Enum ResizeMode 

#[non_exhaustive]
pub enum ResizeMode {
    Default,
    Force,
    Fill,
    Shrink,
    Grow,
    Percent,
    Area,
}

-resize / -thumbnail geometry-modifier suffix.

ImageMagick’s geometry grammar tags the literal WxH with a single trailing character that selects the scaling policy. We honour the six common ones; everything else (%@ combos, gravity flags, …) is a documented follow-up.

The runtime sees the original WxH plus this tag and resolves the final pixel dimensions against the actual source size — most modes can’t be eagerly resolved at parse time because we don’t yet know the source dims.

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.

Default

No suffix — preserve aspect ratio and FIT inside the WxH box (the larger of the two scale factors wins, so neither output dimension exceeds the request). IM’s default geometry policy.

Force

WxH! — IGNORE aspect ratio, force the exact WxH dimensions. Equivalent to the original bang = true.

Fill

WxH^ — preserve aspect ratio and FILL the WxH box (the smaller of the two scale factors wins, so both output dimensions are at least the request). Common pairing with a follow-up -crop to land on exact WxH.

Shrink

WxH> — only resize when the input is LARGER than WxH (otherwise pass through unchanged). IM’s “shrink-only” policy.

Grow

WxH< — only resize when the input is SMALLER than WxH (otherwise pass through unchanged). IM’s “enlarge-only” policy.

Percent

WxH% — interpret W and H as percentages of the source dimensions (independent X / Y scale). WxH are still parsed as integer percentages by parse_wxh; if only one number is given it applies to both axes (handled at parse time).

Area

WxH@ — interpret W*H as the TARGET pixel area; both output dims are scaled by sqrt(target_area / source_area) so the aspect ratio is preserved AND the output area matches the request.

Implementations

impl ResizeMode

pub fn split_suffix(s: &str) -> (ResizeMode, &str)

Strip an IM geometry-modifier suffix off WxH. Returns (mode, geometry-without-suffix). No suffix means Default plus the input verbatim. Multiple suffix chars (e.g. WxH^!) are rejected by the args parser layer; here we only peel the LAST one and report what we found.

pub fn as_tag(self) -> &'static str

Lowercase tag string used in JSON params handed to the resize factory. Stable identifiers — codecs that grow geometry-mode awareness can branch off these.

pub fn resolve( self, req_w: u32, req_h: u32, src_w: u32, src_h: u32, ) -> (u32, u32)

Resolve the final (out_w, out_h) for a request of (req_w, req_h) against a source size of (src_w, src_h).

Output is always >= 1 on both axes; clipping to source dims for Shrink / Grow modes happens here so the caller can blindly hand the result to the resize filter without re-checking.

Trait Implementations

impl Clone for ResizeMode

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for ResizeMode

impl Debug for ResizeMode

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

Formats the value using the given formatter.

impl Default for ResizeMode

fn default() -> Self

Returns the “default value” for a type.

impl Eq for ResizeMode

impl PartialEq for ResizeMode

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for ResizeMode