade(self) -> Result<ViewMut<Buffer, P>, (Error, Self)>where
    Buffer: AsMut<[P::Subpixel]>,

Try to convert this into an image with mutable pixels.

The resulting image implements GenericImage in addition to GenericImageView. While this has mutable samples, it does not enforce that pixel can not alias and that samples are packed enough for a mutable pixel reference. This is slightly cheaper than the chain self.into_inner().as_view_mut() and keeps the View alive on failure.

let mut buffer = RgbImage::new(480, 640).into_flat_samples();
let view = buffer.as_view_with_mut_samples::<Rgb<u8>>().unwrap();

// Inspect some pixels, …

// Doesn't fail because it was originally an `RgbImage`.
let view_mut = view.try_upgrade().unwrap();

Trait Implementations

impl<Buffer: Clone, P: Clone + Pixel> Clone for View<Buffer, P>where
    Buffer: AsRef<[P::Subpixel]>,

fn clone(&self) -> View<Buffer, P>

Returns a copy of the value.

const fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<Buffer: Debug, P: Debug + Pixel> Debug for View<Buffer, P>where
    Buffer: AsRef<[P::Subpixel]>,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<Buffer, P: Pixel> GenericImageView for View<Buffer, P>where
    Buffer: AsRef<[P::Subpixel]>,

type Pixel = P

The type of pixel.

type InnerImageView = View<Buffer, P>

Underlying image type. This is mainly used by SubImages in order to always have a reference to the original image. This allows for less indirections and it eases the use of nested SubImages.

fn dimensions(&self) -> (u32, u32)

The width and height of this image.

fn bounds(&self) -> (u32, u32, u32, u32)

The bounding rectangle of this image.

fn in_bounds(&self, x: u32, y: u32) -> bool

Returns true if this x, y coordinate is contained inside the image.

fn get_pixel(&self, x: u32, y: u32) -> Self::Pixel

Returns the pixel located at (x, y). Indexed from top left.

fn inner(&self) -> &Self

Returns a reference to the underlying image.

fn width(&self) -> u32

The width of this image.

fn height(&self) -> u32

The height of this image.

unsafe fn unsafe_get_pixel(&self, x: u32, y: u32) -> Self::Pixel

Returns the pixel located at (x, y). Indexed from top left.

fn pixels(&self) -> Pixels<'_, Self>

Returns an Iterator over the pixels of this image. The iterator yields the coordinates of each pixel along with their value

fn view(
    &self,
    x: u32,
    y: u32,
    width: u32,
    height: u32
) -> SubImage<&Self::InnerImageView>

Returns an subimage that is an immutable view into this image. You can use GenericImage::sub_image if you need a mutable view instead. The coordinates set the position of the top left corner of the view.