Enum ConstraintMode 

#[non_exhaustive]
pub enum ConstraintMode {
    Distort,
    Fit,
    Within,
    FitCrop,
    WithinCrop,
    FitPad,
    WithinPad,
    PadWithin,
    AspectCrop,
}

How to fit a source image into target dimensions.

    Source 4:3, Target 1:1 (square):

    Fit           Within         FitCrop       FitPad
    ┌───┐         ┌───┐          ┌───┐         ┌─────┐
    │   │         │   │          │ █ │         │     │
    │   │         │   │          │ █ │         │ ███ │
    │   │         │   │(smaller) │ █ │         │     │
    └───┘         └───┘          └───┘         └─────┘
    exact size    ≤ source       fills+crops    fits+pads

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Distort

Scale to exact target dimensions, distorting aspect ratio.

Fit

Scale to fit within target, preserving aspect ratio. Will upscale small images — use Within to prevent this. Output may be smaller than target on one axis.

Within

Like Fit, but never upscales. Images already smaller than target stay their original size.

FitCrop

Scale to fill target, crop overflow to exact target dimensions. Preserves aspect ratio. Upscales or downscales as needed.

WithinCrop

Like FitCrop, but never upscales.

FitPad

Scale to fit within target, pad to exact target dimensions. Preserves aspect ratio. Upscales or downscales as needed.

WithinPad

Like FitPad, but never upscales. When the source fits within the target on both axes, the image passes through at its original size (identity — no scaling, no padding, no canvas expansion). When the source exceeds the target on either axis, it is downscaled to fit inside the target and centered on the canvas.

PadWithin

Like WithinPad, but always pads to target canvas.

Never upscales. Downscales to fit if the source exceeds target on either axis. The canvas is always the target dimensions, even when the image is smaller — the image is centered (or gravity-positioned) on the canvas.

Compare with WithinPad, which returns identity (no canvas, no padding) when the source fits within the target.

AspectCrop

Crop to target aspect ratio without any scaling.

Trait Implementations

impl Clone for ConstraintMode

fn clone(&self) -> ConstraintMode

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ConstraintMode

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

Formats the value using the given formatter.

impl Hash for ConstraintMode

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for ConstraintMode

fn eq(&self, other: &ConstraintMode) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for ConstraintMode

impl Eq for ConstraintMode

impl StructuralPartialEq for ConstraintMode